# Pop 111 stars intermediat BHs

1. Jul 27, 2005

### wolram

http://arxiv.org/abs/astro-ph/0507593

Title: Core-Collapse Very Massive Stars: Evolution, Explosion, and Nucleosynthesis of Population III 500 -- 1000 $M_{\odot}$ Stars
Authors: T. Ohkubo, H. Umeda, K. Maeda, K. Nomoto, S. Tsuruta, M. J. Rees
Comments: 46 pages, 45 figure files

We calculate evolution, collapse, explosion, and nucleosynthesis of Population III very-massive stars with 500$M_{\odot}$ and 1000$M_{\odot}$. Presupernova evolution is calculated in spherical symmetry. Collapse and explosion are calculated by a two-dimensional code, based on the bipolar jet models. We compare the results of nucleosynthesis with the abundance patterns of intracluster matter, hot gases in M82, and extremely metal-poor stars in the Galactic halo.
It was found that both 500$M_{\odot}$ and 1000$M_{\odot}$ models enter the region of pair-instability but continue to undergo core collapse. In the presupernova stage, silicon burning regions occupy a large fraction, more than 20% of the total mass. For moderately aspherical explosions, the patterns of nucleosynthesis match the observational data of both intracluster medium and M82. Our results suggest that explosions of Population III core-collapse very-massive stars contribute significantly to the chemical evolution of gases in clusters of galaxies. For Galactic halo stars, our [O/Fe] ratios are smaller than the observational abundances. However, our proposed scenario is naturally consistent with this outcome. The final black hole masses are about 500$M_{\odot}$ for our most massive (1000$M_{\odot}$) models. This result may support the view that Population III very massive stars are responsible for the origin of intermediate mass black holes which were recently reported to be discovered.

2. Jul 27, 2005

### Garth

Thank you for the link wolram. Notice IMBH's may have already been found, a tiny sample of a much larger population. These would have come from
. The question is: "How many were there? And where are they now?" My conjecture is the bulk of the DM is in the form of IMBH's and therefore the primordial baryon density has to be over 0.2 closure density, i.e. as predicted by the Freely Coasting model. This would also be consistent with these models with low but not zero primordial metallicity if there were enough of them to homogeneously seed the IGM with metallicity and ionisation.

Garth