Abstract
GW170817–GRB 170817A provided the first observation of gravitational waves from a neutron star merger with associated transient counterparts across the entire electromagnetic spectrum. This ...discovery demonstrated the long-hypothesized association between short gamma-ray bursts and neutron star mergers. More joint detections are needed to explore the relation between the parameters inferred from the gravitational wave and the properties of the gamma-ray burst signal. We developed a joint multimessenger analysis of LIGO, Virgo, and Fermi/GBM data designed for detecting weak gravitational-wave transients associated with weak gamma-ray bursts. As such, it does not start from confident (GWTC-1) events only. Instead, we take the full list of existing compact binary coalescence triggers generated with the PyCBC pipeline from the second Gravitational-Wave Observing Run (O2), and reanalyze the entire set of public Fermi/GBM data covering this observing run to generate a corresponding set of gamma-ray burst candidate triggers. We then search for coincidences between the gravitational-wave and gamma-ray burst triggers without requiring a confident detection in any channel. The candidate coincidences are ranked according to a statistic combining each candidate’s strength in gravitational-wave and gamma-ray data, their time proximity, and the overlap of their sky localization. The ranking is then converted to a false alarm rate using time shifts between the gravitational-wave and gamma-ray burst triggers. We present the results using O2 triggers, which allowed us to check the validity of our method against GW170817–GRB 170817A. We also discuss the different configurations tested to maximize the significance of the joint detection.
GRB 221009A: The BOAT Burns, Eric; Svinkin, Dmitry; Fenimore, Edward ...
Astrophysical journal. Letters,
03/2023, Volume:
946, Issue:
1
Journal Article
Peer reviewed
Open access
Abstract GRB 221009A has been referred to as the brightest of all time (BOAT). We investigate the veracity of this statement by comparing it with a half century of prompt gamma-ray burst ...observations. This burst is the brightest ever detected by the measures of peak flux and fluence. Unexpectedly, GRB 221009A has the highest isotropic-equivalent total energy ever identified, while the peak luminosity is at the ∼99th percentile of the known distribution. We explore how such a burst can be powered and discuss potential implications for ultralong and high-redshift gamma-ray bursts. By geometric extrapolation of the total fluence and peak flux distributions, GRB 221009A appears to be a once-in-10,000-year event. Thus, it is almost certainly not the BOAT over all of cosmic history; it may be the brightest gamma-ray burst since human civilization began.
Gamma-ray bursts (GRBs) are ultra-relativistic jets produced by either the core-collapse of massive, stripped envelope stars (i.e., "collapsars") or the merging of compact binary objects, such as ...neutron stars. GRBs are among the most energetic transients in the Universe, yet despite over 5 decades of study, a full description of their intrinsic energetics remains incomplete. This is primarily due to a combination of cosmological, relativistic, and observational effects that have impeded obtaining GRB redshift measurements and robustly associating GRBs with their progenitors. In this dissertation, I study source-frame properties of GRBs from collapsars and binary neutron star (BNS) mergers. In particular, I constrain the luminosity functions and rate distributions of GRBs by applying a forward-folding method to fit data taken by the Fermi Gamma-ray Burst Monitor (GBM). The data are found to be best-fit with a GRB population composed of ~45% originating from BNS mergers. The collapsar GRBs are fit to the cosmic star formation rate, normalized to a local rate of 3.9 (+9.9, –3.3; 90% confidence) Gpc–3 yr–1 and a broken power law luminosity function with indices αL = –1.5 (+1.1, –0.2) and βL = –2.0 (+0.5, –1.7) and a break at log10L = 52.8 (+1.9, –3.2) ergs s–1. The merger GRBs are described by a delayed star formation rate (P(td) ∝ td–1) with a local event rate of 3.2 (+27.0, –2.4) Gpc–3 yr–1 and a cut-off power law luminosity function with index αL = –0.5 (+0.4, –0.5) and a break at log10L = 51.6 (+0.7, –0.7) ergs s–1. I also search for short GRB progenitors associated with GWs detected in the LIGO/Virgo first and second observing runs (i.e., O1 and O2, respectively). Although no GW/GRB coincidences are found other than GW170817/GRB 170817A, the GBM detection algorithm is improved for weak short GRBs and the joint search statistic method.
