Spherical Gravitational Collapse of Annihilating Dark Matter and the Minimum Mass of CDM Black Holes

Details Spherical Gravitational Collapse of Annihilating Dark Matter and the Minimum Mass of CDM Black Holes Spherical Gravitational Collapse of Annihilating Dark Matter and the Minimum Mass of CDM Black Holes

2005-05-25

arxiv.org/abs/astro-ph/0505497v1

JCAP 0511 (2005) 004

Astronomy and Astrophysics

Astrophysics

Scientific paper

10.1088/1475-7516/2005/11/004

Spherical gravitational collapse of a cold gas of annihilating particles involves a competition between the free-fall rate $\propto\sqrt{\rho}$ and the (s-wave) annihilation rate $\propto\rho$. Thus, there is a critical density $\rhoann$ above which annihilation proceeds faster than free fall. Gravitational collapse of a cloud of (initial) mass $M$ to a black hole is only possible if $3/32\pi G^3M^2\lesssim\rhoann$, or $M\gtrsim\Mann\equiv (3/32\pi G^3\rhoann)^{1/2}$. For a particle mass $m$ and freeze-out temperature $T_f=m/x_f$, the minimum black hole mass is $\Mann\approx 10^{10}\msun \times(x_f\sqrt{g_\star}/100\omcdm g_{\star S}m({\rm Gev}))$, where $g_{\star S}$ and $g_\star$ are degeneracy factors. The formation of a black hole of initial mass $M_{BH}$ is accompanied by the annihilation of about $M_{ann}$ released in a burst lasting a time $\sim GM_{BH}$ that could reach a total annihilation luminosity $\sim 10^{59} {\rm erg s^{-1}}$. The absence of astronomical observations of such spectacular events suggests either: (i) the branching ratio for CDM annihilation to $e^{+}e^{-}$ pairs or quarks $\lesssim 10^{-10}$, while the branching ratio to $\nu{\bar{\nu}}$ is $\lesssim 10^{-5}$; or (ii) CDM is not made of annihilating particles, but may be in some non-annihilating form, such as axions; or (iii) CDM black holes never form.

Affiliated with

Also associated with

No associations

Rating

Spherical Gravitational Collapse of Annihilating Dark Matter and the Minimum Mass of CDM Black Holes does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Spherical Gravitational Collapse of Annihilating Dark Matter and the Minimum Mass of CDM Black Holes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Spherical Gravitational Collapse of Annihilating Dark Matter and the Minimum Mass of CDM Black Holes will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-642199