Martin J. Rees

University of Cambridge, Cambridge, England, United Kingdom

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Publications (171)862.9 Total impact

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    [Show abstract] [Hide abstract] ABSTRACT: In light of the latest IceCube data, we discuss the implications of the cosmic ray energy input from hypernovae and supernovae into the Universe, and their propagation in the hosting galaxy and galaxy clusters or groups. The magnetic confinement in these environments may lead to efficient $pp$ collisions, resulting in a diffuse neutrino spectrum extending from PeV down to 10 TeV energies, with a spectrum and flux level compatible with that recently reported by IceCube. If the diffuse 10 TeV neutrino background largely comes from such the CR reservoirs, the corresponding diffuse gamma-ray background should be compatible with the recent \textit{Fermi} data. In this scenario, the CR energy input from hypernovae should be dominant over that of supernovae, implying that the starburst scenario does not work if the supernova energy budget is a factor of two larger than the hypernova energy budget. Thus, this strong case scenario can be supported or ruled out in near future.
    Preview · Article · Jan 2015 · The Astrophysical Journal
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    P. Meszaros · M. J. Rees
    [Show abstract] [Hide abstract] ABSTRACT: Gamma-ray bursts are the most luminous explosions in the Universe. They appear connected to supernova remnants from massive stars or the merger of their remnants, and their brightness makes them temporarily detectable out to the larges distances yet explored in the Universe. After pioneering breakthroughs from space and ground experiments, their study is entering a new phase with observations from recently launched satellites, as well as the prospect of detections or limits from large neutrino and gravitational wave detectors. The interplay between such observations and theoretical models of gamma-ray bursts and related objects is reviewed.
    Preview · Article · Jan 2014
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    P. Mészáros · M. J. Rees
    [Show abstract] [Hide abstract] ABSTRACT: Magnetic fields may play a dominant role in gamma-ray bursts, and recent observations by the Fermi satellite indicate that GeV radiation, when detected, arrives delayed by seconds from the onset of the MeV component. Motivated by this, we discuss a magnetically dominated jet model where both magnetic dissipation and nuclear collisions are important. We show that, for parameters typical of the observed bursts, such a model involving a realistic jet structure can reproduce the general features of the MeV and a separate GeV radiation component, including the time delay between the two. The model also predicts a multi-GeV neutrino component.
    Preview · Article · Apr 2011 · The Astrophysical Journal Letters
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    P. Meszaros · M. J. Rees
    [Show abstract] [Hide abstract] ABSTRACT: We discuss a model of Poynting-dominated gamma-ray bursts from the collapse of very massive first generation (pop. III) stars. From redshifts of order 20, the resulting relativistic jets would radiate in the hard X-ray range around 50 keV and above, followed after roughly a day by an external shock component peaking around a few keV. On the same timescales an inverse Compton component around 75 GeV may be expected, as well as a possible infra-red flash. The fluences of these components would be above the threshold for detectors such as Swift and Fermi, providing potentially valuable information on the formation and properties of what may be the first luminous objects and their black holes in the high redshift Universe.
    Preview · Article · Apr 2010 · The Astrophysical Journal
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    [Show abstract] [Hide abstract] ABSTRACT: This White Paper to the National Academy of Sciences Astro2010 Decadal Review Committee outlines some of the outstanding questions regarding the assembly history of Massive Black Holes in the nuclei of galaxies and the revolutionary contributions anticipated in this field from low-frequency gravitational wave astronomy.
    Full-text · Article · Mar 2009
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    Max Tegmark · Martin J. Rees
    [Show abstract] [Hide abstract] ABSTRACT: 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 such low virial temperatures that they may be unable to cool and form stars, and they would be so loosely bound that even if they could produce a supernova explosion they might be unable to retain the heavy elements necessary for planetary life. If Q 10-4, dense supermassive galaxies would form, and biological evolution could be marred by short disruption timescales for planetary orbits. If Q were still larger, most bound systems would collapse directly to supermassive black holes. These constraints on Q can be expressed in terms of fundamental constants alone and depend only on the electromagnetic and gravitational coupling constants, the electron-proton mass ratio, and the matter-to-photon ratio. We discuss the implications for inflation and defect models and note that the recent anthropic upper bounds on the cosmological constant Λ would be invalid if both Q and Λ could vary and there were no anthropic constraints on Q. The same applies to anthropic bounds on the curvature parameter Ω.
    Preview · Article · Jan 2009 · The Astrophysical Journal
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    M. J. Rees · P. Mészáros
