Detecting the Cosmic Web: Ly{\alpha} Emission from Simulated Filaments
  at z=3
  The standard cosmological model ($\Lambda$CDM) predicts the existence of the
cosmic web: a distribution of matter into sheets and filaments connecting
massive halos. However, observational evidence has been elusive due to the low
surface brightness of the filaments. Recent deep MUSE/VLT data and upcoming
observations offer a promising avenue for Ly$\alpha$ detection, motivating the
development of modern theoretical predictions. We use hydrodynamical
cosmological simulations run with the AREPO code to investigate the potential
detectability of large-scale filaments, excluding contributions from the halos
embedded in them. We focus on filaments connecting massive
($M_{200c}\sim(1-3)\times10^{12} M_\odot$) halos at z=3, and compare different
simulation resolutions, feedback levels, and mock-image pixel sizes. We find
increasing simulation resolution does not substantially improve detectability
notwithstanding the intrinsic enhancement of internal filament structure. By
contrast, for a MUSE integration of 31 hours, including feedback increases the
detectable area by a factor of $\simeq$5.5 on average compared with simulations
without feedback, implying that even the non-bound components of the filaments
have substantial sensitivity to feedback. Degrading the image resolution from
the native MUSE scale of (0.2")$^2$ per pixel to (5.3")$^2$ apertures has the
strongest effect, increasing the detectable area by a median factor of
$\simeq$200 and is most effective when the size of the pixel roughly matches
the width of the filament. Finally, we find the majority of Ly$\alpha$ emission
is due to electron impact collisional excitations, as opposed to radiative
recombination.