Development of the sensor head for the StarBurst multimessenger pioneer Woolf, Richard S.; Kocevski, Daniel; Grove, J. Eric ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
July 2024, 2024-07-00, Volume:
1064
Journal Article
Peer reviewed
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.
The Zwicky Transient Facility recently announced the detection of an optical transient AT2020blt at redshift \(z=2.9\), consistent with the afterglow of a gamma-ray burst. No prompt emission was ...observed. We analyse AT2020blt with detailed models, showing the data are best explained as the afterglow of an on-axis long gamma-ray burst, ruling out other hypotheses such as a cocoon and a low-Lorentz factor jet. We search \textit{Fermi} data for prompt emission, setting deeper upper limits on the prompt emission than in the original detection paper. Together with \konus{} observations, we show that the gamma-ray efficiency of AT2020blt is \(\lesssim 2.8\%\), lower than \(98.4\%\) of observed gamma-ray bursts. We speculate that AT2020blt and AT2021any belong to the low-efficiency tail of long gamma-ray burst distributions that are beginning to be readily observed due to the capabilities of new observatories like the Zwicky Transient Facility.
GRB 221009A, The BOAT Burns, Eric; Svinkin, Dmitry; Fenimore, Edward ...
arXiv.org,
03/2024
Paper, Journal Article
Open access
GRB 221009A has been referred to as the Brightest Of All Time (the BOAT). We investigate the veracity of this statement by comparing it with a half century of prompt gamma-ray burst observations. ...This burst is the brightest ever detected by the measures of peak flux and fluence. Unexpectedly, GRB 221009A has the highest isotropic-equivalent total energy ever identified, while the peak luminosity is at the \(\sim99\)th percentile of the known distribution. We explore how such a burst can be powered and discuss potential implications for ultra-long and high-redshift gamma-ray bursts. By geometric extrapolation of the total fluence and peak flux distributions GRB 221009A appears to be a once in 10,000 year event. Thus, while it almost certainly not the BOAT over all of cosmic history, it may be the brightest gamma-ray burst since human civilization began.
Classical gamma-ray bursts (GRBs) have two distinct emission episodes: prompt emission from ultra-relativistic ejecta and afterglow from shocked circumstellar material. While both components are ...extremely luminous in known GRBs, a variety of scenarios predict the existence of luminous afterglow emission with little or no associated high-energy prompt emission. We present AT 2019pim, the first secure example of this phenomenon to be identified. Serendipitously discovered during follow-up observations of a gravitational-wave trigger and located in a contemporaneous TESS sector, it is hallmarked by a fast-rising (t ~ 2 hr), luminous (M_UV,peak ~ -24.4 mag) optical transient with accompanying luminous X-ray and radio emission. No gamma-ray emission consistent with the time and location of the transient was detected by Fermi-GBM or by Konus, placing strong limits on an accompanying GRB. We investigate several independent observational aspects of the afterglow in the context of constraints on relativistic motion and find all of them are consistent with an initial Lorentz factor of Gamma_0 ~ 30-50, significantly lower than in any well-observed GRB and consistent with the theoretically-predicted "dirty fireball" scenario in which the high-energy prompt emission is stifled by pair production. However, we cannot rule out a structured jet model in which only the line-of-sight material was ejected at low-Gamma, off-axis from a classical high-Gamma jet core. This event represents a milestone in orphan afterglow searches, demonstrating that luminous afterglows with weak or no detectable gamma-ray radiation exist in nature and can be discovered by high-cadence optical surveys.
