From Stellar Halos to Intracluster Light: the physics of the Intra-Halo Stellar Component in cosmological hydrodynamical simulations

Rodrigo Cañas; Claudia del P. Lagos; Pascal J. Elahi; Chris Power; Charlotte Welker; Yohan Dubois; Christophe Pichon

doi:10.1093/mnras/staa1027

paper

From Stellar Halos to Intracluster Light: the physics of the Intra-Halo Stellar Component in cosmological hydrodynamical simulations

arXiv:1908.02945 · doi:10.1093/mnras/staa1027

Abstract

We study the Intra-Halo Stellar Component (IHSC) of Milky Way-mass systems up to galaxy clusters in the Horizon-AGN cosmological hydrodynamical simulation. We identify the IHSC using an improved phase-space galaxy finder algorithm which provides an adaptive, physically motivated and shape-independent definition of this stellar component, that can be applied to halos of arbitrary masses. We explore the IHSC mass fraction-total halo's stellar mass, $f_{M *, I H S C} - M *$ , relation and the physical drivers of its scatter. We find that on average the $f_{M *, I H S C}$ increases with $M_{*, t o t}$ , with the scatter decreasing strongly with mass from 2 dex at $M_{*, t o t} \sim 1 0^{11} M_{⊙}$ to 0.3 dex at group masses. At high masses, $M_{*, t o t} > 1 0^{11.5} M_{⊙}$ , $f_{M *, I H S C}$ increases with the number of substructures, and with the mass ratio between the central galaxy and largest satellite, at fixed $M_{*, t o t}$ . From mid-size groups and systems below $M_{*, t o t} < 1 0^{12} M_{⊙}$ , we find that the central galaxy's stellar rotation-to-dispersion velocity ratio, V/σ, displays the strongest (anti)-correlation with $f_{M *, I H S C}$ at fixed $M_{*, t o t}$ of all the galaxy and halo properties explored, transitioning from $f_{M *, I H S C}$ <0.1% for high V/σ, to $f_{M *, I H S C} \sim 5$ % for low V/σ galaxies. By studying the $f_{M *, I H S C}$ temporal evolution, we find that, in the former, mergers not always take place, but if they did, they happened early (z>1), while the high $f_{M *, I H S C}$ population displays a much more active merger history. In the case of massive groups and galaxy clusters, $M_{*, t o t} > 1 0^{12} M_{⊙}$ , a fraction $f_{M *, I H S C} \sim$ 10-20% is reached at $z \sim 1$ and then they evolve across lines of constant $f_{M *, I H S C}$ modulo some small perturbations. Because of the limited simulation's volume, the latter is only tentative and requires a larger sample of simulated galaxy clusters to confirm.

arXiv comment21 pages, 17 figures. Submitted to MNRAS. Comments are welcomed

From Stellar Halos to Intracluster Light: the physics of the Intra-Halo Stellar Component in cosmological hydrodynamical simulations

Abstract

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