An important concern in the application of gamma-ray bursts (GRBs) to cosmology is that the calibration of GRB luminosity/energy relations depends on the cosmological model, due to the lack of a sufficient lowredshift GRB sample. In this paper, we present a new method to calibrate GRB relations in a cosmologyindependent way. Since objects at the same redshift should have the same luminosity dis...

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) obtained directly from observations are completely cosmology independent, we obtain the distance modulus of a gammaray burst (GRB) at a given redshift by interpola...

– 2 – We have obtained deep optical images with the Very Large Telescope at ESO of the first well-localized short-duration gamma-ray burst, GRB 050509B. From V and R imaging, initiated ∼ 2 days after the GRB trigger and lasting up to three weeks, we detect no variable object inside the small Swift/XRT X-ray error circle down to 2σ limits of V = 26.5 and R = 25.1. The X-ray error circle includes...

We use the cosmology-independent gamma-ray burst (GRB) distances of Wang (2008) to constrain dark energy cosmological model parameters. Current GRB data alone can not tightly constrain cosmological parameters and allow for a wide range of dark energy models. When used jointly with current Type Ia supernovae data and baryon acoustic peak measurements, the GRB data favor slightly lower values of ...

شور و داوم اه : ،یبرجت همین قیقحت نیا رد 28 نیماتیو ،نیرمت ،لرتنک هورگ راهچ هب یفداصت روط هب و باختنا قاچ رتخد C یبیکرت و دندش میسقت . نیرمت تدش اب يزاوه 50 ات 70 ،رثکادح بلق نابرض دصرد 3 تدم هب و هتفه رد هسلج 8 هتفه دش ماجنا . هورگ ياه نیماتیو C و صرق یبیکرت 500 یلیم نیماتیو یمرگ C ار 3 فرصم هتفه رد راب دندومن . هنومن و لبق اتشان ینوخ ياه 48 هلخادم نیرخآ زا سپ تعاس اه عم...