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arXiv · 1811.06545

Early-type galaxy density profiles from IllustrisTNG: I. Galaxy correlations and the impact of baryons

Yunchong Wang·Mark Vogelsberger·Dandan Xu·Shude Mao·Volker Springel·Hui Li·David Barnes·Lars Hernquist·Annalisa Pillepich·Federico Marinacci·Rüediger Pakmor·Rainer Weinberger·Paul Torrey
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Abstract

We explore the isothermal total density profiles of early-type galaxies (ETGs) in the IllustrisTNG simulation. For the selected 559 ETGs at $z = 0$ with stellar mass $10^{10.7}\mathrm{M}_{\odot} \leqslant M_{\ast} \leqslant 10^{11.9}\mathrm{M}_{\odot}$, the total power-law slope has a mean of $\langleγ^{\prime}\rangle = 2.011 \pm 0.007$ and a scatter of $σ_{γ^{\prime}} = 0.171$ over the radial range 0.4 to 4 times the stellar half mass radius. Several correlations between $γ^{\prime}$ and galactic properties including stellar mass, effective radius, stellar surface density, central velocity dispersion, central dark matter fraction and in-situ-formed stellar mass ratio are compared to observations and other simulations, revealing that IllustrisTNG reproduces many correlation trends, and in particular, $γ^{\prime}$ is almost constant with redshift below $z = 2$. Through analyzing IllustrisTNG model variations we show that black hole kinetic winds are crucial to lowering $γ^{\prime}$ and matching observed galaxy correlations. The effects of stellar winds on $γ^{\prime}$ are subdominant compared to AGN feedback, and differ due to the presence of AGN feedback from previous works. The density profiles of the ETG dark matter halos are well-described by steeper-than-NFW profiles, and they are steeper in the full physics (FP) run than their counterparts in the dark matter only (DMO) run. Their inner density slopes anti-correlates (remain constant) with the halo mass in the FP (DMO) run, and anti-correlates with the halo concentration parameter $c_{200}$ in both types of runs. The dark matter halos of low-mass ETGs are contracted whereas high-mass ETGs are expanded, suggesting that variations in the total density profile occur through the different halo responses to baryons.

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Yunchong Wang, Mark Vogelsberger, Dandan Xu, Shude Mao, Volker Springel, Hui Li, David Barnes, Lars Hernquist, Annalisa Pillepich, Federico Marinacci, Rüediger Pakmor, Rainer Weinberger, Paul Torrey. 2020-01-09. Early-type galaxy density profiles from IllustrisTNG: I. Galaxy correlations and the impact of baryons. https://doi.org/10.1093/mnras%2Fstz3348

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