Related papers: Hints for families of GRBs improving the Hubble di…
A recent spectrum of the optical afterglow of GRB 970508 suggests that gamma-ray bursts (GRBs) are cosmological in origin and it is of crucial importance to derive an accurate distance to each burst. If GRBs occur near their host galaxies…
The nature of Gamma Ray Bursts (GRBs) remains a complete mystery, despite the recent breakthrough discovery of low energy counterparts, although it is now generally believed that at least most GRBs are at cosmological distances. Virtually…
We present an analysis of gamma-ray burst (GRB) progenitor classification, through their positions on a Uniform Manifold Approximation and Projection (UMAP) plot, constructed by Negro et al. 2024, from Fermi-GBM waterfall plots. The…
We consider the form of Hubble diagrams that would be constructed by observers in universes that are homogeneous but anisotropic, when averaged over suitably large length-scales. This is achieved by ray-tracing in different directions on…
Gamma-Ray Bursts (GRBs) are very energetic cosmological transients. Long GRBs are usually associated with Type Ib/c Supernovae (SNe), and we refer to them as GRB-SNe. Since the associated SN for a given GRB is observed only at low redshift,…
Recent observations have accumulated compelling evidence that some short gamma-ray bursts (SGRBs) are associated with the mergers of neutron star (NS) binaries. This would indicate that the SGRB event is associated with a gravitational-wave…
As part of the HST/STIS GRB host survey program we present the detection of three faint gamma-ray burst (GRB) host galaxies based on an accurate localisation using ground-based data of the optical afterglows (OAs). A common property of…
This report is an update and extension of our paper accepted for publication in ApJ (arXiv:0802.4262). Since objects at the same redshift should have the same luminosity distance and the distance moduli of type Ia supernovae (SNe Ia)…
We present constraints on the scaling relations of galaxy cluster X-ray luminosity, temperature and gas mass (and derived quantities) with mass and redshift, employing masses from robust weak gravitational lensing measurements. These are…
The accuracy and reliability of gamma-ray bursts (GRBs) as distance indicators are strongly restricted by their systematic errors which are larger than statistical errors. These systematic errors might come from either intrinsic variations…
The highly luminous and variable prompt emission in Gamma-Ray Bursts (GRBs) arises in an ultra-relativistic outflow. The exact underlying radiative mechanism shaping its non-thermal spectrum is still uncertain, making it hard to determine…
Recent observations support the hypothesis that a large fraction of "short-hard" gamma-ray bursts (SHBs) are associated with compact binary inspiral. Since gravitational-wave (GW) measurements of well-localized inspiraling binaries can…
Gamma Ray Bursts (GRBs) are bright, brief flashes of high energy photons that have fascinated scientists for 30 years. They come in two classes: long (>2 s), softspectrum bursts and short, hard events. The major progress to date on…
Long-duration Gamma-Ray Bursts (GRBs) allow us to pinpoint and study star-forming galaxies in the early universe, thanks to their orders of magnitude brighter peak luminosities compared to other astrophysical sources, and their association…
The Hubble diagram (HD) of Gamma-Ray Bursts (GRBs) having properly estimated redshifts is compared with the predicted one for the Chaplygin gas (CG), a dark energy candidate. The CG cosmology and that of Friedmann and $\Lambda$-CDM models…
This manuscript presents a multilevel analysis of gamma-ray bursts (GRBs). We focus on the plateau phase, which is often observed in the light curves (LCs) of GRBs. We discuss its observational properties and then thoroughly examine…
Bright elliptical galaxies have a markedly different distribution of Hubble types than faint ellipticals; the division occurs near M_B=-20 and bright ellipticals are rounder on average. The Hubble types of galaxies in both groups are…
The narrowness of the distribution of the peak energy of $\nu F_{\nu}$ spectrum of gamma-ray bursts (GRBs) and the unification of GRB population are great puzzles yet to be solved. We investigate the two puzzles based on the global spectral…
The extragalactic distance scale is fundamental to our understanding of astrophysics and cosmology. In recent years, the surface brightness fluctuation (SBF) method, applied in the near-IR, has proven especially powerful for measuring…
Gamma-ray burst (GRB) progenitors are observationally linked to the death of massive stars. X-ray studies of the GRB afterglows can deepen our knowledge of the ionization status and metal abundances of the matter in the GRB environment.…