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

It is evident that most of the hydrogen in the universe was reionized during an Epoch of Reionization (EOR) somewhere between 13.4 and 12.7 Gyr ago, corresponding to redshifts  12 $> z >$ 6 \citep{Fan:2006, Bouwens:2015}, when primordial gas clouds began to collapse into proto-galaxies to form the first stars and black holes.  Whether the overall increase in ionizing radiation that precipitated the EOR was produced by the first stars or black holes is a major unanswered cosmological question.

The total budget for ionizing radiation escaping from these objects remains uncertain \citep{Madau:2015}, but its history plays a crucial role in regulating the subsequent emergence and evolution of structure in the universe \citep[c.f.][]{Madau:1999, Ricotti:2002, Benson:2013, Robertson:2015}.  Lyman continuum (LyC) photons, emitted below the rest frame \ion{H}{1} ionization edge at 911.8 \AA, escape the highly ionized confines of quasars and active galactic nuclei (AGNs) with relative ease \citep{Bahcall:1967, Smith:1981, Bechtold:1987, Scott:2004}, but the potential contribution from the vastly more numerous star-forming galaxies is harder to quantify; this is due to the difficulty of observing this intrinsically weak emission coupled with our poor understanding of the physical conditions that allow ionizing radiation to escape into the intergalactic medium (IGM).

Empirical estimates of the average escape fraction required to sustain an ionized IGM by $z$ = 6, range from  5 $ < f^e_{LyC} < $  40\% \citep[][and references therein]{Bouwens:2015, Finkelstein:2015}.  These estimates depend on the evolution of the steepness of the galaxy luminosity function, the mean production of LyC emission per unit star-formation rate (SFR), and assumptions regarding the ratio of the escape fraction to the ionized hydrogen clumping factor \citep{Madau:1999}.   The conclusion that the EOR is driven solely by star-forming galaxies rests on these assumptions, and on an extrapolation of the faint-end cutoff of the galaxy luminosity function from -17 $ < M_{uv} < $ -13. Moreover, there are no constraints as to how the escape fraction is distributed as a function of galactic mass, luminosity, and environment.

Cosmological hydrodynamical simulations aiming to determine the escape fraction as a function of luminosity and halo mass have produced mixed results \citep[c.f.][]{Gnedin:2008, Razoumov:2010, Yajima:2011, Wise:2014, Yajima:2014}.  In recent work, \citet{Sharma:2016} found that the brighter galaxies have higher escape fractions.  In contrast,  \citet{Xu:2016} find that galaxies with smaller halo masses have the highest escape fractions, however, they also found that star formation in low-mass galaxies is easily suppressed as reionization progresses, leaving higher-mass galaxies, which are less susceptible to photo-evaporation, to complete the process.

One of the key projects for the James Webb Space Telescope ({\em JWST}\/) is to search for those sources responsible for reionizing the universe; however, it will likely only be able to do so indirectly.  The monotonic increase with redshift in the density of Lyman limit systems (LLS) -- those discrete clouds in the IGM having  $\log(N_{HI}(cm^{-2})) > $ 17.2 --  steadily decreases the probability of directly detecting LyC emission  from star-forming galaxies on an unattenuated line of sight \citep[c.f.][]{Madau:1995, Inoue:2008, Inoue:2014, Worseck:2014, Crighton:2015}.  At redshifts of $z$ = [3, 4, 5, 6] the mean transmission of the IGM is estimated to be $\approx$ [0.5, 0.3 0.08, 0.01] \citep[][their Figure 4]{Inoue:2014}, albeit with an large variation about the mean.   The {\em JWST}\/\  short wavelength cutoff is $\approx$ 0.6 $\mu$m, so the LyC region is accessible only for redshifts $z \ga$ 6 where the IGM is essentially completely opaque.  Direct measurements of LyC will be a challenge for {\em JWST}\/, to say the least

The far-UV and near-UV bandpasses provide the most direct path to spatially resolved detection of ionizing radiation, and to the characterization of those environments that favor LyC escape.  Spatial resolution is an especially important diagnostic, as models indicate that LyC photons escaping from any particular galaxy will exhibit gross variations that depend on the line of sight of a star-forming source with respect to intervening neutral and ionized material in disks, superbubbles, and surrounding circumgalactic streams  \cite{Dove:1994, Bland-Hawthorn:1999, Dove:2000, Shull:2015}.

Recent successes in detecting LyC emission from what are apparently star-forming galaxies \citep{Leitet:2013, Borthakur:2014, Izotov:2016b, Leitherer:2016, Naidu:2016, Shapley:2016} have emboldened the design of instrumentation and observing strategies capable of quantifying, on an industrial scale, the relative contributions of star-forming galaxies, quasars, and AGN to the creation and sustenance of the metagalactic ionizing background (MIB) across cosmic time.

The need for understanding those physical processes that enable $f^e_{LyC}$ at low redshift has grown in importance as of late.  Recent determinations of the number density of Ly$\alpha$\ forest lines found at low redshift by  \citet{Danforth:2016} appear to require a MIB $\sim$ 5$\times$ larger than theoretical estimates to explain the low density of the lines \citep{Kollmeier:2014};   \citep[see][for contrasting conclusions]{Shull:2015, Gaikwad:2017}.  These studies are inconclusive as to whether, on average, $f^e_{LyC}$ from star-forming galaxies and quasars is considerably higher than the handful of detections to date indicate, thus underlining the importance of quantifying $f^e_{LyC}$ at both low and high redshift.

Our main goal is to establish effective area requirements for future observatories that will transform what has previously been described as an impossible task \citep{Fernandez-Soto:2003}, into a statistically significant determination of LyC luminosity function evolution across cosmic time envisioned by \citet{Deharveng:1997} and \citet{Shull:2015}, providing a full accounting of the LyC escape budget from star-forming galaxies of all types.

Here we use 1500 \AA\ luminosity functions  to guide estimates of the rest frame EUV flux (the LyC) emitted by characteristic galaxies,  attenuated by a uniform foreground screen of circumgalactic media (CGM) with representative ratios of \ion{H}{1}, \ion{He}{1}, and \ion{He}{2} column densities.   We also include the progressive increase in mean attenuation effected by the increasing \ion{H}{1} distribution of IGM column densities as a function of redshift.  A general result is that the LyC escape fraction measured in a narrow range just shortward of the ionization edge is a poor representation of the total fraction of ionizing photons that escape.

These calculations were developed to support science and technology flowdown exercises for the Large Ultra-Violet Optical InfraRed (LUVOIR) and Habitable Exoplanet (HabEx) survey mission studies commissioned by NASA in preparation for the Astrophysics Decadal Survey for 2020, and to assess the capability of proposed probe and explorer class missions.

A cosmology of $H_0 = $ 70 km s$^{-1}$ Mpc$^{-1}$, $\Omega_m =$ 0.3,   $\Omega_{\Lambda} =$ 0.7 is assumed.

\subsection{Review of Escape Fraction Terminology}

The term  ``escape fraction'' is often used loosely and somewhat conflictingly.  The literature defines a number of slightly different ratios to describe the escape of ionizing radiation from galactic environments, which for the sake of completeness we review briefly.

A useful observable, termed the relative escape fraction ($f_{rel}$) by \citet{Reddy:2016, Shapley:2006}, and \citet{Steidel:2001},  is defined as the ratio of the observed flux in a bandpass just shortward of the Lyman edge ($F^o_{900}$) to that observed at some fiducial UV continuum wavelength ($F^o_{\lambda}$);
\begin{equation}
f_{rel} = F^o_{900}/F^o_{\lambda}.
\end{equation}

\noindent The observed flux is then relatable to the intrinsic flux ($F^i_{\lambda}$) by appeal to a stellar population spectral synthesis model, after accounting for the transmission of flux, $T_{\lambda}$, as attenuated by line of sight neutral gas and dust, such that $F^o_{\lambda} =T_{\lambda} F^i_{\lambda}$.  Just over the edge we have $F^o_{900} =f^e_{900} F^i_{900}$, which
\citet{Reddy:2016} called $f^e_{900}$  the absolute escape fraction (in their notation $f(LyC)_{abs}$).

Solving for $f^e_{900}$ in terms of the relative escape fraction, the attenuation at the fiducial wavelength and the intrinsic flux ratio,
 \begin{equation}
f^e_{900} = T_{\lambda} f_{rel} F^i_{\lambda}/F^i_{900}.
\end{equation}

\noindent  It explicitly includes hydrogen and dust attenuation at the edge.   \citet{Borthakur:2014} made a further distinction between what they called a relative escape fraction at 912$^{-}$, where $T_{\lambda}$ =1, and an absolute escape fraction at 912$^{-}$ where they corrected for dust using the ratio of the integrated LyC luminosity, with respect to the bolometric luminosity.

Implicit in these definitions is the assumption that the observed flux $F^o_{\lambda}$ is averaged over some relatively narrow bandpass.  However, $f^e_{900}$ does not fully account for all the ionizing photons that escape from the CGM and contribute to the MIB.  To do so requires an integration of the attenuated (``observable'') photon number flux ($F^o_{\lambda}/E_{\lambda}$; where $\lambda <$ 911.8 \AA\ and $E_{\lambda}$ is the photon energy)  over the full extent of the spectral energy distribution (SED) shortward of the Lyman edge.  The integrated escape fraction is normalized by the intrinsic SED integrated over the same wavelength interval,

\begin{equation}
f^e_{LyC}= \frac{\int_{0}^{912}F^o_{\lambda}/E_{\lambda} d\lambda}{\int_{0}^{912}F^i_{\lambda}/E_{\lambda} d\lambda}.
\end{equation}

\noindent In practice, $F^o_{\lambda}$ is not observable in its entirety; however, we can estimate it by the integration of a transmission function, multiplied by the intrinsic flux, $T_{\lambda}F^i_{\lambda}$, over the wavelength interval shortward of the Lyman edge.

In \S~\ref{lumfun} we provide estimates of $F^o_{(1+z)900}$ in terms of the characteristic apparent ab-magnitude (abmag) $m_{(1+z)900}$,  as a function of  $f^e_{900}$, scaled from compilations of UV luminosity functions taken from the literature for rest frame wavelengths $\approx$ 1500 \AA.   In \S~\ref{dropins} we will give estimates of the integrated fraction of escaping ionizing photons, $f^e_{LyC}$, by modeling the optical depth in neutral hydrogen, neutral helium, and once-ionized helium column in the CGM in the foreground of a spectral synthesis model.  In \S~\ref{igmatten} we include the IGM attenuation in estimating the LyC flux of redshifted models scaled to the magnitudes of characteristic galaxies at (1+$z$)1500 \AA, and  discuss detection requirements and observing strategies.

\begin{deluxetable}{cccccc}
\tablecaption{\bf Schechter parameters for UV Luminosity Functions \label{t1} }
\tablecolumns{6}
\tablewidth{0pt}
\tablehead{\colhead{$z$}	&  \colhead{$\Delta z$}	&\colhead{$\alpha$} &	\colhead{$M^*_{15}$} & \colhead{$\phi^{*}$\tablenotemark{a} }  &  \colhead{$m^*_{(1+z)1500}$} }
\startdata
0.1& 0 - 0.2		& -1.21	& -18.05 	& 4.07	& 20.17\\
0.3& 0.2 - 0.4	& -1.19	& -18.38	& 6.15	& 22.30\\
0.5& 0.4 - 0.6	& -1.55	& -19.49	& 1.69	& 22.37\\
0.7& 0.5 - 0.8	& -1.60	& -19.84	& 1.67	& 22.73\\
1.0& 0.8 - 1.2	& -1.63	& -20.11	& 1.14	& 23.24\\
2.0& 1.75 - 2.25	& -1.49	& -20.33	& 2.65	& 24.43\\
2.9& 2.4 - 3.4	& -1.47	& -21.08	& 1.62	& 24.38\\
\enddata
\tablenotetext{a}{(10$^{-3}$ Mpc$^{-3}$ \added{mag$^{-1}$} )}
\end{deluxetable}

