Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evidence of self-interacting cold dark matter from galactic to galaxy
  cluster scales   Within the framework of the cold dark matter (CDM) cosmogony, a central cusp
in the density profiles of virialized dark haloes is predicted. This prediction
disagrees with the soft inner halo mass distribution inferred from observations
of dwarf and low surface brightness galaxies, and some clusters of galaxies. By
analysing data for some of these objects, we find that the halo central density
is nearly independent of the mass from galactic to galaxy cluster scales with
an average value of around 0.02 M_sun/pc^3. We show that soft cores can be
produced in the CDM haloes by introducing a lower cut-off in the power spectra
of fluctuations and assuming high orbital thermal energies during halo
formation. However, the scale invariance of the halo central density is not
reproduced in these cases. The introduction of self-interaction in the CDM
particles offers the most attractive alternative to the core problem. We
propose gravothermal expansion as a possible mechanism to produce soft cores in
the CDM haloes with self-interacting particles. A global thermodynamical
equilibrium can explain the central density scale invariance. We find a minimum
cross section capable of establishing isothermal cores in agreement with the
observed shallow cores. If \sigma and m_x are the cross section and mass of the
dark matter particle, and v is the halo velocity dispersion, then (\sigma/m_x)
\~ 4 10^{-25} (100 km s^{-1}/v) cm^2/GeV.

31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess