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24 April 2024 |
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Massive elliptical galaxies at $z sim 0.2$ are well described by stars and a Navarro-Frenk-White dark matter halo | | Anowar J. Shajib
; Tommaso Treu
; Simon Birrer
; Alessandro Sonnenfeld
; | | Date: |
26 Aug 2020 | | Abstract: | We investigate the internal structure of elliptical galaxies at $zsim 0.2$
from a joint lensing-dynamics analysis. We model Hubble Space Telescope images
of a sample of 23 galaxy-galaxy lenses selected from the Sloan Lens ACS (SLACS)
survey. Whereas the original SLACS analysis estimated the logarithmic slopes by
combining the kinematics with the imaging data, we estimate the logarithmic
slopes only from the imaging data. We find that the distribution of the
lensing-only logarithmic slopes has a median $2.08pm0.03$ and intrinsic
scatter $0.13 pm 0.02$, consistent with the original SLACS analysis. We
combine the lensing constraints with the stellar kinematics and constrain the
amount of adiabatic contraction in the dark matter (DM) halos. We find that the
DM halos are well described by a standard Navarro-Frenk-White halo with no
contraction on average for both of a constant stellar mass-to-light ratio
($M/L$) model and a stellar $M/L$ gradient model. For the $M/L$ gradient model,
we find that most galaxies are consistent with no $M/L$ gradient. Comparison of
our inferred stellar masses with those obtained from the stellar population
synthesis method supports a heavy initial mass function (IMF) such as the
Salpeter IMF. We discuss our results in the context of previous observations
and simulations, and argue that our result is consistent with a scenario in
which active galactic nuclei feedback counteracts the baryonic-cooling-driven
contraction in the DM halos. | | Source: | arXiv, 2008.11724 | | Services: | Forum | Review | PDF | Favorites | |
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