Publication Date:
2020-04-28
Description:
We study stellar property statistics, including satellite galaxy occupation, of haloes in three cosmological hydrodynamics simulations: BAHAMAS + MACSIS, IllustrisTNG, and Magneticum Pathfinder. Applying localized linear regression, we extract halo mass-conditioned normalizations, slopes, and intrinsic covariance for (i) Nsat, the number of stellar mass-thresholded satellite galaxies within radius R200c of the halo; (ii) $M_{star ,
m tot}$, the total stellar mass within that radius, and (iii) $M_{star ,
m BCG}$, the gravitationally bound stellar mass of the central galaxy within a $100 ,
m kpc$ radius. The parameters show differences across the simulations, in part from numerical resolution, but there is qualitative agreement for the $N_{
m sat}!-! M_{star ,
m BCG}$ correlation. Marginalizing over Mhalo, we find the Nsat kernel, $p(ln N_{
m sat}, |, M_{
m halo}, z)$ to be consistently skewed left in all three simulations, with skewness parameter γ = −0.91 ± 0.02, while the $M_{star ,
m tot}$ kernel shape is closer to lognormal. The highest resolution simulations find γ ≃ −0.8 for the z = 0 shape of the $M_{star ,
m BCG}$ kernel. We provide a Gaussian mixture fit to the low-redshift Nsat kernel as well as local linear regression parameters tabulated for $M_{
m halo}gt 10^{13.5} , {
m M}_odot$ in all simulations.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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