Martin J. Rees

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The Swift mission, scheduled for launch in 2004, is a multiwavelength observatory for gamma-ray burst (GRB) astronomy. It is a first-of-its-kind autonomous rapid-slewing satellite for transient astronomy and pioneers the way for future rapid-reaction and multiwavelength missions. It will be far more powerful than any previous GRB mission, observing more(More)
Recent numerical simulations of the fragmentation of primordial molecular clouds in hierarchical cosmogonies have suggested that the very first stars (the so–called Population III) may have been rather massive. Here we point out that a numerous population of massive black holes (MBHs) – with masses intermediate between those of stellar and supermassive(More)
The case for collapsed objects in some X-ray binary systems continues to strengthen. But there is now even firmer evidence for supermassive black holes in galactic centres. Gravitational collapse seems to have occurred in the centres of most newly-forming galaxies, manifesting itself in a phase of quasar-like activity (which may be reactivated later). These(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 proÐles, we reduce the problem to that of numerically integrating a system of chemical equations. The results agree well with numerically expensive(More)
The history of the transition from a neutral intergalactic medium (IGM) to one that is almost fully ionized can reveal the character of cosmological ionizing sources. We study the evolution of the volume filling factors of H II and He III regions in a clumpy IGM, and discuss the implications for rival reionization scenarios of the rapid decline in the space(More)
We explore the qualitative changes that would occur if the amplitude Q ∼ 10 of cosmological density fluctuations were different. If Q ∼< 10 , 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 might(More)
We describe a mechanism by which supermassive black holes can form directly in the nuclei of protogalaxies, without the need for “seed” black holes left over from early star formation. Self-gravitating gas in dark matter halos can lose angular momentum rapidly via runaway, global dynamical instabilities, the so-called “bars within bars” mechanism. This(More)
A model of the density distribution in the intergalactic medium, motivated by that found in numerical simulations, is used to demonstrate the effect 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)
We discuss a model for the early assembly of supermassive black holes (SMBHs) at the center of galaxies that trace their hierarchical build-up far up in the dark halo ‘merger tree’. Motivated by the observations of luminous quasars around redshift z ≈ 6 with SMBH masses ≈ 10M⊙, we assess the possibility of an early phase of stable super-critical(More)