text:
\section{Introduction}

   A fundamental question in the quest for understanding the Epoch of Reionization (EoR) is the
amount of ionizing radiation released by primeval galaxies into the intergalactic medium (IGM),
which is at present dominated by two major unknowns:

    First, the fraction of ionizing photons escaping
the interstellar (ISM) and circumgalactic (CGM) media, i.e., the ionizing escape fraction, which is
impossible to measure directly at $z\gtrsim 4$ as the IGM becomes fully opaque to ionizing radiation.
Various {\it indirect} alternative approaches, including relations between the gas covering fraction and
reddening \citep[e.g.,][]{Jones2012,Leethochawalit2016,Reddy2016},  H$\beta$ line equivalent width and
UV spectral slope \citep{Zackrisson2013,Zackrisson2016}, or the analysis of the Ly$\alpha$\  spectral line profile
\citep{Dijkstra2016,Verhamme2016} have been proposed, but the values for the escape fraction
remain within the fairly broad range $0.3 \gtrsim f_{\rm esc}^{\rm ion} \gtrsim 0.01$. Additionally,
measurements of the Thomson scattering optical depth to the CMB have placed the `galaxy population
averaged' ionizing escape fraction value within the range $f_{\rm esc}^{\rm ion}\sim0.1-0.2$
\citep[e.g.,][]{Robertson2015,Mitra2016,Sun2016}.

   Second, the number density of faint (down to $-M_{\rm UV}\sim 12 - 10$) galaxies which are often invoked
to reach the total ionizing photon budget required for reionization. The existence and nature of these
objects is still highly uncertain: {\it indirect} constraints on their abundance arise from, e.g., lensing, local dwarf
galaxies and/or Gamma-Ray Burst (GRB) rates studies
\citep{Kistler2009,Trenti2010,Robertson2012,Kistler2013,Robertson2013,Bouwens2015,Yue2016,
Weisz2017}.

   In this paper, we propose that extended emission observed around star-forming galaxies
can provide valuable new insights into both these two unknowns.

   Diffuse extended Ly$\alpha$\  emission (Ly$\alpha$\  halos; LAHs) around star-forming galaxies is practically
ubiquitous at redshifts $2\lesssim z \lesssim6$ \citep[][although see \citealt{Feldmeier2013,
Jiang2013} for non detections]{Steidel2011,Matsuda2012,Momose2014,Wisotzki2015,
Xue2017}. In addition, observations at redshifts $0\lesssim z \lesssim2.5$ demonstrate the (omni-)
presence of \rm H$\alpha$\  halos, whose extent is usually smaller than that of LAHs but significantly larger than
the region observed in UV continuum \citep{Hayes2013,Matthee2016,Sobral2017}. The main
mechanism responsible for the diffuse halos is still not clear, and it is possible that different mechanisms
dominate at different distances from the center of the galaxies.

   We showed in \cite{Masribas2016} that close to star-forming galaxies, $r\sim20 - 30$ physical
kpc, fluorescent radiation powered by ionizing radiation escaping from the ISM may contribute up to $50-60\%$ to
the total Ly$\alpha$\  surface brightness observed by \cite{Matsuda2012} at $z=3.1$. These values depend in
detail on the adopted CGM model and parameters for the central galaxy. At larger distances from the
central galaxy, the predicted fluorescent surface brightness profiles lie below the observations.
We therefore assessed the contribution of nebular emission produced `in-situ' in satellite sources clustered
around the central galaxy in \cite{Masribas2017}. These satellites would be too faint to
be resolved individually, but their integrated emission may be detectable, analogously to the method of
`intensity mapping' \citep[see][and references therein]{Fonseca2017}, but here applied to much smaller
scales. In general, these models matched the Ly$\alpha$\  profiles observed by \cite{Matsuda2012}
and \cite{Momose2014} at $z=3.1$ remarkably well for different clustering prescriptions. The UV
continuum profiles, however, appeared usually a factor $1.5 - 3$ above the data, and we required a
significant evolution of the Ly$\alpha$\  rest-frame equivalent width with UV magnitude of the sources to recover
the observed values.

   Our previous work ignored scattering, because this is extremely sensitive to the physical
properties, distribution and morphology of the neutral gas, all of which are difficult - and still impossible -
to model or simulate from first principles \citep[see][]{McCourt2016}.  Irrespective of these uncertainties,
we expect scattering to smoothen out the surface brightness profiles close to the center, a few
tens of pkpc. We do not expect scattering to affect the profiles at larger distances \citep[see, e.g.,][]
{Laursen2007,Steidel2011,DijkstraKramer2012,Lake2015}.

   Finally, gravitational `cooling radiation' can give rise to extended Ly$\alpha$\  emission \citep{Haiman2000,
DijkstraLoeb2009,Goerdt2010,FaucherGiguere2010,Rosdahl2012,Lake2015}, although predicting
the cooling luminosity is highly uncertain \citep[e.g.,][]{Yang2006,Cantalupo2008,FaucherGiguere2010}.
For the typical halo masses hosting Lyman alpha emitters (LAEs), cooling luminosities appear to fall below
the observed luminosity in halos \citep{Rosdahl2012}, therefore we expect cooling not to be dominant.

 We demonstrated in \cite{Masribas2017} that comparing the surface brightness profiles of the Ly$\alpha$,
\rm H$\alpha$\  and continuum emission can disentangle the significance of each mechanism. This is because the
`size' of the halos is connected to the physical properties of the CGM and the radiative processes affecting
the Ly$\alpha$, \rm H$\alpha$\  and continuum radiation. In detail, continuum radiation (UV \& VIS) has mostly a stellar
origin and is not affected by radiative transfer effects (scattering), thus precisely tracing the star-forming
regions. \rm H$\alpha$\  photons arise as a by-product of the recombination of ionized hydrogen, which mostly occurs
in the HII regions of the ISM (we refer to this as the `nebular component'), but also in gas in the CGM that
has been ionized by (ionizing) photons that escaped from the ISM (we refer to this as the `fluorescent
component'). Ly$\alpha$\  emission occurs mostly in the same regions as \rm H$\alpha$\  but it is a resonant transition, which
allows the Ly$\alpha$\  photons to scatter through neutral hydrogen gas, travelling large distances if they do not
encounter and are destroyed
by dust. In addition, cooling radiation from cold gas being accreted onto the galaxy
can give rise to more extended Ly$\alpha$\  emission compared to H$\alpha$, even in the absence of scattering.
The required surface brightness levels to detect extended emission at wavelengths other than Ly$\alpha$
are challenging (observations of extended H$\alpha$ emission are usually at redshifts where we do not
have access to Ly$\alpha$). Deeper observations from the ground, in combination with observations by the
James Webb Space Telescope \citep[JWST;][]{Gardner2006} can provide us with a more complete spectral
coverage of extended emission.

   In this paper, we apply the formalisms we developed in previous works to redshifts $z\sim6$,
corresponding to the end of the epoch
of reionization. We expect the fluorescent effect of the central galaxy to clearly dominate the surface
brightness profiles close to the center because the contribution of the satellite sources depends linearly
on the cosmic star formation rate, which at these redshifts is much lower than at $z\sim3$. This is
important because our fluorescent profiles are sensitive to the properties of the central galaxy and the
CGM, specifically to the escape fraction of ionizing photons and neutral gas covering factor. At larger
distances, the nebular signature of the satellite sources, if present, may overcome that of the central
galaxy, thus providing evidence for their existence and relevance to the reionization process.
In \S~\ref{sec:formalism}, we summarize the formalism for the calculation of the surface brightness
profiles. In \S~\ref{sec:results}, we present our results for Ly$\alpha$\  (\S~\ref{sec:lya}), and the observational
strategy and predicted \rm H$\alpha$\  and continuum surface brightness profiles (\S~\ref{sec:havis}).
Our findings are discussed and we conclude in \S~\ref{sec:discussion}.

   We assume a flat $\Lambda$CDM cosmology with values ${\rm \Omega_{\Lambda}=
0.7}$, ${\rm \Omega_{ m}}=0.3$ and ${\rm H_0=68\, km\,s^{-1}\,Mpc^{-1}}$.

\section{Formalism}\label{sec:formalism}

   We decompose the total line emission surface brightness profile at impact parameter $b$
from the central galaxy into two components,
\begin{equation}
SB (b) = SB^{\rm cen} (b) + SB^{\rm sat}(b)~,
\end{equation}
where $SB^{\rm cen} (b)$ denotes the fluorescent component (discussed in \S~\ref{sec:sbcen}), and
$SB^{\rm sat}(b)$ the nebular component of satellite sources (discussed in \S~\ref{sec:sbext}).

