text:
\section{Introduction}
\label{introduction}

Since the very early stage of human history, our ancestors have already imagined the existence of aliens.
Numerous science fiction movies, television series, and fiction have demonstrated extraterrestrial intelligence in different forms.
However, even to this day, the debate on the existence of aliens or extraterrestrial intelligence in reality continues.
Despite the controversy, the search for extraterrestrial intelligence (SETI) has been conducted since the 1960s (Project Ozma)\footnote{\url{https://www.seti.org/seti-institute/project/details/early-seti-project-ozma-arecibo-message}}.
Fortunately, after around 30 years since SETI began, the first exoplanet (Gamma Cephei Ab) was discovered \citep{Campbell1988}, and a new window was opened for the search for extraterrestrial life.
In the next decade, the James Webb Space Telescope (JWST) plans to study the atmosphere of the exoplanet.
Hence, JWST has a potential to reveal the origin of life and find extraterrestrial intelligence\footnote{\url{https://www.jwst.nasa.gov/content/science/origins.html}}.
Although there has hitherto been negative results, it never diminishes human curiosity in SETI.

Many studies discussed and provided different concepts related to the advanced civilisations \citep[e.g.,][]{Dyson1960,Shkadov1988,Lee2013}.
One of the most famous concepts is the "Dyson Sphere", which was first described by \citet{Dyson1960}.
\citet{Dyson1960} argued that if there was an advanced civilisation in the Universe, it must consume extremely high energy to maintain itself.
In such a civilisation, its parent star (the star which its planets orbit around) could be a candidate to provide ample energy for development and sustainability.
Assuming that the highly-developed civilisation is eager to absorb the energy from its sun, a Dyson Sphere is a spherical structure that fully surrounds the star and directs all the radiative energy outward.
For instance, if a Dyson sphere is built around the Sun, the total luminosity of the Sun ($\rm{L_{\odot}\sim4\times10^{26}\,{\rm W}}$) can be utilised, which is approximately nine orders of magnitude larger than the power intercepted by the Earth ($\sim1.7\times10^{17}\,{\rm W}$).
After receiving the energy from the star, the civilisation would be able to convert the energy from low-entropy to high-entropy and emanate the waste heat (e.g., in mid-infrared wavelengths) into the background, suggesting this kind of energy waste is detectable \citep{Dyson1960}.

However, building a rigid Dyson Sphere is almost mechanically impossible due to the gravity and the pressure from the central star \citep[e.g.,][]{Wright2020}.
Hence, some variants of the concept were proposed.
For instance, a Dyson Swarm\footnote[3]{\label{fn3}\url{https://www.aleph.se/Nada/dysonFAQ.html}} is a group of collectors that orbits the central energy source \citep[see also][]{Dyson1960b}.
This method allows the civilisation to grow incrementally.
Nevertheless, due to the orbital mechanics, the arrangement of such collectors would be extraordinarily complex.
Another variant is a Dyson Bubble$^{\ref{fn3}}$ which contains a host of collectors as well.
However, the collectors are instead stationary in space assuming equilibrium between the outward radiative pressure and the inward gravity, which are usually called "solar sails" or "light sails".

Based on energy consumption, \citet{Kardashev1964} classified the hypothetical civilisations into three categories (Kardashev scale).
A Type I civilisation uses infant technology and consumes $4\times10^{16}\,{\rm W}$ (or $4\times10^{23}\,{\rm erg\ s^{-1}}$)\footnote[4]{In \citet{Kardashev1964}'s original definition, a Type I civilisation consumes an energy of that close to a planet, i.e., $4\times10^{12}\,{\rm W}$. Nowadays, a Type I civilisation is usually defined as harvesting all the power of a planet.}, the energy of its planet.
A Type II civilisation harvests all the energy of its parent star, namely $4\times10^{26}
\,{\rm W}$ (or $4\times10^{33}\,{\rm erg\ s^{-1}}$).
A Type III civilisation represents the highest technological level, which can engulf its entire galaxy as its energy source.
A typical energy used by a Type III civilisation is about $4\times10^{37} \,{\rm W}$ (or $4\times10^{44}\,{\rm erg\ s^{-1}}$).
To represent the civilisations that have not been able to use all of their available energy sources,  \citet{Sagan1973} suggested a logarithmic interpolation in the form of $K=0.1(\rm{log}\it{P}-6)$, where $K$ is the Kardashev index and $P$ (in the unit of Watts) indicates the energy consumption.
Currently, our civilisation level is approximately 0.73\footnote[5]{According to the world energy report of 2020: \url{https://www.bp.com/content/dam/bp/business-sites/en/global/corporate/pdfs/energy-economics/statistical-review/bp-stats-review-2020-full-report.pdf}, the total world energy consumption in 2019 is 583.9 exajoule ($\sim1.85\times10^{13}W$).}.
We may become a Type I civilisation in 200 to 800 years, a Type II in 1000 to 3000 years, and a Type III in 2000 to 5000 years, assuming the energy consumption increases by $1\%-3\%$ per year \citep[e.g.,][]{Gray2020}.

The purpose of this study is to discuss the possibility of black holes being a candidate for an energy source to build a Dyson Sphere of a civilisation between a Type II and a Type III ($2<K<3$; a Type II civilisation).
As we mentioned in the previous paragraph, after a Type II civilisation absorbs all the energy from the parent star, a Type II civilisation would seek another star to maintain itself.
We would like to answer the question if black holes can be regarded as proper energy sources, or if they are inefficient to provide ample energy for civilisations to thrive.
\citet{Inoue2011} discussed a similar idea by describing a Dyson Sphere around a supermassive black hole (SMBH).
They assumed the energy from the accretion disk of a SMBH as the only energy source for a Type III civilisation. Their Dyson Sphere (collectors of power plants) is located between the accretion disk and the molecular torus, and is built to partly cover a SMBH to avoid absorbing the piercing jets to melt the Dyson Sphere.
However, the possibility to detect these structures is extremely low \citep[the chance to detect an unexpected signal from $1\,{\rm {\mu}arcsecond}$ is less than $10^{-23}$;][]{Inoue2011}.

Moreover, \citet{Opatrny2017} discussed a Dyson Sphere which absorbs the energy from the cosmic microwave background (CMB).
Compared with the CMB, a black hole should be a "cold" sun, turning the idea of the Dyson Sphere inside out (Here we name it as the Inverse Dyson Sphere; IDS).
Based on their results, a black hole with one solar mass could only provide (literally the CMB provides ${T_{\rm CMB}=2.725\,{\rm K}}$) $250\,{\rm W}$ in the recent Universe.
If there is a SMBH in the early Universe ($z\sim109$) with a habitable temperature ${T_{\rm CMB}=300\,{\rm K}}$ \citep{Loeb2014}, it would provide $\sim3\times10^{20}\,{\rm W}$.
However, compared to a main sequence star (e.g., $1\,{\rm L_{\odot}}$ $=4\times10^{26}\,{\rm W}$), this available energy is much less.

In this paper, we consider and discuss {six} types of energy sources: the CMB, the Hawking radiation, an accretion disk, {Bondi accretion}, a corona, and the relativistic jets
from two types of black holes: a non-rotating black hole (Schwarzschild black hole) and a rotating black hole (Kerr black hole), ranging from micro, stellar-mass, intermediate-mass to SMBH (i.e, $10^{-5}-10^{10}\,{\rm M_\odot}$).
The structure and outline of this paper are as follows:
we discuss the possible energy sources from a black hole in Sec. \ref{Energy source}.
In Sec. \ref{Dyson Sphere}, we describe the possible location, type, efficiency, and detectability of such a Dyson Sphere.
The conclusion of this study is presented in Sec. \ref{Conclusion}.

\section{Energy source}

In this section, we demonstrate {six} energy sources if a Type II civilisation aims to build a Dyson Sphere around a black hole.
In this paper, we utilise the terminology "promising" and "enough" to indicate when the energy is larger than one solar luminosity for a Type II civilisation.
{We mainly discuss three scenarios: two stellar black holes with masses $5{\rm M_{\odot}}$ and $20{\rm M_{\odot}}$, and a SMBH with mass $4\times10^{6}{\rm M_{\odot}}$.
Their physical parameters are organised in Table \ref{tab1}.}

    \begin{table*}
    	\centering
    	\caption{Three scenarios of a Dyson Sphere around a black hole at different efficiency.}
    	\label{tab1}
    	\begin{flushleft}
    	\begin{tabular}{|c|c|c|c|}\hline
    	Scenario & A(stellar mass black hole) & B(stellar mass black hole) & C(SMBH)\\ \hline \relax
    	Mass (${\rm M_{\odot}}$) & 5 & 20 & $4\times10^{6}$ \\ \relax
    	Eddington ratio (${\frac{L_{\rm disk}}{L_{\rm Edd}}}$) &$10^{-2}$ & $10^{-1}$ & $10^{-3}$\\ \relax
    	Schwarzschild radius (${\rm km}$) & 14.77 & 59.08 & $1.18\times10^{7}$\\ \relax
    	Dyson sphere radius at $T=3000{\rm K}$ ($R_{\rm sch}$) & {$7.12\times10^{6}$} & {$1.13\times10^{7}$} & {$2.54\times10^{3}$}\\ \relax
        disk luminosity{$^{*}$}   & $1.6\times10^{3}$ (2.38) &$6.4\times10^{4}$ (2.54) &$1.3\times10^{8}$ (2.87)\\ \relax
    	total luminosity{$^{*}$}   & $3.5\times10^{3}$ (2.41) &$1.4\times10^{5}$ (2.57) &$2.8\times10^8$ (2.90)\\ \relax
    	total power{$^{*}$}   & $1.7\times10^{4}$ (2.48) & $6.1\times10^{5}$ (2.63) &$1.1\times10^9$ (2.96)\\

    	\hline    	\multicolumn{4}{|c|}{50\% efficiency}  \\ \hline \relax
        disk luminosity{$^{*}$}   &{$800$ (2.35)} & $3.2\times10^4$ (2.51) & $6.4\times10^7$ (2.84) \\ \relax
    	total luminosity{$^{*}$}   & {$1750$ (2.38)} & $6.9\times10^4$ (2.54) &$1.4\times10^8$ (2.87) \\ \relax
    	total power{$^{*}$}   & {8450 (2.45)} & $3.1\times10^5$ (2.61) &$5.5\times10^8$ (2.93)\\

    	\hline    	\multicolumn{4}{|c|}{10\% efficiency}  \\ \hline \relax
        disk luminosity{$^{*}$}   & {$160$ (2.28)} & $6.4\times10^3$ (2.44) & $1.3\times10^7$ (2.77) \\ \relax
    	total luminosity{$^{*}$}   & {$350$ (2.31)} & $1.4\times10^4$ (2.47) &$2.8\times10^7$ (2.80) \\ \relax
    	total power{$^{*}$}   & {1690 (2.38)} & $6.1\times10^4$ (2.54) &$1.1\times10^8$ (2.86)\\

    	\hline    	\multicolumn{4}{|c|}{1\% efficiency}  \\ \hline \relax
        disk luminosity{$^{*}$}   & {$16$ (2.18)} & $6.4\times10^2$ (2.34) & $1.3\times10^6$ (2.67) \\ \relax
    	total luminosity{$^{*}$}   & {$ 35 $ (2.21)} & $1.4\times10^3$ (2.37) &$2.8\times10^6$ (2.70) \\ \relax
    	total power{$^{*}$}   & {169 (2.28)} &$6.1\times10^3$ (2.44) &$1.1\times10^7$ (2.76)\\

        \hline
        \end{tabular}\\

        {$^{*}$ Numbers outside parentheses are in units of $L_{\odot}$, while numbers inside the parentheses are in units of Kardashev index.}
        \end{flushleft}
    \end{table*}

\label{Energy source}
\subsection{Cosmic Microwave Background}

The CMB is the remnant temperature from the early Universe which is an evidence of the Big Bang.
In the mid-20th century, \citet{Gamow1948} predicted the existence of the CMB while its first measurement was conducted later by \citet{Penzias1965}.
Here, we show the possibility for a Dyson Sphere to collect the CMB energy.

