Dark-matter spike at the galactic center?

By P. Ullio, HongSheng Zhao, M. Kamionkowski. 2001

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The past growth of the central black hole (BH) might have enhanced the density of cold dark matter halo particles at the galactic center. We compute this effect in realistic growth models of the present (2-3)×106M⊙ BH from a low-mass seed BH, with special attention to dynamical modeling in a realistic galaxy environment with merger and orbital decay of a seed BH formed generally outside the exact center of the halo. An intriguing “very-dense spike” of dark matter has been claimed in models of Gondolo and Silk with a density high enough to contradict with experimental upper bounds of neutralino annihilation radiation. This “spike” disappears completely or is greatly weakened when we include important dynamical processes neglected in their idealized or restrictive picture with cold particles surrounding an at-the-center zero-seed adiabatically growing BH. For the seed BH to spiral in and settle to the center within a Hubble time by dynamical friction, the seed mass must be at least a significant fraction of the present BH. Any subsequent at-the-center growth of the BH and steepening of the central Keplerian potential well can squeeze the halo density distribution only mildly, whether the squeezing happens adiabatically or instantaneously.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/0219791534e1bbffec0cb2a937ba40a5be604983

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Citations in the corpus

Stellar Orbits around the Galactic Center Black Hole (2003, background): “…or, more likely, an extended mass distribution (Rubilar & Eckart 2001), in the form of either an entourage of stellar remnants surrounding the central supermassive black hole, a spike of dark matter particles (Gondolo & Silk 1999; Ullio et al. 2001; Gnedin & Primack 2004), or a binary black hole.”
Baryonic pinching of galactic dark matter halos (2006, background): “We do not attempt to model the complicated dynamics at subparsec scales of the galaxy [41, 42, 43] other than trying to take into account the maximum density due to self-annihilations.”
Gamma Ray Signals from Dark Matter: Concepts, Status and Prospects (2012, background): “ also form only in the very center of a contracted proﬁle [91]). The adiabati c growth of the central supermassive black hole (SMBH) could also generate a central spike of DM within the inner ∼ 10 pc [92] if the SMBH seed starts out close to the GC [93] (SMBH mergers, on the other hand, would rather”
ΛCDM-based Models for the Milky Way and M31. I. Dynamical Models (2001, methodology): “Following Ullio et al. (2001) we take into account the effect of adiabatic growth from a seed BH of half the final value.”
Galactic Searches for Dark Matter (2012, background): “…an initial dark matter profile in the Galactic center of the form ρ ∝ r−γ , it can be shown from both conservation of mass and conservation of angular momentum that the after the appearance of the black hole, the final mass profile scales as ρ ∝ r−A, where A = (9− 2γ)/(4− γ) (Ullio et al., 2001).”
Measuring Distance and Properties of the Milky Way’s Central Supermassive Black Hole with Stellar Orbits (2008, background): “Furthermore, theoretical estimates of the density of cold dark matter halo particles suggest that 1000M of dark matter might reside in the inner 0.01 pc of the Galactic center (Gondolo & Silk1999; Ullio et al. 2001; Merritt et al. 2002; Gnedin & Primack 2004).”