\subsection{Surface Brightness from the Central Galaxy:\\  Fluorescent emission}\label{sec:sbcen}

  Following \cite{Masribas2016}, we compute the fluorescent surface brightness due to the central
galaxy as
\begin{equation}\label{eq:sb}
SB^{\rm cen} (b) = \frac{2}{(1+z)^4}\int_{b}^{\infty}\frac{r\,{\rm d}r}{\sqrt{r^2\,-\,b^2}}\, C\,\dot n_{\rm ion}(r)\,f_c(r)\,f_{\rm esc}^{\rm ion} (r) ~.
\end{equation}
Here, $\dot n_{\rm ion}(r)$ denotes the total rate at which ionizing photons are produced by the central
galaxy divided by $4\pi r^2$, and $C$ represents the \rm H$\alpha$\  and Ly$\alpha$\  energy
emitted per ionizing photon and unit of solid angle (see \S~\ref{sec:sfr}). The term $f_c(r)$ is the radial
gas covering factor, which quantifies the spatial distribution of neutral gas in the CGM, and
$f_{\rm esc}^{\rm ion}(r)$ denotes the ionizing photon escape fraction (see \S~\ref{sec:medium}).
In practice, we set the upper limit of the integral in Eq.~\ref{eq:sb} to 100 physical kpc. This choice is
somewhat arbitrary and motivated by the virial radius of the dark matter halo hosting the central galaxies.
We tested that variations of a few tens of kpc around this value do not alter our results. We assume that
line emission produced by fluorescence escapes with $100\%$ efficiency. Values other than this,
rescale linearly our central galaxy profiles.

 \begin{figure}
\includegraphics[width=0.47\textwidth]{fc_fesc.pdf}
\caption{{\it Left panel:} Radial profiles of neutral gas covering factor, which denotes
the number of self-shielding clumps along a differential length at a distance $r$ from the central
galaxy. {\it Right panel:} Profiles for the escape fraction of ionizing photons, i.e.,
the fraction of the total number of photons reaching a distance $r$ without being absorbed or destroyed.
The {\it solid and dashed dark cyan lines} represent the two CGM models, parametrized accounting for
the value of the escape fraction at the virial radius (denoted as {\it dashed vertical line}).}
\label{fig:fcfesc}
\end{figure}

\subsubsection{Central Galaxy, $C$ and $\dot n_{\rm ion}(r)$}\label{sec:sfr}

   We consider a $5L^*$ galaxy at $z=6.17$ for our calculations, which corresponds to $M_{\rm
UV}\simeq -22.2$ adopting the fitting formula for $M^*$ from \citealt{Kuhlen2012} (their FIT model).
We require a bright galaxy for the fluorescent component to dominate above the possible nebular
satellite signal and avoid contamination, and at a level that can yield a good signal-to-noise ratio (S/N)
for the observations. As we will show later, targeting fainter galaxies would require the stack of several
objects  or averaging the signal in larger radial bin sizes in order to obtain reasonable S/N. However,
brighter galaxies are rare, and the probability of finding one in the field of view (FOV) considered in our
calculations becomes undesirably small (see \S~\ref{sec:jwst}). The conversion factor between UV
luminosity and star formation rate (SFR) for high redshift by \cite{Madau2014},
\begin{equation}\label{eq:madau}
L_{\rm UV}{\rm [erg\,s^{-1}\,Hz^{-1}]}  = 8.7\times 10^{27}\,{\rm SFR}\,{\rm [M_\odot \, yr^{-1}]}~,
\end{equation}
yields a SFR $\sim 41.4\,{\rm M_\odot \, yr^{-1}}$ for the central galaxy. We have not considered
additional dust attenuation for this calculation because we expect the effect of dust at these redshifts to
be low \citep[see section 3.1.3 in][for further discussion]{Madau2014}. This assumption results in
a lower limit for the SFR and, in turn, for the surface brightness which depends linearly on SFR.

   The SFR then determines the total production rate of ionizing photons as \citep{Robertson2013},
\begin{equation}\label{eq:lumlya}
\dot N_{\rm ion}\,{\rm [photons\,s^{-1}]} =1.38\times10^{53}\, {\rm SFR\,[M_{\odot}\,yr^{-1}] }~,
\end{equation}
which we use to compute $n_{\rm ion}(r)$ as
\begin{equation}\label{eq:lumlya}
\dot n_{\rm ion}(r) =  \frac{\dot N_{\rm ion}}{4\pi r^2}~.
\end{equation}

   We assume that each ionizing photon is converted into H$\alpha$ and Ly$\alpha$ with an efficiency
that is set by case-B recombination. Under this assumption, the parameter $C$ for Ly$\alpha$\  and \rm H$\alpha$\  is
\begin{equation}\label{eq:Cpara}
C\,{\rm [erg\,sr^{-1}]} = \frac{ 1}{4\pi }\,\frac{\alpha_{\rm X}^{\rm eff}}{\alpha_{\rm B}}\,h\nu_X~.
\end{equation}
The fraction $\alpha_{\rm X}^{\rm eff}/\alpha_{\rm B}$ denotes the number of line photons per ionizing
photon
(X takes on `H$\alpha$' or `Ly$\alpha$'), and equals $0.68$ for Ly$\alpha$ and $0.45$ for H$\alpha$.
In detail, both the production rate of ionizing photons and the conversion efficiency into \rm H$\alpha$\  and Ly$\alpha$\  line
photons depend on the IMF, metallicity, stellar populations, etc., at these redshifts \citep[][see also the
discussion in \citealt{Masribas2017}]{Raiter2010,Masribas2016b}. The factors $h\nu_X$ and $1/4\pi$
account for the energy and isotropic emission of the line photons, respectively.

\subsubsection{CGM, $f_c(r)$ and $f_{\rm esc}^{\rm ion}(r)$}\label{sec:medium}

   The characteristics of the CGM at the redshifts of reionization are not known. We
parametrize our ignorance by considering the two most extreme CGM models at $z=3.1$
developed in \cite{Masribas2016}. In these models, the CGM is composed of a spherically symmetric
distribution of neutral hydrogen clumps embedded within a hot medium. The distribution of clumps is
characterized by the cold gas covering fraction, $f_c(r)$, which denotes the number of neutral clumps along
a differential length, at a distance $r$ from the central galaxy. The escape fraction of ionizing photons
is distance dependent in our models, and relates to the covering fraction as $f_{\rm esc}^{\rm ion}(r)= {\rm
exp}[-\int_0^r f_c(r) {\rm d}r]$. To stress, this parameter represents the escape fraction of ionizing photons
out to a distance $r$. Our calculations assume a $100\%$ escape fraction at $r=0$, but our results
scale linearly with this value. We parametrize the two CGM
models using the value of the escape fraction of ionizing photons at the virial radius of the central galaxy
($\sim 25$ pkpc, for a dark matter halo $M_h \sim1.5\times10^{11}\,{\rm M_\odot}$), and describe them
below:

\begin{enumerate}[leftmargin=*]

\item $f_{\rm esc,vir}^{\rm ion}=40\%$: This CGM model derives from that proposed by \cite{Steidel2010},
where the neutral hydrogen clumps are in pressure equilibrium with a radially accelerating
outflowing hot medium. The {\it dark cyan solid lines} in the left and right panels of Figure \ref{fig:fcfesc}
display the gas covering factor and ionizing escape fraction profiles, respectively. This model
produces an escape fraction at the virial radius of $40\%$.

\item $f_{\rm esc,vir}^{\rm ion}=5\%$: This CGM model is obtained after applying an inverse
Abelian transformation to the two-dimensional neutral hydrogen covering factor from the simulations by
\cite{Rahmati2015}, in order to obtain a radial dependent covering factor (see \citealt{Masribas2016} for
this transformation). The corresponding profiles are
represented by the {\it dashed dark cyan lines} in the left and right panels of Figure \ref{fig:fcfesc}.
The escape fraction in this model reaches a value $\sim5\%$ at the virial radius.

\end{enumerate}

   Figure \ref{fig:fcfesc} shows that the radial dependence of the escape fraction is mostly driven by the
covering factor profile in the first $\sim50$ pkpc from the central galaxy. The left panel shows that
the covering factor in the $f_{\rm esc,vir}^{\rm ion}=40\%$  model is smaller at those distances,
which yields a smoother decrease of the ionizing escape fraction in this case. Conversely, the escape
fraction profile for the $f_{\rm esc,vir}^{\rm ion}=5\%$ model reaches a low value rapidly at
$r\sim 25$ pkpc since the covering fraction decreases slowly with radial distance.

\subsection{Surface Brightness from Satellite Sources:\\  Nebular radiation}\label{sec:sbext}

   We calculate the Ly$\alpha$\  and \rm H$\alpha$\  surface brightness of the satellite sources as in \cite{Masribas2017},
\begin{equation}
SB^{\rm sat}(b)=\frac{2}{(1+z)^4} \int_b^{\infty} \epsilon_X [1+\xi_X (r)] f_{\rm esc,X}\, \frac{r{\rm
d}r}{\sqrt{r^2-b^2}} ~,
\end{equation}
where $\epsilon_X$ refers to the average cosmic emissivity for Ly$\alpha$\  or \rm H$\alpha$\  (see \S~\ref{sec:emiss}),
$\xi_X$ is the correlation function for the corresponding radiation (see \S~\ref{sec:clust}), and
$f_{\rm esc,X}$ denotes the escape fraction from the satellites for the transition ${\rm X}$. We (arbitrarily)
set a fiducial value $f_{\rm esc,X}= 40\%$, but also explore the broad ranges $0.2 \ge f_{\rm esc,X} \ge
0.7$ and $0.1 \ge f_{\rm esc,X} \ge 1.0$, because the escape fraction is not known at these high redshifts,
especially for faint satellite sources, and is linked to the uncertain presence of dust,  which
likely affects more the Ly$\alpha$\  photons than those of \rm H$\alpha$\  due to radiative transfer effects and
the frequency dependence of the attenuation curve. We again limit the
integral to 100 pkpc, and enable the presence of satellites at distances above 10 pkpc.