In principle, the CMB is hotter than a black hole (discussed in Sec. \ref{Hawking radiation}).
\citet{Opatrny2017} discussed the concept that a Dyson Sphere absorbs energy from the hot CMB and emits waste energy into a cold black hole.
\citet{Opatrny2017} derived the limiting power from the CMB for a Dyson Sphere as:
\begin{equation}
    \label{limiting energy}
    \begin{split}
    P_{\rm{max}}\sim\frac{27}{256}\sigma ST_{\rm CMB}^{4}, \rm{where} \:\it
    S={\rm 4}\pi \left(\frac{\sqrt{\rm 27}}{\rm 2}R_{\rm Sch}\right)^{\rm 2}=\frac{{\rm 108}\pi G^{\rm 2}M^{\rm 2}}{c^{\rm 4}},
    \end{split}
\end{equation}
where $\sigma$ is the Stefan-Boltzmann constant.
$S$ indicates the surface area of the black hole while $T_{\rm CMB}$ is the temperature of CMB.
$R_{\rm Sch}$ stands for the Schwarzschild radius, $G$ is the gravitational constant, $M$ indicates the mass of the black hole, and $c$ is the light speed in the vacuum.

{{According to \citet{Loeb2014}, the habitable epoch of the Universe starts around when the temperature of the CMB is} ${T_{\rm CMB}=300\,{\rm K}}$. For this purpose, we also discuss the early Universe when the CMB temperature is ${\rm 300\,{\rm K}}$.
The following two conditions, recent Universe with $T_{\rm CMB}=2.725{\rm K}$ \citep{Fixsen2009} and habitable Universe with $T_{\rm CMB}=300{\rm K}$ of $P_{\rm max}$ can be written in the following numerical form, respectively:
\begin{equation}
    \label{recent}
    \frac{P_{\rm{max}}(2.725{\rm K})}{\rm Watt}\sim2.45\times10^{2}\left(\frac{M}{M_{\odot}}\right)^{2},
\end{equation}
and
\begin{equation}
    \label{early}
    \frac{P_{\rm{max}}(300{\rm K)}}{\rm Watt}\sim3.59\times10^{10}\left(\frac{M}{M_{\odot}}\right)^{2}.
\end{equation}}
{We caution readers that black holes when $T_{\rm CMB}=300{\rm K}$ ($z\sim109$) were probably primordial black holes since the first stars are thought to have formed afterwards \citep[e.g.,][]{Carr1977}.}
If a Type II civilisation wants to harvest the CMB power {, no matter in the recent or early Universe, the power is too low to maintain a Type II civilisation.
Even in the early stage of the Universe, we need to find a SMBH {($M>10^{8}\,{\rm M_{\odot}}$)} to gain the energy of a solar luminosity, which seems to be inefficient.

\subsection{Hawking radiation}
\label{Hawking radiation}

\citet{Hawking1974} predicted and derived the theory of black body radiation emitted from outside the event horizon of a black hole, which was named "Hawking radiation".
Although there is no direct detection hitherto, it is a result of the quantum effects and expected to reduce the black hole mass.

Based on \citet{Hawking1974}, the temperature of a Schwarzschild black hole can be expressed as:
\begin{equation}
    \label{Hawking temperature}
    T_{\rm Sch}=\frac{\hbar c^3}{8 \pi k_{\rm B} GM},
\end{equation}
where $\hbar$ is the reduced Planck constant, and $k_{\rm B}$ stands for the Boltzmann constant.
Nevertheless, we calculate the power of black body luminosity ($L_{\rm Hawking}=4\pi R_{\rm Sch}^{2}\sigma T^{4}_{\rm Sch}$) of Hawking radiation as follows \citep[e.g.,][]{Lopresto2003}:
\begin{equation}
    \label{Hawking luminosity}
    L_{\rm{Hawking}}=\frac{\hbar c^6}{15360 \pi G^2M^2}{\sim9.00\times10^{-29}\left(\frac{M}{M_{\odot}}\right)^{-2}{\rm Watt}}.
\end{equation}
{The} total radiation from a black hole itself is extremely low.

In terms of a rotating black hole, the temperature of the Hawking radiation from a rotating black hole (here we assume Kerr-Vaidya metrics) can be expressed as follows \citep[e.g.,][]{Chou2020}:
\begin{equation}
    \label{eqHawking radiation}
    T_{\rm Kerr}=\gamma\frac{\hbar c^3}{8 \pi k_{\rm B} GM},
    \rm{where} \: \it
    \gamma=\frac{\sqrt{\rm 1-{\it a}^2}}{\rm 1+\sqrt{1-{\it a}^2}},
\end{equation}
where $a$ stands for the spin parameter of a black hole.
As the spin parameter increases, the factor $\gamma$ decreases.
We conclude that collecting the Hawking radiation from a Kerr black hole is harder than a Schwarzschild black hole (although both ways are almost impossible).
We will not discuss the luminosity of a Kerr black hole further since it is harder to harvest the energy from a Kerr black hole.

\subsection{Accretion disk}
The massive object in the centre would accrete the gas and the material close to it into a vortex disk.
Due to the strong gravity from a black hole, the material in an accretion disk would be heated by friction.
After the igniting process, an accretion disk emits strong radiation.
Hence, a Type II civilisation could harvest the radiation from the accretion disk.

We first consider the Eddington luminosity of a black hole in different mass ranges \citep{Rybicki1979}:
\begin{equation}
    \label{Eddington luminosity}
    L_{\rm{Edd}}=\frac{4\pi GMm_{\rm p}c}{\sigma_{\rm T}}{\sim3.2\times10^{4}\left(\frac{M}{M_{\odot}}\right)L_{\odot}},
\end{equation}
where $m_{\rm p}$ suggests the mass of a proton, and $\sigma_{\rm T}$ is Thomson scattering cross-section ($\sigma_{\rm T}=6.65\times10^{-29}\,{\rm m^{-2}}$).
{The result suggests} that if a Type II civilisation finds a black hole with accretion disk reaching the Eddington limit, even if the black hole is only the size of a stellar black hole ($5\,{\rm M_{\odot}}<M<20\,{\rm M_{\odot}}$), it could provide up to $\sim10^{5}\,{\rm L_{\odot}}$.
Additionally, we consider the luminosity as a function of mass accretion rate:
\begin{equation}
    \label{Disk luminosity}
    L_{\rm{disk}}=\eta_{\rm disk}{\frac{dm}{dt}}c^2,
\end{equation}
where $\eta_{\rm disk}$ is the accretion efficiency, $dm/dt$ indicates the mass accretion rate.
According to \citet{Thorne1974}, the accretion efficiencies of different types of black holes are $\eta_{\rm disk}=0.057$ for a Schwarzschild black hole and $\eta_{\rm disk}=0.399$ for an Extreme Kerr black hole ($a=1$), respectively.
Adopting these efficiencies, we calculate the luminosity at different accretion rates.
The result is shown in Fig. \ref{figdisk}.
The different coloured regions indicate the Eddington limit of stellar-mass black holes ($5\,{\rm M_{\odot}}<M<20\,{\rm M_{\odot}}$), intermediate-mass black holes ($10^2\,{\rm M_{\odot}}<M<10^5\,{\rm M_{\odot}}$), and SMBHs ($10^5\,{\rm M_{\odot}}<M<10^9\,{\rm M_{\odot}}$).
The results suggest that even for a stellar-mass black hole with a low Eddington ratio ($10^{-3}$), the luminosity of the accretion disk is several hundred times of a solar luminosity.

Furthermore, an intermediate-mass black hole with a high accretion rate would emit an energy up to $\sim 10^{9}\,{\rm L_{\odot}}$, which is only 1\% of the required energy of a Type III civilisation.
At the same mass accretion rate, the luminosity of an extremely Kerr black hole accretion disk is seven times larger than the Schwarzschild black hole due to the accretion efficiency.
Therefore, we conclude that the accretion disks of both types of black holes (non-rotating and extremely rotating) have the potential as a Type II civilisation's energy source.

    \begin{figure}

    	\includegraphics[width=\columnwidth]{disk_f.jpg}
    	\caption{Accretion disk luminosity as a function of the mass accretion rate. The orange line suggests $\eta=0.399$ which is the case of the extreme Kerr black hole ($a=1$) while the yellow line shows $\eta=0.057$ which is the case of non-rotating black holes. The blue line and the purple line indicate the required energy of a Type II and a Type III civilisations, respectively. Shaded regions suggest Eddington luminosity limits of different types of black hole: grey for stellar-mass black holes ($5\,{\rm M_{\odot}}<M<20\,{\rm M_{\odot}}$), red for intermediate-mass black holes ($10^2\,{\rm M_{\odot}}<M<10^5\,{\rm M_{\odot}}$) and green for SMBHs ($10^5\,{\rm M_{\odot}}<M<10^9\,{\rm M_{\odot}}$).}

        \label{figdisk}
    \end{figure}

{
\subsection{Bondi Accretion}
Bondi accretion is a spherical gas accretion onto a compact gravitating object from the interstellar medium with no angular momentum and no magnetic field \citep{Hoyle1939,Bondi1952}.
Considering the Bondi accretion around the vicinity of black holes, the analytical solution of the luminosity from Bondi accretion can be expressed as follows:
\begin{equation}
L_{\rm Bondi}=\eta c^{2}\left(\frac{\pi G^{2} M^{2} \rho}{c_{s}^{3}}\right),
\end{equation}
where $L_{\rm Bondi}$ is the luminosity of Bondi accretion, $\rho$ is the ambient density, and $c_{s}$ is the sound speed.
The sound speed in a gas cloud can be expressed as follows:
\begin{equation}
c_{s}=\sqrt{\frac{k_{\rm B}T_{\rm gas}}{\mu m_{\rm H}}},
\end{equation}
where $T_{\rm gas}$ is the temperature of the gas, $\mu$ is molecular weight, and $m_{\rm H}$ is mass of a hydrogen atom.
Adopting $\mu=1$, $m_{\rm H}=1.67\times10^{-27}\,{\rm kg}$, $T_{\rm gas}=10^{7}\,{\rm K}$ for the SMBH \citep[e.g.,][]{DiMatteo2003} and $T_{\rm gas}=10^{4}\,{\rm K}$ for the stellar mass black holes \citep[e.g.,][]{Alvarez2009}, and $\rho=1.67\times10^{-27}\,{\rm kg/cm^{3}}$, the Bondi luminosity can be expressed as:
{
\begin{equation}
L_{\rm Bondi}\sim2.8\times10^{3}\left(\frac{M}{M_{\odot}}\right)^{2}\left(\frac{n}{\#/{\rm cm}^{3}}\right)\left(\frac{T}{\rm K}\right)^{-3/2}.
\end{equation}
}
For scenarios A, B, and C, we obtained $0.07$, $1.11$, $1.40\times10^{6}\,L_{\odot}$, respectively.
These are $\sim10^{-6}$ and $\sim1\%$ of their accretion disk luminosities for the stellar mass black holes and the SMBH, respectively.
These radiative energies are too faint compared to the energy from the accretion disk.}

\subsection{Corona}
The gas around a black hole is in the plasma state due to the high temperature from the accretion disk, and this surrounding gas is called the corona.
Meanwhile, the corona generates high energy radiation as well \citep[e.g.,][]{Haardt1993}.
Thus, the radiation from the corona could be a good candidate in providing additional energy, aside from the radiation from the accretion disk.

