The rate and luminosity function of long gamma ray bursts

Pescalli, A.; Ghirlanda, G.; Salvaterra, R.; Ghisellini, G.; Vergani, S. D.; Nappo, F.; Salafia, O. S.; Melandri, A.; Covino, S.; Götz, D.

doi:10.1051/0004-6361/201526760

Cited by 100 publications

(140 citation statements)

References 63 publications

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“…While for the complete Swift -Ryan 2012 sample, our models consistently show that an excess of LGRB is always presence below a redshift of 2, regardless of how we modify our model parameter values to fit both the preSwift and Swift distributions. Interestingly, Pescalli et al (2016) reach similar conclusion when incomplete sample was used. This suggests that there could be a biased in the Swift -Ryan-2012 sample relating to the afterglow selection effect based on the Swift -Perley sample; or that the Swift -Ryan 2012 sample needs to be constrained using the "well-fitted" beaming opening angle.…”

Section: Ld07supporting

confidence: 61%

Resolving the excess of long GRB’s at low redshift in the Swift era

Ratke

Mehta

2020

Monthly Notices of the Royal Astronomical Society

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Utilizing more than 100 long gamma-ray bursts (LGRBs) in the Swift -Ryan-2012 sample that includes the observed redshifts and jet angles, Le & Mehta performed a timely study of the rate density of LGRBs with an assumed broken power-law GRB spectrum and obtained a GRB-burst-rate functional form that gives acceptable fits to the preSwift and Swift redshift, and jet angle distributions. The results indicated an excess of LGRBs at redshift below z ∼ 2 in the Swift sample. In this work, we are investigating if the excess is caused by the cosmological Hubble constant H 0 , the gamma-ray energy released E * γ , the low-and high-energy indices (α, β) of the Band function, the minimum and maximum jet angles θ j,min and θ j,max , or that the excess is due to a bias in the Swift -Ryan-2012 sample. Our analyses indicate that none of the above physical parameters resolved the excess problem, but suggesting that the Swift -Ryan-2012 sample is biased with possible afterglow selection effect. The following model physical parameter values provide the best fit to the Swift -Ryan-2012 and preSwift samples: the Hubble constant H 0 = 72 kms −1 Mpc −1 , the energy released E * γ ∼ 4.47 × 10 51 erg, the energy indices α ∼ 0.9 and β ∼ −2.13, the jet angles of θ j,max ∼ 0.8 rad, and θ j,min ∼ 0.065 and ∼ 0.04 rad for preSwift and Swift, respectively, s ∼ −1.55 the jet angle power-law index, and a GRB formation rate that is similar to the Hopkins & Beacom observed star formation history and as extended by Li. Using the Swift Gamma-Ray Burst Host Galaxy Legacy Survey (SHOALS) Swift -Perley LGRB sample and applying the same physical parameter values as above, however, our model provides consistent results with this data set and indicating no excess of LGRBs at any redshift.

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Section: Ld07supporting

confidence: 61%

Resolving the excess of long GRB’s at low redshift in the Swift era

Ratke

Mehta

2020

Monthly Notices of the Royal Astronomical Society

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“…52 of them have measured redshift so that the completeness level is ∼ 90%. Pescalli et al (2016) revised the BAT6 sample and extended it with additional bursts that satisfy its selection criteria. The BAT6 extended (BAT6ext) sample contains 99 GRBs up to 2014 July, of which 81 bursts have measured z and L. Its completeness in redshift is ∼ 82%.…”

Section: The Samplementioning

confidence: 99%

The luminosity function and formation rate of a complete sample of long gamma-ray bursts

