MusE GAs FLOw and Wind (MEGAFLOW)

Astronomy and Astrophysics, vol. 694, pp. A117

Abstract

Aims. The circumgalactic medium (CGM) is a key component in understanding the physical processes governing the flows of gas around galaxies. Quantifying its evolution and its dependence on galaxy properties is particularly important for our understanding of accretion and feedback mechanisms. Methods. We selected a volume-selected sample of 66 isolated star-forming galaxies at 0.4 < z < 1.5 with log(M⋆/M⊙) > 9 from the MusE GAs FLOw and Wind (MEGAFLOW) survey. Using Mg IIλλ2796,2803 absorptions in background quasars, we measured the covering fraction, fc, and quantified how the cool gas profile depends on galaxy properties (such as star formation rate (SFR), stellar mass (M⋆) or azimuthal angle relative to the line of sight) and how these dependencies evolve with redshift. Results. The Mg II covering fraction of isolated galaxies is a strong function of impact parameter and is steeper than previously reported. The impact parameter, b50, at which fc = 50% is b50 = 50 ± 7 kpc for Wr2796 > 0.5 Å. It is weakly correlated with SFR (∝SFR0.08 ± 0.09) and decreases with cosmic time (∝(1 + z)0.8 ± 0.7), contrary to the expectation of increasingly larger halos with time. The covering fraction is also higher along the minor axis than along the major axis at the ≈2σ level. Conclusions. The CGM traced by Mg II is similar across the isolated galaxy population. Indeed, among the isolated galaxies with an impact parameter below 55 kpc, all have associated Mg II absorption with Wr2796 > 0.3 Å, resulting in a steep covering fraction, fc(b).

Authors 9

1. Maxime Cherrey

   Centre National de la Recherche Scientifique · Centre de Recherche Astrophysique de Lyon

   Affiliation as printed

   Univ Lyon1 , Ens de Lyon , CNRS , Centre de Recherche Astrophysique de Lyon (CRAL) UMR5574 , F-69230 Saint-Genis-Laval , France

2. Johannes Zabl

   Centre National de la Recherche Scientifique · Centre de Recherche Astrophysique de Lyon

   Affiliation as printed

   Institute for Computational Astrophysics and

   Univ Lyon1 , Ens de Lyon , CNRS , Centre de Recherche Astrophysique de Lyon (CRAL) UMR5574 , F-69230 Saint-Genis-Laval , France

3. Ilane Schroetter

   Centre National de la Recherche Scientifique · Institut de Recherche en Astrophysique et Planétologie · Université de Toulouse

   Affiliation as printed

   Institut de Recherche en Astrophysique et Planétologie , Université de Toulouse , Centre National de la Recherche Scientifique ,

4. Martin Wendt

   University of Potsdam

   Affiliation as printed

   Institut für Physik und Astronomie , Universität Potsdam , Karl-Liebknecht-Str. 24/25 , 14476 Potsdam , Germany

5. Ivanna Langan

   Centro de Astrobiología

   Affiliation as printed

   Centro de Astrobiologia (CAB) , CSIC-INTA , Carretera de Ajalvir km 4 , Torrejon de Ardoz , 28850 Madrid , Spain

6. Joop Schaye Aachen Leiden Observatory

   Leiden University · Centre National d'Études Spatiales · Leiden Observatory

   Affiliation as printed

   Centre National d'Etudes Spatiales , 31028 Toulouse , France

   Leiden Observatory , Leiden University , P.O. Box 9513 , NL-2300 AA Leiden , The Netherlands

7. L. Wisotzki

   Leibniz Institute for Astrophysics Potsdam

   Affiliation as printed

   Leibniz-Institut for Astrophysik Potsdam (AIP) , An der Sternwarte 16 , 14482 Potsdam , Germany

8. Yucheng Guo

   Centre National de la Recherche Scientifique · Centre de Recherche Astrophysique de Lyon · Saint Mary's University

   Affiliation as printed

   Department of Astronomy & Physics , Saint Mary's University , 923 Robie Street , Halifax , Nova Scotia B3H 3C3 , Canada

   Univ Lyon1 , Ens de Lyon , CNRS , Centre de Recherche Astrophysique de Lyon (CRAL) UMR5574 , F-69230 Saint-Genis-Laval , France

9. Ismael Pessa

   Leibniz Institute for Astrophysics Potsdam

   Affiliation as printed

   Leibniz-Institut for Astrophysik Potsdam (AIP) , An der Sternwarte 16 , 14482 Potsdam , Germany