   In addition to nebular Ly$\alpha$\  and \rm H$\alpha$\  radiation, the satellite sources will also produce continuum radiation
associated to star formation, which will result in an overall extended continuum profile.
We calculate the visible (rest-frame, VIS) continuum surface brightness profile from that of H$\alpha$ as
\begin{equation}
SB_{\rm VIS}(b)= \frac{(1+z)}{\rm EW_{H\alpha}}\frac{\lambda_{\rm H{\alpha}}^2}{c}\, SB_{\rm H\alpha}^{\rm sat}(b)   ~.
\end{equation}
We assume a fiducial \rm H$\alpha$\  line equivalent width (rest-frame) ${\rm EW_{H\alpha}=300\,\, {\rm \AA}}$,
considering the observations by \citealt{Queralto2016} (and references therein), and also explore the
ranges $450\geq {\rm EW_{H\alpha}\,(\AA) \geq 150}$ and $700\geq {\rm EW_{H\alpha}\,(\AA)
\geq 50}$.
The parameters $\lambda_{\rm H\alpha}$ and $c$ denote the rest-frame \rm H$\alpha$\  wavelength and the speed of light,
respectively and, combined with the term $(1+z)$, yield a surface brightness per unit frequency.

\subsubsection{Emissivity, $\epsilon$}\label{sec:emiss}

   To obtain the average \rm H$\alpha$\  cosmic emissivity for the satellite population, we calculate the cosmic SFR
density at the redshift of interest using equation 2 in \cite{Robertson2015}, which considers radiation from
sources down to $M_{\rm UV}\sim-13$, and assume that the SFR for the satellites equals this value.
In reality, the SFR for the satellites will be a fraction of total cosmic star formation, but its value is unknown
and degenerate with the escape fraction of \rm H$\alpha$\  photons \citep[e.g.,][]{Trenti2012}. We finally use the relation by \cite{Kennicutt2012},
\begin{equation}\label{eq:sfrL}
L_{\rm H\alpha}\,{\rm [erg\,s^{-1}]} =1.86\times10^{41}\, {\rm SFR\,[M_{\odot}\,yr^{-1}] }~,
\end{equation}
to obtain the average volumetric emissivity for \rm H$\alpha$\  radiation. We consider that
the emissivity for Ly$\alpha$\  will simply be a factor $8.1$ higher, which is the proper intrinsic ratio
between the volume emissivities for Ly$\alpha$\  and \rm H$\alpha$\  computed from the tables in \cite{Osterbrock1989},
consistent with the approach adopted in Eq.~\ref{eq:Cpara}, and noting again the
dependence of this value on dust content.

\subsubsection{Clustering, $\xi(r)$}\label{sec:clust}

   We adopt a power-law two-point correlation function for the clustering of satellite sources
around the bright central galaxy, with correlation length $r_0 = 3.79\, {\rm Mpc\,h^{-1}}$
and power-law index $\alpha=-1.8$, as reported by \cite{Harikane2016}, for their sample of
LBG galaxies with average magnitude $\langle M_{\rm UV} \rangle=-19.3$ at $z=5.9$. In
\cite{Masribas2017} we used another clustering prescription because, at small distances,
the departures from a power-law by the data of \cite{Ouchi2010} at $z=3.1$ were significant.
In the current case, however, the power-law approach is consistent within 1$\sigma$ with the
data by \cite{Harikane2016}, which extend up to $\sim12$ pkpc from the central galaxy. We
consider the same bias for the \rm H$\alpha$\  radiation and the satellite sources because radiative transfer effects,
i.e., scattering, are not present for the case of \rm H$\alpha$\  \citep{Masribas2017}. We adopt these same values
for the satellite clustering when comparing with
the LAE data by \cite{Momose2014} and \cite{Jiang2013}, owing to the broad range of uncertainties
and overlap of values between the correlation lengths from $z=5.7$ to  $z=6.8$ in the different data
samples of LAEs and LBGs in \cite{Ouchi2010} and \cite{Harikane2016}, respectively.
Possible variations of the clustering of sources and/or radiation are engulfed in the large range explored
for the escape fraction described above.

\section{Results}\label{sec:results}

   We present below our results. In \S~\ref{sec:lya}, we apply and compare our analytical models to the
observational Ly$\alpha$\  data by \cite{Momose2014} and \cite{Jiang2013} at $z=5.7$ and $z=6.6$. In
\S~\ref{sec:havis}, we detail a potential JWST observational strategy (\S~\ref{sec:jwst}), and present the
predicted \rm H$\alpha$\  and VIS continuum surface brightness profiles at $z=6.17$ (\S~\ref{sec:predict}).

\subsection{{\rm Ly$\alpha$}}\label{sec:lya}

\begin{figure*}
\includegraphics[width=0.49\textwidth]{M14_z57.pdf}\includegraphics[width=0.464\textwidth]{J13_z57.pdf}
\caption{Comparison between our predicted Ly$\alpha$\  surface brightness profiles and the observational data
by \citealt{Momose2014} (their mean values, M+14, {\it left panel}) and \citealt{Jiang2013} (J+13, {\it
right panel}) at
$z=5.7$. The {\it yellow points with uncertainties} denote the observed profiles and the {\it yellow dashed
lines} the PSFs. The profiles of the $f_{\rm esc,vir}^{\rm ion}=40\%$ ($f_{\rm esc,vir}^{\rm ion}=5\%$)
CGM models are displayed as the {\it solid} ({\it dashed}) {\it dark cyan lines}. The {\it solid black line} and
{\it shaded grey bands} represent the fiducial model for the profiles of the satellites and the different
escape fraction ranges, respectively. The {\it solid (dashed) red lines} denote the total (central + satellite)
profiles for the $40\%$ ($5\%$) CGM models. The SFRs for the central galaxies are quoted in every panel.
In general, the low escape fraction models result in a better match to both data sets, although the
contribution of satellites is unclear (see text).}
\label{fig:57}
\end{figure*}

\begin{figure*}
\includegraphics[width=0.49\textwidth]{M14_z66.pdf}\includegraphics[width=0.464\textwidth]{J13_z66.pdf}
\caption{Same as Figure \ref{fig:57} but at $z=6.6$. In this case, the data by Momose et al. (2014) seems
to be better matched by the model with high ionizing escape fraction, although the error bars are consistent
with the two CGM models within 1$\sigma$ for most of the data points, and the possibility for the presence
of artifacts in the observations is elevated (see text). As at $z=5.7$, the data by Jiang et al. (2013) favors
the low escape fraction model and discards the contribution from satellites. }
\label{fig:66}
\end{figure*}

   Figures \ref{fig:57} and \ref{fig:66} display the comparison between our predicted Ly$\alpha$\  surface brightness
profiles and the observational data at $z=5.7$ and $z=6.6$, respectively, by Momose et al. 2014 (their
mean values, {\it left panels}) and Jiang et al. 2013 ({\it right panels}). The {\it yellow data points and error
bars} denote the data and uncertainties, and the {\it yellow dashed lines} the point-spread functions
(PSFs) quoted by these authors. In general, the data by Momose et al. show significant extended
emission well beyond the PSF. Jiang et al. argue that the extended emission in their observations is
due to the fact that the central galaxy is resolved, but not to the presence
of an extended halo. The Ly$\alpha$\  data by Jiang et al. corresponds to the stack of 43 (40) LAEs at $z=5.7$
($z=6.6$), a subsample selected from the observations by \cite{Ouchi2008,Ouchi2010,Kashikawa2011},
reaching a surface brightness limit $\sim1.2\times10^{-19}\,{\rm erg\,s^{-1}\, {\rm cm}^{-2}\,arcsec^{-2}}$. The
stacked profiles in Momose et al. arise from 397 (119) LAEs at $z=5.7$ ($z=6.6$), selected from the parent
sample of observations by \cite{Ouchi2008,Ouchi2010}, and reach similar (within a factor $\sim2$) Ly$\alpha$\
surface brightness limits compared to the Jiang et al. data. The two datasets of overlapping (but
different) galaxy samples do not agree with each other; Momose et al. attributes the lack of extended
emission in the analysis by Jiang et al. to the small sample size.

   To obtain consistent comparisons, we calculate the star formation rates for the central galaxy in
the observed data sets as follows: We integrate the corresponding UV continuum surface brightness profiles by
\citealt{Momose2014} (their figure 3) to calculate the UV luminosity and then use Eq.~\ref{eq:madau} to
obtain the SFRs. Since the UV surface brightness profiles or galaxy sample are not available in
\cite{Jiang2013}, we calculate the ratio between the integrated Ly$\alpha$\  surface brightness profiles in
the inner regions, where the central galaxy dominates, in \cite{Momose2014} and
\cite{Jiang2013}, and assume these Ly$\alpha$\  ratios to be the same as for the SFRs. At $z=5.7$, integrating
up to a distance of 4 (1) arcsec, the ratio is $\sim5.5$ ($\sim4$). At $z=6.6$, the same upper limits
for the integral result in ratios $\sim12.8$ and $\sim 6.6$, respectively. For simplicity, we set
the ratios to 5.5 and 10 at $z=5.7$ and $z=6.6$, respectively, and stress that the results depend linearly
on these parameters.

   The {\it dark cyan solid (dashed) lines} in Figures \ref{fig:57} and \ref{fig:66} denote the surface
brightness profiles for the $f_{\rm esc,vir}^{\rm ion}=40\%$ ($f_{\rm esc,vir}^{\rm ion}=5\%$) CGM models,
with the SFR of the central galaxy quoted in each panel. The {\it black lines and shaded grey areas}
represent the profiles for the fiducial model and the two ranges of nebular radiation escape fraction,
respectively, for the satellite sources. The {\it red solid (dashed) lines} represent the total, central +
satellite galaxies, surface brightness profiles for the $40\%$ ($5\%$) CGM models.

