Redshift Distribution Of Gamma-ray Bursts Research Articles

Expected Gamma-Ray Burst Detection Rates and Redshift Distributions for the BlackCAT CubeSat Mission

We report the results of an extensive set of simulations exploring the sensitivity of the BlackCAT CubeSat to long-duration gamma-ray bursts (GRBs). BlackCAT is a NASA APRA-funded CubeSat mission for the detection and real-time subarcminute localization of high-redshift (z ≳ 3.5) GRBs. Thanks to their luminous and long-lived afterglow emissions, GRBs are uniquely valuable probes of high-redshift star-forming galaxies and the intergalactic medium. In addition, each detected GRB with a known redshift serves to localize a region of high-redshift star formation in three dimensions, enabling deep follow-on searches for host galaxies and associated local and large-scale structures. We explore two distinct models for the GRB redshift distribution and luminosity function, both consistent with Swift observations. We find that, for either model, BlackCAT is expected to detect a mean of 42 bursts per year on orbit, with 6.7% to 10% of these at z > 3.5. BlackCAT bursts will be localized to an r 90 ≲ 55″ precision and reported to the community within seconds. Due to the mission orbit and pointing scheme, bursts will be located in the night sky and well placed for deep multiwavelength follow-up observations. BlackCAT is on schedule to achieve launch readiness in 2025.

Probing Electromagnetic Gravitational-wave Emission Coincidence in a Type I Binary-driven Hypernova Family of Long Gamma-Ray Bursts at Very High Redshift

The repointing time of the X-Ray Telescope (XRT) instrument on the Neil Gehrels Swift Observatory satellite has posed challenges in observing and studying the early X-ray emissions within ≈40 s after a gamma-ray burst (GRB) trigger. To address this issue, we adopt a novel approach that capitalizes on the cosmological time dilation in GRBs with redshifts ranging from 3 to 9. Applying this strategy to Swift/XRT data, we investigate the earliest X-ray emissions of 368 GRBs from the Swift catalog, including short and long GRBs. We compare the observed time delay between the GRB trigger and the initial Swift/XRT observation, measured in the GRB observer frame, and the corresponding cosmological rest-frame time delay (RTD). This technique is here used in the analysis of GRB 090423 at z = 8.233 (RTD ∼8.2 s), GRB 090429B at z ≈ 9.4 (RTD ∼10.1 s), and GRB 220101A at z = 4.61 (RTD ∼14.4 s). The cosmological time dilation enables us to observe the very early X-ray afterglow emission in these three GRBs. We thus validate the observation of the collapse of the carbon–oxygen core and the coeval newborn neutron star (νNS) formation triggering the GRB event in the binary-driven hypernova (BdHN) scenario. We also evidence the νNS spin-up due to supernova ejecta fallback and its subsequent slowing down due to the X-ray/optical/radio synchrotron afterglow emission. A brief gravitational-wave signal may separate the two stages owing to a fast-spinning νNS triaxial-to-axisymmetric transition. We also analyze the long GRB redshift distribution for the different BdHN types and infer that BdHNe II and III may originate the NS binary progenitors of short GRBs.

Revisiting the luminosity and redshift distributions of long gamma-ray bursts

ABSTRACT In this work, we update and enlarge the long gamma-ray burst (GRB) sample detected by the Swift satellite. Given the incomplete sampling of the faint bursts and the low completeness in redshift measurement, we carefully select a subsample of bright Swift bursts to revisit the GRB luminosity function (LF) and redshift distribution by taking into account the probability of redshift measurement. Here we also explore two general expressions for the GRB LF, i.e. a broken power-law LF and a triple power-law LF. Our results suggest that a strong redshift evolution in luminosity (with an evolution index of $\delta =1.92^{+0.25}_{-0.37}$) or in density ($\delta =1.26^{+0.33}_{-0.34}$) is required in order to well account for the observations, independent of the assumed expression of the GRB LF. However, in a one-to-one comparison using the Akaike Information Criterion, the best-fitting evolution model involving the triple power-law LF is statistically preferred over the best-fitting one involving the broken power-law LF with a relative probability of ∼94.3 per cent versus ∼5.7 per cent. Extrapolating our fitting results to the flux limit of the whole Swift sample, and considering the trigger probability of Swift/Burst Alert Telescope in detail, we find that the expectations from our evolution models provide a good representation of the observed distributions of the whole sample without the need for any adjustment of the model free parameters. This further confirms the reliability of our analysis results.

