Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.mrao.cam.ac.uk/~anthony/latex/Firmani.ps Дата изменения: Thu Jun 15 21:09:24 2000 Дата индексирования: Tue Oct 2 03:06:21 2012 Кодировка: Поисковые слова: galactic cluster

Self-interacting cold dark matter haloes
C. Firmani et al.
Osservatorio Astronomico di Brera, Italy
Cosmological models of structure formation with no-interacting
cold dark matter (CDM) probed to be the most succesful ones at
large scales. However, the fact that the CDM haloes are cuspy
disagrees with some astronomical observations. High-resolution
lensing for a cluster of galaxies and the rotation curves of several
dark matter dominated dwarf and LSB galaxies show evidence of
shallow halo cores. Using published data we nd that the halo
central density is nearly independent of the mass from galactic to
galaxy cluster scales with an average value around 0:02 M=pc 3 .
Investigating mechanisms for halo core formation within the hi-
erarchical scenario, we conclude that although shallow cores are
produced with a lower cut-o in the CDM power spectra and as-
suming high orbital thermal energies, the mass invariance of c
is not reproduced. A more viable solution to the core problem
is the introduction of self-interaction in the CDM particles. Be-
ing this the case, we propose the gravothermal expansion as the
mechanism responsible for the formation of shallow cores in a hi-
erarchical scenario. We estimate c for the haloes when either a
global or a partial thermodynamical equilibrium is reached. If x
and mx are the cross section and mass of the CDM particle, and
V the halo velocity dispersion then x=mx  4 10 25 (100=V )
cm 2 =GeV . It is of paramount importance to further investigate
the scale invariance density of soft core. To this end the con-
struction of high-resolution mass maps with gravitational lensing
techniques for the inner regions of clusters are of great interest.
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