Evolution of cold streams in hot gaseous halos

Abstract

In the prevailing model of galaxy formation and evolution, the process of gas accretion onto central galaxies undergoes a transition from cold-dominated to hot-dominated modes. This shift occurs when the mass of the parent dark matter halos exceeds a critical threshold known as $M_{shock}$. Moreover, cold gas usually flows onto central galaxies through filamentary structures, currently referred to as cold streams. However, the evolution of cold streams in halos with masses around $M_{shock}$, particularly how they are disrupted, remains unclear. To address this issue, we conduct a set of idealised hydrodynamic simulations. Our simulations show that (1) for a gas metallicity $Z=0.001-0.1Z_{\odot }$, cold stream with an inflow rate $\sim 3{\mathrm{M}}_{\odot }/yr$ per each can persist and effectively transport cold and cool gas to the central region ($<0.2$ virial radius) in halos with mass $10^{12}{\mathrm{M}}_{\odot }$, but is disrupted at a radius around $0.2$ virial radius due to compression heating for halos with mass $3\times 10^{12}{\mathrm{M}}_{\odot }$. (2) At $z\sim 2$, the maximum halo mass that capable of hosting and sustaining cold streams $M_{stream}$ is between $1\times 10^{12}{\mathrm{M}}_{\odot }$ and $1.5\times 10^{12}{\mathrm{M}}_{\odot }$ for gas metallicity $Z=0.001Z_{\odot }$, while for a higher gas metallicity $Z=0.1Z_{\odot }$, this value increases to $\sim 1.5\times 10^{12}{\mathrm{M}}_{\odot }$. (3) The evolution and ultimate fate of cold streams are determined primarily by the rivalry between radiative cooling and compression. Stronger heating due to compression in halos more massive than $M_{stream}$ can surpass cooling and heat the gas in cold streams to the hot ($\ge 10^6$ K) phase.

26 pages, 18 figures, accepted for publication in MNRAS

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Cited by in corpus (4)

• Entrainment of Hot Gas into Cold Streams: The Origin of Excessive Star-formation Rates at Cosmic Noon
• The cooler past of the intracluster medium in TNG-Cluster
• Magnetising galaxies with cold inflows
• The abundance and origin of cool gas in galaxy clusters in the TNG-Cluster simulation