Redshift distribution of gamma-ray bursts: Evidence for the long GRBs sources population nonuniformity

The results of redshifts distribution investigation for 275 γ-ray bursts (GRBs) with defined duration from the Swift experiment catalogue are discussed. Detailed investigation of the redshift distribution shows that the former has at least two maxima at the 95% significance level in contradiction with the similar distribution for uniform samples in our Metagalaxy. This pattern (demonstrating the nonuniformity of the long GRB sources population) persists even if short GRBs with durations of t90 < 2 s without redshift correction, which corresponds to the classical definition of short GRB events, are excluded from consideration and if the analysis uses any sample of a smaller size for previous years. Preliminary investigation of the GRBs distribution on redshift and duration also reveals another subgroup that can be interpreted as intermediate GRB events. This subgroup persists if the analysis is confined to the distribution of those GRBs whose redshifts z are determined using one method only, e.g., from analyzing afterglow absorption lines.

The Swift gamma-ray burst redshift distribution: selection biases and optical brightness evolution at high z?

We employ realistic constraints on astrophysical and instrumental selection effects to model the Gamma-Ray Burst (GRB) redshift distribution using {\it Swift} triggered redshift samples acquired from optical afterglows (OA) and the TOUGH survey. Models for the Malmquist bias, redshift desert, and the fraction of afterglows missing because of host galaxy dust extinction, are used to show how the "true" GRB redshift distribution is distorted to its presently observed biased distribution. We also investigate another selection effect arising from a correlation between $E_{{\rm iso}}$ and $L_{{\rm opt}}$. The analysis, which accounts for the missing fraction of redshifts in the two data subsets, shows that a combination of selection effects (both instrumental and astrophysical) can describe the observed GRB redshift distribution. Furthermore, the observed distribution is compatible with a GRB rate evolution that tracks the global SFR, although the rate at high-$z$ cannot be constrained with confidence. Taking selection effects into account, it is not necessary to invoke high-energy GRB luminosity evolution with redshift to explain the observed GRB rate at high-$z$.

Neutrinos from GRBs in the Fermi Era

We investigate the consequences of the redshift distribution of gamma-ray bursts on diffuse gamma-ray burst neutrino fluxes using a Monte Carlo simulation. We determine the systematic error introduced by the extrapolation from small samples to the quasi-diffuse flux. In addition, we reanalyze the computation of neutrino spectra from photon spectra measured for example by the Fermi Gamma-Ray Burst Monitor.

The dust extinction curves of gamma-ray burst host galaxies

The composition and amount of interstellar dust within gamma-ray burst (GRB) host galaxies is of key importance when addressing selection effects in the GRB redshift distribution, and when studying the properties of their host galaxies. As well as the implications for GRB research, probing the dust within the high-z hosts of GRBs also contributes to our understanding of the conditions of the interstellar medium and star-formation in the distant Universe. Nevertheless, the physical properties of dust within GRB host galaxies continues to be a highly contended issue. In this paper we explore the mean extinction properties of dust within the host galaxies of a sample of 17 GRBs with total host galaxy visual extinction Av<1 (<Av>=0.4), covering a redshift range z=0.7-3.1. We find the average host extinction curve to have an ultraviolet slope comparable to that of the LMC, but with little evidence of a 2175Angs dust extinction feature as observed along Milky Way and LMC sightlines. We cannot at present rule out the presence of a 2175Angs feature, and both the standard SMC and LMC extinction curves also provide good fits to our data. However, we can reject an extinction curve that has a UV slope as flat as the mean Milky Way extinction curve, whilst also having a 2175Angs feature as prominent as seen in the mean Milky Way extinction curve. This is in contrast to the clear detection of a 2175Angs bump and the flatter extinction curves of some more heavily extinguished GRBs (Av>1), which may be indicative of there being a dependence between dust abundance and the wavelength dependence of dust extinction, as has been previously speculated.

