We detect Ly alpha emission from a approximate to 5 Mpc-long (comoving) portion of the cosmic web hosting an overdensity (delta approximate to 25) of 19 Ly alpha emitters (LAEs) at z approximate to 4 within the MUSE Ultra Deep Field (MUDF), reaching an average surface brightness (SB) of 5 x 10-20 erg s-1 cm-2 arcsec-2. This large-scale structure has an average SB similar to the filament across the two MUDF quasars at z approximate to 3.22. However, deep multiwavelength data do not show a clear presence of active galactic nuclei, suggesting that the emission is mainly regulated by the underlying gas density. We find approximate to 0.2 dex higher star formation compared to control samples and a remarkable predominance (5/7) of blue-peaked emission lines in the spectra of the embedded LAEs, indicative of favorable conditions for gas accretion. Lastly, we quantify the contribution of intragalactic gas to the Ly alpha SB profile at large distances from LAEs. By studying samples of filaments detected in emission within diverse environments, we are finally gaining new insight into the physics of gas accretion within the cosmic web.
Tornotti, D., Fumagalli, M., Fossati, M., Arrigoni Battaia, F., Benitez-Llambay, A., Dayal, P., et al. (2025). The MUSE Ultra Deep Field: A 5 Mpc Stretch of the z ≈ 4 Cosmic Web Revealed in Emission. THE ASTROPHYSICAL JOURNAL LETTERS, 980(2) [10.3847/2041-8213/adb0ba].
The MUSE Ultra Deep Field: A 5 Mpc Stretch of the z ≈ 4 Cosmic Web Revealed in Emission
Tornotti D.;Fumagalli M.;Fossati M.;Benitez-Llambay A.;Dutta R.;
2025
Abstract
We detect Ly alpha emission from a approximate to 5 Mpc-long (comoving) portion of the cosmic web hosting an overdensity (delta approximate to 25) of 19 Ly alpha emitters (LAEs) at z approximate to 4 within the MUSE Ultra Deep Field (MUDF), reaching an average surface brightness (SB) of 5 x 10-20 erg s-1 cm-2 arcsec-2. This large-scale structure has an average SB similar to the filament across the two MUDF quasars at z approximate to 3.22. However, deep multiwavelength data do not show a clear presence of active galactic nuclei, suggesting that the emission is mainly regulated by the underlying gas density. We find approximate to 0.2 dex higher star formation compared to control samples and a remarkable predominance (5/7) of blue-peaked emission lines in the spectra of the embedded LAEs, indicative of favorable conditions for gas accretion. Lastly, we quantify the contribution of intragalactic gas to the Ly alpha SB profile at large distances from LAEs. By studying samples of filaments detected in emission within diverse environments, we are finally gaining new insight into the physics of gas accretion within the cosmic web.
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