Prospects for Observing the Cosmic Web in Lyman-{alpha} Emission. (arXiv:1905.06954v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Witstok_J/0/1/0/all/0/1">Joris Witstok</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Puchwein_E/0/1/0/all/0/1">Ewald Puchwein</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kulkarni_G/0/1/0/all/0/1">Girish Kulkarni</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Smit_R/0/1/0/all/0/1">Renske Smit</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Haehnelt_M/0/1/0/all/0/1">Martin G. Haehnelt</a>
Mapping the intergalactic medium (IGM) in Lyman-$alpha$ emission would yield
unprecedented tomographic information on the large-scale distribution of
baryons and potentially provide new constraints on the UV background and
various feedback processes relevant for galaxy formation. Here, we examine the
Lyman-$alpha$ emission of the moderate-density IGM due to collisional
excitations and recombinations in the presence of a UV background in the
Sherwood simulation suite. We focus on large-scale-structure filaments in which
Lyman-$alpha$ radiative transfer effects are expected to be moderate. At low
density the emission is primarily due to fluorescent re-emission of the
ionising UV background due to recombinations, while collisional excitations
dominate at higher densities. We discuss prospects of current and future
observational facilities to detect this emission and focus on VLT/MUSE for a
more detailed sensitivity analysis. We construct mock MUSE observations
resembling the MUSE Hubble Deep Field South from our simulations and show that
our predictions are consistent with recent analyses of diffuse Lyman-$alpha$
emission using MUSE at redshifts $3 < z < 6$. We find that it should be most
feasible to detect the Lyman-$alpha$ emission from filaments in the IGM in
overdense regions, somewhat surprisingly towards the high-redshift end ($z
gtrsim 4.5$) accessible by MUSE, and if narrowband widths close to the MUSE
spectral resolution limit are used. This is due to the higher densities and
lower temperatures in the IGM at higher redshift. High-redshift protoclusters
therefore appear to be the ideal environment to observe filamentary structures
in the IGM in Lyman-$alpha$ emission.
Mapping the intergalactic medium (IGM) in Lyman-$alpha$ emission would yield
unprecedented tomographic information on the large-scale distribution of
baryons and potentially provide new constraints on the UV background and
various feedback processes relevant for galaxy formation. Here, we examine the
Lyman-$alpha$ emission of the moderate-density IGM due to collisional
excitations and recombinations in the presence of a UV background in the
Sherwood simulation suite. We focus on large-scale-structure filaments in which
Lyman-$alpha$ radiative transfer effects are expected to be moderate. At low
density the emission is primarily due to fluorescent re-emission of the
ionising UV background due to recombinations, while collisional excitations
dominate at higher densities. We discuss prospects of current and future
observational facilities to detect this emission and focus on VLT/MUSE for a
more detailed sensitivity analysis. We construct mock MUSE observations
resembling the MUSE Hubble Deep Field South from our simulations and show that
our predictions are consistent with recent analyses of diffuse Lyman-$alpha$
emission using MUSE at redshifts $3 < z < 6$. We find that it should be most
feasible to detect the Lyman-$alpha$ emission from filaments in the IGM in
overdense regions, somewhat surprisingly towards the high-redshift end ($z
gtrsim 4.5$) accessible by MUSE, and if narrowband widths close to the MUSE
spectral resolution limit are used. This is due to the higher densities and
lower temperatures in the IGM at higher redshift. High-redshift protoclusters
therefore appear to be the ideal environment to observe filamentary structures
in the IGM in Lyman-$alpha$ emission.
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