AN EVOLVING STELLAR INITIAL MASS FUNCTION AND THE GAMMA-RAY BURST REDSHIFT DISTRIBUTION

Recent studies suggest that Swift gamma-ray bursts (GRBs) may not trace an ordinary star formation history. Here we show that the GRB rate turns out to be consistent with the star formation history with an evolving stellar initial mass function (IMF). We first show that the latest Swift sample of GRBs reveals an increasing evolution in the GRB rate relative to the ordinary star formation rate at high redshifts. We then assume only massive stars with masses greater than the critical value to produce GRBs, and use an evolving stellar IMF suggested by Dav\'{e} (2010) to fit the latest GRB redshift distribution. This evolving IMF would increase the relative number of massive stars, which could lead to more GRB explosions at high redshifts. We find that the evolving IMF can well reproduce the observed redshift distribution of Swift GRBs.

Modelling gamma-ray burst observations by Fermi and MAGIC including attenuation due to diffuse background light

Gamma rays from extragalactic sources are attenuated by pair-production interactions with diffuse photons of the extragalactic background light (EBL). Gamma-ray bursts (GRBs) are a source of high-redshift photons above 10 GeV, and could be therefore useful as a probe of the evolving UV background radiation. In this paper, we develop a simple phenomenological model for the number and redshift distribution of gamma-ray bursts that can be seen at GeV energies with the Fermi satellite and MAGIC atmospheric Cherenkov telescope. We estimate the observed number of gamma rays per year, and show how this result is modified by considering interactions with different realizations of the evolving EBL. We also discuss the bright Fermi GRB 080916C in the context of this model. We find that the LAT on Fermi can be expected to see a small number of photons above 10 GeV each year from distant GRBs. Annual results for ground-based instruments like MAGIC are highly variable due to the low duty cycle and sky coverage of the telescope. However, successfully viewing a bright or intermediate GRB from the ground could provide hundreds of photons from high redshift, which would almost certainly be extremely useful in constraining both GRB physics and the high-redshift EBL.

LOW-RESOLUTION SPECTROSCOPY OF GAMMA-RAY BURST OPTICAL AFTERGLOWS: BIASES IN THE SWIFT SAMPLE AND CHARACTERIZATION OF THE ABSORBERS

We present a sample of 77 optical afterglows (OAs) of Swift detected gamma-ray bursts (GRBs) for which spectroscopic follow-up observations have been secured. Our first objective is to measure the redshifts of the bursts. For the majority (90%) of the afterglows, the redshifts have been determined from the spectra. We provide line lists and equivalent widths (EWs) for all detected lines redward of Lyα covered by the spectra. In addition to the GRB absorption systems, these lists include line strengths for a total of 33 intervening absorption systems. We discuss to what extent the current sample of Swift bursts with OA spectroscopy is a biased subsample of all Swift detected GRBs. For that purpose we define an X-ray-selected statistical sample of Swift bursts with optimal conditions for ground-based follow-up from the period 2005 March to 2008 September; 146 bursts fulfill our sample criteria. We derive the redshift distribution for the statistical (X-ray selected) sample and conclude that less than 18% of Swift bursts can be at z > 7. We compare the high-energy properties (e.g., γ-ray (15-350 keV) fluence and duration, X-ray flux, and excess absorption) for three subsamples of bursts in the statistical sample: (1) bursts with redshifts measured from OA spectroscopy; (2) bursts with detected optical and/or near-IR afterglow, but no afterglow-based redshift; and (3) bursts with no detection of the OA. The bursts in group (1) have slightly higher γ-ray fluences and higher X-ray fluxes and significantly less excess X-ray absorption than bursts in the other two groups. In addition, the fractions of dark bursts, defined as bursts with an optical to X-ray slope βOX 39% in group (3). For the full sample, the dark burst fraction is constrained to be in the range 25%-42%. From this we conclude that the sample of GRBs with OA spectroscopy is not representative for all Swift bursts, most likely due to a bias against the most dusty sight lines. This should be taken into account when determining, e.g., the redshift or metallicity distribution of GRBs and when using GRBs as a probe of star formation. Finally, we characterize GRB absorption systems as a class and compare them to QSO absorption systems, in particular the damped Lyα absorbers (DLAs). On average GRB absorbers are characterized by significantly stronger EWs for H I as well as for both low and high ionization metal lines than what is seen in intervening QSO absorbers. However, the distribution of line strengths is very broad and several GRB absorbers have lines with EWs well within the range spanned by QSO-DLAs. Based on the 33 z > 2 bursts in the sample, we place a 95% confidence upper limit of 7.5% on the mean escape fraction of ionizing photons from star-forming galaxies. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, under programs 275.D-5022 (PI: Chincarini), 075.D-0270 (PI: Fynbo), 077.D-0661 (PI: Vreeswijk), 077.D-0805 (PI: Tagliaferri), 177.A-0591 (PI: Hjorth), 078.D-0416 (PI: Vreeswijk), 079.D-0429 (PI: Vreeswijk), 080.D-0526 (PI: Vreeswijk), 081.A-0135 (PI: Greiner), 281.D-5002 (PI: Della Valle), and 081.A-0856 (PI: Vreeswijk). Also based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Some of the data obtained herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck foundation.