\section{Far-UV Luminosity Functions}\label{lumfun}

We  use far-UV luminosity functions listed by \citet{Arnouts:2005} to estimate areal density of candidates and their corresponding LyC flux as functions of assumed escape fraction and redshift.  In Table~\ref{t1} we list the \citet{Schechter:1976}  function parameters.  \added{The luminosity function in units of absolute magnitude is expressed as}

\begin{equation}
\label{eq0}
\phi(M_{15})=\frac{\ln{10}}{2.5}\phi^*10^{-\frac{(M_{15}-M^{*}_{15})(\alpha+1)}{2.5}}e^{-\frac{(M_{15}-M^*_{15})}{2.5}},
\end{equation}
\explain{The equation has changed.  The $^*$ was dropped on the left side to create the proper independent variable $M_{15}$ and the $M$ in the exponential function on the right was changed to $M_{15}$ to agree with the formula as expressed in Yoshida et al. (2006).}

\begin{figure}
\includegraphics[width=.5\textwidth]{f1_UVLumFunAreal_Arnouts.eps}
\caption{Star-forming galaxy surface density as a function of redshift derived from the luminosity functions listed in Table~\ref{t1}.  \label{fig1}}
\end{figure}

\noindent \added{where $M^*_{15}$ is the characteristic absolute magnitude of the Schechter function at 1500 \AA, $\alpha$ is the faint-end power-law slope, $\phi^*$ is the normalization factor (in Mpc$^{-3}$ mag$^{-1}$),  and $M_{15}$ is the independent variable for the absolute magnitude at restframe 1500 \AA.}

We convert \added{this function} from the number per comoving volume to the number per square degree by multiplying by the comoving volume per solid angle, calculated at \replaced{for}{about} the mid-point in each redshift interval.  \added{The characteristic absolute magnitude in the 1500 \AA\ rest frame was shifted to a characteristic apparent magnitude in the observer's frame using the formula \citep{Yoshida:2006} }
\begin{equation}
\label{eq5}
m^{*}_{(1+z)1500}=M^*_{15}+2.5log{\left[\frac{(d_l(z)*10^5)^2}{(1.+z)}\right]}.
\end{equation}
 Here $d_l(z)$ is the luminosity distance in Mpc, and $z$ is the redshift.

In Figure~\ref{fig1} we show the \added{ultraviolet} luminosity functions listed in Table~\ref{t1} recast into  \added{a differential areal density, graphed logarithmically as}  the number of galaxies per unit magnitude per square degree.  Each curve has an $*$ to indicate the location of the characteristic magnitude $m^*_{(1+z)1500}$ where the Schechter function makes the transition from the exponential cutoff in galaxy counts at the bright end of the luminosity function to the power law extension of the faint end.  The interval for the abscissa of each curve spans 5 mag (a factor of 100 in flux) centered on $m^*_{(1+z)1500}$.    The figure is useful for estimating the number of targets within a given patch of sky down to an instrument's brightness limit.

\added{The estimate for the apparent characteristic magnitude at $(1+z)900$ \AA\ in the observer's frame, $m^*_{(1+z)900}$, is scaled from $m^{*}_{(1+z)1500}$ using}

\begin{equation}
\label{eq2}
m^*_{(1+z)900} = m^{*}_{(1+z)1500}  + \delta m^{1500}_{900} + \delta m_{esc}.
\end{equation}
where \added{the escape fraction just over the ionization edge is} $\delta m_{esc} = 2.5 \log{f^e_{900}}$, \added{and the ratio of the intrinsic rest frame flux at 1500 \AA\ to that at 900 \AA, }
\deleted{We convert the estimates for the 1500 \AA\ rest frame magnitude to LyC magnitudes, using the scale factors} $\delta m^{1500}_{900} = 2.5\log{F^i_{1500}/F^{i}_{900}}$, \added{was} determined from the STARBURST99 \citep[hereafter SB99]{Leitherer:1999, Leitherer:2014} intrinsic SED \replaced{discussed}{described} in \S~\ref{intrinsicspec}.   Conveniently, in the  rotating stellar evolution model \added{that we have adopted}, $ F^i_{1500}/F^i_{900} \approx$ 1.  \replaced{For constant star-formation this ratio is relatively insensitive to age.}{This ratio is relatively insensitive to age in constant star-formation models.}   In the older, non-rotating SB99 models the range is 1.5 $ \lesssim F^{i}_{1500}/F^{i}_{900} \lesssim$ 3 for ages 10 -- 900 Gyr.  A factor of 2 in the flux ratio amounts to $\delta m^{1500}_{900} = 2.5\log{F^i_{1500}/F^{i}_{900}} \approx 0.75$.

\begin{figure}
\includegraphics[bb= .75in 4.75in 8in 10.5in, clip=false, width=.5\textwidth]{f2_LyCestimatesApJnew.eps}
\caption{Estimate of each luminosity function's characteristic magnitude,  $m^*_{(1+z)900}$, as a function of redshift and assumed  $f^e_{900}$ escape fraction just shortward of the edge Lyman edge.  These estimates do not include IGM attenuation. \label{fig2}}
\end{figure}

The estimates for $m^*_{(1+z)900}$, shown as magenta lines in Figure~\ref{fig2}, are based on the  rotating evolutionary models.  \replaced{The estimates can}{They may} be adjusted to adhere to the older models by shifting the ordinate by the preferred  $\delta m^{1500}_{900}$ (= 0 for the rotational models).   Likewise, offsets to account for differences in dust attenuation between 1500 and 900 \AA\ may also be applied.

We  have neglected here the stochastic attenuation expected from intervening neutral hydrogen absorption systems associated with the IGM.   We will quantify the effects of this additional attenuation in \S~\ref{igmatten}.

The  estimate for $m^*_{(1+z)900}$ at a given $f^e_{900}$ is intended to provide guidance for detecting LyC emission at the most \replaced{difficult}{attenuated} wavelength, just over the Lyman edge.  The green dashed contours in Figure~\ref{fig2}  indicate the flux levels $F_{(1+z)900}$ in units of femto erg flux units (1 FEFU = 10$^{-15}$ erg cm$^{-2}$ s$^{-1}$ \AA$^{-1}$ ), which was roughly the background limit for the {\it Far Ultraviolet Spectroscopic Explorer (FUSE)}.  Current space-based UV background limits are $\sim$ 1 - 1000 times lower and will be discussed in \S~\ref{future}.

It should be kept in mind that $f^e_{900}$ is not a measure of the ratio of the total number of ionizing photos that escape to the total number that are emitted.  In the following section we show that while the LyC flux in the relatively narrow wavelength range just shortward of the Lyman edge can be essentially zero,  the fraction of escaping continuum  photons integrated over the entire LyC emitting region, from the  edge into the extreme UV (EUV), is significantly greater than zero.

\section{Lyman Drop-ins}\label{dropins}

The abrupt drop-out in flux shortward of the LyC is a useful diagnostic for the photometric identification of star-forming galaxies \citep{Steidel:1995}.   The wavelength of the band where the flux drops out provides a constraint on the redshift.  The technique was originally developed using ground-based surveys, which can efficiently identify objects at redshifts $z \approx$ 3 -- 4.   Lyman drop-outs at these redshifts are commonly referred to as Lyman Break Galaxies (LBGs).   \citet{Cooke:2014} have emphasized that the standard LBG technique is biased toward star-forming galaxies with zero detectable flux in the LyC, i.e. when line of sight column densities of $N_{HI} >> 1 \times $10$^{18}$ cm$^{-2}$.   For $N_{HI} \sim 1 \times $10$^{18}$ cm$^{-2}$ the drop-out does not extend completely throughout the EUV range, so we expect to find a class of star-forming galaxies that we call Lyman ``drop-ins'' as described below.

\subsection{\ion{H}{1}, \ion{He}{1}, \ion{He}{2} CGM transmission model \label{LyCTrans} }

In principal, the shape of the continuum emission shortward of the Lyman edge contains a great deal of information regarding the distribution of ionization states for hydrogen and helium, and the distribution of dust along those unresolved line of sight(s) through an individual galaxy's CGM favoring the escape of LyC radiation.  The attenuation at each photoionization edge increases sharply followed by a relatively gentle recovery, varying approximately as $\propto (\frac{\lambda}{\lambda_e})^3$, where the $\lambda_e$ for \ion{H}{1}, \ion{He}{1}, and \ion{He}{2} are 911.75, 504.26, and 227.84 \AA, respectively.

In general, the transmission below the Lyman edge is a exponential function of the sum of dust, neutral hydrogen, neutral helium, and singly ionized helium optical depths,
 \begin{equation}
 T_{CGM}(\lambda) = \exp[{-\tau_d(\lambda)-\tau_{HI}(\lambda)-\tau_{HeI}(\lambda)-\tau_{HeII}(\lambda)}],
\end{equation}

\noindent where the various optical depths are \deleted{a} products of the column densities and cross-sections for each species, $\tau_x(\lambda) = N_x\sigma(\lambda)$.  For the hydrogen and helium photoionization cross-sections we use the analytic fits from \citet{Verner:1996}, which differ slightly from the $\lambda^3$ relation.  For the \ion{H}{1}, \ion{He}{1}, and \ion{He}{2} resonance line cross-sections calculations we use the wavelengths and oscillator strengths for the 1 $< n <$ 79 lines of each species found in the online repository complied by Kurucz in CD-ROM 23.\footnote{\url{http://www.cfa.harvard.edu/amp/ampdata/kurucz23/sekur.html}}

We calculated the total optical depth template for each species, following a procedure used by \citet{McCandliss:2003}, wherein Voigt profiles were generated for individual\deleted{s} lines with fine enough sampling and range to resolve the doppler core and return the optical depth in the damping wing to near 0.  Individual line profile optical depths were interpolated onto an common grid spanning the entire wavelength range of interest, for summation with all other lines and photoionization cross-sections.  The doppler velocity was set to $b$ = 35 km s$^{-1}$, as is commonly assumed \citep{Madau:1995, Inoue:2008, Inoue:2014} and is sufficient for our flux estimation exercise; however, it should be kept in mind that observations of the differential distribution of $b$ have been matched to $\frac{dN}{db} = \frac{4b^4_{\sigma}}{b^5}\exp(-(\frac{b_{\sigma}}{b})^4)$ with $b_{\sigma} \approx$ 26 km s$^{-1}$ \citep{Hui:1999}.  How $\frac{dN}{db}$ varies with redshift is an open question.