    [Show abstract] [Hide abstract] ABSTRACT: We consider fireball models where the ejecta have a range of bulk Lorentz factors, so that the inner (lower Γ) parts may carry most of the mass, or even most of the energy. The outer shock and contact discontinuity decelerate as the fireball sweeps up external matter. This deceleration allows slower ejecta to catch up, replenishing and reenergizing the reverse shock and boosting the momentum in the blast wave. In consequence, the energy available to power the afterglow may substantially exceed that of the burst itself. Such models allow a wide range of possibilities for the afterglow evolution, even in the case of spherically symmetric expansion.
    Preview · Article · Jan 2009 · The Astrophysical Journal
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    Martin J. Rees
    [Show abstract] [Hide abstract] ABSTRACT: In this talk I shall try to highlight some themes that seem to promise specially interesting progress in the coming decades. I can't claim to be much of a prophet myself, but I'd like to recall someone who was: Arthur C. Clarke. He lived in Sri Lanka, and died in 2007, aged 90. I'd like to discuss three issues that he would have found interesting: space and alien life; galaxies and their origin; and (more speculatively) the size of our universe.
    Preview · Article · Dec 2008 · Proceedings of the International Astronomical Union
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    P. Mészáros · M. J. Rees
    [Show abstract] [Hide abstract] ABSTRACT: Subphotospheric internal shocks and transverse differences of the bulk Lorentz factor in relativistic fireball models of gamma-ray bursts (GRBs) lead to neutron diffusion relative to protons, resulting in inelastic nuclear collisions. This results in significant fluxes of νμ(μ) of ~3 GeV and νe(e) of ~2 GeV, scaling with the flow Lorentz factor η < ηπ ~ 400. This extends significantly the parameter space for which neutrinos from inelastic collision are expected, which in the absence of the above effects requires values in excess of ηπ. A model with sideways diffusion of neutrons from a slower wind into a fast jet can lead to production of νμ(μ) and νe(e) in the range 2-25 GeV or higher, depending on the value of η. The emission from either of these mechanisms from GRBs at redshifts z ~ 1 may be detectable in suitably densely spaced detectors.
    Preview · Article · Dec 2008 · The Astrophysical Journal
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    Zoltán Haiman · Martin J. Rees
    [Show abstract] [Hide abstract] ABSTRACT: The early stage in the formation of a galaxy inevitably involves a spatially extended distribution of infalling, cold gas. If a central luminous quasar turned on during this phase, it would result in significant extended Lyα emission, possibly accompanied by other lines. For halos condensing at redshifts 3 z 8 and having virial temperatures 2 × 105 K Tvir 2 × 106 K, this emission results in a "fuzz" of characteristic angular diameter of a few arcseconds and surface brightness ~10-18 to 10-16 ergs s-1 cm-2 arcsec-2. The fuzz around bright, high-redshift quasars could be detected in deep narrowband imaging with current telescopes, providing a direct constraint on galaxy formation models. The absence of detectable fuzz might suggest that most of the protogalaxy's gas settles to a self-gravitating disk before a quasar turns on. However, continued gas infall from large radii, or an on-going merger spreading cold gas over a large solid angle, during the luminous quasar phase could also result in extended Lyα emission, and can be constrained by deep narrowband imaging.
    Preview · Article · Dec 2008 · The Astrophysical Journal
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    P. Mészáros · M. J. Rees
    [Show abstract] [Hide abstract] ABSTRACT: The role of a photospheric component and of pair breakdown is examined in the internal shock model of gamma-ray bursts. We discuss some of the mechanisms by which they would produce anomalously steep low-energy slopes, X-ray excesses and preferred energy breaks. Subrelativistic Comptonization should dominate in high comoving luminosity bursts with high baryon load, while synchrotron radiation dominates the power-law component in bursts which have lower comoving luminosity or have moderate to low baryon loads. A photosphere leading to steep low-energy spectral slopes should be prominent in the lowest baryon load cases.
    Preview · Article · Dec 2008 · The Astrophysical Journal
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    [Show abstract] [Hide abstract] ABSTRACT: We investigate the relationship between the quasi-thermal baryon-related photosphere in relativistic outflows and the internal shocks arising outside them, which out to a limiting radius may be able to create enough pairs to extend the optically thick region. Variable gamma-ray light curves are likely to arise outside this limiting pair-forming shock radius, while X-ray excess bursts may arise from shocks occurring below it; a possible relation to X-ray flashes is discussed. This model leads to a simple physical interpretation of the observational gamma-ray variability-luminosity relation.
    Preview · Article · Dec 2008 · The Astrophysical Journal
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    P. Madau · M. J. Rees · M. Volonteri · F. Haardt · and S. P. Oh