Are GRB optical afterglows relatively brighter at high z?

Abstract The redshift distribution of gamma-ray bursts (GRBs) is strongly biased by selection effects. We investigate, via Monte Carlo simulations, one possible selection effect that may be modifying the Swift GRB redshift distribution. We show how telescope response times to acquire a GRB redshift may, via the Malmquist effect and GRB optical afterglow (OA) brightness distribution, introduce a bias into the average of the observed redshift distribution. It is difficult to reconcile a recently reported correlated trend between telescope response time and average redshifts unless we employ a redshift-dependent OA distribution. Simulations of this selection effect suggest that GRB OAs may have been either intrinsically brighter early in the Universe or suffered less local host galaxy extinction.

GAMMA-RAY BURST LUMINOSITY FUNCTIONS BASED ON A NEWLY DISCOVERED CORRELATION BETWEEN PEAK SPECTRAL ENERGY ANDV/Vmax

We have discovered a correlation between the observed peak spectral energy E_(pk,obs) and the Euclidean value of of gamma-ray bursts (GRBs). We present the evidence for the correlation in the GUSBAD catalog and use it to derive the luminosity function of GRBs without using any redshifts. The procedure involves dividing GUSBAD GRBs into five spectral classes based on their E_(pk,obs). The overall luminosity function is derived assuming that each of the spectral classes contributes a Gaussian luminosity function. Their central luminosity is derived from the observed Euclidean . We explore various forms for the GRB rate function GR(z) in predicting redshift distributions of GRBs detected by Swift. We find that GR(z) peaks at a higher redshift than the typical star formation history currently favored in the literature. We consider two examples of GR(z) that successfully predict the observed redshift distribution of Swift GRBs. With the luminosity functions in hand, we convert the E_(pk,obs) – V/V_(max) correlation into an E_(pk,obs) – L_(iso) correlation and a rest-frame E_(pk) – L_(iso) correlation. By comparing the E_(pk) – L_(iso) correlation with a published correlation based on GRBs with known E_(pk,obs) and redshifts, we discuss the effect of Malmquist bias.

Probing the low-luminosity gamma-ray burst population with new generation satellite detectors

We compare the detection rates and redshift distributions of low-luminosity (LL) gamma-ray bursts (GRBs) localized by Swift with those expected to be observed by the new generation satellite detectors on the Gamma-ray Large Area Space Telescope (GLAST )( nowFermi) and, in future, the Energetic X-ray Imaging Survey Telescope (EXIST). Although the GLAST burst telescope will be less sensitive than Swift’s in the 15–150 keV band, its large FoV implies that it will double Swift’s detection rate of LL bursts. We show that Swift, GLAST and EXIST should detect about 1, 2 and 30 LL GRBs, respectively, over a 5-yr operational period. The burst telescope on EXIST should detect LL GRBs at a rate of more than an order of magnitude greater than that of Swift’s BAT. We show that the detection horizon for LL GRBs will be extended from z � 0.4 for Swift to z � 1.1 in the EXIST era. Also, the contribution of LL bursts to the observed GRB redshift distribution will contribute to an identifiable feature in the distribution at z � 1.