The Interplanetary Network (IPN) is a detection, localization and alert system that utilizes the arrival time of transient signals in gamma-ray detectors on spacecraft separated by planetary ...baselines to geometrically locate the origin of these transients. Due to the changing astrophysical landscape and the new emphasis on time domain and multi-messenger astrophysics (TDAMM) from the Pathways to Discovery in Astronomy and Astrophysics for the 2020s, this Gamma-ray Transient Network Science Analysis Group was tasked to understand the role of the IPN and high-energy monitors in this new era. The charge includes describing the science made possible with these facilities, tracing the corresponding requirements and capabilities, and highlighting where improved operations of existing instruments and the IPN would enhance TDAMM science. While this study considers the full multiwavelength and multimessenger context, the findings are specific to space-based high-energy monitors. These facilities are important both for full characterization of these transients as well as facilitating follow-up observations through discovery and localization. The full document reports a brief history of this field, followed by our detailed analyses and findings in some 68 pages, providing a holistic overview of the role of the IPN and high-energy monitors in the coming decades.
The Fermi Gamma-ray Burst Monitor (GBM) triggers on-board in response to \(\sim\) 40 short gamma-ray bursts (SGRBs) per year; however, their large localization regions have made the search for ...optical counterparts a challenging endeavour. We have developed and executed an extensive program with the wide field of view of the Zwicky Transient Facility (ZTF) camera, mounted on the Palomar 48 inch Oschin telescope (P48), to perform target-of-opportunity (ToO) observations on 10 Fermi-GBM SGRBs during 2018 and 2020-2021. Bridging the large sky areas with small field of view optical telescopes in order to track the evolution of potential candidates, we look for the elusive SGRB afterglows and kilonovae (KNe) associated with these high-energy events. No counterpart has yet been found, even though more than 10 ground based telescopes, part of the Global Relay of Observatories Watching Transients Happen (GROWTH) network, have taken part in these efforts. The candidate selection procedure and the follow-up strategy have shown that ZTF is an efficient instrument for searching for poorly localized SGRBs, retrieving a reasonable number of candidates to follow-up and showing promising capabilities as the community approaches the multi-messenger era. Based on the median limiting magnitude of ZTF, our searches would have been able to retrieve a GW170817-like event up to \(\sim\) 200 Mpc and SGRB afterglows to z = 0.16 or 0.4, depending on the assumed underlying energy model. Future ToOs will expand the horizon to z = 0.2 and 0.7 respectively.
Gamma-rays, the most energetic photons, carry information from the far reaches of extragalactic space with minimal interaction or loss of information. They bring messages about particle acceleration ...in environments so extreme they cannot be reproduced on earth for a closer look. Gamma-ray astrophysics is so complementary with collider work that particle physicists and astroparticle physicists are often one in the same. Gamma-ray instruments, especially the Fermi Gamma-ray Space Telescope, have been pivotal in major multi-messenger discoveries over the past decade. There is presently a great deal of interest and scientific expertise available to push forward new technologies, to plan and build space- and ground-based gamma-ray facilities, and to build multi-messenger networks with gamma rays at their core. It is therefore concerning that before the community comes together for planning exercises again, much of that infrastructure could be lost to a lack of long-term planning for support of gamma-ray astrophysics. Gamma-rays with energies from the MeV to the EeV band are therefore central to multiwavelength and multi-messenger studies to everything from astroparticle physics with compact objects, to dark matter studies with diffuse large scale structure. These goals and new discoveries have generated a wave of new gamma-ray facility proposals and programs. This paper highlights new and proposed gamma-ray technologies and facilities that have each been designed to address specific needs in the measurement of extreme astrophysical sources that probe some of the most pressing questions in fundamental physics for the next decade. The proposed instrumentation would also address the priorities laid out in the recent Astro2020 Decadal Survey, a complementary study by the astrophysics community that provides opportunities also relevant to Snowmass.
