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The StarBurst Multimessenger Pioneer is a highly sensitive wide-field gamma-ray monitor designed to detect the prompt emission of short gamma-ray bursts, a key electromagnetic signature of neutron star mergers. StarBurst is designed to enhance the new era of multimessenger astronomy by using the advancements in gamma-ray detectors made over the past decade, namely in silicon photomultipliers (SiPMs) for light readout. With >400% the effective area of the Fermi Gamma-ray Burst Monitor and full coverage of the unocculted sky, the StarBurst observations of electromagnetic counterparts to neutron star mergers make it a key partner to the gravitational wave network in discovering these mergers at a fraction of the cost of currently operating gamma-ray missions. The StarBurst Sensor Head consists of 12 thallium-doped cesium iodide (CsI:Tl) scintillation detectors, each of which uses a custom array of low-mass, low-voltage SiPMs to cover an energy range 50 keV–2000 keV. The manuscript outlines the science of StarBurst; the predecessor technology demonstrator instrument, Glowbug; instrument design including mechanical, electrical, and data acquisition; and, the performance results from a crystal detector unit. [ABSTRACT FROM AUTHOR]

We examine the effects of time dilation on the temporal profiles of gamma-ray burst (GRB) pulses. By using prescriptions for the shape and evolution of prompt gamma-ray spectra, we can generate a simulated population of single-pulsed GRBs at a variety of redshifts and observe how their light curves would appear to a gamma-ray detector here on Earth.We find that the observer frame duration of individual pulses does not increase with redshift as 1 + z, which one would expect from cosmological expansion. This time dilation is masked by an opposite and often stronger effect: with increasing redshift and decreasing signal-to-noise ratio only the brightest portion of the light curve can be detected. The results of our simulation are consistent with the fact that the simple time dilation of GRB light curves has not materialized in either the Swift or Fermi detected GRBs with known redshift.We show that the measured durations and associated Eiso estimates for GRBs detected near the instrument's detection threshold should be considered lower limits to the true values. Furthermore, we conclude that attempts at distinguishing between long and short GRBs, at even moderate redshifts, cannot be done based on a burst's temporal properties alone. [ABSTRACT FROM AUTHOR]

I investigate the origin of the observed correlation between a gamma-ray burst's (GRB's) vFv spectral peak Epk and its isotropic equivalent energy Eiso through the use of a population synthesis code to model the prompt gamma-ray emission from GRBs. By using prescriptions for the distribution of prompt spectral parameters as well as the population's luminosity function and comoving rate density, I generate a simulated population of GRBs and examine how bursts of varying spectral properties and redshift would appear to a gamma-ray detector here on Earth. I find that a strong observed correlation can be produced between the source frame Epk and Eiso for the detected population despite the existence of only a weak and broad correlation in the original simulated population. The energy dependance of a gamma-ray detector's flux-limited detection threshold acts to produce a correlation between the source frame Epk and Eiso for low-luminosity GRBs, producing the left boundary of the observed correlation. Conversely, very luminous GRBs are found at higher redshifts than their low-luminosity counterparts due to the standard Malquest bias, causing bursts in the low Epk, high Eiso regime to go undetected because their Epk values would be redshifted to energies at which most gamma-ray detectors become less sensitive. I argue that it is this previously unexamined effect which produces the right boundary of the observed correlation. Therefore, the origin of the observed correlation is a complex combination of the instrument's detection threshold, the intrinsic cutoff in the GRB luminosity function, and the broad range of redshifts over which GRBs are detected. Although the GRB model presented here is a very simplified representation of the complex nature of GRBs, these simulations serve to demonstrate how selection effects caused by a combination of instrumental sensitivity and the cosmological nature of an astrophysical population can act to produce an artificially strong correlation between observed properties. [ABSTRACT FROM AUTHOR]