Star formation history up toz= 7.4: implications for gamma-ray bursts and cosmic metallicity evolution

The current Swift sample of gamma-ray bursts (GRBs) with measured redshifts allows us to test the assumption that GRBs trace star formation in the Universe. Some authors have claimed that the rate of GRBs increases with cosmic redshift faster than the star formation rate, whose cause is not yet known. In this paper, I investigate the possibility of interpreting the observed discrepancy between the GRB rate history and the star formation rate history using cosmic metallicity evolution. I am motivated by the observation that cosmic metallicity evolves with redshift and GRBs tend to occur in low-metallicity galaxies. First, I derive a star formation history up to redshift z = 7.4 from an updated sample of star formation rate densities. This is obtained by adding the new ultraviolet measurements of Bouwens et al. and the new ultraviolet and infrared measurements of Reddy et al. to the existing sample compiled by Hopkins & Beacom. Then, adopting a simple model for the relation between GRB production and the cosmic metallicity history as proposed by Langer & Norman, I show that the observed redshift distribution of the Swift GRBs can be reproduced with good accuracy. Although the results are limited by the small size of the GRB sample and the poorly understood selection biases in detection and localization of GRBs and in redshift determination, they suggest that GRBs trace both star formation and metallicity evolution. If the star formation history can be accurately measured with other approaches, which is presumably achievable in the near future, it will be possible to determine the cosmic metallicity evolution using the study of the redshift distribution of GRBs.

Contribution of GRB Emission to the GeV Extragalactic Diffuse Gamma‐Ray Flux

TeV gamma rays emitted by gamma-ray bursts (GRBs) are converted into electron-positron pairs via interactions with the extragalactic infrared radiation fields. In turn, the pairs produced, whose trajectories are randomized by magnetic fields, will inverse Compton scatter off the cosmic microwave background photons. The beamed TeV gamma-ray flux from GRBs is thus transformed into a GeV isotropic gamma-ray flux, which contributes to the total extragalactic gamma-ray background emission. Assuming a model for the extragalactic radiation fields, the GRB redshift distribution, and the GRB luminosity function, we evaluate the contribution of the GRB prompt and scattered emissions to the measured extragalactic gamma-ray flux. To estimate this contribution we optimistically require that the energy flux at TeV energies is about 10 times stronger than the energy flux at MeV energies. The resulting gamma-ray diffuse background is only a small fraction of what is observed, allowing blazars and other sources to give the dominant contribution.

Observations of GRBs at high redshift

The extreme luminosity of gamma-ray bursts and their afterglows means they are detectable, in principle, to very high redshifts. Although the redshift distribution of gamma-ray bursts (GRBs) is difficult to determine, due to incompleteness of present samples, we argue that for Swift-detected bursts, the median redshift is between 2.5 and 3, with a few per cent probably at z>6. Thus, GRBs are potentially powerful probes of the era of reionization and the sources responsible for it. Moreover, it seems probable that they can provide constraints on the star-formation history of the Universe and may also help in the determination of the cosmological parameters.

Redshift distribution of gamma-ray bursts and star formation rate

Aims. The redshift distribution of gamma-ray bursts collected in the BATSE Catalog is compared with the star formation rate.We aim to clarify the accordance between them. We also study the case of comoving number density of bursts monotonously increasing up to redshift \simeq �(6−20). Methods. A method independent of the models of the gamma-ray bursts is used. The short and the long subgroups are studied separately. Results. The redshift distribution of the long bursts may be proportional to the star formation rate. For the short bursts this can also happen, but the proportionality is less evident. For the long bursts the monotonously increasing scenario is also less probable but still can occur. For the short bursts this alternative seems to be excluded.