Guang-Xuan

Zeng

Wei

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We study the luminosity function and formation rate of long gamma-ray bursts (GRBs) by using a maximum likelihood method. This is the first time this method is applied to a well-defined sample of GRBs that is complete in redshift. The sample is composed of 99 bursts detected by the Swif t satellite, 81 of them with measured redshift and luminosity for a completeness level of 82%. We confirm that a strong redshift evolution in luminosity (with an evolution index of δ = 2.22 +0.32 −0.31 ) or in density (δ = 1.92 +0.20 −0.21 ) is needed in order to reproduce the observations well. But since the predicted redshift and luminosity distributions in the two scenarios are very similar, it is difficult to distinguish between these two kinds of evolutions only on the basis of the current sample. Furthermore, we also consider an empirical density case in which the GRB rate density is directly described as a broken power-law function and the luminosity function is taken to be non-evolving. In this case, we find that the GRB formation rate rises like (1 + z) 3.85 +0.48 −0.45 for z < ∼ 2 and is proportional to (1 + z) −1.07 +0.98 −1.12 for z > ∼ 2. The local GRB rate is 1.49 +0.63 −0.64 Gpc −3 yr −1 . The GRB rate may be consistent with the cosmic star formation rate (SFR) at z < ∼ 2, but shows an enhancement compared to the SFR at z > ∼ 2.

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“…the peak in νF ν spectrum) outside the energy coverage of the BAT instrument: we estimated the peak by using the correlation between E γ,peak and spectral index Γ, found by Sakamoto et al (2009), and then computed E γ,iso and L γ,iso in the extrapolated 1-10 000 keV range (e.g. Pescalli et al 2016). …”

Section: Metallicity Distributionmentioning

confidence: 99%

Are long gamma-ray bursts biased tracers of star formation? Clues from the host galaxies of theSwift/BAT6 complete sample of bright LGRBs

Japelj

Vergani

Salvaterra

et al. 2016

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100

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Aims. Long gamma-ray bursts (LGRBs) are associated with the deaths of massive stars and might therefore be a potentially powerful tool for tracing cosmic star formation. However, especially at low redshifts (z < 1.5) LGRBs seem to prefer particular types of environment. Our aim is to study the host galaxies of a complete sample of bright LGRBs to investigate the effect of the environment on GRB formation. Methods. We studied host galaxy spectra of the Swift/BAT6 complete sample of 14 z < 1 bright LGRBs. We used the detected nebular emission lines to measure the dust extinction, star formation rate (SFR), and nebular metallicity (Z) of the hosts and supplemented the data set with previously measured stellar masses M . The distributions of the obtained properties and their interrelations (e.g. mass-metallicity and SFR-M relations) are compared to samples of field star-forming galaxies. Results. We find that LGRB hosts at z < 1 have on average lower SFRs than if they were direct star formation tracers. By directly comparing metallicity distributions of LGRB hosts and star-forming galaxies, we find a good match between the two populations up to 12 + log O H ∼ 8.4−8.5, after which the paucity of metal-rich LGRB hosts becomes apparent. The LGRB host galaxies of our complete sample are consistent with the mass-metallicity relation at similar mean redshift and stellar masses. The cutoff against high metallicities (and high masses) can explain the low SFR values of LGRB hosts. We find a hint of an increased incidence of starburst galaxies in the Swift/BAT6 z < 1 sample with respect to that of a field star-forming population. Given that the SFRs are low on average, the latter is ascribed to low stellar masses. Nevertheless, the limits on the completeness and metallicity availability of current surveys, coupled with the limited number of LGRB host galaxies, prevents us from investigating more quantitatively whether the starburst incidence is such as expected after taking into account the high-metallicity aversion of LGRB host galaxies.

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The rate and luminosity function of long gamma ray bursts

Cited by 100 publications

References 63 publications

Resolving the excess of long GRB’s at low redshift in the Swift era

Resolving the excess of long GRB’s at low redshift in the Swift era

The luminosity function and formation rate of a complete sample of long gamma-ray bursts

Are long gamma-ray bursts biased tracers of star formation? Clues from the host galaxies of theSwift/BAT6 complete sample of bright LGRBs

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