The relative contributions of the three species are linked through the cosmic abundance of helium by number and imposed assumptions for the neutral fractions with respect to the total for the element (molecular hydrogen is neglected); i.e., $N^{tot}_{H} = N_{HI}+N_{HII}$, $N^{tot}_{He} = N_{HeI}+N_{HeII}+N_{HeIII}$ and $N^{tot}_{He}$ = 0.08 $N^{tot}_{H}$.  The independent variables are the column of \ion{H}{1}, its neutral fraction, $\chi_{HI} \equiv \frac{N_{HI}}{N^{tot}_{H}}$, and the helium neutral fraction, $\chi_{HeI} \equiv \frac{N_{HeI}}{N^{tot}_{He}}$.

\begin{figure}
\includegraphics[angle=90,width=.5\textwidth]{f3_controt1.000hi0.900heiheii.eps}
\includegraphics[angle=90,width=.5\textwidth]{f3_controt0.100hi0.900heiheii.eps}
\caption{LyC transmission functions for $\log{N_{HI}(cm^{-2})}$ = 16.00, 17.00, 17.25, 17.50, 17.75, 18.00, 18.25, 18.50 that span the transition from optically thin to thick at the Lyman edge.  Top --  $\chi_{HI}$ =1, $\chi_{HeI}$ = 0.9.  Bottom --  $\chi_{HI}$ =0.1, $\chi_{HeI}$ = 0.9.\label{fig3}}.
\end{figure}

In Figure~\ref{fig3} we show two sets of transmission models, having ($\chi_{HI}$, $\chi_{HeI}$) = (1.0, 0.9), and (0.1, 0.9), top and bottom, respectively.   The overall blackness of $f^e_{900}$ is set by the $N_{HI}$ column density, but total fraction of escaping LyC photons is set by the ionization state \added{of} hydrogen relative to that of helium.   The strength of the neutral and ionized helium edges becomes enhanced for $\chi_{HI} <$ 1.

The nature of dust attenuation in a highly ionized density bounded medium below the hydrogen Lyman edge is highly uncertain, so we have neglected it here.  This should not be too serious, as the extinction near the Lyman edge in the canonical Milky Way model of \citet[][their Figure 14]{Weingartner:2001} is $N_{HI}/A(912) \approx$  2.4 $\times$ 10$^{20}$ cm$^{-2}$ mag$^{-1}$.  For $N_{HI}$ = 10$^{18}$ cm$^{-2}$ this yields  $A(912)$ =0.0042, so with $\tau_d(912)= A(912)/1.086$, we estimate a miniscule effect on transmission at the edge of  $\exp{(-\tau_d(912))}$ = 0.996.  However, if the dust abundance follows the total hydrogen instead of just \ion{H}{1}, then $\tau_d$ will be higher.

In principal, a proper accounting of the neutral and ionized gases could lead to important observational insights into the temperature of the CGM along with the survivability and attenuation properties of dust grains with respect to the total gas content in LyC-leaking environments.

\subsection{Intrinsic SB99 Star Formation Model \label{intrinsicspec} }

We employ here an SB99 spectral synthesis model, forming stars at a continuous rate of 1 $M_{\odot} $yr$^{-1}$ \citep{Leitherer:1999, Leitherer:2014} for the intrinsic SED.  We specified a Kroupa initial mass function, which has double power law exponents of -1.3, over the mass interval from 0.1 $< M_{\odot} <$ 0.5, and -2.3 for 0.5 $< M_{\odot} <$ 100.  We also chose the Geneva evolutionary tracks with rotation at 40\%\ of the break-up velocity (v0.4 models) and solar metallicity were also selected.  After about 10 Myr the number of ionizing photons emitted by this model below the Lyman edge saturates at a rate of $\log{[Q_{0}(s^{-1})]} \sim$  53.4 \citep{Leitherer:1999}.  The mass at this point is 10$^{7} M_{\odot}$.

\subsection{SB99 models with CGM attenuation \label{cgmatten} }

\begin{figure}
\includegraphics[angle=90,width=0.5\textwidth]{f4_fe_lyc_shift20controt1.000hi0.900hei.eps}
\includegraphics[angle=90,width=0.5\textwidth]{f4_fe_lyc_shift20controt0.100hi0.900hei.eps}
\caption{LyC drop-ins with ($\chi_{HI}$, $\chi_{HeI}$) as in Figure~\ref{fig3}.  SB99 v0.4 evolution model\deleted{s}  \added{(10 Myr, continuous star formation,  10$^{7} M_{\odot}$),} attenuated with the transmission functions in Figure~\ref{fig3}.   \added{The inset table columns are: $\log{N_{HI}(cm^{-2})}$, the neutral hydrogen column;  $\log{[Q(s^{-1})]}$, the rate of escaping ionizing radiation; $f^e_{LyC}$ = $Q/Q_0$, the integrated escape fraction; and $f^e_{900}$, the escape fraction just shortward of the ionization edge, which is defined as the ratio of the attenuated flux to the intrinsic flux in the $\Delta \lambda$ = 20 \AA\ wide hatched region in the figures.}  For $\log{N_{HI}(cm^{-2})} > $18 the escape fraction measured at 900 \AA\ $f^e_{900} << $1\%, yet the integrated fraction of ionizing photons that escape, $f^e_{LyC}$, is significantly  greater than $f^e_{900}$.  The top panel shows a relatively smooth Lyman drop-in at $\log{N_{HI}(cm^{-2})} = $18.  The bottom panel shows a double drop-in. \label{fig4}}
\end{figure}

\begin{figure}
\includegraphics[angle=90,width=0.47\textwidth]{f5_fetrue_lyc_shift20controt1.000hi0.900hei.eps}
\includegraphics[angle=90,width=0.47\textwidth]{f5_fetrue_lyc_shift20controt0.100hi0.900hei.eps}
\caption{Integrated fraction of escaping LyC photons, $f^e_{LyC}$ on ordinate, escape fraction at 900 $f^e_{900}$on abscissa.  Top--bottom order for  ($\chi_{HI}$, $\chi_{HeI}$) as in Figure~\ref{fig3}.  Left linear--linear.  Right log--log.    The relationship is decidedly non-linear.  Top to bottom shows varying degrees of significant escape even when $f^e_{900}$ has become black. \label{fig5}}
\end{figure}

In Figure~\ref{fig4} we show the effect of attenuating the SB99 model with the transmission functions depicted in Figure~\ref{fig3}.  The shape of the continuum emitted below the Lyman edge, and hence the number of ionizing photons that ultimately escape from a star-forming region, is linked to the ionization state of hydrogen and helium in the surrounding column of gas.  There is very little intrinsic stellar flux emitted below the \ion{He}{2} edge at 228 \AA, so the inclusion of \ion{He}{2} has little effect on the overall total escape fraction.   However, it would become important for the harder SEDs typical of quasars and AGN.

The top panel has ($\chi_{HI}$, $\chi_{HeI}$) = (1.0, 0.9), where we have assumed that helium is slightly ionized for the purpose of showing the location of the \ion{He}{2} Lyman series.  This model shows signs of a slight break shortward of the \ion{He}{1} ionization edge at 504 \AA, but overall it exhibits a relatively smooth Lyman drop-in with decreasing wavelength.  In the bottom panel ($\chi_{HI}$, $\chi_{HeI}$) = (0.1, 0.9),  so the break shortward of 504 \AA\ is strengthened by the lower \ion{H}{1} abundance with respect to \ion{He}{1}, causing a Lyman "double drop-in" to appear in the EUV region.  The strength of the \ion{He}{1} break with respect to the \ion{H}{1} break becomes more enhanced as $\chi_{HI}$ decreases.

In each figure we have tabulated logarithms of the \ion{H}{1} column density, the rate of ionizing photon production, the escape fraction integrated over the entire EUV band, $f^e_{LyC}$, and the escape fraction of ionizing photons in the narrow 20 \AA\ wide region shortward of the Lyman edge, $f^e_{900}$.  The table entries are color-coded to the spectra.

In Figure~\ref{fig5} we show that the relationship between $f^e_{LyC}$ and $f^e_{900}$, (logarithmic scales left and liner scales right) is decidedly nonlinear.    We have overplotted an interpolation formula of the form

\begin{equation}
f^e_{LyC}  =\frac{(f^e_{900})^{\zeta_1} + (f^e_{900})^{\zeta_2} + \epsilon}{(2+\epsilon)},
\label{eq8}
\end{equation}

\noindent where ($\zeta_1, \zeta_2$, and $\epsilon$) = (0.25, 0.75, 0.018) and (0.37, 0.95, 0.0011), for ($\chi_{HI}$, $\chi_{HeI}$) = (1.0, 0.9) and ($\chi_{HI}$, $\chi_{HeI}$) = (0.1, 0.9), respectively.

In all cases a column density $\log{N_{HI}(cm^{-2})}$ = 18 produces essentially zero flux at the edge, yielding an edge escape fraction of $f^e_{900}$= 0.003, yet the integrated escape fraction is 13 and 6\%, for the two cases, respectively.  Using the interpolation formulae, we find that for the Lyman edge escape fractions used in Figure~\ref{fig2}, where $f^e_{900}$ = (0.01, 0.02, 0.04, 0.08, 0.16, 0.32, 1.00),  the corresponding integrated escape fraction is $f^e_{LyC}$ = (0.18, 0.22, 0.27, 0.35, 0.45, 0.59, 1.00)  and (0.10, 0.13, 0.18, 0.24, 0.34, 0.50, 1.00) for the two cases, respectively.

We conclude that measurements of the Lyman edge escape fraction, $f^e_{900}$, only provide, at best, lower limits to the the true integrated fraction of escaping ionizing photons, and generally offer poor representations of the total number of ionizing photons that escape.    The tables in Figures~\ref{fig4} show that LBGs may emit significant amounts of LyC radiation, at the level of 5 to 1\%, even if the optical depth at the edge is $\approx$ 10 ( $\log{N_{HI}(cm^{-2})}$ = 18.25).   By way of example, we note that \citet{Izotov:2016a} found an edge escape fraction $f^e_{900}$ = 0.08.  Using Eq.~\ref{eq8}, we derived an integrated escape fraction of $f^e_{LyC}$  = 0.35 or 0.25 for our two cases, respectively.  This suggests that the ``f-escape'' problem might not be as bad as it seems.  The only definitive way to rule this out is through deep UV observations in the redshifted rest frame of the EUV in an attempt to observe the LyC drop-in.

In the next section we address the observability of of the Lyman drop-ins in the face of the steadily increasing mean optical depth of the IGM with increasing redshift.

\section{Redshifted models, including mean IGM transmission  } \label{igmatten}

\begin{figure}
\includegraphics[width=0.5\textwidth]{f6_MeanTransNsum.eps}
\caption{Mean IGM transmission functions for redshifts $z$ = (0.1, 0.3, 0.5, 0.7, 1.0, 2.0, 2.9).  Computed from the ($\chi_{HI}$, $\chi_{HeI}$) = (1.0, 0.9) model.  The vertical bar indicates the level of expected variation at the edge as found in Monte Carlo study of IGM absorbers distributed over a range of column densities from LAF to DLA with a piecewise break at the LL transition \citet{Inoue:2008}.   \label{fig6}}
\end{figure}

\begin{figure*}
\includegraphics*[width=\textwidth,clip=false]{f7_IGMSB99magzcorr_attencontrot1.000hi0.900hei.eps}
\caption{Redshifted  ($\chi_{HI}$, $\chi_{HeI}$) = (1.0, 0.9) model with logarithmic scaling, showing LyC drop-in towards shorter wavelengths. Contours of constant abmag appear as dashed lines.  Column density colors as in Figure~\ref{fig4}.  The edge escape fractions are $f^e_{900}$ (\added{0.000,} 0.000, 0.003, 0.041, 0.166, 0.364, 0.566, 0.945)   for (\added{olive,} red, orange, light green, green, blue, violet, and grey) respectively.  \added{The $z$ = 0.1 panel, top-right, shows the  $f^e_{900}$ escape fractions and associated column densities.} \label{fig7}}
\end{figure*}

\begin{figure*}
\includegraphics*[width=\textwidth,clip=false]{f8_IGMSB99magzcorr_attencontrot0.100hi0.900hei.eps}
\caption{Redshifted  ($\chi_{HI}$, $\chi_{HeI}$) = (0.1, 0.9) model with logarithmic scaling.  The $z$ = \replaced{1}{2.0} and \replaced{2}{2.9} models show the pronounced double drop-in structure is severely depressed, but the structure survives albeit at a difficult to detect level.  Colors and edge escape fractions as in Figure~\ref{fig7}.  \label{fig8}}
\end{figure*}