    [Show abstract] [Hide abstract] ABSTRACT: Motivated by the recent detection by the Wilkinson Microwave Anisotropy Probe of a large optical depth to Thomson scattering, implying a very early reionization epoch, we assess a scenario where the universe was reionized by "miniquasars" powered by intermediate-mass black holes (IMBHs), the remnants of the first generation of massive stars. Pregalactic IMBHs form within minihalos above the cosmological Jeans mass collapsing at z > 20, get incorporated through mergers into larger and larger systems, sink to the center as a result of dynamical friction, and accrete cold material. The merger history of dark halos and associated IMBHs is followed by Monte Carlo realizations of the merger hierarchy in a ΛCDM cosmology. Our model is based on the assumptions that quasar activity is driven by major mergers and nuclear IMBHs accrete at the Eddington rate a fraction of the gas in the merger remnant. The long dynamical frictional timescales leave many IMBHs "wandering" in galaxy halos after a minor merger. While seed IMBHs that are as rare as the 3.5 σ peaks of the primordial density field evolve largely in isolation, a significant number of BH binary systems will form if IMBHs populate the more numerous 3 σ peaks instead. In the case of rapid binary coalescence a fraction of IMBHs will be displaced from galaxy centers and ejected into the intergalactic medium (IGM) by the "gravitational rocket" effect, rather than accrete and shine as miniquasars. We show that, under a number of plausible assumptions for the amount of gas accreted onto IMBHs and their emission spectrum, miniquasars powered by IMBHs, and not their stellar progenitors, may be responsible for cosmological reionization at z ~ 15. Reionization by miniquasars with a hard spectrum may be more "economical" than stellar reionization, as soft X-rays escape more easily from the dense sites of star formation and travel farther than EUV radiation. Energetic photons will permeate the universe more uniformly, make the low-density diffuse IGM warm and weakly ionized prior to the epoch of reionization breakthrough, set an entropy floor, and reduce gas clumping. Future 21 cm observations may detect a preheated, weakly ionized IGM in emission against the cosmic microwave background.
    Full-text · Article · Dec 2008 · The Astrophysical Journal
  • [Show abstract] [Hide abstract] ABSTRACT: We calculate evolution, collapse, explosion, and nucleosynthesis of Population III very massive stars with 500Msolar and 1000Msolar. It was found that both 500Msolar and 1000Msolar models enter the region of pair-instability but continue to undergo core collapse to black holes. For moderately aspherical explosions, the patterns of nucleosynthesis match the observational data of intergalactic and intercluster medium and hot gases in M82, better than models involving hypernovae and pair instability supernovae. 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. The final black hole masses are about 500Msolar for our most massive 1000Msolar 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.
    No preview · Article · Mar 2008
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    M. J. Rees · P. Meszaros
    [Show abstract] [Hide abstract] ABSTRACT: The recent report of X-ray Fe features in the afterglow of the gamma-ray burst GRB 991216 may provide important clues for identifying the nature of its progenitor and constraining the burst mechanism. We argue that the strong line emission can be attributed to the interaction of a continuing (but decaying) post-burst relativistic outflow from the central engine with the progenitor stellar envelope at distances less than a light-hour. Only a small mass of Fe is then required, which could have been readily produced by the star itself.
    Preview · Article · Jan 2008 · The Astrophysical Journal
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    Mitchell C. Begelman · Andrew C. Fabian · Martin J. Rees
    [Show abstract] [Hide abstract] ABSTRACT: We discuss the implications of rapid (few-minute) variability in the TeV flux of blazars, which has been observed recently with the HESS and MAGIC telescopes. The variability time-scales seen in PKS 2155−304 and Mrk 501 are much shorter than inferred light-crossing times at the black hole horizon, suggesting that the variability involves enhanced emission in a small region within an outflowing jet. The enhancement could be triggered by dissipation in part of the black hole magnetosphere at the base of the outflow, or else by instabilities in the jet itself. By considering the energetics of the observed flares, along with the requirement that TeV photons escape without producing pairs, we deduce that the bulk Lorentz factors in the jets must be ≳50. The distance of the emission region from the central black hole is less well-constrained. We discuss possible consequences for multi-wavelength observations.
    Preview · Article · Sep 2007 · Monthly Notices of the Royal Astronomical Society
  • M. Volonteri · M. J. Rees
    [Show abstract] [Hide abstract] ABSTRACT: Some powerful quasars have been detected with redshifts exceeding 6. This implies surprisingly rapid growth of at least a few supermassive holes within the first billion years after the Big Bang and suggests that such objects could have important; effects at even higher redshifts. We discuss the nature of "seed" black holes, their subsequent growth via accretion and mergers, and the implications of the existence of holes in Most quiescent galaxies. The feedback from black holes is important for the formation of galaxies and for the energy balance within clusters. Accretion and mergers play a fundamental role in determining the two parameters defining a black hole: mass and spin. There is growing interest; in the detailed mechanisms that occur in the strong-field regime; especially if these can offer clues to the spin of the hole and how it acquired its mass.
