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The central slope of dark matter cores in dwarf galaxies: Simulations vs. THINGS | | Se-Heon Oh
; Chris Brook
; Fabio Governato
; Elias Brinks
; Lucio Mayer
; W.J.G. de Blok
; Alyson Brooks
; Fabian Walter
; | | Date: |
11 Nov 2010 | | Abstract: | We make a direct comparison of the derived dark matter (DM) distributions
between hydrodynamical simulations of dwarf galaxies assuming a LCDM cosmology
and the observed dwarf galaxies sample from the THINGS survey in terms of (1)
the rotation curve shape and (2) the logarithmic inner density slope alpha of
mass density profiles. The simulations, which include the effect of baryonic
feedback processes, such as gas cooling, star formation, cosmic UV background
heating and most importantly physically motivated gas outflows driven by
supernovae (SNe), form bulgeless galaxies with DM cores. We show that the
stellar and baryonic mass is similar to that inferred from photometric and
kinematic methods for galaxies of similar circular velocity. Analyzing the
simulations in exactly the same way as the observational sample allows us to
address directly the so-called "cusp/core" problem in the LCDM model. We show
that the rotation curves of the simulated dwarf galaxies rise less steeply than
CDM rotation curves and are consistent with those of the THINGS dwarf galaxies.
The mean value of the logarithmic inner density slopes alpha of the simulated
galaxies’ dark matter density profiles is ~$-0.4 pm 0.1$, which shows good
agreement with $alpha = -0.29 pm 0.07$ of the THINGS dwarf galaxies. The
effect of non-circular motions is not significant enough to affect the results.
This confirms that the baryonic feedback processes included in the simulations
are efficiently able to make the initial cusps with $alpha ~ -1.0 ext{to}
-1.5$ predicted by dark-matter-only simulations shallower, and induce DM halos
with a central mass distribution similar to that observed in nearby dwarf
galaxies. | | Source: | arXiv, 1011.2777 | | Services: | Forum | Review | PDF | Favorites | |
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