We have thus far not included attenuation of the escaping LyC due to resonant scattering and photoelectric absorption (photoionization) from discrete collections of intervening clouds in the IGM.   Here we use the rest frame LyC transmission models described in \S~\ref{LyCTrans} to compute the mean transmission of the IGM as a function of the fiducial redshifts in Table~\ref{t1}.

\begin{figure*}
\includegraphics*[angle=90,width=\textwidth]{f9_IGMallSB99magzcorr_attencontrot1.000hi0.900hei.eps}
\includegraphics*[angle=90,width=\textwidth]{f9_IGMallSB99magzcorr_attencontrot0.100hi0.900hei.eps}
\caption{\added{Attenuated SB99 models overplotted for the fiducial redshifts ($z$ = 0, 0.1, 0.3, 0.5, 0.7, 1.0, 2.0, 2.9).  The z = 0 models extend to 91 \AA; all others cut off at 911.8 \AA. }  Column density colors as in Figure~\ref{fig4}, but the lowest column 18.5 is omitted.  Asterisks mark (1+$z$)1500 \AA .  Contours of constant abmag appear as dashed lines.  Top --  ($\chi_{HI}$, $\chi_{HeI}$) = (1.0, 0.9) model with logarithmic scaling.  Bottom -- ($\chi_{HI}$, $\chi_{HeI}$) = (1.0, 0.9).      \label{fig9}}
\end{figure*}

The mean transmission function is derived from a mean optical depth \citep{Paresce:1980, Madau:1995, Inoue:2014}, expressed here as a numeric integral

\begin{equation}
<\tau(\lambda)> = \sum_{i=0}^{L}\sum_{j=0}^{M} \left(\frac{\partial^{2}n}{\partial{N_{HI}}\partial{z}}\right)_{i,j} (1-e^{-\tau(\lambda_{o})} )\Delta z_i  \Delta N_j .
\end{equation}

\noindent Here the observed wavelength is related to the rest frame wavelength by $\lambda_{o} = \lambda_{r}(1+z_i)$.  The optical depth is $\tau(\lambda_{o}) = \tau_{HI}(\lambda_{o}) +\tau_{HeI}(\lambda_{o}) +\tau_{HeII}(\lambda_{o})$.  The redshift range from 0 $ \le z_i \le z_{L}$ is in fixed increments of $\Delta z_{i}$ =0.0005.  The logarithm of the column densities range from  12.3 $ \le \log({N_j}) \le$ 22 in variable increments of $\Delta N_{j} = N_{j+1/2} - N_{j-1/2}$ with 0 $ \le j \le M$ .

The differential distribution of the number of discrete absorbers with respect to  \ion{H}{1}  column density and redshift, $\frac{\partial^{2}n}{\partial{N_{HI}}\partial{z}}$, is typically characterized by a piecewise continuous function in redshift and column density \citep[c.f.][]{Madau:1995, Inoue:2014}.   There are three basic \ion{H}{1} absorption regimes: the Ly$\alpha$\ forest regime (LAF), $  \log{N_{HI}(cm^{-2})} \lesssim $ 17; the Lyman limit (LL) regime,  17 $\lesssim \log{N_{HI}(cm^{-2})} \lesssim$ 20, and the damped Ly$\alpha$\ (DLA) regime,  $ 20 \lesssim \log{N_{HI}(cm^{-2})} $.

We employ the $\frac{\partial^{2}n}{\partial{N_{HI}}\partial{z}}$  described by \citet{Inoue:2014}, which uses a "Schechter-like" distribution function for the column density multiplied by a piecewise-continuous multiple power law distribution to describe the evolution in redshift.    The distribution function is broken down into the sum of two different products, which in combination reasonably agrees with the evolution of \ion{H}{1} absorption systems from the LLA  to  DLA regimes as detailed in the literature \citep{Weymann:1998, Prochaska:2005, Prochaska:2010, Ribaudo:2011, Noterdaeme:2012, Fumagalli:2013, Kim:2013, O'Meara:2013, Prochaska:2014}.   We note that the \citet{Inoue:2014} distribution function produces a mean transmission that is generally less aggressive than that produced by the distribution function used by \citet{Madau:1995}, even though it does not include a contribution from DLAs.

The mean IGM transmission functions in the observers frame, $T_{IGM}(\lambda_o) = \exp{<-\tau(\lambda)>}$,  are plotted in Figure~\ref{fig6} for $z$ = (0.1, 0.3, 0.5, 0.7, 1.0, 2.0, 2.9).  These transmission functions were computed from the ($\chi_{HI}$, $\chi_{HeI}$) = (1.0, 0.9) model.  We emphasize that they are just mean relationships.  Significant stochastic deviations are expected along any given line of sight.   We give an indication of the level of such variations at the Lyman edge by overplotting the 68\% deviations found by \citet[][their Figure 8]{Inoue:2008} in a Monte Carlo simulation of IGM absorbers distributed over a range of column densities from LAF to DLA with a piecewise break at the LL transition.  The appearance, or absence, of an LL system in the Monte Carlo simulation drives much of the expected transmission stochasticity.   We see that while the mean attenuation is significant at $z$ =2.9, reaching a lower trough of $\approx$ 15\% at 2000 \AA, it is by no means complete.  The transmission at the Lyman edge  for each redshift is  $T(z)$ = (0.98, 0.97, 0.95, 0.94, 0.92,      0.80, 0.57), which translates to a decrease in abmag at the respective edges of $\delta m^*_{(1+z)900}$ = (0.02, 0.03, 0.05, 0.07, 0.09, 0.24, 0.61).

In Figures~\ref{fig7}, \ref{fig8} and \ref{fig9} we show the result of applying $T_{IGM}(\lambda_o)$ to the ($\chi_{HI}$, $\chi_{HeI}$) = (1.0, 0.9) and ($\chi_{HI}$, $\chi_{HeI}$) = (0.1, 0.9) luminosity density models respectively.  \added{Following \citet{Oke:1983},} using abmag = -2.5$\log{F_{\nu}}$-48.6 and substituting $F_{\nu} = \frac{\lambda^2}{c}F_{\lambda}$, we determined the flux, $F_{(1+z)1500}$  in the observer's frame from \deleted{the characteristic abmag}  $m^*_{(1+z)1500}$ \deleted{of Eq.~\ref{eq5}} in Table~\ref{t1}, such that
\begin{equation}
\log(F_{(1+z)1500}) = \frac{m^*_{(1+z)1500} + 5\log{[(1+z)1500]} +2.408}{-2.5},
\end{equation}
\explain{This formula has been corrected.  Originally there was a 4 in front of the log when it should have been a 5.  The zero point has been changed from 2.406 to 2.408 = 48.6 - log c, where c is the speed of light expressed in \AA\ s$^{-1}$.}

\noindent and found a scale factor, $M_7$, matching the redshifted SB99 luminosity density at luminosity distance $d_{l}(z)$ to the observed SED $F_{(1+z)1500}$ such that

\begin{equation}
F_{\lambda_o} = M_7\left(\frac{L_{(1+z)\lambda_r} }{4 \pi d_{l}^{2}(z) (1+z)}\right).
\end{equation}

\noindent Here the luminosity distance $d_{l}(z)$ is in cm \added{and $M_7$ = $\frac{M^{\star}_g}{(10^7 M_{\odot})}$, where $M^{\star}_g$ is the galaxy stellar mass and $10^7 M_{\odot}$ is the mass of the SB99 model with its SFR of 1 $M_{\odot}$ yr$^{-1}$ and age of 10$^7$ years.  We find} $M_7 = $ [0.8, 1.1, 3.2, 4.4, 5.6, 6.9, 13.7]  for the fiducial redshifts in Table~\ref{t1}.   The $z = 0 $ model is fixed to $m_{1500}$ = 18.0, with $M_7 =1 $ at a distance of $d_{l}$ = 177 Mpc.  The mean \added{IGM} transmission function was applied as a uniform screen \replaced{after redshifting and scaling}{to $F_{\lambda_o}$.  The CGM transmission is applied to $L_{\lambda_r}$ in the rest frame prior to redshifting.}    Lines of constant abmag are overplotted on the figures.

\subsection{LyC Detection Requirements \label{detreq}}

The results of the previous section show that detection and quantification of the fraction of LyC flux escaping from star-forming galaxies out to $z \sim$ 3 will be a formidable, but not  insurmountable, challenge for future space observatories.  Moreover, they are consistent with the paucity of detections to date.

\subsubsection{Current Capabilities}
Examining the $z =$ 0.1 models, we see that very little of the LyC region peeks out below $\sim$ 1000 \AA.   The Cosmic Origins Spectrograph (COS) on the {\it Hubble Space Telescope} ({\em HST}\/)  has limited sensitivity in this bandpass ($A_{eff} \sim$ 10 cm$^{-2}$), with a background equivalent flux (BEF) of $\sim$ 10$^{-15}$ erg cm$^{-2}$ s$^{-1}$ \AA$^{-1}$ \ $\sim$  20 abmag \citep{McCandliss:2010, Redwine:2016}.  Galaxies brighter than this are in the region of the exponential falloff in the luminosity function, so they become increasingly rare with increasing luminosity.  Characteristic galaxies with edge escape fractions $f^e_{900} < 0.4$, will have an attenuated edge flux more than an order of magnitude lower than the COS BEF. Consequently, they will be background limited, requiring extraordinarily long integration times to detect with confidence.  We can expect to detect only a handful of such objects over the lifetime of COS.  The three detections by \citet{Leitherer:2016} at $z \approx$ 0.04 had edge fluxes $\sim$ 1 to 2 $\times$ 10$^{-15}$ erg cm$^{-2}$ s$^{-1}$ \AA$^{-1}$ .

The situation is somewhat more favorable at $z$ = 0.3, 0.5, and 0.7, where the  $m^*_{(1+z)1500}$ are quite similar  ($m^*_{1950}$, $m^*_{2250}$, $m^*_{2550}$ = 22.3, 22.4, 22.7)  and the LyC region extends shortward of  $\sim$ 1200, 1350, and 1550 \AA, respectively, into a wavelength region where the COS effective area $A_{eff} >$ 1000 cm$^{-2}$.  Although the $m^*_{(1+z)1500}$ for galaxies at these redshifts are nearly an order of magnitude fainter than at $z$ = 0.1, the COS BEF is much lower than at $z =$ 0.1 ($\sim$ 10$^{-17}$ to 10$^{-18}$ erg cm$^{-2}$ s$^{-1}$ \AA$^{-1}$ \ $\sim$ 25 to 27.5 abmag -- depending on orbital attitude and solar activity),  thus allowing for more efficient observing programs to be constructed.  Still, the background limit is reached for characteristic galaxies at $f^e_{900} \approx$ 0.04 to 0.16.  The depth of such observations will be limited and robust statistical samples difficult to come by, especially for $z$ = 0.5 and 0.7, where the number density is nearly 4 times lower.   Nevertheless, the spectral baseline is relatively longer, which along with the higher effective area favors the detection of LyC drop-ins toward these higher redshifts.

