2010A&A...510A..90L


Query : 2010A&A...510A..90L

2010A&A...510A..90L - Astronomy and Astrophysics, volume 510, A90-90 (2010/2-1)

Gamma rays from annihilations at the galactic center in a physical dark matter distribution.

LAPI A., PAGGI A., CAVALIERE A., LIONETTO A., MORSELLI A. and VITALE V.

Abstract (from CDS):

We discuss the γ-ray signal to be expected from dark matter (DM) annihilations at the Galactic center. We describe the DM distribution in the Galactic halo, based on the Jeans equation for self-gravitating, anisotropic equilibria. In solving the Jeans equation, we adopted the specific correlation between the density ρ(r) and the velocity dispersion σ2r(r) expressed by the powerlaw behavior of the DM ``entropy'' K=σr22/3∝rα with α≃1.25-1.3. Indicated (among others) by several recent N-body simulations, this correlation is privileged by the form of the radial pressure term in the Jeans equation, and it yields a main-body profile consistent with the classic self-similar development of DM halos. In addition, we required the Jeans solutions to satisfy regular boundary conditions both at the center (finite pressure, round gravitational potential) and on the outskirts (finite overall mass). With these building blocks, we derived physical solutions, dubbed ``α-profiles''. We find the one with α=1.25, suitable for the Galaxy halo, to be intrinsically flatter at the center than the empirical NFW formula, yet steeper than the empirical Einasto profile. On scales of 10–1deg it yields annihilation fluxes lower by a factor 5 than the former, yet higher by a factor 10 than the latter. Such fluxes will eventually fall within the reach of the Fermi satellite. We show the effectiveness of the α-profile in relieving the astrophysical uncertainties related to the macroscopic DM distribution, and discuss its expected performance as a tool instrumental in interpreting the upcoming γ-ray data in terms of DM annihilation.

Abstract Copyright:

Journal keyword(s): cosmology: dark matter - galaxies: evolution - Galaxy: halo - methods: analytical

Simbad objects: 2

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Number of rows : 2
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NAME Galactic Center gam 17 45 39.60213 -29 00 22.0000           ~ 12316 0
2 NAME Local Group GrG ~ ~           ~ 7319 0

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2021.07.31-08:48:42

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