For simplicity, we adopt the empirical relation between the corona luminosity and the disk luminosity from \citet{Sazonov2012}:
\begin{equation}
    \label{corona}
    {\rm log}\left(\frac{L_{\rm corona}}{\rm 10^{44}\,{\rm erg\ s^{-1}}}\right)={\rm 1.03log}\left(\frac{L_{\rm disk}}{\rm 10^{44}\,{\rm erg\ s^{-1}}}\right)-0.207,
\end{equation}
where $L_{\rm corona}$ represents the luminosity of corona in the unit $10^{44}\,{\rm erg\ s^{-1}}$.
This relation is the best-fit of the luminosity of hot corona versus disk luminosity using 60 active galactic nuclei from International Gamma-Ray Astrophysics Laboratory (INTEGRAL) all-sky hard X-ray survey.
{The samples have similar X-ray flux variations with X-ray binaries, which can be expressed as a log-normal distribution.
We assume that this formula extends to different mass ranges including stellar mass black holes \citep[e.g.,][]{Uttley2005}.}
For a stellar-mass black hole, the corona luminosity is approximately one-third of the radiation from the accretion disk while the ratio between the corona luminosity and the accretion disk luminosity increases to $1/2$ for a SMBH.
If a Type II civilisation includes the corona luminosity as well, the useful energy becomes 1.3 to 1.5 times of the accretion disk luminosity, which would be another promising energy source for maintaining civilisation.

\subsection{Relativistic jets}

Relativistic jets are high-energy and piercing phenomena, which are common among compact objects.
These plasma flow contain tremendous energy and are usually along the axis of rotation of the object.
The particles inside the jets could reach the Lorentz factor up to $100$ ($\gamma=(\sqrt{1-v^2/c^2})^{-1}$).
Although the relation between the accretion disk and the relativistic jets is not clear so far, it is believed that the jets are driven by the tangled magnetic field \citep[e.g.,][]{Blandford1977,Hawley2002,McKinney2004}.

For simplicity, according to \citet{Ghisellini2014}, the radiation of relativistic jets has an empirical relation with the luminosity of the accretion disk for a SMBH as follows:

\begin{equation}
    \label{jetsdisk}
    {\rm log}\left(\frac{L_{\rm jets}}{\rm erg\ s^{-1}}\right)={\rm 0.98log}\left(\frac{L_{\rm disk}}{\rm erg\ s^{-1}}\right)+0.639,
\end{equation}
where ${L_{\rm jets}}$ is the electromagnetic radiation of the jets.
This relation is based on the least-squares best fit of the radiative jet power versus disk luminosity using objects detected with Fermi/Large Area Telescope (LAT) and spectroscopic optical observations.
{Most of the Eddington ratios of the samples are in the range between $1\%$ to $100\%$, suggesting that the disks are geometrically thin, \citep[e.g.,][]{Shakura1973}.
X-ray binaries in the soft state are usually in this case \citep[e.g.,][]{Fender2002}.
Therefore, we assume that this empirical formula holds in different mass ranges.}
A stellar-mass black hole with a low Eddington ratio can even produce several orders of solar luminosity, suggesting that the energy in jets has the potential to provide the energy required by a Type II civilisation.

According to Eq. \ref{jetsdisk}, the radiation from the jets would be $\sim80\%$ and $\sim60\%$ of the radiation from an accretion disk for a stellar-mass black hole and a SMBH, respectively.
In addition, the radiation from the jets is believed to be $\sim10\%$ of the total energy of jets \citep[e.g.,][]{Ghisellini2014}.
If the technology is able to collect the energy from not only the luminosity but also the total energy of the jets, the energy available would be 10 times larger.
According to our results, only with the mass $M=0.003\,{\rm M_{\odot}}$ and Eddington ratio$=10^{-3}$, could the energy reach one solar luminosity.
For a stellar-mass black hole with $5\,{\rm M_{\odot}}$, the total jet energy becomes $\sim1.7\times10^{6}\,{\rm L_{\odot}}$.
The results suggest that the relativistic jets could be promising sources in the Universe regardless of the high temperature.

\section{Dyson Sphere}
\label{Dyson Sphere}
In this study, we only discuss the civilisations which were born and raised from other stars.
We speculate that this kind of civilisation can collect the energy remotely or treat the energy source as a power station rather than living around a black hole with a harsh environment.
Therefore, throughout the paper, we do not discuss whether the temperature and the gravity of our configurations are suitable for life \citep[e.g.,][]{Schwartzman1977,Inoue2011}.
{Moreover, we discuss two scenarios for the Dyson Sphere: (1) assuming that a Type II civilisation has the technology advanced enough to afford extreme high temperatures (hot Dyson Sphere hereafter) and (2) the realistic solid material to avoid melting $T\sim3000\,{\rm K}$ (solid Dyson Sphere hereafter)\footnote[6]{\url{https://pubchem.ncbi.nlm.nih.gov/compound/23964}}.}

\subsection{Possible Type and Location}
In reality, a monolithic Dyson Sphere is mechanically unstable due to the pressure and the gravity from the central star \citep[e.g.,][]{Wright2020}.
Hence, a structure similar to a Dyson Swarm or a Dyson Bubble becomes a more promising candidate to collect energy.
Moreover, considering a Type II civilisation might want to transfer energy from jets as well, a Dyson Bubble would be a more possible case to collect the energy from jets since the celestial mechanics of a Dyson Swarm is complicated and chaotic.
Therefore, we discuss two scenarios for a Dyson Sphere.
At the early stage of building a Dyson Sphere, the most simplified configuration is a Dyson Ring (a type of a Dyson Swarm), which contains numerous collectors sharing the same orbit.

Taking the widely discussed stellar-mass black hole, Cygnus X-1, as an example \citep[e.g.,][]{Shapiro1976,Ichimaru1977,Fabian1989}, with the mass of $M=8.7\,{\rm M_{\odot}}$ \citep{Iorio2008}, the accretion disk extends to ${r\sim500R_{\rm Sch}}$ \citep{Young2001}.
For a simplified discussion, we assume the inner radius of the accretion disk is around ${R_{\rm in}=3R_{\rm Sch}}$, which is the radius outside the {innermost stable circular orbit (ISCO)} of a Schwarzschild black hole.
In terms of the outer radius of the accretion disk, which has not been studied well so far, we assume its outer radius extends to ${R_{\rm out}=1000R_{\rm Sch}}$ \citep[e.g.,][]{Inoue2011,You2012}.
For a stellar-mass black hole, since its accretion disk size is smaller than the size of the Sun, the radius of its Dyson Sphere is smaller than that of a stellar Dyson Sphere (${R_{\rm out}=1\,{\rm AU}}$ corresponds to $M=5\times10^{4}\,{\rm M_{\odot}}$).
At this stage, the possible radius for the Dyson Sphere to collect the energy from the accretion disk should be around $10^{3}R_{\rm Sch}<R_{\rm DS}<10^{5}R_{\rm Sch}$, which locates outside the accretion disk.
If a Dyson Sphere is constructed farther away from the accretion disk, the efficiency may be too low (e.g., if two Dyson Spheres of the same size are built at distances of $10^{3}R_{\rm Sch}$ and $10^{6}R_{\rm Sch}$, respectively, the latter one could only intercept $10^{-6}$ times the energy of the former one), and might crush into the dusty torus.

{
For a given black hole mass, luminosity, and temperature for a Dyson Sphere to afford, we can rewrite the luminosity of a spherical blackbody ($L=4\pi \sigma R^{2}T^{4}$) into the following form to calculate the radius of a Dyson Sphere in units of $R_{\rm Sch}$:
\begin{equation}
    \label{DSradius}
\left(\frac{R_{\rm DS}}{R_{\rm Sch}}\right)=\frac{c^{2}}{2GM}\sqrt{\frac{L_{\rm disk}}{4\pi \sigma T^4}}\sim8.01\times10^{12}\left(\frac{M}{M_{\odot}}\right)^{-1}\left(\frac{L}{L_{\odot}}\right)^{\frac{1}{2}}\left(\frac{T}{{\rm K}}\right)^{-2},
    \end{equation}
where $T$ is the temperature a Dyson Sphere wants to absorb rather than emitting.
In terms of the solid material which can absorb $\sim3000K$, the Dyson Sphere should be located at $R_{\rm DS}\gtrsim7.12\times10^{6}R_{\rm Sch}$ and $R_{\rm DS}\gtrsim1.13\times10^{7}R_{\rm Sch}$ for Scenario A and B, respectively, to avoid melting.
For a SMBH, Scenario C, the Dyson Sphere could be set at $R_{\rm DS}\gtrsim2.54\times10^{3}R_{\rm Sch}$.}

{Not surprisingly, if a Type II civilisation wishes to build a Dyson Sphere receiving $T=3000\,{\rm K}$ and $1\,{\rm L_{\odot}}$, the total area required is independent from the mass of the source black hole (or a star), which is $\sim8.65\times10^{19}\,{\rm m^{2}}$.
Compared to the total area ($7.03\times10^{22}\,{\rm m^{2}}$) of the Dyson Sphere around the Sun at $1\,{\rm AU}$, this area is $\sim100$ times smaller.
Indeed, if the Dyson Sphere is closer to the black hole, the temperature is higher but the needed surface area decreases.
However, the maximum luminosity a Type II civilisation can absorb is different.}

In terms of energy from jets, utilising the pressure that balances the inward gravity and without the need to be in orbit (stationary in space), a Dyson Bubble is considered to be built with a huge amount of light sails.
First of all, we consider the balance between different types of pressures and the gravitational force from a black hole:
\begin{equation}
    \label{lightsail}
F_{\rm G}=\oint_S {(p_{\rm rad}+p_{\rm dyn}+p_{\rm B})} \,ds,
    \end{equation}
where $S$ is the surface area of a light sail, and the notations of $p$ stands for different types of pressure outwards:
radiation pressure ($p_{\rm rad}\propto I$ {$\propto R_{\rm DS}^{-2}$}; $I$: flux (${\rm W/m^{2}}$)), dynamical pressure ($p_{\rm dyn}\propto\rho v^{2}$ {$\propto R_{\rm DS}^{-3}$}; $\rho$: density of the jets and $v$: speed of jets) and magnetic pressure ($p_{\rm B}\propto B^{2}$ {$\propto R_{\rm DS}^{-4}$}; $B$: magnetic flux density).
{Note that $R_{\rm DS}$ stands for the distance of the Dyson Sphere to the black hole rather than the radius of the light sail itself.}
Along the path of jets, pressure decreases as radius increases {($p_{\rm{total}}\propto \frac{c_{1}}{R^{2}_{\rm DS}}+\frac{c_{2}}{R^{3}_{\rm DS}}+\frac{c_{3}}{R^{4}_{\rm DS}}$,
where
$c_{1}$, $c_{2}$, and $c_{3}$ represent the coefficients of different types of pressures).}
Moreover, the increase of the surface area of a light sail increases the outward force on the sail.
The surface area of a light sail is proportional to $R^{2}_{\rm DS}$ if a light sail is designed to cover the whole opening angle of the jet{, which leads to $F_{\rm G}\propto \frac{m}{R^{2}_{\rm DS}} \propto R^{2}_{\rm DS}\left(\frac{c_{1}}{R^{2}_{\rm DS}}+\frac{c_{2}}{R^{3}_{\rm DS}}+\frac{c_{3}}{R^{4}_{\rm DS}}\right)$}.
Considering an outward pressure and inward gravitational force, the mass $m$ required to build a light sail would be smaller when a light sail is closer to the black hole {($m\propto c_{1}R^{2}_{\rm DS}+c_{2}R^{1}_{\rm DS}+c_{3}$)}.
Thus, to save the materials, it is better to locate a light sail close to where the jets originate from {no matter how large the coefficients are}.