For galaxies at $z \approx$ 1 the detection of escaping LyC with COS becomes even more difficult, as the unattenuated LyC region is of order the BEF.  This was also the case for LyC leak photometric searches conducted \replaced{by}{using} {\em GALEX}\/.  The FUV ($\lambda_{eff}$ = 1528 \AA, $\Delta\lambda$ =1344 - 1786)  and  NUV ($\lambda_{eff}$ = 2271 \AA, $\Delta\lambda$ =1771 - 2831 channels on {\em GALEX}\/\ straddle the break for objects at a redshift of $z \approx$ 1.1.  The {\em GALEX}\/\  5$\sigma$ flux limit was $\sim$25 to 24 abmag for 30 ks integration in the FUV and NUV, respectively \citep{Morrissey:2005}.  In the NUV  a $z$ = 1  characteristic galaxy  is $\sim$23 abmag, while the unattenuated FUV SED  ($f^e_{900}$ =1) has $\sim$25 abmag at 1530 \AA; this is too faint for robust detections at near unity escape fraction.  These limits are consistent with the \citet{Cowie:2009} analysis of deep {\em GALEX}\/\ exposures of the GOODS-N field with spectroscopic redshifts, where  they  found no objects with FUV $<$ 25 for redshifts of $z > 0.6$.   We conclude that the limiting flux of {\em GALEX}\/\ was not low enough to adequately survey LyC\ leakage at a redshift of $z \ga$ 1.

Observations by \citet{Siana:2007} using the Space Telescope Imaging Spectrograph (STIS) and Advanced Camera for Surveys Solar Blind Channel (ACS/SBC) found no detections in deep far-UV observations around 1600 \AA\  of 21  HUDF objects with known spectroscopic redshifts 1.1 $< z < $ 1.5.  The $3\sigma$ limits in the ACS/SBC F150LP channel were estimated to be $\approx$28 abmag.  Their median abmag at 1500(1+1.3) = 3450 \AA\ was 24.5, which is about 1 mag fainter than our characteristic magnitude at $z$ = 1.  The non-detection to a 28 abmag limit at observer frame 1600 \AA\ implies a $\log{N_{HI}(cm^{-2})} \ga$ 17.75, yielding a $f^e_{900}$ $\sim$ 0.04  (an integrated 0.17 $< f^e_{LyC} <$  0.26).  These values compare fairly well to their stacked limit of $f_{esc,rel} <$ 0.08 evaluated at 700 \AA\ in the rest frame.

\added{\citet{Naidu:2016} analyzed} Hubble Deep UV (HDUV) imaging of the GOODS-north and -south fields, using the Wide-Field Camera 3 (WFC3) filters F275W and F336W and redshifts supplied by 3D-{\em HST}\/\ Grism,   \deleted{were used} to  explore the redshift range $z \sim$ 2--3.  The 5$\sigma$ detection limit was $\sim$ 28 abmag.  The candidate leakers were estimated to have $f_{esc} >$ 0.6.  This  result is consistent with our $z $ = 2 and 2.9 calculations, showing that a characteristic galaxy at these redshifts with an abmag of 28 in the LyC will have $f^e _{900}>$ 0.4 at $z$ = 2 and $f^e _{900} >$ 0.6 at $z$ = 3.

\begin{figure}
\includegraphics[width=.5\textwidth]{f10_ADTDL.eps}
\caption{ The product of effective area $A_{eff}(\lambda)$, observing time $\Delta T$, and bandwidth $\Delta \lambda$
required to detect flux from a characteristic galaxy, attenuated by a $\log{N_{HI}(cm^{-2})}$ = [18.25, 18.00, 17.75, 17.50, 17.25, 17.00, 16.00], in the wavelength region just over the Lyman edge, with a signal to noise of 5.  The corresponding edge escape fractions are $f^e_{900}$ = [0.000, 0.003, 0.041, 0.166, 0.364, 0.566, 0.945] in color code of [red, orange, light green, green, blue, violet, grey].  The example given in the text (Eq.~\ref{eq12}) is marked with black horizontal and vertical lines.
  \label{fig10}}
\end{figure}

\subsubsection{Future Capability Requirements \label{future}}

It is clear from Figure~\ref{fig2}  that if we are to achieve the goal of statistically significant determination of LyC luminosity function evolution wherein we probe down to $f^e_{900} \approx$  0.01 out to a redshift of 3, then we need to reach an abmag  from 25 to  30 for the characteristic objects in the redshift range from 0.1 $< z < $ 2.9 .  This corresponds to a flux range of  $F_{(1+z)900} \sim$ 10$^{-17}$ to 10$^{-20}$ erg cm$^{-2}$ s$^{-1}$ \AA$^{-1}$ .  The luminosity function spans a range of $\approx \pm$ 2.5 mag about the characteristic value, so the flux range will need to be another factor of 10 lower to obtain adequate numbers of  low-luminosity objects.

By way of example, \replaced{let us}{if we} assume a limiting flux requirement of $F^{lim}_{1800}$ =2 $\times$ 10$^{-20}$ erg cm$^{-2}$ s$^{-1}$ \AA$^{-1}$ \ at a 1800 \AA\ as a representative goal for $\sigma$ = 5  of edge detection with a $f^e_{900} \ga$ 0.003 for faint-end objects at $z \approx$ 1, then we arrive at the following criteria for the product of effective area ($A^{eff}_{1800}$, observing time $\Delta T$, and $\Delta \lambda$ spectral bandwidth, assuming negligible background):
\begin{equation}
 A^{eff}_{1800}~\Delta T~\Delta \lambda = \frac{\sigma^2}{F_{1800}/E_{1800}} = 1.3 \times 10^{10} \ifmmode {\rm cm^2\;s\;\AA} \fi,
 \label{eq12} \end{equation}

\noindent where $E_{1800}$ is the photon energy at 1800 \AA.  This formula assumes that there is negligible background.   It may be used for estimating effective area, observing time, and bandwidth requirements for photometric and spectroscopic applications.   In Figure~\ref{fig10} we show the area-time-bandwidth product Lyman edge detection requirement for $\log{N_{HI}(cm^{-2})}$ = [18.25, 18.00, 17.75, 17.50, 17.25, 17.00, 16.00] as a function of redshift.

\subsubsection{Target Sample Goals }

\added{Figure~\ref{fig1} shows that} there are $\sim$ 300 objects per unit magnitude per square degree at $z =$ 0.1 at the faint-end.  By 0.3 $z =$ 0.3 the faint end areal density are $\sim$ 3000 objects per unit magnitude per square degree, being flat out to $z =$ 1.  For $z =$ 2 the areal density at the faint end rises to $\sim$ 50,000 objects per unit magnitude per square degree.

The construction of high-fidelity luminosity functions places a requirement on sample size, where 25 objects per luminosity bin per redshift interval will yield an approximate rms deviation of $\sim$ 20\% for each point. Luminosity range should be ~ 2 - 3 orders of magnitude with $\sim$ 20 to 40 bins covering 10 redshift intervals. Redshifts are required for each object. This suggests an observing program with 500--1000 objects per redshift interval, yielding 5000--10,000 objects in total.

The development of a wide-field multi-object spectroscopic (MOS) capability and complementary photometric observations will be essential to providing these samples.  Angular coverage requirements will be driven by low-redshift objects, which have lower areal number densities than higher-redshift objects, while observing time requirements will be driven by the faintest objects.

\subsection{Observing Strategies}

Spectroscopy and photometry provide complementary approaches to this problem. Spectroscopy offers an opportunity to examine in detail the variation of the flux escaping at wavelengths below the Lyman edge along with the compositional properties of the objects.  Photometry can go deeper and offer higher spatial resolution at the expense of spectral information. Spectroscopy provides an avenue for training photometry.

A comprehensive program will incorporate photometry into the search for candidates and the deep probe of the faint end of the LyC luminosity function, while low-resolution precision spectroscopy will be used to characterize the shape of the LyC in a search for drop-ins, offering clues for the total ionizing photon budget and potentially dust attenuation in a completely unexplored bandpass.  Spectral multiplexing over several square arcminutes will be of great importance for acquiring statistically significant samples in a reasonable amount of observing time.

These observations should be complemented by medium- to high-resolution ($R \sim$ 10,000 - 50,000) spectroscopy longward of the Lyman edge,  providing a baseline assessment of intervening \ion{H}{1} and metallic absorption systems associated with the CGM and IGM.  Such observations, supported by spatially resolved imaging at the scale of 10 to 100 pc, can be used to account for the partial covering of emission regions, wherein the uniform screen assumption assumed here could be relaxed in favor of the informed modeling of foreground sources using measured superpositions of \ion{H}{1} columns and metallic absorption distributions.  This is especially important for determining the randomly distributed IGM attenuation prior to quantifying the actual escape from the CGM for the higher-$z$ objects.   Success at high $z$ is likely to rely on the identification of ``lucky sight-lines''  aided by gravitational lens and/or a several $\sigma$-low deviation from the average number of obscuring line of sight IGM absorption systems. \\

\section{Conclusion} \label{sumcon}

Measurements of $f^e_{LyC}$ at $z \la$ 3 across all types of star-forming galaxies are crucial to informing our understanding of how the universe came to be ionized.  UV observations, far and near, provide the most direct path to the spatially resolved detection of ionizing radiation, and the opportunity to characterize the physical state of galactic environments that favor LyC escape.

The primary purpose of this work is to provide estimates of the flux in the LyC from star-forming galaxies, as  functions of escape fraction and redshift.  \deleted{,  for the purpose of} \added{These estimates are useful for} quantifying science return,  \replaced{developing}{defining} technical requirements, and \added{developing} observing strategies for future large, medium, and small scale missions to be considered by the Astrophysics Decadal for 2020.  A model has been developed based on a uniform foreground screen of \ion{H}{1}, \ion{He}{1}, and \ion{He}{2}, attenuating a young continuous star-forming object \replaced{, having}{with}  fluxes at  (1+z)1500 \AA\ \replaced{set to }{scaled to reproduce} the characteristic apparent magnitudes of the \citet{Arnouts:2005} luminosity functions.  The uniform screen model has as free parameters the ionization fractions of H and He ($\chi_{HI}$, $\chi_{HeI}$), wherein the ratio of H to He is set to the cosmic abundance.  We also account for the mean attenuation by power law distributions of Ly$\alpha$\ forest, LL, and DLA systems associated with the IGM as a function of increasing redshift.

\added{The paucity of current detections to date are broadly consistent with the characteristic flux levels found here.  Sensitivity to an abmag $\approx$ 30 is required to detect an attenuated edge from a characteristic galaxy with $f^e_{900} \approx 0.003$, ($\log{N_{HI}(cm^{-2})} = 18.0$) out to $z \la$ 1.  For redshifts 1 $\la z \la$ 2.9, an abmag of 31 $\la m_{(1+z)900} \la$ 33 is required.}

We \replaced{find}{caution} that the escape fraction measured just below the Lyman edge ($f^e_{900}$) at 911.8 \AA\ provides only a lower limit to the  fraction of LyC photons that escape as integrated over the entire EUV region ($f^e_{LyC}$).  For 18.5 $ > \log{N_{HI}(cm^{-2})} > $17.9, the Lyman edge can appear black (essentially zero) yet the integrated escape fraction can range from 1 to 20\%, depending on the choice of ionization fractions ($\chi_{HI}$, $\chi_{HeI}$).

More accurate assessments of the integrated escape fraction could be made from spectroscopic observations that resolve the recovery of flux $\propto (\frac{\lambda}{\lambda_e})^3$; a phenomena that we have dubbed Lyman ``drop-ins''.  Observations of the LyC spectral shape could provide, in principle, the following: enhanced fidelity to the determination of the contribution of star-forming galaxies to the MIB; important observational insights into the  temperature of the CGM and IGM; and  constraints on the survivability and attenuation properties of dust grains with respect to the total gas content in LyC-leaking environments.

The uniform screen model adopted here is considerably simpler than the more realistic case of an undulating, highly discontinuous and chaotic ``unity \ion{H}{1} optical depth'' surface of the CGM surrounding a star-forming galaxy, which must have a $\tau$ low enough for LyC radiation to  escape.  The model should be thought of as a kind of ensemble average of the galaxy's partially covered star-forming regions, wherein much of the total star-formation may be buried by a more heavily attenuating ISM.