   At $z=5.7$ (Figure \ref{fig:57}), both data sets are better matched by the low escape fraction CGM
model, despite the factor $5.5$ between the respective SFRs. The contribution of satellites appears,
however, unclear: For the Jiang et al. data (right panel), the match to the observations
is the best when satellites are ignored while, for the Momose et al. case (left panel), the satellites
provide the necessary signal to reach the observed values at distances $r\gtrsim15$ pkpc.

   At $z=6.6$ (Figure \ref{fig:66}), the data by Jiang et al. (right panel) is better reproduced by the low
escape fraction CGM model again but, contrary to the previous findings, for the Momose et al. data (left
panel), even the high escape fraction model lies below the observations in this case, and the contribution
of the satellite sources is not enough to approach the observed levels. However, the uncertainties in the
data by Momose et al. here are significantly large, resulting in the low escape fraction model being
at a $\lesssim1\sigma$ level for most of the data points. The high observed profile might be a consequence
of the high star formation rate, ${\rm SFR\sim20\,M_{\odot}\,yr^{-1}}$, but it is more likely that the
observations below $\sim1-2\times10^{-19}\,{\rm erg\,s^{-1}\, {\rm cm}^{-2}\,arcsec^{-2}}$ are mostly driven
by systematic effects, as tested by \citealt{Momose2014} (their section 3.2 and figure 8).

   Taking into account the possible systematic effects in the data by \cite{Momose2014} at $z=6.6$, the low
ionizing escape fraction CGM model, $f_{\rm esc,vir}^{\rm ion}=5\%$, seems to be the most consistent one
with the observed Ly$\alpha$\  profiles in general, regardless the average SFR values for the central galaxies, which
cover the corresponding magnitude range $-19\gtrsim M_{\rm UV} \gtrsim -21.5$. If this result is confirmed,
these galaxies would not have contributed significantly to the reionization process, and a large
population of fainter galaxies with a high ionizing escape fraction would be necessary. However,
the presence of satellite sources is never required by the data in \cite{Jiang2013}, and only at distances
$r\gtrsim15-20$ physical kpc from the central galaxy by the observations of \cite{Momose2014}, where
the uncertainties and possible systematic effects are important. The apparent discrepancy between the
two different data-sets prevents us from drawing firm conclusions. We present below the H$\alpha$
and visual continuum predicted profiles and JWST observations, which will constitute additional probes,
and will further extend this discussion in \S~\ref{sec:discussion}.

\subsection{\rm H$\alpha$\  and VIS}\label{sec:havis}

   We present below the predicted \rm H$\alpha$\  and visible (VIS) continuum surface brightness profiles
(\S~\ref{sec:predict}), and the approach we adopt for future JWST observations of these extended
halos (\S~\ref{sec:jwst}). Contrary to Ly$\alpha$, the \rm H$\alpha$\  transition is not resonant, implying that the \rm H$\alpha$\
photons do not scatter the neutral hydrogen gas. This characteristic facilitates the interpretation of
the \rm H$\alpha$\  profiles compared to those of Ly$\alpha$: \rm H$\alpha$\  photons, either come from star formation or
fluorescence, thus tracing their production sites.

\subsubsection{\rm H$\alpha$\  \& VIS: JWST Observational Strategy}\label{sec:jwst}

   We consider the near infrared camera, NIRCam, instrument onboard JWST for our observations,
with a field of view ${\rm FOV=9.68}\, {\rm arcmin^2}$. We perform the calculations at $z=6.17$ for
the \rm H$\alpha$\  radiation to match the position of the F470N narrow-band (NB) filter, with a band width (BW)
${\rm BW=0.051\,\mu}$m, and centered at $4.708\,\mu$m observer-frame. For the visible continuum, we
adopt the filter F410M, with ${\rm BW=0.438\,\mu}$m, and centered at $4.082\,\mu$m, corresponding to
a rest-frame wavelength $\sim 5693\,{\rm \AA}$. In both cases, we consider a total observing time
$t_{\rm exp}=10^5$ s. We compute the sky background at $4.708\,\mu$m following the technical note
\url{http://www.stsci.edu/~tumlinso/ nrs_sens_2852.pdf} (Eq.~22), resulting in a surface brightness
$SB_{\rm sky}=6\,\mu {\rm Jy\, arcsec^{-2}\,(\sim 22\,mag\,arcsec^{-2})}$.

\begin{figure*}
\includegraphics[width=0.47\textwidth]{sb_ha62_7LBG22.pdf}\includegraphics[width=0.50\textwidth]{sb_cont62_7LBG22.pdf}
\caption{ {\it Left panel:} Radial surface brightness profiles with physical distance for one $5L^*$ galaxy.
The {\it solid} ({\it dashed}) {\it dark cyan lines} denote the \rm H$\alpha$\  profiles of the
$f_{\rm esc,vir}^{\rm ion}=40\%$ ($f_{\rm esc,vir}^{\rm ion}=5\%$) CGM models. The {\it black line}
represents the profile from the satellite sources considering $f_{\rm esc}^{\rm H\alpha}=40\%$, while the
{\it grey shaded areas} denote the ranges $0.2 \ge f_{\rm esc}^{\rm H\alpha} \ge 0.7$ and $0.1 \ge
f_{\rm esc}^{\rm H\alpha} \ge 1.0$. The {\it solid (dashed) red line} denotes the total (central + satellite)
profile for the $40\%$ ($5\%$) CGM model, and the {\it blue} and {\it green data points} with their
uncertainty, are the predicted corresponding JWST observations for these total profiles. The {\it inset
figure} zooms in the inner $r \le 30$ pkpc. The green vertical lines denoting uncertainties in the
observations are slightly shifted from the original position to facilitate the visualization.
{\it Right panel:} Radial visible (VIS) continuum profile due to the satellite sources, obtained after
stacking the images of $\sim 18\,L>0.1 L^*$ galaxies detected in one NIRCam pointing.
The {\it black solid line} denotes the fiducial model (${\rm EW_{H\alpha}=300\,\, {\rm \AA}}$),
and the shaded regions the equivalent width ranges $450\geq {\rm EW_{H\alpha}\,(\AA) \geq 150}$ and
$700\geq {\rm EW_{H\alpha}\,(\AA) \geq 50}$. The observations and uncertainties are displayed in red.}
\label{fig:sb}
\end{figure*}

   Following \citealt{Masribas2017} (Appendix B), we derive the uncertainties in the observations from
the signal-to-noise ratio (S/N), computed as ${\rm S/N}=N_s / \sqrt{N_s+N_{\rm sky}}$, where $N_s$
and $N_{\rm sky}$ are the azimuthally integrated source and sky photon number counts, respectively,
defined as
\begin{eqnarray}
N_s &=& \frac{f_{\rm H\alpha}}{h\,\nu_{\rm H\alpha}^{\rm obs}}\, {\rm A_{ aper}}\, \eta\, t_{\rm exp} ~,\\
N_{\rm sky} &=& \frac{f_{\rm sky}}{h\,\nu_{\rm H\alpha}^{\rm obs}}\,{\rm BW}\, {\rm A_{ aper}}\, \eta\, t_{\rm exp} ~.
\end{eqnarray}
The aperture for JWST is ${\rm A_{ aper}=25\,m^2}$, and $\eta=0.469\, (0.274)$ is the total system
throughput for the continuum (line) filter. The terms ${f_{\rm H\alpha}}$ and ${f_{\rm sky}}$ are the
source and sky fluxes,
respectively, resulting from the integration of the surface brightness over the area of the corresponding
radial annulus around the central galaxy, and ${h\nu_{\rm H\alpha}^{\rm obs}}$ denotes the \rm H$\alpha$\  photon
energy at the observer frame, $z=6.17$. We include the term BW in the sky background
and VIS calculations because the sky and continuum are in units of flux density. We have not
accounted for other systematics or noise effects in this simple calculation but we have checked that
our S/N results are in broad agreement with those produced using the JWST on-line Time Exposure
Calculator\footnote{\url{https://jwst.etc.stsci.edu/}} (ETC).

   We obtain the profile driven by the PSF as follows: We compute the encircled energy (EE) radial profile
for the narrow band F470N filter with the publicly available package
\texttt{WebbPSF}\footnote{\url{http://pythonhosted.org/webbpsf/}}, and convolve it with the total \rm H$\alpha$\
luminosity produced by the central galaxy, assumed to be a point source. We plot the resulting PSF
profile as the {\it yellow dashed line} in Figure \ref{fig:sb}, after applying the luminosity distance and
geometric factors to transform the luminosity into surface brightness.

