Tracing the simulated high-redshift circum-galactic medium with Lyman α emission

Monthly Notices of the Royal Astronomical Society

Abstract

Abstract With the Multi Unit Spectroscopic Explorer (MUSE), it is now possible to detect spatially extended Lyman α (Lyα) emission from individual faint (MUV ∼ −18) galaxies at redshifts, 3 < z < 6, tracing gas out to circum-galactic scales. To explore the implications of such observations, we present a cosmological radiation hydrodynamics simulation of a single galaxy, chosen to be typical of the Lyα-emitting galaxies detected by MUSE in deep fields. We use this simulation to study the origin and dynamics of the high-redshift circum-galactic medium (CGM). We find that the majority of the mass in the diffuse CGM is comprised of material infalling for the first time towards the halo center, but with the inner CGM also containing a comparable amount of mass that has moved past first-pericentric passage, and is in the process of settling into a rotationally supported configuration. Making the connection to Lyα emission, we find that the observed extended surface brightness profile is due to a combination of three components: scattering of galactic Lyα emission in the CGM, in-situ emission of CGM gas (mostly infalling), and Lyα emission from small satellite galaxies. The weight of these contributions vary with distance from the galaxy such that (1) scattering dominates the inner regions (r < 7 kpc), at surface brightness larger than a few 10−19 cgs, (2) all components contribute equally around r ∼ 10 kpc (or SB∼10−19), and (3) the contribution of small satellite galaxies takes over at large distances (or SB∼10−20).

Authors 6

1. Peter Mitchell corresponding Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, the Netherlands

   Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden, the Netherlands

2. Jérémy Blaizot

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

   Affiliation as printed

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

3. Corentin Cadiou

   University College London

   Affiliation as printed

   Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK

4. Yohan Dubois

   Centre National de la Recherche Scientifique · Institut d'Astrophysique de Paris · Sorbonne Université

   Affiliation as printed

   Institut d’Astrophysique de Paris, Sorbonne Université, CNRS, UMR 7095, 98 bis bd Arago, 75014 Paris, France

5. Thibault Garel

   Centre National de la Recherche Scientifique · University of Geneva · Centre de Recherche Astrophysique de Lyon

   Affiliation as printed

   Observatoire de Genève, Université de Genéve, 51 chemin de Pégase, 1290 Versoix, Switzerland

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

6. Joakim Rosdahl

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

   Affiliation as printed

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