{If} the jet opening angle also changes with the radius, we assume $S\propto R^{k}_{\rm DS}$, where $S$ is the surface area of a light sail and $k$ is an arbitrary real number.
Eq. \ref{lightsail} becomes {$\frac{m}{R^{2}_{\rm DS}}\propto R_{\rm DS}^k( \frac{c_{1}}{R^{k}_{\rm DS}}+\frac{c_{2}}{R^{k+1}_{\rm DS}}+\frac{c_{3}}{R^{4}_{\rm DS}})$.}
Regardless of the value of $k$, the mass of a light sail required decreases at the location closer to the origin of the jets.
These two scenarios are visualised in Fig. \ref{figscheme}.
{Fig. \ref{figscheme}(b) shows the schematic of changing angle jets  described by an arbitrary power law.}
Under these assumptions, a Type II civilisation could build a light sail with fewer materials.
However, a Type II civilisation needs to consider the ISCO ($r={\frac{6GM}{c^{2}}}$ and $r={\frac{GM}{c^{2}}}$ for a Schwarzschild black hole and an extreme Kerr black hole, respectively) if a Type II civilisation wants to collect energy in situ instead of remotely.
{However, we caution readers that the luminosity of accretion disks of black holes varies with time.
Accretion disks switch between bright and dim states \citep[e.g.,][]{Done2007}.
If the accretion disk becomes too bright, the structures might be blown away while if the accretion disk gets too faint, the Dyson Sphere may fall into the black hole.
}

\subsection{Efficiency}
Even in reality, considering the transfer efficiency and the covering fraction, the accretion disk could still play a pivotal role for a Type II civilisation.
We combine two concepts, energy transfer efficiency and the sky covering fraction, into the terminology "efficiency" (e.g., if a Dyson Sphere covers 10\% of the sky and 50\% of energy transfer to usable energy, the efficiency is 5\%).
Most of the solar cell efficiency on the Earth reaches $15\%$.
In the world record, the highest efficiency is $\sim47\%$ \citep{Geisz2018}.
For instance, if there is a 50\% energy-conversion efficiency in the future, a Dyson sphere covering 2\% of the sky can extract 1\% available energy from the 5 M$_{\odot}$ black hole.
This corresponds to {16 $L_{\odot}$} which is sufficient for a Type II civilisation.
In this case, only 10\% surface area of the Earth is needed to cover the 2\% of the sky at a distance of $r_{\rm out}=1000R_{\rm Sch}$.

Assuming a Type II civilisation collects the energy from a $5\,{\rm M_{\odot}}$ black hole with a low Eddington ratio {(${\frac{L_{\rm disk}}{L_{\rm Edd}}}=10^{-2}$)}, the total luminosity from the accretion disk is {$1600\,{\rm L_{\odot}}$} (${\frac{L_{\rm disk}}{L_{\rm Edd}}}\times L_{\rm Edd}$).
Moreover, if a Type II civilisation could find a stellar-mass black hole with higher Eddington ratio (${\frac{L_{\rm disk}}{L_{\rm Edd}}}=10^{-1}$) and larger mass ($M=20\,{\rm M_{\odot}}$), the total available energy from the accretion disk is $6.4\times10^{4}\,{\rm L_{\odot}}$.
In other words, the accretion disk alone can provide sufficiently enormous luminosity to be collected by a Type II civilisation.
If a Type II civilisation could find such a way, it could utilise an accretion disk rather than hunting ten thousand stars.
The black hole could play an important role for a Type II civilisation whether or not they just reach a Type II civilisation or will soon become a Type III civilisation.
Furthermore, if a Type II civilisation becomes a Type III civilisation in a short period, it will likely seek a SMBH located at the galactic centre such as Sgr A* in the Milky Way.
If a SMBH with the mass ($M=4\times10^{6}\,{\rm M_{\odot}}$) and low Eddington ratio (${\frac{L_{\rm disk}}{L_{\rm Edd}}}=10^{-3}$), the total luminosity from the accretion disk is $10^{8}\,{\rm L_{\odot}}, \rm{or} \: 10^{34}\,{\rm W}$, which makes up $0.025\%$ of the required by a Type III civilisation ($4\times10^{37}{\,\rm W}$).
It would be much more efficient than collecting a host of stars distributed in a galaxy.

Additionally, if a Type II civilisation not only absorbs the energy from an accretion disk but also collects the radiation from a corona and relativistic jets, the available energy would be larger.
We consider two kinds of energy: total luminosity (${L_{\rm total}=L_{\rm disk}+L_{\rm corona}+L_{\rm jets}}$) and total energy including the kinetic energy of the jet (${P_{\rm total}=P_{\rm jets}+L_{\rm total}}$).
For the first scenario ($5\,{\rm M_{\odot}}$ and {${\frac{L_{\rm disk}}{L_{\rm Edd}}}=10^{-2}$}), if 1\% energy could be transferred to usable energy, the usable energy are ${L_{\rm total}\sim{35}\,{\rm L_{\odot}}}$ and ${P_{\rm total}\sim{169}\,{\rm L_{\odot}}}$ while Kardashev indices could reach {$K=2.21$ and $K=2.28$}.
As for the second scenario ($20\,{\rm M_{\odot}}$ and ${\frac{L_{\rm disk}}{L_{\rm Edd}}}=10^{-1}$), the total luminosity and the total power are $1.4\times10^5\,{\rm L_{\odot}}$ and $6.1\times10^5\,{\rm L_{\odot}}$, which could boost the civilisation up to $K=2.57$ and $K=2.63$.
In the last scenario for the SMBH ($4\times10^{6}\,{\rm M_{\odot}}$ and ${\frac{L_{\rm disk}}{L_{\rm Edd}}}=10^{-3}$), the total power is $\sim10^{9}\,{\rm L_{\odot}}$, giving $K\sim3$.
We organise different configurations of power for three scenarios with different efficiencies in Table \ref{tab1}.

\subsection{Detectablility}
In terms of detectability, direct evidence from a Dyson Sphere seems to be impossible because even if a Type II civilisation covers 90\% of the luminosity from the accretion disk, we can only expect an Eddington ratio 10 times smaller.
For instance, if there is a black hole with the Eddington ratio $\frac{L_{\rm disk}}{L_{\rm Edd}}=10\%$ in the true Universe and a Type II civilisation covers 90\% of the luminosity from the accretion disk, we would falsely measure the Eddington ratio of this black hole as 1\%.

A more promising way to detect Dyson Spheres is from the waste heat in IR.
After utilising the energy, the wasted IR energy would be released to the background by a typical Dyson Sphere.
Here we calculate the spectrum of an accretion disk with a Dyson Sphere.
We assume multi-colour black body radiation \citep[e.g.,][]{Mitsuda1984,Makishima1986,Merloni2000} for the disk spectrum:
\begin{equation}
    \label{dbb}
f_{\rm disk}=\frac{\rm{cos(\theta)}}{D^2}{\int_{r_{\rm in}}^{r_{\rm out}}}2\it{\pi r{B(T(r))}\,dr},
    \end{equation}
adopting the temperature profile $\propto r^{-3/4}$ (optically thick{, geometrically thin} accretion disk).
{$f_{\rm disk}$ is the flux of the accretion disk. $\theta$ stands for the inclination angle of the disk ($\theta=0^{\circ}$ in our spectrum), $D$ is the distance between the observer and the disk, while {$B(T(r))$} is the Planck function.}
The luminosity of an accretion disk is as follows:
\begin{equation}
    \label{dbbL}
L_{\rm disk}=\int_{r_{\rm in}}^{r_{\rm out}}4\pi r\sigma T(r)^4\,dr\sim4\pi r_{\rm in}^2\sigma T_{\rm in}^4.
    \end{equation}
We assume Scenario A with the inner radius $r_{\rm in}=3R_{\rm sch}$ and the outer radius $r_{\rm out}=1000R_{\rm sch}$, and according to Eq. \ref{dbbL}, { $T_{\rm in}\sim4.6\times10^6\,{\rm K}$}.
In addition, we assume the transfer efficiency is $\eta=50\%$ and the covering fraction is $R_{\rm c}=50\%$ {for the hot Dyson Sphere while $\eta=80\%$ and $R_{\rm c}=2\%$ for the solid Dyson Sphere.}
The distance between the black hole and the observer is set at $10\,{\rm kpc}$.
The resulting {hot and solid Dyson Sphere} spectra of the accretion disk, waste heat, and total flux which we could measure are shown in Fig. \ref{figdet}.
In {these configurations}, the AB magnitude ($m_{\rm AB}$) of the waste heat at {$10\,{\rm nm}$ to $300\,{\rm nm}$ and $10^{3}\,{\rm nm}$ to $10^{4}\,{\rm nm}$ are} approximately {$17$ to $20\,{\rm mag}$ and $18$ to $20\,{\rm mag}$ for the hot and solid Dyson Sphere, respectively.}
{The limiting magnitude of Wide Field Camera 3 (WFC3)/UVIS of Hubble Space Telescope ({\it HST}) in NUV(F225W) filter over 1 hour is $\sim27$ mag\footnote[7]{\url{https:// HST-docs.stsci.edu/wfc3ihb/chapter-6-uvis-imaging-with-wfc3/6-8-uvis-sensitivity}}, suggesting that in this scenario, the hot Dyson Sphere could be detected by our current ultraviolet (UV) space telescope.}
With the {\it HST}, one can look for these around known black holes/X-ray binaries because the {\it HST}'s Field of View (FoV) is not so large.
Alternatively, if one wants to survey a large area, a telescope with a larger FoV would be more suitable such as Galaxy Evolution Explorer ({\it GALEX}) Ultra-violet Sky Surveys, {\it SDSS}, Pan-STARRS1 $3\pi$ Steradian Survey (optical), VISTA Hemisphere Survey ({\it VHS}; near-infrared),Wide-Field Infrared Survey Explorer ({\it WISE}; mid-infrared), and Sloan Digital Sky Survey ({\it SDSS}; optical).
{These limiting magnitudes are summarised in Table \ref{tab2} and included in Fig. \ref{figdet}.}

{
If a black hole is closer to us and has a higher mass, the source will be brighter than our scenario ($D=10{\,\rm kpc}$ and $M=5\,M_{\odot}$).
For instance, if the source is at $1\,{\rm kpc}$, the AB magnitude of the waste heat at $10\,{\rm nm}$ to $300\,{\rm nm}$ and $10^{3}\,{\rm nm}$ to $10^{4}\,{\rm nm}$ are approximately $12$ to $13$ and $13$ to $17\,{\rm mag}$ of the hot Dyson Sphere and the solid Dyson Sphere under the same configurations.
If the source is under the scenario B ($M=20\,M_{\odot}$ and Eddington ratio$=0.1$), the AB magnitude of the waste heat at $10\,{\rm nm}$ to $100\,{\rm nm}$ and $10^{3}\,{\rm nm}$ to $10^{4}\,{\rm nm}$ are approximately $13$ to $15$ and $14$ to $18\,{\rm mag}$ of the hot Dyson Sphere and the solid Dyson Sphere at $10\,{\rm kpc}$.
}

Interestingly, with little algebra ($L_{\rm DS}=R_{\rm c}(1-\eta)L_{\rm disk}$), we derive the temperature of the waste heat, which is not related to the covering fraction:
\begin{equation}
    \label{wasteT}
T_{\rm waste}=\left[\frac{(1-\eta)L_{\rm disk}}{4\pi \sigma R_{\rm DS}^2}\right]^{1/4}.
    \end{equation}
In our simulated spectrum, the waste heat of the {hot} Dyson Sphere is {$\sim9.5\times10^{4}\,{\rm K}$.}
We assume that with the range of $\eta=[0.01,0.99]$, Eddington ratio $=[0.1\%,100\%]$ and radius of the Dyson Sphere $=[10^3R_{\rm Sch},10^5R_{\rm Sch}]$.
The possible wavelength (peak wavelength in the blackbody spectrum of the waste heat) to detect {a hot} Dyson Sphere as a function of the black hole mass is shown in Fig. \ref{figwav}.
Our result suggests that the waste heat of a {hot} Dyson Sphere around a black hole is detectable in the UV, optical, near-infrared (NIR), and mid-infrared (MIR) band.
We caution readers that star forming activity and dusty torus would be detected in the longer wavelengths such as IR, which do not disturb the detection of the {hot} Dyson Sphere in the spectrum.
{However, we caution readers that in our simulation, we assume there is no dust extinction.
The waste heat may be severely affected by dust extinction within the Milky Way.
Only if the black hole is close to the Earth or is observed in the infrared wavelength, this problem can be avoided.
Similarly, a Dyson Sphere of more massive black holes are redder, and less affected by the dust extinction. For example, at $M\gtrsim10^{5}-10^{6}\,{\rm M_{\odot}}$, most emissions from Dyson spheres are in the infrared.
}