   To obtain a high S/N for the \rm H$\alpha$\  profiles, it would be desirable to observe the brightest possible galaxies,
$L ~\rlap{$>$}{\lower 1.0ex\hbox{$\sim$}} 10 L^*$, but these objects are sufficiently rare that it is unlikely to find one in a single JWST NIRCam
pointing (observation). Fainter objects, $L\sim L^*$, result in larger number densities but, in this case, the signal
from possible satellites easily overcomes that of the central galaxy, contaminating the escape fraction
measurements. In addition, the stacking of a large number of these objects would be required to reach a good
S/N, introducing possible systematics from the complex stacking methodology, and increasing the number
of JWST pointings, i.e., observing time. We consider the case of observing one $5L^*$ galaxy previously
detected by a wide-field spectroscopic or NB imaging survey covering an area in the sky of 10 deg$^2$.
We adopt these numbers as a compromise between the number of $5L^*$ objects in the volume adopted,
$\sim 2$ when integrating the UV luminosity function at $z=6.17$ with the parameters from the fitting formula
by \citealt{Kuhlen2012} ($M_{\rm UV}^*=-20.374$, $\phi^*=9.5\times10^{\rm -4}\,{\rm Mpc^{-3}\, mag^{-1}}$,
and $\alpha=-1.85$), the required observing time, and the S/N.

    The signal from the satellite sources is
independent of the brightness of the central galaxy, assuming that the clustering is similar for a range
of galaxy luminosities. We consider the stacked image of $\sim 18\,L>0.1 L^*\,(M_{\rm {UV}}<-18)$
galaxies for the calculation of the visible continuum observation, which is the number of objects present in
the NIRCam FOV (a single pointing).

\subsubsection{\rm H$\alpha$\  \& VIS: Predicted Surface Brightness Profiles}\label{sec:predict}

   We present the resulting \rm H$\alpha$\  and continuum surface brightness profiles, considering one
$5L^*$ and eighteen $L>0.1L^*$ galaxies, respectively, at $z=6.17$. The analysis of the continuum
will be useful to probe the satellite contribution for both, assessing their existence and separating
their contribution from that of the central galaxy.
The {\it left panel} in Figure \ref{fig:sb} displays the surface brightness profiles for H$\alpha$,
where the {\it dark cyan solid (dashed) line} denotes the predictions for the $f_{\rm esc,vir}^{\rm ion}=
40\%$ ($f_{\rm esc,vir}^{\rm ion}=5\%$) CGM model for the central galaxy.
The {\it black line} represents the fiducial profile for the satellite sources at $r\ge10$ pkpc, considering
$f_{\rm esc}^{\rm H\alpha}=40\%$, and the {\it grey shaded areas} represent
the ranges $0.2 \ge f_{\rm esc}^{\rm H\alpha} \ge 0.7$ and $0.1 \ge f_{\rm esc}^{\rm H\alpha}
\ge 1.0$. The {\it solid (dashed) red line} denotes the total (central + satellites)
profile for the $40\%$ ($5\%$) CGM model, and the {\it blue} and {\it green error bars} represent the
uncertainties in the JWST observations described in the previous section for the corresponding total
profiles. The {\it yellow dashed line} denotes the PSF profile. The {\it inset figure}
zooms into the range $5 \lesssim r \lesssim 30$ pkpc. The {\it right panel} shows
the surface brightness profiles and observations of the visible continuum from the satellite galaxies, for
the fiducial model (${\rm EW_{H\alpha}=300\,\, {\rm \AA}}$), and the equivalent width ranges $450\geq
{\rm EW_{H\alpha}\,(\AA) \geq 150}$ and $700\geq {\rm EW_{H\alpha}\,(\AA) \geq 50}$. The {\it red data
and error bars} denote the JWST observations, which present detections up to $\sim 40$ pkpc from the
center of the galaxy.

   The left panel in Figure \ref{fig:sb} indicates that JWST observations will be able to probe the
surface brightness profiles up to distances $r\sim 50$ pkpc for the case of the $f_{\rm esc}^{\rm
ion}\sim40\%$ model. These observations would imply that a significant fraction of the ionizing radiation
from galaxies reaches large distances from the center, contributing to the reionization of the
intergalactic medium (IGM). Instead, a low ionizing escape fraction similar to the $f_{\rm esc}^{\rm ion}
\sim5\%$ model, results in a profile detectable up to $r\sim 15$ pkpc. This result would indicate that
most of the ionizing radiation does not escape beyond the CGM, thus
not contributing significantly to cosmic reionization.

   The fluorescent profile of the central galaxies, especially for the low ionizing escape fraction cases,
might be contaminated by the PSF and the nebular radiation from the satellite sources. Observations of the
VIS continuum profile will contribute differentiating between the two processes. A steep (almost non-existent)
continuum profile beyond the central galaxy would imply that satellite radiation (and sources) are
not important, and the extended profiles are driven by fluorescence. Conversely, an extended continuum
signal would imply the presence of star formation (satellite sources) in the halo of the central galaxy,
and would allow for the investigation of the nature and contribution of these faint source population to
reionization. It is likely that the faint sources are too faint to be individually detected but their collective
emission would produce the observable predicted profile, resembling the intensity mapping methodology.
The right panel in Figure \ref{fig:sb}, however, demonstrates that the observation and stacking of
several sources is necessary to obtain high S/N and differentiate between the different escape fraction
scenarios for the satellite sources. Alternatively, larger radial bins sizes than the ones adopted here
would provide higher S/N values at the cost of spatial resolution.

\section{Discussion and Conclusion}\label{sec:discussion}

   We have proposed that extended emission around galaxies at $z\sim6$ can be used to constrain the
escape fraction of the ionizing radiation and/or the presence of faint satellite galaxies
during the late stages of cosmic reionization. We have predicted radial surface brightness profiles
which include the contribution from ({\it i}) fluorescent emission powered by ionizing radiation leaking from the
central galaxy \citep[as in][for two different CGM prescriptions]{Masribas2016}, and ({\it ii}), nebular emission
from faint satellite sources that possibly resided within the halo of the central galaxies \citep[as in][]{Masribas2017}.
We have compared our predictions with observations of Ly$\alpha$\  halos at $z=5.7$
and $z=6.6$, and have also predicted \rm H$\alpha$\  and visible continuum surface brightness profiles which may be
detectable within future JWST observations.

   We present and discuss our findings below:

\begin{itemize}[leftmargin=*]

\item Our comparison of models to observations favors the model with a very low escape fraction of ionizing
radiation, $f_{\rm esc}^{\rm ion}\sim 5\%$, from galaxies within the range of magnitudes $-19\gtrsim M_{\rm
UV} \gtrsim -21.5$. This scenario implies that these galaxies do not contribute significantly to the reionization
process. Therefore, if galaxies are the major contributors to the reionization process, as recently
restated by \cite{Parsa2017}, a large population of faint sources with a high ionizing escape fraction
is necessary.

\item The presence of faint satellite sources is unclear.
Two out of four comparisons with current Ly$\alpha$\  data indicate that satellite sources might
contribute to the extended Ly$\alpha$\  emission, but the
effect of systematics and uncertainties in the observations do not allow for a clear conclusion. Given the
required existence of faint sources driven by the low escape fraction results, if the presence of satellite
sources around brighter galaxies is ruled out by the observations, this might imply that the population
of faint objects is spread out within the intergalactic medium, making its detection more challenging.

\item JWST will be able to probe the ionizing escape fraction from one bright,
$L\gsim5L^*$, galaxy up to distances of a few tens of pkpc from the center. Fainter galaxies
and/or a high signal-to-noise ratio for the continuum observations require the observation
and stacking of several objects.

\end{itemize}

   We stress that we have adopted and extrapolated two CGM models that were derived to match
observables at redshifts around $z\sim3$. The validity of our results, therefore, depends on the ability of
these two models to realistically describe the medium surrounding $z\sim6$ galaxies. While a more detailed
parametrization of the CGM at high redshift (if currently feasible) is beyond the scope of our work, future
observations of extended emission together with absorption studies \citep[e.g.,][see also
\citealt{Steidel2010,Steidel2011}]{DijkstraKramer2012,HennawiProchaska2013,Prochaska2013} will clearly enable
us to use our proposed method to further constrain the escape fraction.

   The prospects for doing this experiment at lower redshifts, $z \sim 3-4$, are interesting as the
surface brightness for emission lines depends on redshift as $(1+z)^4$. However, the contribution from
satellites can be more important at these low redshifts and overlap with the signal from the central
galaxy \citep{Masribas2017}. At $z \sim3.5$, we may be also benefiting from the observations by
HETDEX \citep{Hill2008} or MUSE \citep{Bacon2014}, for constraints on Ly$\alpha$\  halos.
While the escape fraction of ionizing photons at $z\sim3.5$ is not directly relevant for
reionization, using our approach may provide new insights for constraining $f_{\rm esc}^{\rm ion}$ and,
in turn, the physical properties of the circumgalactic medium.

\section*{acknowledgements}
LMR is grateful to the ENIGMA group at the MPIA in Heidelberg for kind hospitality and
inspiring discussions. Thanks to Chuck Steidel and Charlotte A. Mason for useful discussions
about the use of \rm H$\alpha$\  radiation for high-z studies, Erick Zackrisson for clarifying several
observational aspects and Dan Weisz for an inspiring discussion on the presence of
faint galaxies during reionization. LMR and MD are grateful to the Astronomy Department at
UCSB for kind hospitality.