We present results of an extensive observing campaign of the short-duration, hard spectrum gamma-ray burst (GRB) 070724A, aimed at detecting the radioactively powered emission that might follow from a binary merger or collapse involving compact objects. Our multiband observations span the range in time over which this so-called Li–Paczyński mini-supernova (mini-SN) could be active, beginning within 3 h of the GRB trigger and represent some of the deepest and most comprehensive searches for such emission. We find no evidence for such activity and place limits on the abundances and the lifetimes of the possible radioactive nuclides that could form in the rapid decompression of nuclear density matter. Furthermore, our limits are significantly fainter than the peak magnitude of any previously detected broad-lined Type Ic SN associated with other GRBs, effectively ruling out a long GRB-like SN for this event. Given the unambiguous redshift of the host galaxy , GRB 070724A represents one of a small, but growing, number of short-hard GRBs for which firm physical/rest-frame quantities currently exist. The host of GRB 070724A is a moderately star-forming galaxy with an older stellar population component and a relatively high metallicity of . We find no significant evidence for large amounts of extinction along the line of sight that could mask the presence of an SN explosion and estimate a small probability for chance alignment with the putative host. We discuss how our derived constraints fit into the evolving picture of short-hard GRBs, their potential progenitors and the host environments in which they are thought to be produced. [ABSTRACT FROM AUTHOR]

Since their first discovery in the late 1960s, gamma-ray bursts have attracted an exponentially growing interest from the international community due to their central role in the most highly debated open questions of the modern research of astronomy, astrophysics, cosmology, and fundamental physics. These range from the intimate nuclear composition of high-density material within the core of ultra-dense neuron stars, to stellar evolution via the collapse of massive stars, the production and propagation of gravitational waves, as well as the exploration of the early universe by unveiling the first stars and galaxies (assessing also their evolution and cosmic re-ionization). GRBs in the past ∼50 years have stimulated the development of cutting-edge technological instruments for observations of high-energy celestial sources from space, leading to the launch and successful operations of many different scientific missions (several of them still in data-taking mode currently). In this review, we provide a brief description of the GRB-dedicated missions from space being designed and developed for the future. The list of these projects, not meant to be exhaustive, shall serve as a reference to interested readers to understand what is likely to come next to lead the further development of GRB research and the associated phenomenology. [ABSTRACT FROM AUTHOR]

We present multiwavelength modeling of the afterglow from the long γ-ray burst (GRB) 160625B using Markov Chain Monte Carlo techniques of the afterglowpy Python package. GRB 160625B is an extremely bright burst with a rich set of observations spanning from radio to γ-ray frequencies. These observations range from ∼0.1 days to >1000 days, thus making this event extremely well suited to such modeling. In this work we compare top-hat and Gaussian jet structure types in order to find best-fit values for the GRB jet collimation angle, viewing angle, and other physical parameters. We find that a Gaussian-shaped jet is preferred (2.7σ–5.3σ) over the traditional top-hat model. Our estimate for the opening angle of the burst ranges from 1.°26 to 3.°90, depending on jet-shape model. We also discuss the implications that assumptions on jet shape, viewing angle, and particularly the participation a fraction of electrons have on the final estimation of GRB intrinsic energy release and the resulting energy budget of the relativistic outflow. Most notably, allowing the participation fraction to vary results in an estimated total relativistic energy of ∼1053 erg. This is two orders of magnitude higher than when the total fraction is assumed to be unity; thus, this parameter has strong relevance for placing constraints on long GRB central engines, details of the circumburst media, and host environment. [ABSTRACT FROM AUTHOR]

Spectra of broad-lined Type Ic supernovae (SNe Ic-BL), the only kind of SN observed at the locations of long-duration gamma-ray bursts (LGRBs), exhibit wide features indicative of high ejecta velocities (∼0.1c). We study the host galaxies of a sample of 245 low-redshift (z < 0.2) core-collapse SNe, including 17 SNe Ic-BL, discovered by galaxy-untargeted searches, and 15 optically luminous and dust-obscured z < 1.2 LGRBs. We show that, in comparison with Sloan Digital Sky Survey galaxies having similar stellar masses, the hosts of low-redshift SNe Ic-BL and z < 1.2 LGRBs have high stellar mass and star formation rate densities. Core-collapse SNe having typical ejecta velocities, in contrast, show no preference for such galaxies. Moreover, we find that the hosts of SNe Ic-BL, unlike those of SNe Ib/Ic and SNe II, exhibit high gas velocity dispersions for their stellar masses. The patterns likely reflect variations among star-forming environments and suggest that LGRBs can be used as probes of conditions in high-redshift galaxies. They may be caused by efficient formation of massive binary progenitor systems in densely star-forming regions, or, less probably, a higher fraction of stars created with the initial masses required for an SN Ic-BL or LGRB. Finally, we show that the preference of SNe Ic-BL and LGRBs for galaxies with high stellar mass and star formation rate densities cannot be attributed to a preference for low metal abundances but must reflect the influence of a separate environmental factor. [ABSTRACT FROM AUTHOR]