Calibration of gamma-ray burst luminosity indicators

Abstract Several gamma-ray burst (GRB) luminosity indicators have been proposed which can be generally written in the form of , where c is the coefficient, xi is the ith observable, and ai is its corresponding power-law index. Unlike in Type Ia supernovae, calibration of GRB luminosity indicators using a low-redshift sample is difficult. This is because the GRB rate drops rapidly at low redshifts, and some nearby GRBs may be different from their cosmological brethren. Calibrating the standard candles using GRBs in a narrow redshift range (Δz) near a fiducial redshift has been proposed recently. Here we elaborate such a possibility and propose to calibrate {ai} based on the Bayesian theory and to marginalize the c value over a reasonable range of cosmological parameters. We take our newly discovered multivariable GRB luminosity indicator, Eiso = cEa1pta2b, as an example and test the validity of this approach through simulations, where Eiso is the isotropic energy of prompt gamma-rays, Ep is the spectral break energy, and tb is the temporal break time of the optical afterglow light curve. We show that while c strongly depends on the cosmological parameters, neither a1 nor a2 does as long as Δz is small enough. The selection of Δz for a particular GRB sample could be judged according to the size and the observational uncertainty of the sample. There is no preferable redshift to perform the calibration of the indices {ai}, while a lower redshift is preferable for c-marginalization. The best strategy would be to collect GRBs within a narrow redshift bin around a fiducial intermediate redshift (e.g. zc ∼ 1 or zc ∼ 2), as the observed GRB redshift distribution is found to peak around this range. Our simulation suggests that with the current observational precisions of measuring Eiso, Ep and tb, 25 GRBs within a redshift bin of Δz ∼ 0.30 would give fine calibration to the Liang–Zhang luminosity indicator.

High‐Redshift Gamma‐Ray Bursts from Population III Progenitors

Detection of gamma-ray bursts (GRBs) from redshifts z k7 would open a new window into the earliest epoch of cosmicstarformation.Weconstructseparatestarformationhistoriesathighredshiftsfornormal(PopulationIandII) stars and for predominantly massive (Population III) stars. Based on these separate histories, we predict the GRB redshift distribution to be observed by the Swift mission. Regardless of whether Population III progenitors are able to trigger GRBs, we find that a fraction, � 10%, of all bursts detected by Swift will originate at z k 5. This baseline contribution is due to Population I/II star formation, which must have extended out to high redshifts in rare massive galaxies that were enriched by heavy elements earlier than the typical galaxies. In addition, we consider the possible contribution of Population III progenitors to the observable GRB rate. Population III stars are viable progenitors for long-duration GRBs that are triggered by the collapsar mechanism, as long as they can lose their outer envelope through mass transfer to a companion star in a close binary. We find that the likelihood of Population III binaries to satisfy the conditions required by the collapsar mechanism could be enhanced significantly relative to Population I/II binaries. If PopulationIII binariesare common,Swiftwillbethefirst observatory to probe Population III starformation at redshifts z k 7. Subject headings: binaries: general — cosmology: theory — gamma rays: bursts — stars: formation

The redshift distribution of gamma-ray bursts revisited

Abstract In this Letter, we calculate the redshift distribution of gamma-ray bursts assuming that they trace (i) the globally averaged star formation rate or (ii) the average metallicity in the Universe. While at redshifts 5 and below both the star formation rate and the metallicity are observationally determined modulo some uncertainties, at higher redshifts there are few constraints. We extrapolate the star formation rate and metallicity to higher redshifts and explore models that are broadly consistent with bounds on the optical depth from WMAP results. In addition, we also include parametric descriptions of the luminosity function, and the typical spectrum for gamma-ray bursts (GRBs). With these essential ingredients included in the modelling, we find that a substantial fraction (75 per cent) of GRBs are expected to originate at redshifts below 4, in variance with some previous estimates. Conversely, if we assume as expected for the collapsar model that gamma-ray bursts favour a low-metallicity environment, and therefore relate the GRB rate to a simple model of the average metallicity as a function of redshift, we find that a higher fraction of bursts, about 40 per cent, originate from z &amp;gt; 4. We conclude with the implications of Swift GRB detections.