Martin J. Rees

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We explore the qualitative changes that would occur if the amplitude Q ∼ 10 −5 of cosmological density fluctuations were different. If Q ∼ < 10 −6 , the cosmological objects that form would have so low virial temperatures that they may be unable to cool and form stars, and would be so loosely bound that even if they could produce a supernova explosion, they(More)
We study the expected distribution of massive black hole (MBH) spins and its evolution with cosmic time in the context of hierarchical galaxy formation theories. Our model uses Monte Carlo realizations of the merger hierarchy in a ΛCDM cosmology, coupled to semi-analytical recipes, to follow the merger history of dark matter halos, the dynamics of the MBHs(More)
The dark matter that appears to be gravitationally dominant on all scales larger than galactic cores may consist of axions, stable photinos, or other colli-sionless particles whose velocity dispersion in the early universe is so small that-fluctuations of galactic size or larger are not damp~ed by free streaming. An attractive feature of this cold dark(More)
The formation of massive black holes may precede the epoch that characterises the peak of galaxy formation, as characterized by the star formation history in luminous galaxies. Hence protogalactic star formation may be profoundly affected by quasar-like nuclei and their associated extensive energetic outflows. We derive a relation between the mass of the(More)
  • Jordi Miralda-Escud, Martin Haehnelt, Martin J Rees, Alfred P Sloan Fellow
  • 1999
A model of the density distribution in the intergalactic medium, motivated by that found in numerical simulations, is used to demonstrate the eeect of a clumpy IGM and discrete sources on the reionization of the universe. In an inhomogeneous universe reionization occurs outside-in, starting in voids and gradually penetrating into overdense regions.(More)
The minimum mass that a virialized gas cloud must have in order to be able to cool in a Hubble time is computed, using a detailed treatment of the chemistry of molecular hydrogen. With a simple model for halo prooles, we reduce the problem to that of numerically integrating a system of chemical equations. The results agree well with numerically expensive 3D(More)
In hierarchical models of structure formation, an early cosmic UV background (UVB) is produced by the small (T vir ∼ < 10 4 K) halos that collapse before reionization. The UVB at energies below 13.6eV suppresses the formation of stars or black holes inside small halos, by photo–dissociating their only cooling agent, molecular H 2. We self–consistently(More)
We investigate the ability of primordial gas clouds to retain molecular hydrogen (H 2) during the initial phase of the reionization epoch. We nd that before the Strr omgren spheres of the individual ionizing sources overlap, the UV background below the ionization threshold is able to penetrate large clouds and suppress their H 2 abundance. The consequent(More)