A warm mode of gas accretion on forming galaxies

Abstract

We present results from high--resolution cosmological hydrodynamical simulations of a Milky--Way-sized halo, aimed at studying the effect of feedback on the nature of gas accretion. Simulations include a model of inter-stellar medium and star formation, in which SN explosions provide effective thermal feedback. We distinguish between gas accretion onto the halo, which occurs when gas particles cross the halo virial radius, and gas accretion onto the central galaxy, which takes place when gas particles cross the inner one-tenth of the virial radius. Gas particles can be accreted through three different channels, depending on the maximum temperature value, $T_{\max }$, reached during the particles' past evolution: a cold channel for $T_{\max }<2.5\times 10^5$ K, a hot one for $T>10^6$K, and a warm one for intermediate values of $T_{\max }$. We find that the warm channel is at least as important as the cold one for gas accretion onto the central galaxy. This result is at variance with previous findings that the cold mode dominates gas accretion at high redshift. We ascribe this difference to the different supernova feedback scheme implemented in our simulations. While results presented so far in the literature are based on uneffective SN thermal feedback schemes and/or the presence of a kinetic feedback, our simulations include only effective thermal feedback. We argue that observational detections of a warm accretion mode in the high--redshift circum-galactic medium would provide useful constraints on the nature of the feedback that regulates star formation in galaxies.

6 pages, 3 figures, accepted for publication in ApJL

References in corpus (2)

• The Role of Pressure in GMC Formation II: The H_2 - Pressure Relation
• Bimodal gas accretion in the Horizon-MareNostrum galaxy formation simulation

Cited by in corpus (13)

• Moving mesh cosmology: tracing cosmological gas accretion
• The impact of feedback on cosmological gas accretion
• The COS/UVES Absorption Survey of the Magellanic Stream. III: Ionization, Total Mass, and Inflow Rate onto the Milky Way
• Hot-mode accretion and the physics of thin-disk galaxy formation
• Gas Accretion is Dominated by Warm Ionized Gas in Milky Way-Mass Galaxies at z ~ 0
• The High-Ion Content and Kinematics of Low-Redshift Lyman Limit Systems
• Impact of filaments on galaxy formation in their residing dark matter haloes
• Angular momentum transfer to a Milky Way disk at high redshift
• Galactic outflow and diffuse gas properties at z>=1 using different baryonic feedback models
• A semi-analytic model comparison: testing cooling models against hydrodynamical simulations
• A minor merger scenario for the ultraluminous X-ray source ESO 243-49 HLX-1 - II. Constraints from photometry
• Cosmic Rays and Non-thermal Emission Induced by Accretion of Cool Gas onto the Galactic Disk
• Go with the Flow: The Self-Similar and Non-Linear Behaviour of Large-Scale In- and Outflows and the Impact of Accretion Shocks from Galaxies to Galaxy Clusters