2023/12/04 by Maxime Cherrey, Cherrey, Maxime, N. Bouché +19
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Galaxy #Halo #Physics #RADIUS #Redshift #Virial theorem
paper · pdf · doi:10.48550/arxiv.2312.01762
openalex publication_date 2023/12/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present a study of the cool gas (≈ 104 K) traced by MgII absorptions around groups of galaxies in the MEGAFLOW survey. Using a combination of two algorithms we blindly identify 32 groups of more than 5 galaxies at 0.3 < z < 1.5 with 10.7 < log10(M/\rm M\odot) < 13.7. Among them 26 can be used to study potential counterpart MgII absorptions. We report that 21 out of the total 120 MgII absorption systems present in MEGAFLOW are associated with groups. We observe that the MgII rest-frame equivalent width (W2796r) drops at an impact parameter of ≈ 150 projected kpc from the closest galaxy and ≈ one virial radius from the identified group center indicating that MgII halos scale with the mass of the groups.The impact parameter where the covering fraction exceeds 50% is log10(b/\rm kpc) = 2.17 ± 0.47 (2 σ) and (b/R\rm vir) = 1.67 ± 0.98, which is ≈ 3 times larger than for field galaxies (log10(b/\rm kpc)=1.67±0.15). Finally, we estimate the cool gas column density profile in groups (from the W2796r) and show that its shape follows closely the typical dark matter column density profile for halos at similar redshift and masses.