Baryonic pinching of galactic dark matter halos

By M. Gustafsson, M. Fairbairn, J. Sommer-Larsen. 2006

169 citations recorded by the source corpus.

High resolution cosmological N-body simulations of four galaxy-scale dark matter halos are compared to corresponding N-body/hydrodynamical simulations containing dark matter, stars and gas. The simulations without baryons share features with others described in the literature in that the dark matter density slope continuously decreases towards the center, with a density {rho}{sub DM}{proportional_to}r{sup -1.3{+-}}{sup 0.2}, at about 1% of the virial radius for our Milky Way sized galaxies. The central cusps in the simulations which also contain baryons steepen significantly, to {rho}{sub DM}{proportional_to}r{sup -1.9{+-}}{sup 0.2}, with an indication of the inner logarithmic slope converging. Models of adiabatic contraction of dark matter halos due to the central buildup of stellar/gaseous galaxies are examined. The simplest and most commonly used model, by Blumenthal et al., is shown to overestimate the central dark matter density considerably. A modified model proposed by Gnedin et al. is tested and it is shown that, while it is a considerable improvement, it is not perfect. Moreover, it is found that the contraction parameters in their model not only depend on the orbital structure of the dark-matter-only halos but also on the stellar feedback prescription which is most relevant for the baryonic distribution. Implications for dark matter annihilation atmore » the galactic center are discussed and it is found that, although our simulations show a considerable reduced dark matter halo contraction as compared to the Blumenthal et al. model, the fluxes from dark matter annihilation are still expected to be enhanced by at least a factor of a hundred, as compared to dark-matter-only halos. Finally, it is shown that, while dark-matter-only halos are typically prolate, the dark matter halos containing baryons are mildly oblate with minor-to-major axis ratios of c/a=0.73{+-}0.11, with their flattening aligned with the central baryonic disks.« less

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/2f4321b71ff5cc95964ea8003952fea40e054115

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Citations in the corpus

Galaxy formation theory (2010, methodology): “More recent simulations (Gustafsson et al. 2006) support this picture, butshow that the optimal values ofA andw vary from galaxy to galaxy and seem to depend on the formation history (i.e. onthe adopted rules for star formation and feedback; see also Abadi et al. 2009).”
How do galaxies populate dark matter haloes (2009, background): “This is plausible, given results from detailed simulations of spiral formation (e.g. Gustafsson et al. 2006; Abadi et al. 2009).”
Fermi LAT Search for Internal Bremsstrahlung Signatures from Dark Matter Annihilation (2012, background): “The possible impact of adiabatic contraction [67–70] can be studied in an effective way by allowing for larger inner slopes of the profile.”
Gamma Ray Signals from Dark Matter: Concepts, Status and Prospects (2012, background): “In particular, the cooling and infall of baryons could – by a mechanism known as adiabatic contraction – lead to a steepening of the inner DM profile [84–86].”
The shape of dark matter haloes in the Aquarius simulations: evolution and memory (2011, background): “It is important to stress that we have neglected the effects induced by the presence of baryons on the dark matter halo shapes (Kazantzidis et al. 2004; Bailin et al. 2005; Gustafsson et al. 2006; Debattista et al. 2008; Pedrosa et al. 2009; Lau et al. 2011; Valluri et al. 2010).”
Search for gamma-ray spectral lines with the Fermi Large Area Telescope and dark matter implications (2013, unknown): “stars, gas, etc) in DM halo simulations suggest the DM halo may be even more centrally contracted than the above models[18].”
Galaxy-induced transformation of dark matter haloes (2009, result): “In this respect, our study is similar to that of Gustafsson et al. (2006), who studied four simulations of galaxysized halos in the ΛCDM scenario.”
THE DENSITY PROFILES OF MASSIVE, RELAXED GALAXY CLUSTERS. I. THE TOTAL DENSITY OVER THREE DECADES IN RADIUS (2012, background): “…modify the structure of the DM. Cooling allows baryons to condense toward the center, which makes the DM more concentrated (Blumenthal et al. 1986; Gnedin et al. 2004; Sellwood & McGaugh 2005; Gustafsson et al. 2006; Pedrosa et al. 2009; Abadi et al. 2010; Sommer-Larsen & Limousin 2010).”
A Tentative Gamma-Ray Line from Dark Matter Annihilation at the Fermi Large Area Telescope (2012, background): “The presence of the super-massive black hole [57] or adiabatic contraction [58–61] can steepen the inner profile, which is here effectively taken into account by allowing that α > 1.”
THE SHAPE OF THE INNER MILKY WAY HALO FROM OBSERVATIONS OF THE PAL 5 AND GD–1 STELLAR STREAMS (2016, background): “…of a galactic baryonic disk causes the halos to become more axisymmetric and aligned with the disk, but the minor-to-major axis ratio c/a changes only by a few tenths to c/a ≈ 0.7 to 0.8 (Dubinski 1994; Gustafsson et al. 2006; Debattista et al. 2008; Abadi et al. 2010; Kazantzidis et al. 2010).”
Spin-independent elastic WIMP scattering and the DAMA annual modulation signal (2008, background): “The inner slope of such a halo is quite steep, but even larger values of γ than this may be expected in dark matter halos where adiabatic contraction due to the presence of baryons has occurred [44].”
Impact of baryon physics on dark matter structures: a detailed simulation study of halo density profiles (2010, methodology): “These findings are in good agreement with Gustafsson et al. (2006).”