\bibliographystyle{apj}

redpajama_set_name: RedPajamaArXiv


TitanFall from Infinity Ward, the developers behind Call of Duty, have delivered their next big title, and it's addictive!
You are a "pilot" in a sci-fi world in the midst of a rebellion between a world-domineering corporation and a rebellion force. But don't think too hard about the narrative, because there isn't much to it (not that you'll mind).
I've shared earlier (blog) that I believe there is a difference between sci-fi shooters (e.g. Halo) and modern‑day shooters (e.g. COD) in that its easier for younger games to remember that they are playing a game and not imagining themselves within today's world. As such, it's easier for me to see younger gamers (12-14) starting with sci-fi shooters over modern day (16+).
Titanfall does not appear to have any/much abrasive dialog in the narrative, and there isn't much detail when the seeing your opponents get shot (no blood spray), so they just fall over and dematerialize a few seconds later. So, other than the language that other real people might use during multiplayer chat and the acknowledgement that you are shooting at people (instead of aliens), I think it would play well with tweens and teens, ideally in a LAN party or closed-session among friends.
The real twist that Titanfall has over other shooters, and it is a fun one, is that you'll spend part of your time in each battle as simply a Pilot (man), shooting as normal, and part of your time inside a mechanized goliath, dealing out massive damage. Each style, man or machine, has a variety of weapons (with customizations for each weapon) and additional options to let you play the way that you want. As you level up (earning XP for almost everything that you do during the game), new weapons, modifications, etc. will be unlocked for your use. As a man, you have some cool acceleration abilities to run on walls, big jumps, etc. – but the biggest reward is when your Titan falls (hence the name) to the planet so you can jump in and get busy. As in many shooter games, there is a "campaign" (story) to get you started and then endless-hours of multiplayer combat.
But even the campaign, isn't. The campaign is a series of cut scenes that knits together around a dozen multiplayer combat sessions. And that's too bad because the faux campaign did something clever – you play on both sides of the conflict, first through the IMC corporation and then through the rebellion. But after those veiled multiplayer combats, then you're free to do what Infinity Ward really wants you to do – lots more multiplayer combat.
If you are used to Call of Duty or Halo style multiplayer matches, you will feel right at home here – with the typical match types such as "attrition" (team deathmatch), "hardpoint" (capture the flag), etc. As the CoD developers that they are, the multiplayer combat is everything that you could hope for – very fast paced, diversity in the battlezones, and customizable Pilot and Titan loadouts (configurations of equipment that let you play your favorite gear, your way).
My only real complaint with the multiplayer is my same complaint with any of the COD games – the matchmaking system.
If you don't jump in to the game early after release and then commit regular time to it, you will be cannon fodder for a while. In my very first match, I was a level 1 and the other five members of my team were between 22 and 45, with a majority of the other team being entirely between levels 11 and 19. I got killed a lot (by the teens on the other side), but my juggernauts killed them more – and our team won (yay?). Imagine a middle-school football player lining up on an NFL front line facing off against a highschool/college team, and you get the idea (with only a little exaggeration). Contrast that with the Halo series, where noobs play against noobs, enthusiasts against each other, and obsessives are challenged by their peers. Levels aren't just a measure of experience, but also enable better weapons and modifiers that give even further advantages.
To the core COD/MW/Titanfall faithful, this disparity won't matter – because the mechanics are close enough that you'll eventually get there, and you are used to starting as cannon fodder. Before long, your long-developed skills will shine through and you'll be using the fresh meat to help you level up further. For the rest of us (especiallly if you do choose to let tweens do this as their first shooter), the lack of equitable matchmaking will likely limit the long-term playability, as the diehards continue to dominate and the casual players fall away in pursuit of the next big title.
But until then, I will be among the mindless masses as I play "just one more round" repeatedly.
It is also a really good example of "Microsoft's vision for Three Screens and a Cloud" that doesn't get a lot of airtime, including offerings for Windows Phone, Windows desktop and (coming soon) to Xbox360 & XboxOne – powered by XboxLive. Interestingly, the game came out for Windows Phone 8 and Windows 8 desktop first – and is only now coming out for consoles. By the way, it plays very nicely on my Surface Pro, including support for a wired Xbox gaming controller and looks great on an HDMI TV/screen (see accessories blog URL).
The 3 Screens thing isn't just about comparable offerings, but a unified offering. After having played through about half of the missions on my tablet, I bought the version for my phone – and my game save, including progress and status, came right in. In fact, a few Xbox Achievements lit up on my phone, shortly after having started playing – because I had finished those objectives (and earned the achievements) in the Tablet edition. I presume that the shared experience will carry to the console versions, though the console versions also promise some big enhancements, such as multi-player.
As stated earlier, you are futuristic "Spartan" (armored super soldier) moving from one combat scene to another. It's hard to say anything negative against H:SA, other than the two-thumbs on sweaty glass controls can be a little frustrating on smaller Windows Phones, but totally works and is surprisingly intuitive on bigger phones, tablets and PCs – and as I mentioned, works great with a gaming controller.
Those familiar with the HALO franchise will immediately be immersed with recognizable Covenant baddies, the standard variety of UNSC and alien weapons, etc.
For younger players who haven't tried Halo yet, this is a great first entry for them – and one that will be more "Mom approved" than the first-person shooters.
And for those newer players, I wholeheartedly also recommend the full-featured Halo Wars (URL) title, which you should be able to pick up used for under $10, with great fun (and co-op) for younger (9-12) gamers and friends/siblings/parents.
December 24th (Merry Christmas, Spartans!!).
As always, thanks for reading … Have fun playing with your kids !
Happy Wars on Xbox Live Arcade may be the cleverest and cutest game that you haven't tried with your gamer-kids. This review, like the game itself, will jump right into the middle of it: it is a game about constant battles of swords, axes, clubs and magic. You'll be battling within a few seconds of the game starting and continue doing so until the timer ends. That may not sound like the description of a normal XboxDad Family-Friendly game, but this one really is.
Your character, as well as all of the other players, looks like a LittlePeople™ or PlaySkool™ figurine that your 4-7 year old might have played with. You will then dress them up in some basic armor, a helmet/hat, perhaps a shield, and then a weapon (sword, axe, club or magic staff). Some weapons look like fish or baseball bats, while the staffs/wands might be flowers, lollipops or plastic flamingos. The three character types (Warrior, Mage, and Cleric) allow for offensive fighting, zapping from a distance or healing/building others, respectively.
It should be noted that there is no blood in the typical sense, such as from sword cuts or other battle damage, nor squirting or puddles upon being killed. Instead, the only blood is seen as some weapons (a sword that already has some red on it, usually referred to as ketchup or strawberry sauce) or costume items (a hat that looks like a bandage covering a wound); but no gore of any kind.
The violence is similar to the Lego games or any other child-friendly action game. You'll run around whacking/zapping people (a lot). You'll whack them, they will whack you, and one of you will eventually run out health points (life). At which point, the color on the screen will fade to black & white, your character might momentarily be seen with X's instead of eyes or some other goofy expression, and then your person will re-spawn at your team's nearest location.
Story Mode (single player) – somewhat similar to the cut scenes from Angry Birds or Lego games, as a way to create a narrative before playing a range of single-player stories. You'll have a few AI players to help you, and battle numerous baddies as you progress through the story.
Quick/Co-Op Mode (multiplayer) – provides two teams of up to 15 players (or AI) each; red and blue. Each side has a home base castle and seeks to take over the other team's castle. Along the way, there are multiple "towers" that can be claimed by either team. When you get killed, your character can re-spawn in your castle or from any tower that your team has claimed. You'll spend a majority of each 12 minute battle round progressing across one of several colorful and interesting scenes, claiming towers and then defending them, while trying to take the towers from the opposing team. When you make it across the map, you'll try to knock down the other castle's gate or scales its walls, before finally winning the game. At which point, each player is rewarded, based on their contributions (see next section).
The only disappointing part of Happy Wars is some glitchy network issues during multiplayer matchmaking, which seems to have been plagued with timeout problems since it first launched. As of March 2013, it seems to still be spotty – and can be frustrating. My suggestion, particularly with younger gamers, if it times out more than once, do something else and play a different day.
Either way, younger players might get along just fine by repeatedly mashing the (X) (A) and (B) buttons, while more mature players will appreciate the variety of attack styles and item customization.
Like most battling games, your character will earn points based on how many people they defeated, as well as how many times they performed different tasks, helped others, etc. As they reach milestones, they will progress from Level 1 up to 50, gaining more life (health points) and magic, defensive resistance, etc. You'll also earn the in-game currency, "Happy Stars," which allows you to purchase new and better equipment, as well as upgrade the items that you already have. You can also purchase items from the Xbox Marketplace, by first buying "Happy Tickets" and then purchasing items from the in-game store.
The Happy Wars game itself is FREE on Xbox Live Arcade, but if you are willing to put even $5 of real money into Happy Tickets and then buying a few premium items (better weapon, stronger armor, etc.) then the first few hours of gaming will be even more exciting and rewarding. Frankly, most new players should just assume that the game costs $5 and then they are set. After 5+ hours of play, your higher-level characters will continue to earn ever improving gear and you'll eventually outgrow those starter weapons, but they do make the first few hours even more exciting, particularly against the rest of the players who started ahead of you.
If you follow XboxDad's blog, you know that I am most passionate about games that we can play together; and Happy Wars is a lot of fun as a family. Simply become an Xbox Live Party before starting the game (or within the main menu) and then you'll be playing together. In my family, all of the gamers can talk to each other through chat, while not hearing any banter or language from anyone else on our side or the other team. At the beginning, it is tempting to run around whacking other folks, and just laughing with your family or other Xbox Live Party members. But after a while, you'll see that the winning teams often have a few folks working together.