{In terms of searching for Dyson Spheres around black holes, since Dyson Spheres may emit similar temperatures as stars, UV, optical, and infrared sky surveys might be inefficient.
We recommend analysing black holes (candidates) in the current catalogue first.
If there is spectroscopic data, we can analyse if there are several abnormal peaks.
If only photometric data are available, at least we need several band detection such as UV, optical, and infrared to perform spectral energy distribution (SED) fitting \citep[e.g.,][]{Hsiao2020} with the Dyson Sphere model spectrum, which will help us to identify the possible Dyson Sphere.}

{There are many factors that may affect the detectability.
First of all, if the covering fraction or the transfer efficiency of the Dyson Sphere is too small, the feature might be hidden beneath the disk/companion star spectrum.
As a result, we may mis-identify them as normal X-ray binaries.
In addition, even if the Dyson Sphere is bright enough, it may be challenging to distinguish it from a companion star or an exoplanet orbiting around the X-ray binaries \citep[e.g.,][]{Imara2018}.
We propose to overcome this problem through model fitting (SED fitting). If the blackbody radiation has an abnormal luminosity with a temperature that cannot be explained by usual models in SED fitting (e.g., star formation histories, etc....), we could further consider the Dyson Sphere scenario (e.g., $T=2000\,{\rm K}$).
{More robust confirmation comes with a spectrum by checking the absorption lines since low-temperature stars have spectra that have strong molecular bands.}
If the waste heat of a Dyson Sphere has a temperature below $\sim2000\,{\rm K}$, there would be a clear bump in the infrared spectrum that is not expected from a companion star with molecular bands.
In addition, if a Dyson Sphere collects a huge amount of the energy from the disk, it is possible that the bolometric luminosity is much lower than expected. For example, the spectrum is thermal blackbody radiation but the Eddington ratio is much smaller than $1\%$, which should be a thick disk and shows a non-thermal feature in the spectra \citep[e.g.,][]{Shakura1973,Narayan1994}.
This may indicate that the real Eddington ratio is higher but a fraction of the energy is absorbed by a Dyson Sphere.
Moreover, a Dyson Sphere should have a much smaller mass than a companion star or an exoplanet.
Operating a telescope to measure the variability of radial velocity will also help distinguishing between companion stars/exoplanets and Dyson Spheres candidates.
}

\citet{Inoue2011} discussed the energy transmitted remotely from a Dyson Sphere to a Type II civilisation's habitat.
In their result, the possibility to detect the transmission of a $1\,{\rm \mu arcsec}$ energy beam is less than $10^{-23}$.
For a stellar-mass black hole, the possibility becomes smaller.
A search for these signals from a black hole in the UV, optical, and IR bands is needed to discover the existence of a Type II civilisation.

    \begin{figure*}

    	\includegraphics[width=\textwidth ]{jet_scheme.jpg}
    	\caption{Schematic of the relativistic jets. (a) linear transmission of jets (i.e., the surface area $\propto R^{2}_{\rm DS}$) and (b) with changing angle (i.e., the surface area $\propto R^{k}_{\rm DS}$, here $k=4$).
    	The color scales with the distance from the black hole. Scales are arbitrary. The panels are not to scale.}
        \label{figscheme}
    \end{figure*}

    \begin{figure}

    	\includegraphics[width=\columnwidth]{Spectra_f_log.jpg}
     	\includegraphics[width=\columnwidth]{spectra_real.jpg}
    	\caption{Example spectra of Scenario A ($M=5\,{\rm M_{\odot}}$ and {$L_{\rm disk}=1600\,{\rm L_{\odot}}$)} {(upper panel:)} A hot Dyson Sphere with covering fraction $R_{\rm c}=20\%$, transfer efficiency $\eta=50\%$ {, and $R_{\rm DS}=5000R_{\rm Sch}$. (lower panel:) A solid Dyson Sphere with covering fraction $R_{\rm c}=2\%$, transfer efficiency $\eta=80\%$, and $R_{\rm DS}=7.12\times10^{6}R_{\rm Sch}$}.

    	The yellow curve suggests the accretion disk flux with the absorption of the Dyson Sphere (($1-R_{\rm c}$) times the original accretion disk flux) while the purple dot curve is the original flux of accretion disk without surrounding a Dyson Sphere. The blue curve shows the flux of the waste heat from the Dyson Sphere while the red dot-line curve indicates the total flux.
    	{The black circles, green diamonds, burgundy asterisks, blue stars, and magenta hexagrams indicate the limiting magnitude of {\it GALEX}, PAN STARRS1, {\it VHS}, {\it WISE}, and {\it SDSS} survey, respectively.}
    	}
        \label{figdet}
    \end{figure}

    \begin{figure}

    	\includegraphics[width=\columnwidth]{final.jpg}
    	\caption{Possible wavelengths for a {hot} Dyson Sphere to be detected in different black hole mass.
    	The purple, blue, green, orange, and red regions indicate X-ray$(\rm 0.01-10\,{\rm nm})$, UV$(\rm 10-400\,{\rm nm})$, optical$(\rm 400-760\,{\rm nm})$, NIR($\rm 760\,{\rm nm}-5\,{\rm \mu m}$), and MIR($\rm 5-40\,{\rm \mu m}$) wavelength, respectively.
    	The shaded region is the peak wavelength from black body radiation of the waste heat, covering a wide range of parameters of a Dyson Sphere.
    	The region enclosed by blue, magenta, and black lines indicate stellar-mass, intermediate-mass and SMBH.
    	Three arrows show how the peak wavelengths change with increasing parameters.
    	The arrow lengths are arbitrary.}
        \label{figwav}
    \end{figure}

    \begin{table*}
    	\centering
    	\caption{Information of the projects.}
    	\label{tab2}
    	\begin{flushleft}
    	\begin{tabular}{|c|c|c|c|c|}\hline
project                                                                  & band & exposure time(sec)    & limiting magnitude($m_{\rm AB}$) & reference \\ \hline
WFC3/UVIS of {\it HST} & NUV(F225W) & 3600(1\,hr) & $\sim27$ & $^{a}$ \\ \hline
\multirow{2}{*}{{\it GALEX} Ultra-violet Sky Surveys} & NUV  & \multirow{2}{*}{100}  & 19.9 &\multirow{2}{*}{\citet{Bianchi2011}} \\
                                                                             & FUV  &                       & 20.8   \\ \hline
\multirow{5}{*}{Pan-STARRS1 $3\pi$ Steradian Survey}                            & $g_{\rm P1}$  & 43                    & 23.3 & \multirow{5}{*}{\citet{Chambers2016}} \\
                                                                             & $r_{\rm P1}$  & 40                    & 23.2  \\
                                                                             & $i_{\rm P1}$  & 35                    & 23.1  \\
                                                                             & $z_{\rm P1}$  & 30                    & 22.3  \\
                                                                             & $y_{\rm P1}$  & 30                    & 21.4  \\ \hline
\multirow{4}{*}{{\it VHS}}                               & $Y$    & \multirow{4}{*}{60}   & 21.2 &\multirow{4}{*}{$^{b}$} \\
                                                                             & $J$    &                       & 21.1  \\
                                                                             & $H$    &                       & 20.6  \\
                                                                             & $K_{s}$   &                       & 20.0  \\ \hline
\multirow{4}{*}{{\it WISE}}                  & $3.3{\rm\,\mu m}$  & \multirow{4}{*}{8.8}  & 18.7 & \multirow{4}{*}{\citet{Mainzer2005}}     \\
                                                                              & $4.7{\rm\,\mu m}$  &                      &18.4       \\
                                                                             & $12{\rm\,\mu m}$   &                       &16.9       \\
                                                                             & $23{\rm\,\mu m}$   &                       &15.4       \\ \hline
\multirow{5}{*}{{\it SDSS}}                             & u    & \multirow{5}{*}{53.9} & 22.0 &\multirow{5}{*}{\citet{Abazajian2004}$^{c}$}  \\
                                                                             & $g$    &                       & 22.2  \\
                                                                             & $r$    &                       & 22.2  \\
                                                                             & $i$    &                       & 21.3  \\
                                                                             & $z$    &                       & 20.5  \\ \hline

        \end{tabular}\\
$^{a}$\url{https:// HST-docs.stsci.edu/wfc3ihb/chapter-6-uvis-imaging-with-wfc3/6-8-uvis-sensitivity}
$^{b}$\url{https://people.ast.cam.ac.uk/~rgm/VHS/v4/PS-VHS-v4p2.pdf}\\
$^{c}$\url{https://www.SDSS.org/dr16/scope/}
        \end{flushleft}
    \end{table*}

\section{Conclusion}
\label{Conclusion}

In this study, we consider an energy source of a well-developed Type II or a Type III civilisation.
They need a more powerful energy source than their own Sun.
We discuss and conclude that the collectable energy from the CMB at present by the Inverse Dyson Sphere would be too low ($\sim10^{15}\,{\rm W}$).
Next, the Hawking radiation as a source seems to be rather infeasible since the Hawking luminosity cannot provide adequate energy (e.g., for $5\,{\rm M_{\odot}},\:L_{\rm Hawking}\sim10^{-30}\,{\rm W}$ $<<10^{26}\,{\rm W}$ (Type II)).

On the other hand, an accretion disk, a corona, and relativistic jets could be potential power stations for a Type II civilisation.
Our results suggest that for a stellar-mass black hole, even at a low Eddington ratio, the accretion disk could provide hundreds of times more luminosity than a main sequence star.
If a Type II civilisation collects the energy from the accretion disk of a SMBH, the energy could boost the Kardashev index, $K\sim2.9$.
Moreover, the energy reserved in a corona and jets can provide additional energy ($\sim30\%-\sim50\%$ for the corona luminosity and $\sim60\%-\sim80\%$ for the jets luminosity) aside from the accretion disk.
Our results suggest that if a Type II civilisation collects the energy from jets and electromagnetic radiation simultaneously, for a SMBH with a mass similar to Sgr A*, the Kardashev index can reach $\sim 3$.
Overall, a black hole can be a promising source and is more efficient than harvesting from a main sequence star.

We also discuss a possible location of a Dyson Sphere around a black hole.
To absorb the accretion disk luminosity, a Dyson ring or a Dyson Swarm could be a possible structure.
A Dyson Sphere should be located outside of the accretion disk, $\sim10^3R_{\rm sch}-10^5R_{\rm sch}$.
{However, in this region, the hot temperature would melt the solid structure.
In order to avoid melting of the solid Dyson Sphere, the solid Dyson Sphere ($T=3000\,{\rm K}$) should be located at $R_{\rm DS}\gtrsim10^{7}R_{\rm Sch}$ and
$R_{\rm DS}\gtrsim10^{3}R_{\rm Sch}$ for a stellar mass black hole and a SMBH, respectively.}
The size of an accretion disk for a stellar-mass black hole is smaller than the size of the Sun, which means that a Dyson Sphere around the stellar-mass black hole can be smaller than that around the Sun.
In terms of relativistic jets, a possible form of a Dyson Sphere is a Dyson Bubble.
Balancing the pressure and the gravity from the black hole, a light sail could be stationary in space and can continuously collect the energy from the jets.
Light sails also absorb the luminosity from the accretion disk at the same time.
Our results suggest that the best way to place a light sail is close to the origin of the jets, which could save the materials to build a light sail.