We suggest a strategy of high spectral and spatial resolution observations in the region longward of the Lyman edge,  to  guide assessment of the line of sight geometry in coordination with a spectroscopic determination of the degree of partial covering, along with the identification of specific Ly$\alpha$\ forest, LL, and DLA systems that may contribute to the attenuation of objects toward higher redshift.  Such information will allow a relaxing of the simple uniform screen model in favor of more realistic radiative transfer models.

\deleted{The paucity of current detections to date are broadly consistent with the characteristic flux levels found here.  An abmag $\approx$ 30 is required to detect an attenuated edge from a characteristic galaxy with $f^e_{900} \approx 0.003$ out to $z \la$ 1.  At 1 $\la z \la$ 2 an abmag $\approx$ 32 is required.}  Achieving the goal of a statistically significant characterization of LyC luminosity function evolution out to $z \la$ 3 can be carried out most efficiently with a wide-field multi-object spectroscopic survey supported by photometric observations.  An instrument with an effective area, observing time, and spectral bandwidth product of 1.3 $\times$ 10$^{10}$ cm$^{2}$~s~\AA\ at 1800 \AA\ would be sufficient to carry out such a program to a redshift of $z =$ 1.

\acknowledgments

We acknowledge useful conversations with Brian Fleming, Kevin France, Keith Redwine, Jason Tumlinson, and Harry Ferguson.  We thank the anonymous referee for keen suggestions that improved the readability and utility of this article.  Support for this work was provided by NASA to the Johns Hopkins University through APRA grants NNX08AM68G, NNX11AG54G, and NNX17AC26G.

redpajama_set_name: RedPajamaArXiv


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British Army Gets 3rd Gurkha Battalion
Posted on March 12, 2019 by Liam, Editor, Warfare.Today
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The 3rd Battalion Royal Gurkha Rifles will be established as a Specialised Infantry Battalion and will begin recruiting in 2019. Armed Forces Minister Mark Lancaster has confirmed that a new specialist Gurkha battalion is being formed.
The 3rd Battalion Royal Gurkha Rifles will join other members of the Specialist Infantry Group, to complete plans set out in the 2015 Defence Review to establish up to five Specialised Infantry Battalions. These specialised Infantry Battalions are designed to provide expert capacity building and training skills with a focus on niche capabilities or areas of the world.
"The Royal Gurkha Rifles is delighted to be able to support the Army by creating a third battalion," said Colonel of the Royal Gurkha Rifles, Major General Gez Strickland DSO MBE. "The specialised infantry role is exciting and challenging and we look forward to learning new skills and making new partnerships around the world as we begin the new task. We are enormously proud of the Army's confidence in our ability to take this on."
For more than 200 years, Gurkhas have been an integral part of the British Armed Forces and have demonstrated exceptional military aptitude, with a 100% pass rate through basic training. Gurkha soldiers continue to make an exemplary contribution to the British Army through the unique skills they offer, including specialist language skills, which enable them to build longstanding relationships with the United Kingdom's global partners.
Alongside this new role, the Ministry of Defence will also be enhancing the support some Gurkha units already provide to the Army, for example the UK led NATO Allied Rapid Reaction Corps, and establishing additional Gurkha Engineer and Signals Squadrons . These are crucial capabilities to enable the UK to meet its global defence commitments.
The new units will allow Gurkhas to access more career opportunities, including promotion and increased chances to serve a full 24-year Army career within the Brigade of Gurkhas.
"The Gurkhas have built an outstanding reputation for their skill and bravery as soldiers through centuries of service and sacrifice," said Armed Forces Minister, Mark Lancaster, "They bring unique expertise and perspective to the United Kingdom and British Army which makes them an ideal choice to form a third battalion of the Royal Gurkha Rifles as a Specialised Infantry Battalion.
Source: MOD
Image: A soldier of the Queens Own Gurkha Logistic Regiment is pictured during a mission in the Lashkah Gah area in Afghanistan. The Gurkhas under command of their Officer Commanding advise and mentor the Afghan Uniformed Police on vehicle check points and other taskings for the Royal Military Police. Photograph by Sergeant Andy Reddy, RLC (Crown Copyright, 2012).
Brigade of Gurkhas British Army Defence Gez Strickland Mark Lancaster Royal Gurkha Rifles
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Sons of Herod (genocide in independent state of Croatia)
Documentary Film "Sons of Herod" is an documentary and analytical story about the genocide of the Serbian people in the Independent State of Croatia (Nezavisna Država Hrvatska, NDH), which for the last seven decades has been hidden from the world, under the political embargo of the Yugoslavian politics, bans and censorship. Children death camps were nowhere to be found except in the Independent State of Croatia (NDH). Therefore, the film especially points to the suffering of children, addressing the causes of this cruel crime, revealing simultaneously its depth, crime against humanity, the role of the Roman Catholic Church but also the ones who were for decades guardians of this horrible secret and the carst pits.
Thank You for this documentary. If there is anything an outsider could do to help spread the word about these gruesome crimes, please do not hesitate to contact me.
Hvala na ovom dokumentarnom filmu. Ako postoji nesto sto bi autsajder mogao uraditi za sirenje svesti kod ljudi koji ne mare ili ne znaju, kontaktirajte me.


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Home Scores Bracket Super Regional brackets Rankings Stats Video History
Millersville Athletics | April 12, 2014
Millersville sweeps No. 9 Shippensburg
Millersville starting pitchers Tad Barton and Jim McDade combined for 14 brilliant innings of work.
MILLERSVILLE, Pa. -- Millersville starting pitchers Tad Barton and Jim McDade combined for 14 brilliant innings of work in a sweep of No. 9 Shippensburg Saturday at Cooper Park. After allowing run in the first inning of game one, Barton tossed six consecutive shutout innings for a 2-1 win. McDade continued the trend and kept the Raiders scoreless for seven innings in a 2-0 game two win.
Barton (5-2) scattered five hits and struck out four. Three of the strikeouts ended innings and stranded Shippensburg runners on base. McDade (4-1) breezed through the Raider lineup in game two. He allowed a first-inning, two-out single to Jimmy Spanos but went the final 6.1 innings without allowing another hit. He allowed only one more Raider to reach base (a walk in the third). McDade retired 14 in a row to secure the win. It was the first time Shippensburg had been one-hit since 2010 and the first against a PSAC East opponent since Derek Kline's one-hitter in a five-inning game in 2009.
With Barton and McDade dealing, the Millersville offense needed only four runs to get two wins. Tyler McDonald went 2-for-3 in the doubleheader with a sacrifice fly that brought home the winning run in the opener. He also made a stellar catch on a line drive that was the final out of game two. Dan Neff brought home both runs in game two with a two-run single.
Millersville boosted its overall record to 25-10 and its PSAC East record to 12-4. Shippensburg fell to 22-10 overall and 9-7 in league play. The Marauders now hold a three-game lead over Shippensburg in the PSAC East standings heading into Sunday's doubleheader at Fairchild Field.
Mike Dougas and Shippensburg put pressure on Barton early in the opener. Douglas drew a first pitch walk and promptly swiped second base. After moving to third on a balk, Pat Kregeloh pushed him home with a single to left. Shippensburg put runners on base in the second and third and had runners in scoring position in the fourth and the fifth, but Barton worked out of each jam.
Millersville missed its own opportunities, leaving runners stranded in each of the first four innings. In the fourth, Dan Johnson and Alex Ramsay were in scoring position with one out but Kregeloh fanned the next two Marauders to keep Ship in front.
Millersville broke through in the fifth with the help of some Shippensburg defensive miscues. Chas McCormick reached on an error, and after stealing second, Tyler Orris single to right field. McCormick initially held at third base but the right fielder booted the ball, allowing McCormick to race home.
Johnson opened the sixth with a double that bounced just inside the left field line. A bunt from Alex Ramsay pushed Johnson to third, and the strategy worked to perfection when McDonald lofted a fly to center that allowed Johnson to sprint home for the go-ahead run.
Millersville and Shippensburg both totaled five hits. Orris accounted for two of the Marauders' hits.
McDade and Rich Michaud dueled for the first three innings, but in the fourth, Zach Stone started the Marauder charge with a single. Coach Jon Shehan employed some small ball, calling Johnson to bunt Stone to third. Ramsay reached on an infield single and moved up to second on a bunt by McDonald. With two on and two out, Neff delivered a clutch hit up the middle. Stone scored easily. Ramsay appeared out at the plate, but he avoided the tag with his slide and then dived back into home head first from the first base side for the second run.
Barton had no problem with the Shippensburg lineup. Only one runner reached second base and he cruised through the final four innings. McDade has now tossed at least six innings in five consecutive starts. He has allowed fewer than three runs in five of eight starts and has held opponents to five or fewer hits in seven of eight. He has also walked only one batter in six straight starts.
These 7 DII women's basketball sophomore standouts are propelling their teams to new levels
Whether they are breaking out or improving on big freshmen campaigns, these seven DII women's basketball sophomores are keys to their team's success.
DII field hockey programs with the most NCAA DII national championships
Here's a look at the programs with the most DII field hockey national championships.
Shippensburg defeats East Stroudsburg for third consecutive DII field hockey championship
Check here for live updates, highlights, scores, and stats from the NCAA DII field hockey championship at the DII festival in Pittsburgh, Pennsylvania.


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MONTGOMERY | Hale County and three of its towns are getting $1.4 million in grants to upgrade water and sewer service.
Gov. Robert Bentley's office announced that Hale County, Akron, Greensboro and Moundville will get grants of $350,000 each. The local governments will contribute matching funds of varying amounts, bringing the total cost of the projects to $1.58 million.
"These grants will enable communities to complete important projects without taking funds from vital services like public safety and other budgetary priorities," Bentley said in a statement earlier this week.
Hale County will contribute $62,000 for a $412,000 project to install larger water lines covering 27,000 feet on Hale County roads 7 and 21. The lines are too small for adequate volumes of water for residents in the growing rural areas.
Probate Judge Leland Avery said Tuesday that the lines will be replaced in rural areas east of Greensboro.
The upgrade will serve 92 residences and 236 people.
Avery said the project has to be bid, possibly by late winter or early spring.
Moundville is matching $50,000 to create a $400,000 project.
The project involves cleaning and re-lining clay sewer lines along Griffin Street and Alabama Avenue, according to Bentley's office. The grant also will enable the city to replace small water lines along Griffin Street with 6-inch lines to improve residential water pressure.
He said the work will be in two blocks west of downtown. "It's not an extremely large area," Wyatt said.
The project in Greensboro will involve replacing cracked sections of clay sewer pipes that were leaking into yards and drainage areas. The city also will clean and re-line sections of worn and corroded iron and PVC sewer pipes.
Greensboro is contributing $70,000 to the project for a total of $420,000.
John Jay, superintendent of the Greensboro water and sewer department, said the work includes the main sewer line that traverses Greensboro around Hale Street.
Akron is contributing $2,000 toward its project that will replace an old sewer pump station that frequently doesn't work. Its malfunction causes sewage backup into homes and yards, Bentley's office said.
The town will install a bigger sewer line near the pump station in order to handle more volume.
Bentley announced the federal U.S. Department of Housing and Urban Development grants that will be administered by the Alabama Department of Economic and Community Affairs. The projects will have to be bid.


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Fu terziaria dell'Ordine dei Servi di Maria.

Biografia

Nacque in Campania da genitori lombardi. Il padre era ufficiale di cavalleria e la famiglia Valtorta traslocò diverse volte, prima di stabilirsi definitivamente a Viareggio. La condizione familiare piuttosto agiata permise alla giovane Maria di frequentare il Collegio "Bianconi" di Monza, dove ricevette un'educazione classica, segnalandosi soprattutto per l'eccellente padronanza della lingua italiana.

