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

Eric Howell, David Coward, G. Stratta, B. Gendre, H. Zhou

    Research output: Contribution to journalArticle

    17 Citations (Scopus)

    Abstract

    © 2014 The Authors. 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 logN-log P brightness distribution and Vmax estimations with two observation-time relations: a redshift- observation-time relation (log z-log T ) and a new luminosity-observation-time relation (logL-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 logL-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 <?0 <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.
    Original languageEnglish
    Pages (from-to)15-28
    Number of pages14
    JournalMonthly Notices of the Royal Astronomical Society
    Volume444
    Issue number1
    Early online date12 Aug 2014
    DOIs
    Publication statusPublished - 11 Oct 2014

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    gamma ray bursts
    luminosity
    brightness distribution
    rate
    complement
    erg
    energy
    power law
    estimates

    Cite this

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    title = "Constraining the rate and luminosity function of swift gamma-ray bursts",
    abstract = "{\circledC} 2014 The Authors. 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 logN-log P brightness distribution and Vmax estimations with two observation-time relations: a redshift- observation-time relation (log z-log T ) and a new luminosity-observation-time relation (logL-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 logL-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 <?0 <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.",
    author = "Eric Howell and David Coward and G. Stratta and B. Gendre and H. Zhou",
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    Constraining the rate and luminosity function of swift gamma-ray bursts. / Howell, Eric; Coward, David; Stratta, G.; Gendre, B.; Zhou, H.

    In: Monthly Notices of the Royal Astronomical Society, Vol. 444, No. 1, 11.10.2014, p. 15-28.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - Constraining the rate and luminosity function of swift gamma-ray bursts

    AU - Howell, Eric

    AU - Coward, David

    AU - Stratta, G.

    AU - Gendre, B.

    AU - Zhou, H.

    PY - 2014/10/11

    Y1 - 2014/10/11

    N2 - © 2014 The Authors. 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 logN-log P brightness distribution and Vmax estimations with two observation-time relations: a redshift- observation-time relation (log z-log T ) and a new luminosity-observation-time relation (logL-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 logL-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 <?0 <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.

    AB - © 2014 The Authors. 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 logN-log P brightness distribution and Vmax estimations with two observation-time relations: a redshift- observation-time relation (log z-log T ) and a new luminosity-observation-time relation (logL-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 logL-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 <?0 <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.

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