Moreover, a {hot} Dyson Sphere around a stellar-mass black hole in the Milky Way ($10\,\rm kpc$ away from us) is detectable in the UV$(\rm 10-400\,{\rm nm)}$, optical$(\rm 400-760\,{\rm nm)}$, NIR($\rm 760\,{\rm nm}-5\,{\rm \mu m}$), and MIR($\rm 5-40\,{\rm \mu m}$), which can be detected by our current telescopes (e.g., WFC3/{\it HST} {and {\it GALEX} survey}).
{For a solid Dyson Sphere, the limiting magnitude of the sky surveys such as Pan STARRS1, VISTA Hemisphere Survey ({\it VHS}) Wide-Field Infrared Survey Explore ({\it WISE}) and Sloan Digital Sky Survey ({\it SDSS}) are smaller than the flux density from the solid Dyson Sphere, which indicates that the solid Dyson Sphere is bright enough to be detected.
In addition, the presence of Dyson Spheres may be imprinted in spectra.
Performing model fitting and measuring the radial velocity will help us to identify these possible artificial structures.}

\section*{Acknowledgements}
{We thank the anonymous referee for useful comments and constructive remarks on the manuscript.
We appreciate Prof. Hsiang-Yi Karen Yang for helpful discussions.}
TG acknowledges the support by the Ministry of Science and Technology of Taiwan through grant 108-2628-M-007-004-MY3.
TH and AYLO are supported by the Centre for Informatics and Computation in Astronomy (CICA) at National Tsing Hua University (NTHU) through a grant from the Ministry of Education of the Republic of China (Taiwan).
AYLO's visit to NTHU was hosted by Prof. Albert Kong and supported through the Ministry of Science and Technology of the ROC (Taiwan) grant 105-2119-M-007-028-MY3.

\section*{Data Availability}
\label{Data availability}
The data underlying this article will be shared on reasonable request to the corresponding author.

\bibliographystyle{mnras}

redpajama_set_name: RedPajamaArXiv


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World Lacrosse
International Federation For Lacrosse Celebrates The Introduction Of Its New Name, Logo and Brand Platform At SportAccord 2019
Less than six months after securing Provisional Recognition from the International Olympic Committee (IOC), the international federation for men's and women's lacrosse is taking yet another significant step forward in its development with the introduction of a new name, logo and brand platform.
The announcement was made today by World Lacrosse President Sue Redfern and Chief Executive Officer Jim Scherr at SportAccord 2019, the largest annual gathering of leaders from across Olympic and international sport. It was particularly significant for the announcement to be made in Australia, a country with a proud tradition of success in international men's and women's lacrosse and a two-time host of the Olympic Games (Sydney 2000 and Melbourne 1956).
The new name, logo and brand platform will add further momentum to the already rapid growth lacrosse is enjoying worldwide, while generating increased awareness and support for the federation, its 62-member National Governing Bodies and its Continental Federations. Lacrosse is one of the fastest-growing sports in the world and membership in the international federation has more than tripled since 2000.
This is a tremendously important and exciting day for our organization and for lacrosse enthusiasts around the world who, through their participation and commitment, are lifting our game to unprecedented heights In particular, I'd like to thank our Board of Directors and membership for their vision and support in setting out this dynamic, new direction.
Sue Redfern stated about the direction of World Lacrosse. She continued:
Coming just months after being honored by the IOC with Provisional Recognition, the introduction of our new brand platform is yet another important milestone for our organization. In introducing our new World Lacrosse name, logo and brand elements, we have attempted to capture the many unique attributes that make lacrosse special — the rich heritage and traditions of our game; the excitement and energy of lacrosse; its growing, global appeal; and, the unique spirit of camaraderie shared by lacrosse enthusiasts the world over. As expressed in our brand messaging, for all of us who care about this great game, we are excited to Experience What's Next.
World Lacrosse CEO Jim Scherr added:
The future for lacrosse has never been brighter, and our new name, logo and brand platform have been designed to capture the spirit of optimism and excitement that permeates our sport. Today's announcement is just the beginning. In the coming weeks and months, we will continue sharing elements of our new brand platform, beginning with our brand style guide, in order to provide stakeholders across the sport with a powerful set of tools and resources to work together in sharing the wonderful stories and attributes of this game.
The name World Lacrosse captures the bold vision and ambition of the federation to continue expanding participation in lacrosse around the globe; to do so in a manner consistent with the Olympic ideals; and, to fulfill its responsibility as an active and engaged partner in the lacrosse and international sport communities. It also aligns with a direction taken by other leading federations in international sport, such as World Sailing and World Archery.
The World Lacrosse logo is emblematic of the rich heritage of the game, which is a gift from the Iroquois Nation and is revered for its healing qualities and power to unite people in a celebration of competition, camaraderie and excellence. The shape of the logo represents a handmade wooden lacrosse stick. The globe in the center, angled at the actual position of the earth at 23.5 degrees, represents the global appeal of lacrosse, but also hints at the uncharted territory and opportunity for continued growth. The colors depicted in the globe pay tribute to the importance of the Olympic Ideals and reflect the aspiration of World Lacrosse to one day secure inclusion for lacrosse in the Olympic Games — the pinnacle of athletic achievement.
In addition, World Lacrosse is announcing today that its new web site address is:
WorldLacrosse.Sport
As a proud member of the Global Association of International Sports Federations (GAISF), World Lacrosse is delighted to join other international federations in utilizing the new .sport domain created by GAISF.
The brand development process was led by Adrenalin, an award-winning brand development and creative agency with clients in international, professional and intercollegiate sport — including lacrosse. Adrenalin was appointed in December 2018 following a review of proposals from a number of outstanding agencies. Within the federation, the process was directed by Chief Brand and Communications Officer Darryl Seibel, who began his role with the organization in mid- January.
Dan Price, Principal and President of Adrenalin, remarked:
The leadership of World Lacrosse came to us with a vision for their new identity system and worked with us to make it a reality I speak for our entire team, Rick Fillmon, Jessica McGurn and all those involved, when I say it was a true pleasure turning their vision into a world-class identity system that represents World Lacrosse as they elevate the sport of lacrosse around the world.
The brand development process included individual interviews with stakeholders from across the sport, along with a workshop in January with members of the federation's Board of Directors and Athletes Advisory Commission.
In April, the membership of the federation (full members) voted in favor of a recommendation from the Board of Directors to adopt the proposed new name for the organization — World Lacrosse.
As part of the brand rollout, later this month, World Lacrosse member-National Governing Bodies will receive a comprehensive brand style guide, which provides guidance on how to implement the new family of logos and messaging that celebrates the unique values and attributes of the sport.
Finally, World Lacrosse is announcing today that it has established its new organizational headquarters in Colorado Springs, Colorado, USA — a city often referred to as Olympic City USA. Colorado Springs is home to more than 50 national and international sport organizations, including the United States Olympic Committee and the United States Anti-Doping Agency.
The World Lacrosse headquarters is located at:
1295 Kelly Johnson Blvd, Suite 260
Colorado Springs, Colorado, USA, 80920
For more information, please contact Darryl Seibel.
[fvplayer id="4″]
World Lacrosse is the international governing body for men's and women's lacrosse. World Lacrosse currently has 62 member nations and holds five World Championships. It is responsible for the governance and integrity of all forms of lacrosse and provides responsive and effective leadership to support the sports' development throughout the world.
PrevPreviousQuint Kessenich: ADVNC Lacrosse Podcast
NextMLL Hires Former NFL Media Executive Mark Burdett As CRONext

redpajama_set_name: RedPajamaCommonCrawl


This application is a a basic WebCam software, that works with all Video4Linux compatible video devices.
Ultimate WEBcam PRO 2001 is a PHP/MySQL based WEBcam publishing system, with many features like put webcam images into a image archive with a single click on the page, guestbook where the visitors can comment the webcam, voting system.
PHP Webcams is a script that displays an index of images that are automatically updated via ftp or some other method on a regular basis.


Peters' contract became fully guaranteed with Los Angeles on Wednesday, Cameron DaSilva of USA Today reports.
Peters is scheduled to play 2019 under the fifth-year option on his rookie contract, Rich Hammond of the Los Angeles Daily News reports.
Peters overcame a bout with cramps and returned to Monday's 54-51 win over the Chiefs, finishing with one tackle and an interception.


text:
Marko Grujic suffers defeat at the hands of ex-Red in a round of mixed fortunes
Joanna Durkan
It was a weekend of mixed results for Liverpool's loanees in Germany, with Marko Grujic falling to defeat at the hands of a familiar face.
Grujic, who had featured in all 360 minutes of Hertha Berlin's games since football resumed, was left to taste defeat for the first time since February thanks to Emre Can's Borussia Dortmund.
The 24-year-old has experienced a topsy-turvy campaign with the Bundesliga outfit but has been an ever-present in central midfield in Berlin alongside Per Ciljan Skjelbred under manager Bruno Labbadia.
Hertha had dropped points on only one occasion prior to Saturday's meeting at Dortmund in their preceding four games, with a 2-2 draw at Leipzig their only setback – a game which saw Grujic open the scoring.
But for Hertha, who currently sit ninth in the table, their unbeaten streak came to a halt thanks to a second-half strike from ex-Red Emre Can.
The outing was largely dominated by Dortmund, with Grujic acting as an important part of the chain linking Hertha's defence to their attack but it was an outing which left few chances to shine beyond his clean disposal rate (92 percent).
He was substituted with two minutes left of regulation time as Hertha rolled the dice in a bid to snatch a point at the death, but they were not to reap any rewards to ensure Dortmund remain seven points adrift of Bayern at the top of the table.
But the most poignant and significant moment of the evening came before the first whistle had even arrived, with all 22 players taking a knee in the centre circle in addition to all those on the sidelines in support of the Black Lives Matter movement.
??????????? #noracism #blacklivesmatter
A post shared by Borussia Dortmund (@bvb09) on Jun 7, 2020 at 5:34am PDT
Elsewhere, Taiwo Awoniyi played the full 90 minutes as Mainz recorded a 2-0 win at Eintracht Frankfurt on Saturday afternoon.
It was the third successive game where the 22-year-old was given a starting berth, only this time he was on the pitch when the final whistle blew having helped his side move three points above the relegation playoff spot.
It comes as a welcome chance to both shine and develop for Awoniyi, who only featured for 147 minutes in the first 25 fixtures of the Bundesliga season.
Awoniyi's confidence will no doubt have received a timely boost as his side battle to stay out of the relegation scrap, where the four games remaining see them face off against top five members in Dortmund and Leverkusen.
And Nat Phillips was an unused substitute as Stuttgart failed to make ground up on 2. Bundesliga leaders Arminia Bielefeld having been held to a scoreless draw against Osnabruck on Sunday.
Tags Loan Watch


My teenage son was involved in a car crash. Will the police blame him because of his age?
Every time we think we've seen the limits of the dumb things people do—we are surprised again by human ingenuity.
We have spoken before about the dangers of distracted driving—especially about the risks of using mobile devices to access the Internet. Emailing and texting while driving in Pennsylvania isn't just against the law: it's also remarkably dangerous. Studies by the Transportation Institute at Virginia Tech estimate that texting while driving increases the chance of an accident by a factor of 23. The U.S. Department of Transportation says that distracted driving causes around 3,300 traffic deaths every year.
Some people have absorbed the message—they turn off their smartphones when they get in the driver's seat.
But some people—and yes, we mean mostly teenage drivers here—think it's cool to flout the rules. Rather than give up phone use while driving, they are actually taking pictures of themselves doing it, and posting those pics online.
The danger is extreme. A driver must devote considerable attention and at least one hand to operate the cell phone to take a picture while driving. This is comparable to composing and sending a text message—which is equivalent to driving blind for more than the length of a football field at highway speeds.
Of course, the driver is endangering himself, his passengers, pedestrians, and other motorists by using his camera phone. What few teens seem to have considered is that they are also posting online definitive proof that they have violated cellphone bans and documented their lack of good judgment. Even if these drivers are fortunate enough to avoid a tragic Pennsylvania traffic accident, they may lose a job offer or other future opportunity when a potential employer finds these images online years later.
Injured by a Distracted Driver in Pennsylvania? We Can Help!
At Schmidt Kramer, our Harrisburg car crash lawyers represent people just like you who have been hurt in Pennsylvania motor vehicle accidents and are seeking to recoup their losses. We have a proven track record of holding dangerous drivers accountable for their actions.
If you or a family member has been hurt a distracted driver in Dauphin County, Perry County, Schuylkill County, or any neighboring community, you should not have to cover your own medical expenses, forfeited income, and other losses. Call our Harrisburg trial lawyers at 717-888-8888 or (888) 476-0807 toll-free to schedule a free, confidential case review or to request a FREE copy of our helpful brochure, Who Pays the Bills When You Are Injured in an Automobile Accident?