So, build a team with a Warrior (or two) who will battle out front, a Mage who throws fireballs or electricity from behind the front line, and a Cleric who will keep everyone amped up and healthy. And then, when you get to the enemy castle, don't waste time knocking on the front gate. Your cleric can build latters to scale the walls, your warriors will knock down whoever stayed behind (since most are out battling mindlessly) and your mage will zap the defending machinery from afar. If you do it right, the game will not only be hilarious fun, but also teach a little bit of strategy and teamwork that your kids and you can learn through.
Parents, this game is fun for the whole family. And if the T rating worries you, it's free. Play it by yourself on Friday night and I guarantee that you and the kids will be playing together on Saturday morning after breakfast.
When my kids were younger, I started this blog as a way to highlight games that were truly "family friendly".
But my kids are getting older, and my oldest (now a teenager) is wanting to play the same shooters as his friends – family friendly or not.
Let me be clear, there is a wide variety of amazing and immersive shooting games out there. And by 15-16, your kids may be playing them – and certainly Dad's and Mom's have lots of choices for themselves. The war-based games are well designed and can be a lot of fun for gamers who are emotionally and intellectually prepared for them. And you don't have to agree with me … so (teenagers) please don't spam me with why CoD is perfectly fine when you are 12. It isn't.
This blog isn't for Game Reviews in general. For those, I use GameInformer.com.
This site is from one dad, trying to help other parents learn more about gaming for and with their kids.
So, here is my opinion. In a pure and Norman Rockwell world, kids wouldn't play Rated M games until they were old enough to watch R Rated movies. It is amazing to me how many parents will let their 8-11 year old kids play shooters.
Most parents wouldn't take their 8-11 kid to R-rated movie, based on its graphical violence and language and themes.
Those movies only last 2 hours – so, why would you let them play a game with the same criteria for 40-60 hours ?
And besides, if they are getting that kind of stimulation at 10, what will they look forward to at 13 or 15 or 17 ? Surprisingly, I often hear about younger kids playing shooters because they watch dad playing night after night, and eventually dad wants a playmate.
Age is not a magic number. If you believe that your child gamer already has a solid moral compass and can differentiate between the fantasy in the game and reality, and that the language and activities in the game won't affect their own personality and behavior – then, 13 vs. 15 vs. 17 becomes more subjective.
In our house, I personally prefer the Halo series over Call of Duty or Battlefield, mostly because it is much more visibly fantasy and less "real". I know it's a slippery slope, but most of parenting arguably is, as you lessen control while still offering guidance.
Kids know that they are not on another planet with laser guns (Halo) … or in 1940's Germany (early CoD's) … so I believe that games set in non-current surroundings help them stay clear that it is only a game. Admittedly, the recent Modern Warfare or Battlefield games are near photo-realistic and look like they came off of CNN or the nightly news. To me, that puts even more "today" into the minds of younger shooters. My preference is that younger shooters have as many visual clues that the games are fantasy as possible.
One of the big draws of the shooter games is multi-player online. Unfortunately, with the CoD matchmaking system, you really have very little control who your kids will be playing with — including objectionable language and ideas. In addition, my experience is that CoD doesn't do a good job of matching newer players with other less-experienced players, so you may find yourself thrown in with experts … and essentially getting repetitively killed without enough time to really learn. (less fun). Some of the other game ecosystems (e.g. Halo) do a better job of matchmaking based on skill levels, and/or have options for only playing multiplayer with other already-established friends instead of the general public.
As I said, this is one dad's opinion – thanks for considering it and I hope it helps you and yours.
One of my New Years Resolutions was to protect what my kids hear on TV … without being an ostrich in the sand and isolating them from the world.
I looked at TV Guardian a few years ago, with their embedded censoring technology within a DVD player — but they were limited to 480 (non-HD) resolutions.
Well, they finally released the TV Guardian HD and it is awesome!
Determine what level of filtering should be applied, based on profiles like "Kids", "Parents" and "Other".
By co-connecting not only the HDMI connectors but also a standard video (yellow plug) connection, the TVG is able to read the Closed-Captioning associated with your TV or DVD feed (including most Cable and Satellite devices).
2. If an objectionable word is seen in the text, then the sound mutes out in its place – and the text phrase appears on the screen below to ensure you see the context.
3. That's it — it really is just that simple!!
In the diagram above, pretend that the word "four" is a bad word. If an actor were counting out-loud, the audio would literally sound like "One … Two … Three … (silence) … Five" … with the same words (and blank) appearing below for just a second.
Currently, it appears that the only media types that TVG can't support are Blu-Ray and Internet-Streaming. Coincidently, there is an online petition to include standardized Closed-Captioning within Internet Streaming as well, which would benefit families that want to use technologies like TVG but also our hearing impaired friends. Please click here, if you would like to add your voice to that petition.
Bottom Line on TV Guardian — There are several programs that I wouldn't mind my kids watching, but today's actors and game participants just seem compelled to add expletives like they were any other part of speech. And since the FCC and network censors have lowered their standards so much, my family viewing is continually strict.
TV Guardian opens up new options in my house.
Check out the TVGuardian and thanks for reading.
Co-op titles – there are very few … but Green Lantern is one, and a pretty good one at that.
Loosely based on the same premise and setting as last year's Green Lantern movie, Hal Jordan is player 1 as a relatively new Green Lantern, still being coached by fellow lanterns Sinestro and Kilowog. Almost immediately upon starting the game, the lanterns' headquarters planet of OA is attacked by Manhunter robots.
Over the next several levels, you will use your ring energy to create a range of weapons ranging from huge hammers to maces to a robotic mech-battle suit. There isn't any blood. The bad guys/robots disintegrate into energy — which not only charges your ring but also provides the currency for purchasing new 'constructs' (stuff to make with the ring) and upgrades to your existing ring powers.
The boss fights get progressively challenging, and the storyline and enemy scenarios vary enough to keep it interesting. And with up to 12 different ring constructs, along with various upgrades, gameplay will feel diverse enough to not be just another action button-masher and let each player beat up bad guys with whichever energy-formed weapons that they want. The constructs are chosen by mapping to each of the four buttons (A-B-X-Y) in combination with either the left or right triggers. Hence, up to eight constructs are available, along with immediate and charge-able regular (X) and strong (Y) attack buttons.
While Player 1 is the lead movie character, Hal Jordan of Earth; Player 2 is the equally capable Lantern, Sinestro. The folks at Double-Helix did a pretty good job of enabling a good co-op experience.
All of the energy points (currency) that are collected during game play by both players ends up being shared when purchasing upgrades and new constructs. In fact, once a construct is purchased by Player One, Player Two has full use as well. In fact, the eight construct buttons are separately map-able by Player One and Player Two. When my son and I played through the game, we chose different constructs so that each of us had unique capabilities and ways to participate in the game.
This is not to say that the Co-Op experience is perfect – it isn't.
Player Two's button mapping doesn't get saved – so each time that you start the game, or re-start a previously played level, player two will inherit player one's buttons. Since my son and I played together, we eventually agreed that our right-trigger four would be consistent, so that he only had to re-map his left-trigger four, as needed. It's a minor thing, but something that really ought to get addressed as a fix.
Player Two doesn't get achievement points. I understand that it is more work on developers to track two game save files and so some accumulation "Did <Something> X times" might be harder to track or "Completed whole game". But, a lot of the GL achievements are "Finished Level X" type. The game knows that two players started the level, finished the level and neither left during the level — so why not give Player Two some of the credit? One of the differences between a good co-op game and a great one is giving both players their due acknowledgements, when reasonably possible.
If on mute, the gameplay, story and co-op-ness is great for gamers as young as 8 and ideal around 10.
If you want to hear the dialogue, my suggested age goes up to 14.
Ryan Reynolds, from the movie, reprises his role for the game – and does some great work. Having the original actor definitely adds to movie tie-in games. But there enough Darns, Cruds, and Bugards (use your imagination) to really ruin the game for younger gamers and their parental co-players. The only words I don't recall were Fudge and Butch. GL's word choices add nothing to the story and therefore it is truly a shame that Warner Brothers Interactive and DC Comics allowed the game to be inappropriate for what will be their next generation of readers.
If you have a lower tolerance to dialog, or want to use it as a teaching moment (or twenty) — then Green Lantern is otherwise a great game to co-op through while saving the universe.
Earlier this month, I reviewed what I think is one of the very best kid-friendly co-op games, and certainly one of the best movie-based titles (not including the Lego series) — Cloudy with a Chance of Meatballs (CCM).
MegaMind: Ultimate Showdown reminds me of CCM in many ways because for everything CMM did right, MegaMind falls short.
On its own, as a single-player title, it is a mediocre button masher – meaning that you will spend nearly the entire game repeatedly tapping the (X) shoot button, with the only diversity being when you punch (A) to jump over something and then resume shooting.
You are MegaMind, the primary movie character, and you will go through roughly ten levels where you will find numerous goon henchmen that are themed after one of three villains – Destruction Worker, Psycho-Delic and Hot Flash. For each of the three boss styles, the henchmen come in exactly two varieties and appear to bean endless number of clones — of either a wimpy baddie or a slightly-less wimpy/blimpy baddie. After three platforming levels of bad guys, with some very basic navigation, you'll face that boss. Do that series three times and you'll fight the final bad guy, which is loosely based on another character from the movie and has no other real tie-in to the story or the action.
