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

By Se-Heon Oh, C. Brook, Fabio Governato, E. Brinks, Lucio Mayer, W. D. de Blok, A. Brooks, F. Walter. 2010

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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.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/d7a25aefd33661a81b21356c998a98d020c90bec

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Citations in the corpus

Small scale problems of the $\Lambda$CDM model: a short review (2016, methodology): “[190,195], LITTLE THINGS [188], THINGS dwarfs [36,164], Sculptor, Fornax and the Milky Way, examining their respective predictions for the slope-stellar mass, and the slope-circular velocity relationships.”
Hierarchical formation of bulgeless galaxies – II. Redistribution of angular momentum via galactic fountains (2011, background): “Indeed, the ejection of low angular momentum gas by supernova explosions was shown to be key to the success of the first simulated bulgeless dwarf galaxies, which share many characteristics with observed dwarf galaxies (Governato et al. 2010; Oh et al. 2011).”
WHY BARYONS MATTER: THE KINEMATICS OF DWARF SPHEROIDAL SATELLITES (2012, background): “Two of the Little THINGS dwarfs lie below the range we predict, but we stress that the data is preliminary, and that these same set of simulations generally match the central densities of the THINGS and Little THINGS sample at 500pc (Oh et al. 2011; Governato et al. 2012).”
NIHAO – IV: core creation and destruction in dark matter density profiles across cosmic time (2015, background): “Oh et al. 2011b).”
RECONCILING DWARF GALAXIES WITH ΛCDM COSMOLOGY: SIMULATING A REALISTIC POPULATION OF SATELLITES AROUND A MILKY WAY–MASS GALAXY (2016, background): “…USA 7 Department of Astronomy and Theoretical Astrophysics Center, University of California, Berkeley, CA, USA 8 Moore Prize Fellow 9 Carnegie Fellow in Theoretical Astrophysics 10 Einstein Fellow cuspy as CDM predicts (e.g., Flores & Primack 1994; Moore 1994; Simon et al. 2005; Oh et al. 2011).”
Cosmological Simulations with Self-Interacting Dark Matter I: Constant Density Cores and Substructure (2012, background): “…in the range 50 − 130 km/s, constant-density cores with sizes of∼ 0.5 − 8 kpc and central densities of approximately∼ 0.01 − 0.5M⊙/pc 3 have been observed (de Blok et al. 2001; Simon et al. 2005; Sánchez-Salcedo 2005; Kuzio de Naray et al. 2008, 2010; Oh et al. 2011; Salucci et al. 2012).”
Subhaloes going Notts: the subhalo‐finder comparison project (2012, background): “Oh et al. 2011; Pontzen & Governato 2011).”
BARYONS MATTER: WHY LUMINOUS SATELLITE GALAXIES HAVE REDUCED CENTRAL MASSES (2012, methodology): “…de Naray et al. 2006; Salucci et al. 2007; Gentile et al. 2007; Spano et al. 2008; Trachternach et al. 2008; de Blok et al. 2008; Donato et al. 2009; Oh et al. 2011; Del Popolo 2012), and observed in satellites (Kleyna et al. 2002, 2003; Mashchenko et al. 2005; Goerdt et al. 2006; Strigari et al.…”
How supernova feedback turns dark matter cusps into cores (2011, background): “As time progresses, both the simulated and model density profiles gradually flatten out, with the value rising from < −1.0 (cusped) to∼−0.4, consistent with observations (Oh et al. 2011a).”