The weather has finally turned for good. The trees are glorious with crimson and gold. There's comfort food on the menu for Dinner. I'd say all is right with the world, but the Red Sox just won the World Series for the second time in four years and that might actually be a sign of the apocalypse.
Corn Pudding is one of the only recipes for which I advocate the use of a pre-made store-bought mix. This is not quite as Alice Waters as it seems. It is maybe 30% me being puritanical about being able to pronounce all the ingredients in the food I eat. The other 70% has to do with the realities of growing up outside of the United States.
Growing up we lived hither and yon, and moved in between the two a lot. In practical terms what this means is that a lot of the time not only did we not have access to Cheerios (apparently for years this was the first thing I'd ask for when we got off the plane in the US), but we also didn't have access to a lot of the packaged mixes that are familiar to a lot of my friends.
My mother made almost everything from scratch, and taught me how to cook the same way. When I was a teenager this wasn't an ethical or political decision, it was a reflection of where we lived and what was available. This makes it sound like we lived in Outer Mongolia. We didn't. We lived in Europe. My mother is now retired and has started channeling Alice Waters on occasion, but when I was learning to cook making things from scratch wasn't about being a purist, it was about being pragmatic.
That being said, I am a big believer in making food from scratch. I'm not really trying to make a political or ethical statement either, I mostly just think it tastes better. I make my own biscuits. I'm not really all that convinced that using Bisquick is any faster than making my own pancake batter. And seriously y'all, salad dressing is not that hard to make.
There are, obviously, exceptions. I buy my pie dough from the freezer case at the supermarket because I make bad pie dough, and Pillsbury tastes better than anything I can achieve. There is always a box of Ghirardelli brownie mix in my pantry for those Friday nights when you suddenly decide that you have to have something chocolaty. Then there's corn pudding, my Class A drug of choice.
Corn Pudding is the easiest recipe in the entire world. I'm not even sure you can call it cooking it's so easy. A friend asked me recently if you could make it from scratch – this is not because she's masochistic, this is because she had an unending amount of fresh corn lying around her house and wanted to use it. And, you could. Corn kernels are corn kernels, and creamed corn isn't all that hard to make. Corn muffin mix probably has more sugar in it than I would put in a home made recipe for corn muffins, but it wouldn't be that hard to approximate. On the other hand, why bother?
By preference I use chicken tenderloins to make chicken fingers because the meat is so tender. But, cutting chicken breasts into strips works just fine too.
It always takes more egg wash and more bread crumbs than I think it will, so seriously over estimate how much you will need.
Dip the chicken in the flour. Then the egg wash. Then the bread crumbs. This is messy and at the end of it you'll have so much breading on your fingers you could fry them up for dinner too.
Place on a plate and allow to rest for 15-20 minutes before you try to cook it. You can cook them right away, but they fry up better if you let them rest.
Melt butter and vegetable oil in a pan (butter for flavor, vegetable oil for the higher smoke point). When a bit of flour dropped into the pan sizzles add your chicken fingers and fry until done (usually somewhere around 3-5 minutes per side).
I make a lot of chicken fingers and fry them in batches. I cover them with tin foil and a towel to keep them warm while I fry the next batch. Add a little more oil/butter in between batches. If your pan dries up all you'll end up doing is scorching the breading.
I made your corn pudding for Thanksgiving this year to try something different. It was such a hit that there was almost nothing left over! win!
In my experience no matter how much corn pudding you make there are never leftovers.


text:
The Life of the Rev. John Wesley, A.M., Fellow of Lincoln College ..., Volym 2
AvHenry Moore
REV. JOHN WESLEY, A. M.
FELLOW OF LINCOLN COLLEGE, OXFORD ;
IN WHICH ARE INCLUDED,
THE LIFE OF HIS BROTHER,
THE REV. CHARLES WESLEY, A. M.
STUDENT OF CHRIST CHURCH;
AND MEMOIRS OF THEIR FAMILY:
COMPREHENDING AN ACCOUNT OF
The Great Revival of Religion,
IN WHICH THEY WERE THE FIRST AND CHIEF INSTRUMENTS,
BY THE REV. HENRY MOORE,
ONLY SURVIVING TRUSTEE OF MR. WESLEY'S Mss.
According to this time it shall be said, "WHAT HATH GOD WROUGHT !"
NUMBERS xxiii, 23.
"Not by might, nor by power, but by my Spirit," saith the Lord of Hosts.
ZECHARIAH iv, 6.
Venturæque biemis memores, æstate laborem
Experiuntur, et in medium quæsita reponunt.
VIRGILII GEORG
IN TWO VOLUMES.
NEW-YORK,
PUBLISHED BY N. BANGS AND J. EMORY, FOR THE METHODIST
EPISCOPAL CHURCH, AT THE CONFERENCE OFFICE,
13 CROSBY-STREET.
Az Hoyt, Printer.
BOOK THE FIFTH.
Progress of Religion, with the Persecutions that followed..
Accounts from Germany the State of Religion in the English Army—The
First Conferences—The Labours of the Brothers, and of their Assistants,
during the Rebellion in Scotland..
Progress of Religion, with its Attendant Sufferings Mr. Wesley's Expostula-
tion with the Opposing Clergy–His Advice to the People respecting their Per-
secutors.
Mr. Wesley's Correspondence with some Eminent Men in Scotland and Eng-
land-Rough Sketch concerning Justifying Faith-Opening of Kingswood
School.....
BOOK THE SIXTH.
Of the Labours of Mr. Wesley, and of his Brother Mr. C. Wesley, and of the
Preachers in connexion with them in Ireland, with the Persecutions that
followed-Mr. C. Wesley's Marriage..
Mr. Wesley's Labours and Providential escapes-His Opinion of the Monta-
nists--Death of Mr. Jane-His Private Correspondence-Fall of Wheatley,
and renewed Labours of Mr. C. Wesley......
Extraordinary Event preceding Mr. Wesley's Marriage-Verses on that Occa-
sion-His Marriage-Renewed Engagement between Him and his Brother
-Mr. Wesley's Private Correspondence....
Mr. Wesley's dangerous Illness-Mr. C. Wesley's renewed Labours-Mr. Wes-
ley's re-assumption of itinerancy–His Correspondence with the Rev. Mr.
Walker, of Truro-His Proposal for a Union of the Evangelical Clergy of that
Day-Account of Mr. Grimshaw..
BOOK THE SEVENTH.
Great Revival of Religion-Separation of Maxfield and others-Minutes of
the Conference against Antinomianism-Protest by the Rev. Mr. Shirley and
others---Mr. Fletcher's Writings..
Labours of Mr. Wesley, and his Assistants, in Scotland-Controversy respect,
ing Mr. Hervey's Letters-Recent Revival of that Controversy by Dr.
Erskine's Biographer...
Proposal to Mr. Fletcher fully to unite' with Mr. Wesley in the Work-Remark-
able Death of Mr. Downs-Mr. Wesley's dangerous Alness in Ireland-Dis-
pute concerning the American Revolution-Curious Anecdote concerning
Mr. Wesley's Plate. .....
Labours and Opposition in the Isle of Man-Secession of an Eminent Preacher
- Protestant Association-Mr. Wesley's Letter on that Occasion-His Letter
to the Bishop of London, and Sir Henry Trelawney-Thoughts on "Dr. Par-
son's Remains of Japhet"-Curious Questions put to Mr. Wesley-His Letter
respecting the Sabbath-day, addressed to one of His Majesty's Ministers-
Curious Fragment-Mr. Wesley's visits to Holland...
BOOK THE EIGHTH.
The Deed of Declaration-Mr. Wesley's Ordinations-Short Account of Dr.
Coke...
Progress of Religion in America Ordination for the American Societies~
Objections considered....
Continuance of Mr. Wesley's Labours-His Visit to Ireland - Account of the
Work of God in the French Islands Mr Wesley's visits to them-Latter
days and Death of Mr. Charles Wesley-A Review of his Character.... 205
The Three Last Years of Mr. Wesley's Life--His Last Illness and Death-
The Inscription on his Tomb--His Last Will and Testament..
CHAPTER V.
A Review of Mr. Wesley's Labours as a Writer, and as a Minister of Christ
--Testimonies of Eminent Men concerning Him-Concluding Observations
on the Fellowship and Discipline established in the Societies...
Letters between the Rev.*******, who passes by the Name of John Smith,
and the Rev. John Wesley
THE REV. JOHN WESLEY, A. M.
PROGRESS OF RELIGION, WITH THE PERSECUTIONS THAT FOLLOWED.
MR. Wesley having now several helpers after his own heart, the work of God prospered in many places. Many societies were formed in Somersetshire, Wiltshire, Gloucestershire, Leicestershire, Warwickshire, Lincolnshire, Nottinghamshire, and in several parts of Yorkshire. And those in London, Bristol, Kingswood, and Newcastle-upon-Tyne, were much increased. But as in the beginning of Christianity, so it was now
This sect was every where spoken against,
But its enemies were not content with this. In the year 1740, several rioters, who had long disturbed the meetings in Bristol, were emboldened by impunity. Their numbers also increased, so as to fill, not only the court before the preachinghouse, but a considerable part of the street. The mayor sent them orders to disperse ; but they set him at defiance. He then despatched several of his officers, who took the ringleaders into custody. The next day they were brought into court, it being the time of the quartersessions. There they received a severe reprimand; and from that time, the Society in Bristol enjoyed almost uninterrupted peace.
In London the rioters were not so easily subdued. They assembled at various places, and frequently treated Mr. Wesley and many of his serious hearers in a shameful manner. They followed them with showers of stones, and once attempted to unroof the Foundery, where the congregation was assembled, and had nearly accomplished their design. The common cry was, " You may treat them as you please, for there is no law for them." But Sir John Ganson, the chairman of the Middlesex Justices, called on Mr. Wesley, and informed him, " that he had no need to suffer these riotous mobs to molest him ; adding, "Sir, I and the other Middlesex Magistrates have orders from above, to do you justice whenever you apply to us." A short time after, he did apply. Justice was done, though not with rigour; and from that period the Society had peace in London. It was very confidently stated, in that day, that when the question concerning the persecutions suffered by the Societies at this time, camè before the Council, the King declared, that "No man in his dominions should be persecuted on the account of religion, while he sat on the throne." His late Majesty also, and indeed all that dynasty, have acted on the same principle.


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Daltons in AFRICA -- 2002.
Make sure to check out the ADDITIONAL LINKS on the LONDON, KENYA, and UGANDA web pages. Also look at the ANIMAL FACTS links to learn all about what we saw in Africa (I'm a walking encyclopedia now!). And please send me your comments!
This vacation was so amazing and such a life altering trip, that some day I hope that you're blessed to be able to experience Africa for yourselves. It's definitely worth the effort to get there, and I hope Jeff and I are able to return to experience its wonders again.
We're dedicating this web site to Marsha Dalton, Jeff's mother. She passed away unexpectedly in August 2002. She was such a big fan of our travels abroad. We miss her dearly. Please click here for memorial pages in her honor.
Copyright � 2002, Dawn M. Dalton.