There is some cool potential in the gadgets in that they are upgradable and have some different affects on the environment and the baddies. But THQ lets you down because you can only carry one at a time – and it is completely scripted. Right about when you need a different item (meaning you truly cannot progress further in the level), the item you need is floating right there in the path. Game play would have been sooooo much better (or at least seemed less monotonous) if all of the gadgets were available on the four-position D-pad or other menu.
Along the way, you'll want to destroy everything in the area – since any destruction of people or items results in glowing 'Blinky' which is the currency of the game, to be spent on upgrading the various items. The upgrades do enhance gameplay slightly – but since you are stuck with whatever item the story gives you, it is negligible.
If you have a 6-8 year old who absolutely loves everything about the movie and must have/play with all MegaMind-themed item, then this game is for them. For almost everyone else, THQ disappoints.
Note: THQ is no stranger to movie-related titles. Nor is this the first movie THQ game that disappoints in — see the earlier Xbox Dad blog post on Cars Race-O-Rama. In that title, most of the game goes well, but there are still glitches that THQ has never addressed, which is a shame.
MegaMind had a lot of potential for a solid co-op title. After all, in the movie, the primary character had a side-kick named Minion. Player 2 is not Minion. Minion appears via an off-screen voice and the occasional pop-up in the corner of the screen, constantly telling you what to do next or where to go. Instead, Player 2 who can drop in and out easily (one plus) is a nameless floating robotic fish.
The real disappointment comes in that Player 2 isn't a legitimate partner player.
Player 2 cannot use the gadgets described above, which makes their experience even more monotonous than Player 1′s. They have a simple ray gun permanently attached.
Player 2 doesn't actually walk, so none of the platforming or navigation elements apply. Instead, they float around and collect blinky that the might be laying around or not picked up by Player 1.
And of course, Player 2 doesn't earn achievement points/trophies, even though almost all of those are earned by completing this level or beating that boss.
Again, this game had a great deal of potential for being a neat co-op title … but falls short due to what can only be described as poor design decisions by the developer.
If you have an game savvy player 1 (older sibling or parent) who wants to run a younger MegaMind fan (ages 6-8) through the game that you purchased in a bargain bin, preferably used at that, then play it for an easy set of achievement points and 4-5 hours of distraction. Otherwise, there are many better movie-related games available — most of which come from someplace other than THQ.
It is based-on but not a scene-by-scene repetition of a movie (or TV show) – in this case, you'll be battling and/or getting-rid of the overgrown food that has been created.
The 2nd player can drop-in/drop-out at will, without affecting game play.
It isn't just a button masher — in that you have multiple tools available to you.
It's fun on its own!
Throughout the game, as you gather gameplay points, you will have the option to upgrade each of these from rinky to cool! The tools are varied enough to add an extra dimension to gameplay, and yet intuitive enough for younger players.
As the levels progress, navigating some of the platforms to reach locations becomes more challenging. So, if your youngster is playing solo, a parent may want to jump in as player two on a few levels to help find the last food items.
Nothing gets killed, though you will dissolve, slice or punch a lot of stuff.
Player 1 is the lead character, Flint Lockwood … Player 2 can join as his faithful monkey friend from the movie. When my daughter and I played through, she was my monkey … and we both had a great time. Player 2 can use all of the same items, independent of the primary player. This works out well, so that each player can take on specific "jobs" and directly contribute to the team's success.
Points accrued during the game are scored separately during gameplay, but combined at the end of the level. Any weapon upgrade purchases apply to both players without distinction.
My only co-op disappointment, and it is a fairly common one, is that Player 2 does not receive Achievement Points for their contributions. Come on developers – even my 7 year old notices when the achievements pop-up, but she doesn't get them! Other than the recognition, gameplay is nearly identical for both players and therefore is a great co-op title for kids!
This week, Microsoft is releasing it newest system update for the Xbox 360, which is something of an annual event to add new capabilities and such. Over the next several weeks, Xbox consoles will be able to gain access to a broader range of TV services (depending on where you are in the world), tighter integration and manageability with Kinect and Bing, etc.
But my favorite feature, by far, is "Cloud Storage".
Until now, you've had local hard drives, sometimes internal memory, proprietary memory cartridges and some USB sticks. The Cloud Storage feature is a 512MB repository per gamer, that is cached locally on the Xbox console hard drive and automatically sync's with XboxLive in the background.
My house has more than one Xbox. So, in my family, we each have our own memory stick – some using the proprietary cartridges and others with USB. We have both formats because the older consoles only offered two cartridge slots, and the current OS only supports 2 USB sticks (even with a USB hub). And when we want to play family four-player games, someone inevitably has to copy their profile from one place to another so we can co-exist. Think "sneaker-net" for gamers.
My nephew, Matthew, is the quintessential gaming teen, having grown up on game consoles and has certainly schooled his Uncle more than once in Halo. I imagine that that over the years, he has often visited buddies' houses with either a memory stick in hand or needed to "Recover GamerTag". The (RG) feature was a way to recreate your gamer profile on a console, when you don't have it with you. But in the process, it invalidated the old profile. So, if you retrieved it while at your friend's house, the original at home was no longer valid. So, when you got home, you would have to recover it again, to bring it back where it belonged.
Instead, the "Recover Profile" has been replaced with "Download Profile".
The primary difference, other then being light-years faster, is that you can leave your profile on more than one Xbox.
For roaming gamers like my nephew, there is the default option to "require password", so that the profile isn't used by anyone other than him.
For families like mine, with more than one console, we can turn off this feature and now happily roam from the family room to a bedroom, as our game choices vary.
In my day job, I am a backup/disaster-recovery guy (my other blog is http://CentralizedBackup.com). So, every few months, I would browse my Xbox360 USB memory stick and selectively copy my most recent game saves to a separate memory stick. Why? Because I didn't want to lose 100's of hours of game progress to a faulty bit on a flash-drive. But now, I don't have to because the cloud-storage is stored locally on the console and then automatically synchronizes with the XboxLive cloud service, and then to any other console, when I log on.
Once, my wife swore off gaming for about six months, because the game save that she had worked on became corrupt. Every time she thought about playing, she got so angry thinking of the lost time, that she just avoided it for a while.
To turn it on, go to System Properties > Storage > Cloud Storage. Click the radio-button to "Enable Cloud Storage" and you are good to go.
When you first log-in with an Xbox Live Gold Subscribing ID, Xbox Live will check which console you most recently logged in from. If it was from another console, it will notify you as a security precaution, which also lets your new console know that it needs to sync your cloud-based data down to this console. Okay, now it has a local copy, which in technology terms, we call the cache. The cache enables games to play with the local copy of the data, instead of waiting on the slightly slower XboxLive copy. It also ensures that if your Xbox Live Internet connection were to break, you still have your game saves to play from locally. Note, you may need to temporarily copy them from the local Cloud cache to the hard drive or USB stick for offline play.
With only 512MB (the size of the larger proprietary Xbox memory cartridges), you won't be able to keep all of your downloadable content in the cloud. Instead, for add-on packs and multimedia, you will need to manually download those items to each console. You could admittedly keep them on a USB stick too, since they won't change near as often. To re-download them, simply use your dashboard and go to Settings > Account > Download History and re-download the items to second console.
It is also important to note that this is a feature for Xbox Live Gold Subscribers only. While there will likely be some Silver (free) members who complain, this is just one more way that Microsoft is creating value for those that pay for their gaming service. Hey, how else do you pay for all of that extra storage and bandwidth that is about to be consumed in the Xbox datacenter? It wont be from the minor margins made off each console sold.
So, there you have it. Backups, Share-ability, and its too easy not to do. There are other cool things in the dashboard update, but hopefully, now you are as excited about Cloud Storage as I am.
And last week's Windows Phone release (K/Wp7) – now available from Windows Phone Marketplace.
In my opinion, the original Kinectimals was the best launch title from the original Kinect wave – and it recently received new life with the Bears add-on pack. Kinectimals is a richly immersive experience where your Kinect actions were full motion and logical for the game, from running in place through challenge courses to broad gestures for training the cub to do new tricks.
Before getting into the K/WP7 game itself, let's quickly celebrate another great integration between the Xbox360 & Windows Phone. With Xbox Live as the glue, along with achievements and the ability to transfer your cubs from your phone to your console and vice versa, this is why every gamer should carry a Windows Phone.
With all of that being said, let's talk about the K/WP7 game itself.
See original Kinectimals blog post for more detail on these.
For everything you do, you get training points which unlock additional cubs as well as new tricks, challenges, food items, and most importantly — unlock additional pieces of the map to continue your journey. In K/WP7, you'll visit most of the same venues of the original K/360 game, including beaches, temple ruins, blossom orchards, etc.
In lieu of the full-body controls of using Kinect, K/WP7 does a great job of using finger gestures to control your cub — with precise flicks of your finger to toss balls (with varying speed for varying distance thrown) and motions to induce the myriad of trained tricks that your cub will learn. The mini-games (challenges) test your memory and precision, though some of them can be a little finicky with the gestures. And of course, it comes with Xbox Live achievements and gamerscore.
In my family, my seven-year-old daughter finds K/WP7 easier and more fun than full-fledged handheld pet games (e.g. Nintendogs), my wife is obsessively fixated on winning Gold in all of the challenges and I am happy to have another immersive WP7 game that yields some pleasant downtime and some achievement points. Being able to earn new animals and send them to my 360 game is yet another perk … which, to paraphrase Pokémon, "ya gotta get 'em all".
Hats off to the folks at Microsoft Game Studios for extending one of the best Kinect launch titles yet again — this time to Windows Phone.