Related papers: Cosmological Time Dilation in Gamma Ray Bursts?
Gamma-ray burst sources are distributed with a high level of isotropy, which is compatible with either a cosmological origin or an extended Galactic halo origin. The brightness distribution is another indicator used to characterize the…
Many models of cosmological gamma-ray bursts involve the sudden release of $\sim 10^{51}$ erg which produce shells which expand at relativistic speeds (Lorentz $\Gamma$ factors of $10^{2-3}$). We investigate the kinematic limits on the…
Observations of a long-lasting Gamma-ray burst, one that has the brightest optical counterpart yet discovered, challenge theoretical understanding of these bursts but may enhance their usefulness as cosmic probes.
Gamma-ray burst time histories often consist of many peaks. These peaks tend to be narrower at higher energy. If gamma-ray bursts are cosmological, the energy dependence of gamma-ray burst time scales must be understood in order to correct…
In recent years there has been considerable activity in using gamma-ray bursts as cosmological probes for determining global cosmological parameters complementing results from type Ia supernovae and other methods. This requires a…
We suggest that the collapsing core of a massive rotating star may fragment to produce two or more compact objects. Their coalescence under gravitational radiation gives the resulting black hole or neutron star a significant kick velocity,…
A fundamental prediction of relativistic cosmologies is that, due to the expansion of space, observations of the distant cosmos should be time dilated and appear to run slower than events in the local universe. Whilst observations of…
The cosmic time dilation observed in Type Ia supernova light curves suggests that the passage of cosmic time varies throughout the evolution of the Universe. This observation implies that the rate of proper time is not constant, as assumed…
In this paper we shed light on late time (i.e. with peak time t_{pk} \gtrsim 1000 s) flaring activity. We address the morphology and energetic of flares in the window \sim 10^3-10^6 s to put constraints on the temporal evolution of the…
The association of a short gamma-ray burst with a core-collapse supernova seems to challenge current scenarios for the origin of these extreme events. But how much can we rely on observed duration for pinpointing their progenitors?
Apparently, Gamma-Ray Bursts (GRBs) are all but standard candles. Their emission is collimated into a cone and the received flux depends on the cone aperture angle. Fortunately we can derive the aperture angle through an achromatic…
The cosmic gamma-ray burst (GRB) formation rate, as derived from the variability-luminosity relation for long-duration GRBs, is compared with the cosmic star formation rate. If GRBs are related to the collapse of massive stars, one expects…
The launch of the Fermi telescope in 2008 opened up the possibility of measuring the energy dependence of the speed of light by considering the time delay in the arrival of gamma ray bursts emitted simultaneously from very distant…
Gamma-ray bursts are believed to result from the coalescence of binary neutron stars. However, the standard proposals for conversion of the gravitational energy to thermal energy have difficulties. We show that if the merger of the two…
A fundamental property of an expanding universe is that any time dependent characteristic of distant objects must appear to scale by the factor $(1+z$). This is called time dilation. Light curves of type Ia supernovae and the duration of…
Several claims have been put forward that an essential fraction of long-duration BATSE gamma-ray bursts should lie at redshifts larger than 5. This point-of-view follows from the natural assumption that fainter objects should, on average,…
From recent observations of gamma-ray bursts (GRBs), it appears that spectral time lags between higher-energy gamma rays photons and lower-energy photons vary with energy difference and time (distance) traveled. These lags appear to be…
Cosmic gamma-ray bursts are one of the great frontiers of astrophysics today. They are a playground of relativists and observers alike. They may teach us about the death of stars and the birth of black holes, the physics in extreme…
We show that, if the long GRBs are produced by the collapse of massive stars, GRBs and their afterglows may provide a powerful probe of cosmology and the early universe.
We show that, if the long GRBs are produced by the collapse of massive stars, GRBs and their afterglows may provide a powerful probe of cosmology and the early universe.