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THE CENTRAL SLOPE OF DARK MATTER CORES IN DWARF GALAXIES: SIMULATIONS VERSUS THINGS

Se-Heon OhAstronomy Department, Astrophysics, Cosmology, and Gravity Centre (ACGC), University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa; [email protected], [email protected]Chris B. BrookJeremiah Horrocks Institute, University of Central Lancashire, Preston, Lancashire, PR1 2HE, UK; [email protected]Fabio GovernatoAstronomy Department, University of Washington, Seattle, WA 98195, USA; [email protected]E. BrinksCentre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, AL10 9AB, UK; [email protected]Lucio MayerInstitute for Theoretical Physics, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland; [email protected]W. J. G. de BlokAstronomy Department, Astrophysics, Cosmology, and Gravity Centre (ACGC), University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa; [email protected], [email protected]Alyson BrooksTheoretical Astrophysics, California Institute of Technology, MC 350-17, Pasadena, CA 91125, USA; [email protected]Fabian WalterMax-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany; [email protected]

2011en

ABI

Annotatsiya

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.

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DOI: 10.1088/0004-6256/142/1/24

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