Ma, prima ancora della conclusione degli studi, la sua vita fu segnata dai primi scontri con la madre, la quale infranse il suo sogno di sposarsi. Dopo la battaglia di Caporetto decise di entrare nel corpo volontario delle Infermiere Samaritane; per diciotto mesi si prodigò a curare i soldati italiani feriti nell'Ospedale militare di Firenze.
Nel 1920 subì una aggressione da parte di un giovane sovversivo il quale, sferrando un forte colpo alle reni con una spranga di ferro, le lesionò la spina dorsale: questo fu l'inizio di un interminabile calvario medico che, nel 1934, la vide infine costretta a letto, semiparalizzata dalla vita in giù.

Nonostante le crescenti difficoltà, Maria Valtorta si dedicò interamente all'approfondimento della fede cristiana cattolica, anche come delegata dell'Azione Cattolica, finché glielo permisero le sue forze. La lettura dell'autobiografia di Teresa di Lisieux, Storia di un'anima, fece maturare in lei la decisione di offrirsi come anima-vittima:

Sopraggiunta la paralisi, pensò di dedicarsi alla scrittura e abbozzò un romanzo a sfondo autobiografico, che non venne mai pubblicato. Negli anni successivi alla sua esperienza mistica la stessa Maria Valtorta, fece bruciare il suo lavoro: «Brucia tutto. Solo per l'Opera mia devi esser conosciuta come scrittrice».Nel corso del 1943, la sua vita, che ella credeva ormai prossima alla conclusione, infatti, conobbe una svolta radicale.

Nel giugno del 1942, incontrò un sacerdote servita, padre Romualdo Maria Migliorini, ex-missionario destinato al convento di Viareggio; questi divenne il suo direttore spirituale e all'inizio del 1943 le chiese di scrivere la propria autobiografia. Maria, superata l'iniziale riluttanza a rivangare un passato doloroso, accettò e nell'arco di pochi mesi riempì sette quaderni autografi. Profondamente devota a Maria Addolorata, entrò nel Terz'Ordine dei Servi di Maria il 25 marzo 1944, solennità dell'Annunciazione, proprio presso la comunità di Viareggio.

Il secondo e cruciale evento dell'anno si verificò il Venerdì Santo: il 23 aprile 1943 Maria avrebbe udito una "voce", che pensò essere la voce di Gesù, la quale la induceva a scrivere, come sotto dettatura. Quel primo "dettato" segnò l'inizio di un'opera monumentale: tra il 1943 e il 1947, con "punte" fino al 1951, Maria vergò di getto, senza rileggere, senza correzioni, ben centoventidue quaderni autografi (che contengono tutte le opere diverse dallAutobiografia), scritte a episodi, di getto e in contemporanea. Eppure, da quelle condizioni di salute e di lavoro - per di più aggravate dagli eventi bellici, che la videro anche sfollata - nacquero testi corposi e organici.

Ben presto, la presunta "voce" di Gesù — cui, nei "dettati", si aggiunsero via via anche l'Eterno Padre, lo Spirito Santo, Maria Santissima e l'Angelo custode della scrittrice — indicò come principale la grande opera sul Vangelo, che, una volta completata, avrebbe visto descritta (in una serie di "visioni") e commentata (nei "dettati" che accompagnano i singoli episodi) la vita di Gesù e Maria, dall'Immacolata Concezione fino all'Assunzione.

Padre Migliorini cominciò ben presto a formare copie dattiloscritte di quanto Maria andava scrivendo e anche a farle circolare, sebbene ella e anche questa "voce" fossero contrarie a qualsiasi divulgazione degli scritti prima della morte di Maria stessa. Tale divulgazione, tuttavia, attirò l'attenzione del Sant'Uffizio, che ordinò il ritiro di tutti i dattiloscritti in circolazione e il trasferimento a Roma di padre Migliorini, avvenuto nel marzo del 1946.

L'intera opera della Valtorta fu comunque sottoposta, per una sua valutazione e giudizio, all'allora pontefice Pio XII (vedi L'Osservatore Romano di venerdì 27 febbraio 1948), il quale, dopo averla attentamente consultata, disse ai tre padri serviti che aveva ricevuto in udienza privata: «Pubblicate quest'opera così come sta; chi legge capirà». L'opera ha subito inoltre analisi da parte di molti teologi cattolici i quali dichiararono unanimemente che questa era assolutamente conforme alla ortodossia cattolica. Il mariologo padre Gabriele Maria Roschini, fondatore della Facoltà Teologica Marianum di Roma e tra i maggiori mariologi del XX secolo, nel 1973 scrisse un libro intitolato La Madonna negli scritti di Maria Valtorta dove elogiava l'opera valtortiana e ricevette l'apprezzamento e la benedizione di papa Paolo VI per questo suo lavoro.

Nell'introduzione al suo libro scrive:«Mi sento però in dovere di confessare candidamente che la Mariologia quale risulta dagli scritti, editi e inediti, di Maria Valtorta, è stata per me una vera rivelazione. Nessun altro scritto mariano, e neppure la somma degli scritti mariani da me letti e studiati, era stato in grado di darmi, del Capolavoro di Dio, un'idea così chiara, così viva, così completa, così luminosa e così affascinante: semplice e sublime insieme».Maria Valtorta inoltre, mentre era impegnata nella stesura del suo Evangelo, riuscì a riempire una grande quantità di quaderni tanto da poter formare in seguito ben 3 volumi di oltre 400 pagine l'uno il cui contenuto risultava integrativo dell'opera principale. Questi volumi sono titolati rispettivamente I Quaderni del 1943, I Quaderni del 1944, I Quaderni del 1945-1950.

Si pensò allora ad un'edizione a stampa di tutta l'opera principale, ma svariate difficoltà si frapposero alla realizzazione del progetto: soltanto nel 1956 vide la luce il primo di quattro volumi, intitolato Il Poema di Gesù, per i tipi delle Edizioni Pisani. Peraltro, nei volumi successivi, che furono pubblicati con cadenza annuale fino al 1959, il titolo - suggerito dal noto clinico Nicola Pende, estimatore dell'opera - fu modificato in Il Poema dell'Uomo-Dio, poiché la versione originaria era già stata usata da un'altra casa editrice.

All'indomani della pubblicazione del quarto volume, il 16 dicembre 1959, e dopo la morte di papa Pio XII, il Sant'Uffizio condannò l'opera e la iscrisse nell'Indice dei libri proibiti. Il decreto della "Suprema" non era motivato; su L'Osservatore Romano del 6 gennaio 1960, esso fu riportato insieme con un articolo di commento, intitolato Una vita di Gesù malamente romanzata. Anche dopo l'abrogazione dell'Indice, in una lettera del 31 gennaio 1985 indirizzata al cardinale arcivescovo di Genova Giuseppe Siri, il prefetto della Congregazione per la Dottrina della Fede, il cardinale Joseph Ratzinger, confermò la "validità morale" dell'indice.

Morì nella propria casa di Viareggio il 12 ottobre 1961. Fu sepolta nel cimitero viareggino, ma, nel 1973, la salma fu riesumata e traslata a Firenze, nella Cappella del Capitolo della Basilica della Santissima Annunziata.

L'8 novembre del 2000, l'Ordine dei Servi di Maria ha tentato di introdurre un processo di beatificazione, ma mons. Bruno Tommasi, arcivescovo di Lucca, nella cui Diocesi è morta Maria Valtorta, ha proposto di udire l'arcivescovo di Firenze cardinale Silvano Piovanelli adducendo, tra le altre, ragioni di ordine, per essere il Tribunale diocesano già impegnato in un processo di beatificazione alquanto ponderoso. Il cardinale Piovanelli, una volta designato quale giudice dalla Congregazione per le Cause dei Santi, ha negato l'introduzione della causa, forte del parere negativo, pressoché unanime, dei Vescovi toscani; parere le cui ragioni, peraltro, non sono state comunicate al Postulatore.

 Le opere presunte come "ispirate"
Sono quelle di cui Maria Valtorta ha sempre sostenuto l'origine soprannaturale. In particolare, quanto al contenuto, nei testi si riscontrano agevolmente brani di carattere personale e altri, preponderanti, che sarebbero quelli propriamente "ispirati": essi si suddividono in visioni e in dettati. Nella parte relativa alle visioni è la stessa Maria Valtorta, con le proprie capacità di scrittrice, a scegliere parole e termini per descrivere ciò che vedeva. Nella parte relativa ai dettati, invece, Maria Valtorta asserisce di aver sempre trascritto, con fedeltà e precisione, ciò che ascoltava durante la sua esperienza mistica.

L'Evangelo come mi è stato rivelato
Dopo la condanna del Sant'Uffizio, l'editore Pisani stimò che fosse opportuno prepararne una nuova edizione, questa volta basata sul testo dei quaderni autografi e corredata di note bibliche e dottrinali, curate da p. Corrado M. Berti, servita. Emilio Pisani, figlio dell'editore, si occupò della costituzione del testo. Nel 1960 poté così uscire il primo di dieci volumi. Nel 1993 vide la luce un'edizione revisionata dell'opera, sempre in dieci volumi, con il nuovo titolo L'Evangelo come mi è stato rivelato.

La raccolta pretende di narrare la vita di Gesù, riportando episodi e fatti di vita quotidiana che non compaiono nei Vangeli canonici o che compaiono in forma ridotta. Maria Valtorta ha sempre sostenuto di non essere stata lei a inventare i nuovi episodi della biografia di Cristo, bensì di essersi limitata a descrivere minuziosamente le visioni di carattere mistico che ella sosteneva di avere e che riteneva esserle inviate da Gesù e dalla Beata Vergine Maria.

Libro di Azaria
Quest'opera raccoglie i dettati in cui Azaria, ritenuto dalla scrittrice stessa il proprio Angelo Custode, ha commentato, seguendo fedelmente il calendario liturgico, le 58 Messe festive, nel testo del Messale "tridentino" o di San Pio V, allora di uso corrente.
Oggetto del commento è il cosiddetto Proprio del giorno; quasi mai, però, il Vangelo, che è lasciato all'opera principale.

Lezioni sull'Epistola di Paolo ai Romani
Iniziate nel 1948 e concluse nel 1950, dopo una lunga pausa intermedia e una serie di interruzioni, le Lezioni sono dettati che l'autrice attribuisce direttamente allo Spirito Santo, che commenta il testo paolino nella versione della Sacra Bibbia usata da Maria Valtorta (cur. p. Eusebio Tintori OFM).

I Quaderni
Maria Valtorta scrisse tutta una serie di visioni e dettati che sono stati raccolti in tre volumi dei cosiddetti Quaderni (I Quaderni del 1943, I Quaderni del 1944 e I Quaderni del 1945-1950). In essi sono contenute esperienze e riflessioni di carattere mistico e spirituale, oltre che teologico. Proprio per il loro carattere miscellaneo, non è agevole riassumerne i contenuti in maniera soddisfacente perché in essi confluiscono tutti gli scritti che non sono pertinenti al L'Evangelo come mi è stato rivelato, al Libro di Azaria e alle Lezioni sull'Epistola di Paolo ai Romani. I brani sono raccolti in ordine cronologico e contengono ammaestramenti, dettati, visioni, tematiche teologiche e dottrinali, e anche episodi della vita personale che Maria Valtorta ha avuto in quegli anni, come ad esempio l'esperienza della "notte spirituale" durante la quale, tra l'aprile e il maggio del 1944 vive l'abbandono di Dio. Nel volume I Quaderni del 1945-1950 è presente un commento ai primi capitoli dell'''Apocalisse, l'ultimo libro del Nuovo Testamento della Sacra Bibbia. Tra le altre sono presenti anche le visioni dei primi martiri cristiani a Roma, la visione delle stigmate di San Francesco d'Assisi, le apparizioni di Lourdes, e molte altre visioni di santi e sante della storia cristiana, nonché la visione di Satana, della fine del mondo, dei regni soprannaturali e di altre tematiche appartenenti all'escatologia cristiana.