Perfact love is not receiving,it is giving and forgiving.….
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text:
Anson T. Hemingway
Anson Tyler Hemingway, the son of Allen Hemingway and Harriet Louisa Tyler, was born in East Plymouth, Connecticut on August 26, 1844. The family came to Chicago in 1854 and within ten years all three Hemingway brothers had enlisted in the Civil War. Anson served in the Army as a private with the 72nd Illinois Regiment (known as the Young Men's Christian Association regiment) and fought in the deadly Battle of Vicksburg. He later re-enlisted in Company H, US Colored 70th Regiment as 1st Lieutenant and also served as provost marshall of the Freedman's Bureau in Natchez. Anson's other two brothers died during the war.
After his time in the military, Anson attended Wheaton College. After two years of study, as a friend and admirer of Dwight L. Moody, he went on to serve as general secretary of the Chicago YMCA for ten years before establishing a real estate business in Oak Park, Illinois. Hemingway was appointed secretary in 1878. During his tenure Hemingway won the confidence of his associates and of the business men of the city by his devoted and self-sacrificing efforts in behalf of the work and by his never-failing sympathy with young men. The membership and the financial standing of the association increased under his management.
Anson married fellow Wheaton student Adelaide Edmonds, who graduated in 1867. Together they had four sons and two daughters. While living in Oak Park they were members of the First Congregational Church. An avid outdoorsman, Anson gave his grandson Ernest a special tenth birthday present of a 20-gauge shotgun, believed to have sparked the future author's lifelong hunting pursuits. Anson Hemingway passed away in 1926 at the age of eighty-two.


text:
Haslar – a place of no return
Ukrainian asylum seeker, 42-year-old Mikhail Bognarchuk, was found hanged by his shoelaces in a toilet at Haslar Removal Centre on 31 January.
He was due to be deported that day to the Ukraine – a country with a questionable human rights record. A Home Office Country Assessment Report on the Ukraine states that 'police and prison officials regularly beat detainees and prisoners, and there have been persistent reports that Berkut (special militia units or riot police) troops beat and torture inmates as part of regular training exercises.' Ironic then, that Mikhail met his death in a British prison.
The Haslar Centre's sole purpose is to hold asylum seekers pending their removal. It is a place of no return. Haslar, formerly a prison, became Haslar Removal Centre on 8 February 2002 and is run for the Immigration and Nationality Department by prison service staff.
Michael Woolley of the Haslar Visitors Group told IRR News 'we regularly hear reports of self-harm'. Bail for Immigration Detainees (BID) estimates that there have been at least 10 serious self-harm attempts at Haslar since it became an immigration removal centre.
In September 2001, 75 men went on hunger strike at Haslar to protest at their imprisonment. One refugee commented 'some people escaped cruel regimes. But we are treated like criminals yet we have committed no crime.'
The IRR's research shows that since January 2000 at least nine asylum seekers have taken their lives because their asylum claim had been refused.
Asylum policy: the human cost
7/5/02, Shiraz Pir, (25) Afghani, living in Bristol for eighteen months in hostel accommodation, was found hanged, but still alive. He died five days later in Bristol Royal infirmary. His application for refugee status was refused. At the inquest the coroner criticised the Home Office delay in dealing with his asylum application.
12/3/02, Mohsen Amri, (27) Iranian, who took his own life at his home in Handsworth, Birmingham. He had been in the UK for two years and made repeated requests for work permits (he did not want to work illegally) but had been refused. His asylum application was refused on a technicality.
1/1/02, Souleyman Diallo, (28) Jumped 100 feet to his death from Redheugh bridge, Tyneside because he was to be deported back to Guinea.
21/8/01, Nasser Ahmed, (36) Eritrean, dispersed to Nelson, Lancashire found hanged after his asylum claim was refused. A friend of his claimed that he was 'very afraid' of being sent back.
20/1/01, Unnamed Kosovan, He was discovered on a ferry travelling from Ostend to Dover. At Dover he was put back on a ferry to deport him to Calais and he jumped from the ship to his death.
18/1/01, Ramin Khaleghi, (27) Iranian, dispersed to Leicester, took his own life after his asylum claim was refused.
21/12/00, Saeed Alaei, (26) Iranian, dispersed to Nelson, Lancashire, found hanged after his asylum claim was refused.
24/01/00, Robertas Grabys, (49) Lithuanian found hanged in Harmondsworth detention centre.
2000, Glynnis Cowley, South African mother of three who took her own life after her asylum claim was refused.
12/98, Lin Yan-Guang, Chinese asylum seeker who committed suicide in Warley hospital, Brentwood, Essex.
07/98, Sofonias Alemsged, (22) Eritrean with psychological problems who had made previous attempts to commit suicide was found hanged in Brixton prison just weeks before an appeal on his asylum claim.
1998, Mehretab Kidane, (28) Eritrean who committed suicide on the final day of his asylum appeal hearing because he was so afraid of being sent back.
25/8/95, Muttavel Vasanthan, (25) Sri Lankan found hanged in his cell at Norwich prison. Muttavel had been held for four months.
Haslar Visitor Group
Bail for Immigration Detainees
journey:
I am not familiar with Haslar…..you might write a story about that place; sounds frightening……..


Plumber in Alkimos - Yes, we do retic cut-ins!
Getting the garden ready for summer? Yes, we do retic cut-ins! When you're installing reticulation you need a licensed Plumber, like Calvin, to tee-in to the existing water pipe and install an approved isolation valve with backflow prevention.
If you need a plumber in Alkimos – Call me at Calvin's Plumbing and Gas on 0411 358 890.


In many cases, that sluggish and even bloated feeling we get during the day can be the result of excess toxins in the body. Detoxing with essential oils and other natural remedies help to reduce inflammation, boost energy, support digestion, cleanse the liver, promote healthy skin and more.
In this episode of Ancient Medicine Today, I talk to you about how to detox your body naturally, using essential oils, herbal extracts and superfoods as well as the warning signs your body is giving you that show you need to detox now.
Dr. Josh Axe, DC, DNM, CNS, is a doctor of chiropractic, certified doctor of natural medicine and clinical nutritionist with a passion to help people eat healthily and live a healthy lifestyle.
This content is strictly the opinion of Dr. Josh Axe and is for informational and educational purposes only. It is not intended to provide medical advice or to take the place of medical advice or treatment from a personal physician. All viewers of this content are advised to consult their doctors or qualified health professionals regarding specific health questions. Neither Dr. Axe nor the publisher of this content takes responsibility for possible health consequences of any person or persons reading or following the information in this educational content. All viewers of this content, especially those taking prescription or over-the-counter medications, should consult their physicians before beginning any nutrition, supplement or lifestyle program.
Is there some exercises before starting parkouring????
i can't tell if they just want my money or not lol.
I'm a 23 years old women with no athletics experience and I wanna stat learning parkour, do I still have a shot or have I missed my shot?
I feel like the "signs" needed to detox can be signs of various other reasons. Acne, mood swings, cravings, etc. are all signs of hormonal imbalances.. that cannot be cured with a detox.
What am i doing here? I already kwon this.
The color that you see when you add water it's not the same of the one you see when you take the pad off. I have felt the result with the pads and I recommend this product!
How do you use these oils you listed?
I take chlorella for detox. Is that ok?
What is to old for Parkour?
Last year I bought this eBook all about green smoothies.It was honestly the best decision ever.I had various health problems like high blood pressure, I was overweight and depressed because of the toxins in our food.Green smoothies enhance your health so much!
All diseases start in gut.
How is ginger a herb?
Can you do a video about silica ? Is it better then taking collagen?
Fascinating all encompassing talk on Detox!
If I spent all my ingame minecraft time into mastering this, I would be unstoppable.
Awesome video! I couldn't agree more. Take it from somebody who has Leukemia.
Can you over detox? Or can you do this for as long as you want?
I have all these symptoms! OMG! I'M GONNA DIE!
And that is why Islam commands us to fast one month in every year. Now scientists came to know the benefits of fasting. Alhamdulilah.
Isnt that our liver and kidney's job?


text:
Tove Lo Leaves A Relationship Behind On 'Sadder Badder Cooler'
Derrick RossignolMusic News EditorTwitter
Tove Lo's Sunshine Kitty was one of last year's more fun pop albums, and now she has brought it into 2020. Today, she releases a deluxe version of the album — dubbed the "Paw Prints Edition" — and shares her new album-opener, "Sadder Badder Cooler."
On the track, Tove Lo is done with a former lover, singing in the chorus, "I'm sadder, I'm badder, I'm cooler, yeah / than I was when I met you." Elsewhere on the track, she sings about how she is over her past relationship: "You toast your friends 'cause I left / But you know I'm never coming back in / Once I walk out the door / Screw all loose ends in this war / It was all about the power play, babe / And I can't do it no more."
The "Paw Prints Edition" of Sunshine Kitty adds eight new tracks to the album, including remixes, live versions, and an English-language cover of Veronica Maggio's Swedish single "Jag kommer" (now titled "I'm Coming"), which was released on Spotify back in March. She previously said of the song, "It's the soundtrack to so many of my memories. I've always been so impressed with Veronica's way with words. I could never write in swedish the way she can. It's the perfect mix of poetic, 'everyday romance' and making the Swedish summer time feel epic and melancholic all at once."
Listen to "Sadder Badder Cooler" above.
Sunshine Kitty (Paw Prints Edition) is out now via Universal. Get it here.
Tags: Sadder Badder Cooler, sunshine kitty, Tove Lo


text:
Why Resilience Is Important for Entrepreneurial Leaders
By Karl Klaussen
When life takes uncertain and unpredictable turns, it's important to meet the moment with grit and flexibility. We call this resilience, and it's what keeps us moving forward even when faced with adversity.
As it turns out, resilience also is a central capability of effective leaders. Resilient leadership is about creating a connection with others and an overall positive tone within an organization. Resilience also is a key strength found in entrepreneurial leaders.
Scott Taylor, associate professor of organizational behavior, says, "Resilience is not something we have or don't have—I believe resilience is something we find."
Register for Babson Executive Education's upcoming online course with Scott Taylor: Resilient Leadership, October 27–November 17, 2020.
Taylor explains that in our brains, we have numerous networks. But, the two that are most relevant to resilience are the task-positive network and the default-mode network.
"The task-positive network is your analytical thinking network. It's the network that helps you create a sense of control. It is not social, it is analytical," he says.
In contrast, the default-mode network is far more empathetic than analytical. "The empathetic network is where emotional self-awareness, creativity, innovation, and the desire to be connected to and interact with others comes from," says Taylor.
Addressing participants at a recent Babson Executive Education seminar on resilient leadership, Taylor described how these two networks are at odds with one another. In other words, when one is active, the other one is suppressed.
"Some of what we've used as our approach to dealing with setbacks comes from the task-positive network, and is actually cognitively restraining our ability to be resilient," he says.
"We all have setbacks. They don't define us. But, do we let them?"
Associate Professor Scott Taylor
Taylor found that some unintended consequences of your task-positive network taking over in trying times include lower engagement in corporations and less innovation or creativity. And, it can often lead to physical exhaustion because task-positive processing isn't as renewing as the default-mode network.
"The task-positive network converges our focus, whereas the default-mode network opens our focus and we see more of ourselves and others, and a broader world view," says Taylor.
The Power of Positive Emotion
According to Taylor, resilience is the ability to bounce back when faced with setbacks. Resilience also is the return to equilibrium after disruption.
"We all have setbacks. They don't define us. But, do we let them?" asks Taylor.
Positive emotion also plays a role in renewal, resilience, and the ability to retain resilience over the long term. "Positive emotion broadens our cognitive repertoire. Positive emotion increases almost every factor of human performance and makes us more receptive to new ideas and feedback. Positive emotion renews us in terms of immune system functioning as well as the ability to persist in an endeavor that we're involved in," says Taylor.
Taylor believes that anyone can develop the capability to more actively, effectively, and efficiently find resilience.
But, where to start? For achieving resilience, one must remember the brain networks.
"Resilience is connected to our cognitive functioning. And, once we understand that the networks are antagonistic, we can draw upon the networks that will help us be more resilient," he says.
To do that, we have to be aware of, and pay attention to, our own emotions, and in particular, garner positive emotions in ourselves and others as a way to activate that default-mode network.
Finally, our relationships play a key role in our ability to be resilient. "We're not on an island by ourselves. We need others," says Taylor.
Tagged Executive Education, leadership, Faculty
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