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The Central Slope of Dark Matter Cores in Dwarf Galaxies: Simulations versus THINGS

Oh, Se-Heon and Brook, Chris and Governato, Fabio and Brinks, Elias and Mayer, Lucio and de Blok, W. J. G. and Brooks, Alyson and Walter, Fabian (2011) The Central Slope of Dark Matter Cores in Dwarf Galaxies: Simulations versus THINGS. Astronomical Journal, 142 (1). Art. No. 24. ISSN 0004-6256.

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We make a direct comparison of the derived dark matter (DM) distributions between hydrodynamical simulations of dwarf galaxies assuming a ΛCDM 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 α 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, 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 ΛCDM model. We show that the rotation curves of the simulated dwarf galaxies rise less steeply than cold dark matter rotation curves and are consistent with those of the THINGS dwarf galaxies. The mean value of the logarithmic inner density slopes α of the simulated galaxies' DM density profiles is ~–0.4 ± 0.1, which shows good agreement with α = –0.29 ± 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 α ~–1.0 to –1.5 predicted by DM-only simulations shallower and induce DM halos with a central mass distribution similar to that observed in nearby dwarf galaxies.

Item Type:Article
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URLURL TypeDescription
Brinks, Elias0000-0002-7758-9699
Walter, Fabian0000-0003-4793-7880
Additional Information:© 2011 American Astronomical Society. Received 2010 November 5; accepted 2011 March 30; published 2011 June 9. S.-H.O. acknowledges financial support from the South African Square Kilometre Array Project. F.G. acknowledges support from HST GO-1125, NSF ITR grant PHY-0205413 (also supporting TQ), NSF grant AST-0607819 and NASA ATP NNX08AG84G. The work ofW.J.G.d.B. is based upon research supported by the South African Research Chairs Initiative of the Department of Science and Technology and National Research Foundation. We thank the computer resources and technical support by TERAGRID, ARSC, NAS, and the UW computing center, where the simulations were run.
Funding AgencyGrant Number
South African Square Kilometre Array ProjectUNSPECIFIED
Hubble Space TelescopeGO-1125
Subject Keywords:dark matter; galaxies: dwarf; galaxies: halos; galaxies: kinematics and dynamics
Issue or Number:1
Classification Code:PACS: 95.35.+d; 98.62.Dm; 98.52.Wz; 98.80.Cq
Record Number:CaltechAUTHORS:20110628-112056451
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Official Citation:The Central Slope of Dark Matter Cores in Dwarf Galaxies: Simulations versus THINGS Se-Heon Oh et al. 2011 The Astronomical Journal 142 24
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:24243
Deposited By: Jason Perez
Deposited On:28 Jun 2011 20:06
Last Modified:09 Mar 2020 13:18

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