Quadernetti
Nel 2006, il CEV (Centro Editoriale Valtortiano) ha dato alle stampe un volume in cui sono raccolti gli scritti valtortiani rimasti fin qui inediti. Si tratta, per lo più, di pagine sciolte, datate o databili tra il 1943 e il 1954, di taccuini, di quinterni, di tutto il materiale che non ha trovato spazio nella pubblicazione dei Quaderni e che li integra. È presente in appendice la storia relativa alle visioni e ai dettati che Maria Valtorta ha ricevuto in merito alla Tomba di San Pietro a Roma. Sulla base di tali scritti si desume una inedita e diversa sepoltura del primo papa. Il giornalista e saggista Antonio Socci, sulla base delle informazioni contenute in questo libro, ha scritto e pubblicato il romanzo I giorni della Tempesta dove ricostruisce la storia della scoperta della tomba dell'apostolo Pietro.

 Le opere "non ispirate"
Autobiografia
Maria Valtorta scrisse la propria autobiografia per ubbidienza al proprio direttore spirituale, padre Migliorini, che gliela aveva richiesta. All'inizio fu molto riluttante a scriverla perché era molto riservata, inoltre non trovava né utile né piacevole farlo. Poi si decise ma ad una condizione, quella di essere spietatamente sincera, con sé stessa e con gli altri. L'autobiografia fu realizzata nei primi mesi del 1943 e terminata prima dell'inizio della sua presunta esperienza mistica. Il manoscritto originale dellAutobiografia riempie ben sette quaderni dell'epoca per complessive 761 pagine. Il racconto della sua vita inizia con i ricordi dell'infanzia, la storia della sua famiglia, gli spostamenti per varie città italiane, il rapporto particolarmente difficile con la madre e amorevole con il padre. Vi sono poi gli anni del collegio, le proprie esperienze di giovane ragazza, i primi amori, l'attentato che subì per mano di un sovversivo, le complicazioni della sua salute e il successivo stato d'inferma.

Lettere a Mons. Carinci
Con questo titolo il CEV ha pubblicato la corrispondenza intercorsa tra la scrittrice e mons. Alfonso Carinci (1862 - 1963), segretario della Sacra Congregazione dei Riti, negli anni 1949 - 1955. Mons. Carinci era un convinto estimatore degli scritti valtortiani - nonché della persona della scrittrice - perciò le lettere trattano soprattutto dell'atteggiamento dell'autorità ecclesiastica nei confronti dell'opera, prima e dopo il provvedimento del Sant'Uffizio. Mons. Carinci fu uno strenuo difensore degli scritti e della persona di Maria Valtorta anche all'interno della Santa Sede in Vaticano e lasciò l'incarico di segretario della sua congregazione il 5 gennaio 1960, alla veneranda età di 98 anni. É interessante notare come la sentenza di condanna del Sant'Uffizio che poneva all'Indice dei Libri Proibiti gli scritti di Maria Valtorta sia stata resa pubblica proprio all'indomani di quella data. Le lettere scambiate tra l'alto prelato e la mistica sono importanti per ricostruire la vicenda storica della pubblicazione dell'opera valtortiana e mostrano la profonda stima reciproca che li legava. Recandosi a Viareggio, Mons. Carinci ebbe modo di conoscere personalmente Maria Valtorta, inferma, e di celebrare la Santa Messa nella camera che la ospitava.

Lettere a Padre Migliorini
In questo volume il CEV ha pubblicato la corrispondenza intercorsa tra la Maria Valtorta e padre Romualdo M. Migliorini (1884-1953), appartenente all'Ordine dei Servi di Maria e priore del convento di Viareggio. Fu il direttore spirituale di Maria Valtorta a partire dal 1942 e colui che la spinse a scrivere la sua autobiografia all'inizio del 1943. La seguì direttamente durante tutto il periodo della sua esperienza mistica, aiutandola spiritualmente e materialmente, anche durante il suo sfollamento, a causa della guerra, a Sant'Andrea di Compito, in Lucchesia. Le fu vicino fino al marzo del 1946, quando venne allontanato da Viareggio e trasferito a Roma. Fu in quella fase che i rapporti tra padre Migliorini e Maria Valtorta divennero sempre più tesi, a causa di incomprensioni e divergenze inerenti alla pubblicazione dell'opera e alle disposizioni che la Valtorta riceveva durante la sua esperienza mistica.

Lettere a Madre Teresa Maria - vol.1 e vol. 2
In questi due volumi il CEV ha pubblicato parte della corrispondenza intercorsa tra Maria Valtorta e Madre Teresa Maria di San Giuseppe (1900-1985), una monaca carmelitana di clausura che fu come una madre spirituale per la mistica. La grande affinità spirituale esistente tra le due donne le spingeva verso una reciproca e completa confidenza, espressa attraverso un serrato e decennale rapporto epistolare, iniziato nel dicembre del 1945. Lidia Korompay, questo il nome secolare di Madre Teresa Maria, era nata il 18 febbraio 1900 a Venezia, da un'agiata famiglia, e aveva preso i voti nel monastero delle Carmelitane Scalze di Santo Stefano Rotondo a Roma. Nel 1938 venne destinata al monastero di Camaiore, del quale tre anni più tardi diventò Priora. I bombardamenti della Seconda Guerra Mondiale cagionarono gravi danni all'edificio del monastero di Camaiore; a causa di ciò, le monache di clausura furono costrette a spostarsi in alloggi alternativi provvisori. Nel 1955, la donazione di una villa che venne destinata all'uso monastico permise alla comunità di trasferirsi a San Colombano (nei pressi di Lucca), dove Madre Teresa Maria di San Giuseppe fu rieletta più volte Priora, fino al giorno della morte, avvenuta il 7 dicembre del 1985, dopo due anni di infermità.

Nel primo volume sono raccolte le lettere che Maria Valtorta e Madre Teresa Maria si sono scambiate tra il dicembre 1945 e il dicembre 1946, mentre nel secondo quelle scambiate dal 1947 al 1957. Circa duecento lettere sono andate definitivamente perdute, poiché bruciate da Madre Teresa Maria su richiesta della stessa Maria Valtorta, in ottemperanza a una disposizione divina da quest'ultima ricevuta.

 Posizioni della Chiesa Cattolica sull'Opera di Maria Valtorta L'Osservatore Romano, mercoledì 6 gennaio 1960, pubblica un articolo anonimo titolato Una vita di Gesù malamente romanzata dove si poteva leggere:

 Posizione della Sacra Congregazione per la Dottrina della Fede
In tempi più recenti, anche il card. Joseph Ratzinger si è espresso in merito alla posizione della Chiesa Cattolica circa "Il Poema dell'Uomo Dio", in una lettera privata del 31 gennaio 1985 indirizzata al card. Giuseppe Siri, arcivescovo di Genova (documento Prot. N. 144/58). La lettera nasce come corrispondenza tra due eminenti autorità ecclesiali e, in quanto tale, avrebbe dovuto rimanere privata, ma è stata invece successivamente resa di dominio pubblico:

 Posizione della C.E.I. (Conferenza Episcopale Italiana)
Il 6 maggio 1992 l'editore degli scritti di Maria Valtorta (Centro Editoriale Valtortiano) ricevette una lettera dal Segretario Generale della Conferenza Episcopale Italiana, mons. Dionigi Tettamanzi, che ad oggi rappresenta l'ultima posizione ufficiale dell'Autorità Ecclesiale circa l'Opera di Maria Valtorta. L'editore ha recepito la richiesta formulata dal Segretario Generale della C.E.I. e ha pubblicato il testo integrale della lettera nell'Introduzione de L'Evangelo come mi è stato rivelato (vol. 1):

 Note

 Scritti
Le informazioni sulla vita di Maria Valtorta sono desunte anche dai suoi scritti:
 Autobiografia, 1997, ISBN 88-7987-034-3L' Evangelo come mi è stato rivelato, 2001, ISBN 88-7987-100-5
 I Quaderni del 1943, 2006, ISBN 978-88-7987-135-8I Quaderni del 1944, 2006, ISBN 978-88-7987-136-5I Quaderni del 1945-1950, 2006, ISBN 978-88-7987-137-2Libro di Azaria, 2007, ISBN 978-88-7987-143-3Lezioni sull'Epistola di San Paolo ai Romani, 2008, ISBN 978-88-7987-150-1Quadernetti, 2006, ISBN 978-88-7987-139-6Lettere a Mons. Carinci, 2006, ISBN 978-88-7987-140-2Lettere a Padre Migliorini, 2011, ISBN 978-88-7987-169-3Lettere a Madre Teresa Maria - vol. 1, 2012, ISBN 978-88-7987-175-4Lettere a Madre Teresa Maria - vol. 2, 2013, ISBN 978-88-7987-177-8

 Bibliografia
 Gabriele M. Roschini, La Madonna negli scritti di Maria Valtorta, Isola del Liri, Centro Editoriale Valtortiano, 2017.ISBN 978-88-7987-297-3
Albo Centoni, Una vita con Maria Valtorta. Testimonianze di Marta Diciotti, Isola del Liri, Centro Editoriale Valtortiano, 1987. ISBN 88-7987-044-0
 Albo Centoni, Ricordi di donne che conobbero Maria Valtorta, Isola del Liri, Centro Editoriale Valtortiano, 1998. ISBN 88-7987-040-8
 Emilio Pisani, Padre Pio e Maria Valtorta, Isola del Liri, Centro Editoriale Valtortiano, 1999. ISBN 88-7987-070-X
 Emilio Pisani, Pro e contro Maria Valtorta, Isola del Liri, Centro Editoriale Valtortiano, 2005. ISBN 88-7987-130-7
 Jean-François Lavère, L'enigma Valtorta vol. 1, Isola del Liri, Centro Editoriale Valtortiano, 2012. ISBN 978-88-7987-174-7
 Jean-François Lavère, L'enigma Valtorta vol. 2, Isola del Liri, Centro Editoriale Valtortiano, 2016. ISBN 978-88-7987-273-7
 Liberato De Caro, I cieli raccontano vol. 1, Isola del Liri, Centro Editoriale Valtortiano, 2014. ISBN 978-88-7987-212-6
 Liberato De Caro, I cieli raccontano vol. 2, Isola del Liri, Centro Editoriale Valtortiano, 2015. ISBN 978-88-7987-243-0
 Liberato De Caro, I cieli raccontano vol. 3, Isola del Liri, Centro Editoriale Valtortiano, 2017. ISBN 978-88-7987-296-6
Liberato De Caro, I cieli raccontano vol. 4, Isola del Liri, Centro Editoriale Valtortiano, 2019. ISBN 978-88-7987-333-8
don Ernesto Zucchini, il Cielo in una stanza'', Fede e Cultura, 2019. ISBN 9788864097190

Voci correlate
 Gesù
 Mistica
 Sant'Uffizio
 Servi di Maria
 Casa di Maria

Altri progetti

Collegamenti esterni

 Un mensile di spiritualità e catechesi, curato da padre Enzo Redolfi, che propone regolarmente brani degli scritti valtortiani.
Biografia di Maria Valtorta redatta da fra Giuseppe Galassi OSM su sito ufficiale dell'Ordine dei Servi di Maria. URL consultato il 9 settembre 2019

Scrittori cattolici

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