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

Journal Article · Fri Jul 15 00:00:00 EDT 2011 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/142/1/24· OSTI ID:21583060

Oh, Se-Heon; Brook, Chris ^[1]; Governato, Fabio ^[2]; Brinks, Elias ^[3]; Mayer, Lucio ^[4]; Brooks, Alyson ^[5]; Walter, Fabian ^[6]

---

1. Jeremiah Horrocks Institute, University of Central Lancashire, Preston, Lancashire, PR1 2HE (United Kingdom)
2. Astronomy Department, University of Washington, Seattle, WA 98195 (United States)
3. Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, AL10 9AB (United Kingdom)
4. Institute for Theoretical Physics, University of Zurich, Winterthurerstrasse 190, 8057 Zuerich (Switzerland)
5. Theoretical Astrophysics, California Institute of Technology, MC 350-17, Pasadena, CA 91125 (United States)
6. Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, 69117 Heidelberg (Germany)

We make a direct comparison of the derived dark matter (DM) distributions between hydrodynamical simulations of dwarf galaxies assuming a {Lambda}CDM 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, 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 {Lambda}CDM 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 {alpha} of the simulated galaxies' DM density profiles is {approx}-0.4 {+-} 0.1, which shows good agreement with {alpha} = -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 {alpha} {approx}-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.

• OSTI ID: 21583060
• Journal Information: Astronomical Journal (New York, N.Y. Online), Vol. 142, Issue 1; Other Information: DOI: 10.1088/0004-6256/142/1/24; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
BARYONS
COSMOLOGY
GALAXIES
GAS COOLING
MASS DISTRIBUTION
NONLUMINOUS MATTER
ROTATION
SIMULATION
STAR EVOLUTION
SUPERNOVAE
BINARY STARS
COOLING
DISTRIBUTION
ELEMENTARY PARTICLES
ERUPTIVE VARIABLE STARS
EVOLUTION
FERMIONS
HADRONS
MATTER
MOTION
SPATIAL DISTRIBUTION
STARS
VARIABLE STARS