    No preview · Article · Sep 2007 · Il Nuovo Cimento B
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    Alan Wells · Ralph A M J Wijers · Martin J Rees
    [Show abstract] [Hide abstract] ABSTRACT: Gamma-ray bursts (GRBs) are immensely powerful explosions, originating at cosmological distances, whose outbursts persist for durations ranging from milliseconds to tens of seconds or more. In these brief moments, the explosions radiate more energy than the Sun will release in its entire 10Gyr lifetime. Current theories attribute these phenomena to the final collapse of a massive star, or the coalescence of a binary system induced by gravity wave emission. New results from Swift and related programmes offer fresh understanding of the physics of GRBs, and of the local environments and host galaxies of burst progenitors. Bursts found at very high red shifts are new tools for exploring the intergalactic medium, the first stars and the earliest stages of galaxy formation. This Royal Society Discussion Meeting has brought together leading figures in the field, together with young researchers and students, to discuss and review the latest results from NASA's Swift Gamma-ray Burst Observatory and elsewhere, and to examine their impact on current understanding of the observed phenomena.
    Preview · Article · Jun 2007 · Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences
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    Asaf Pe'er · Peter Mészáros · Martin J Rees
    [Show abstract] [Hide abstract] ABSTRACT: A thermal radiative component is likely to accompany the first stages of the prompt emission of gamma-ray bursts (GRBs) and X-ray flashes. We analyse the effect of such a component on the observable spectrum, assuming that the observable effects are due to a dissipation process occurring below or near the thermal photosphere. For comparable energy densities in the thermal and leptonic components, the dominant emission mechanism is Compton scattering. This leads to a nearly flat energy spectrum (nuFnu proportional, 0) above the thermal peak at approximately 10-100 keV and below 10-100 MeV, for a wide range of optical depths 0.03 less, similar tau less, similar 100, regardless of the details of the dissipation mechanism or the strength of the magnetic field. For higher values of the optical depth, a Wien peak is formed at 100 keV to 1 MeV. In particular, these results are applicable to the internal shock model of GRBs, as well as to slow dissipation models, e.g. as might be expected from reconnection, if the dissipation occurs at a sub-photospheric radii. We conclude that dissipation near the thermal photosphere can naturally explain (i) clustering of the peak energy at sub-MeV energies at early times, (ii) steep slopes observed at low energies, and (iii) a flat spectrum above 10 keV at late times. Our model thus provides an alternative scenario to the optically thin synchrotron-synchrotron self-Compton model.
    Preview · Article · Jun 2007 · Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences
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    [Show abstract] [Hide abstract] ABSTRACT: In recent years increasing evidence has emerged for a thermal component in the gamma- and X-ray spectrum of the prompt emission phase in gamma-ray bursts. The temperature and flux of the thermal component show a characteristic break in the temporal behavior after a few seconds. We show here, that measurements of the temperature and flux of the thermal component at early times (before the break) allow the determination of the values of two of the least restricted fireball model parameters: the size at the base of the flow and the outflow bulk Lorentz factor. Relying on the thermal emission component only, this measurement is insensitive to the inherent uncertainties of previous estimates of the bulk motion Lorentz factor. We give specific examples of the use of this method: for GRB970828 at redshift z=0.9578, we show that the physical size at the base of the flow is r_0 = (2.9+-1.8)*10^8 Y_0^{-3/2} cm and the Lorentz factor of the flow is Gamma = (305\+-28) Y_0^{1/4}, and for GRB990510 at z=1.619, r_0=(1.7+-1.7)*10^8 Y_0^{-3/2} cm and Gamma=(384+-71) Y_0^{1/4}, where Y = 1 Y_0 is the ratio between the total fireball energy and the energy emitted in gamma- rays. Comment: Discussion added on gamma-ray emission efficiency. Accepted for publication in Ap.J. Lett
    Preview · Article · Mar 2007 · The Astrophysical Journal

Publication Stats

16k Citations
862.90 Total Impact Points

Institutions

  • 1985-2011
    • University of Cambridge
      • Institute of Astronomy
      Cambridge, England, United Kingdom
  • 2006
    • Cancer Research UK Cambridge Institute
      Cambridge, England, United Kingdom
  • 1996-2006
    • Pennsylvania State University
      • Department of Astronomy and Astrophysics
      University Park, Maryland, United States
  • 2000
    • University of California, Santa Cruz
      • Department of Astronomy and Astrophysics
      Santa Cruz, California, United States
  • 1992-1999
    • Scuola Internazionale Superiore di Studi Avanzati di Trieste
      Trst, Friuli Venezia Giulia, Italy
  • 1997
    • University of Pennsylvania
      • Department of Physics and Astronomy
      Philadelphia, Pennsylvania, United States
  • 1996-1997
    • Cambridge Healthtech Institute
      Needham, Massachusetts, United States