Details

Autor(en) / Beteiligte

• Howell, E. J
• Coward, D. M
• Stratta, G
• Gendre, B
• Zhou, H

Titel

Constraining the rate and luminosity function of Swift gamma-ray bursts

Ist Teil von

• Monthly notices of the Royal Astronomical Society, 2014-10, Vol.444 (1), p.15-28

Ort / Verlag

London: Oxford University Press

Erscheinungsjahr

2014

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• We compute the intrinsic isotropic peak luminosity function (LF) and formation rate of long gamma-ray bursts (LGRBs) using a novel approach. We complement a standard log N-log P brightness distribution and V max estimations with two observation–time relations: a redshift–observation-time relation (log z-log T) and a new luminosity–observation-time relation (log L-log T). We show that this approach reduces degeneracies that exist between the rate and LF of a brightness distribution. To account for the complex triggering algorithm employed by Swift, we use recent results of Lien et al. (2014) to produce a suite of efficiency functions. Using these functions with the above methods, we show that a log L-log T method can provide good constraints on the form of the LF, particularly the high end. Using a sample of 175 peak luminosities determined from redshifts with well-defined selection criteria, our results suggest that LGRBs occur at a local rate (without beaming corrections) of [0.7 < ρ0 < 0.8] Gpc−3 yr−1. Within this range, assuming a broken power-law LF, we find best estimates for the low- and high-energy indices of −0.95 ± 0.09 and −2.59 ± 0.93, respectively, separated by a break luminosity 0.80 ± 0.43 × 1052 erg s−1.