This is the astro-ph blog of the Theoretical Modelling of Cosmic Structures group (TMoX) at the Max-Planck-Institute for Extraterrestrial Physics. We are an independent Max-Planck Research Group focusing on the various aspects in the formation and evolution of galaxies. Part of our focus is on the formation and evolution of early-type galaxies, super-massive black holes, the formation of the first structures in the universe and the enrichment history of the Universe. We are theoreticians using analytic modelling as well as numerical simulations in our work.

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28 October 2010

Fluctuations in the high-z LW background: close halo pairs as the origins of SMBH

Author: Dijkstra et. al.

The paper discusses the variation of the LW background required to dissociate the hydrogen molecules and prevent fragmentation of gas clouds into stars-thereby producing SMBH candidates.

They take into account the (i) the clustering of DM halos, (ii) Poisson fluctuations in the number of corresponding star forming galaxies, and (iii) scatter in the LW luminosity produced by halos. Although most of the haloes would be exposed to global mean value of the LW background, some haloes could be exposed to the high critical LW flux (Jcrit) that can prevent fragmentation.

This fraction, although low ~ 10e-8 to 10e-6 of all the haloes with Tvir>10e4 K, has an exponential dependance on the value of the flux; i.e. any small change in the value of J(crit) will exponentially affect the number of haloes that are exposed to this critical flux.
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1 comment:

  1. BA2 November 2010 at 16:32

    The paper is important when it comes to the relation between the change in Jcrit vs. fraction of haloes that are exposed to it.

    They ignore haloes of mass ~10^4 solar masses and various other parameters are also not treated explicitly. However, some of their arguments on the treatment of certain parameters are convincing enough.

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