scholarly journals Murchison Widefield Array rapid-response observations of the short GRB 180805A

2021 ◽  
Vol 38 ◽  
Author(s):  
G. E. Anderson ◽  
P. J. Hancock ◽  
A. Rowlinson ◽  
M. Sokolowski ◽  
A. Williams ◽  
...  
Keyword(s):  
Radio Emission ◽  
Gamma Ray ◽  
Response Times ◽  
Low Frequency ◽  
Rapid Response ◽  
Gamma Ray Burst ◽  
Upper Limit ◽  
Emission Models ◽  
Murchison Widefield Array ◽  
Prompt Emission

Abstract Here we present stringent low-frequency (185 MHz) limits on coherent radio emission associated with a short-duration gamma-ray burst (SGRB). Our observations of the short gamma-ray burst (GRB) 180805A were taken with the upgraded Murchison Widefield Array (MWA) rapid-response system, which triggered within 20s of receiving the transient alert from the Swift Burst Alert Telescope, corresponding to 83.7 s post-burst. The SGRB was observed for a total of 30 min, resulting in a $3\sigma$ persistent flux density upper limit of 40.2 mJy beam–1. Transient searches were conducted at the Swift position of this GRB on 0.5 s, 5 s, 30 s and 2 min timescales, resulting in $3\sigma$ limits of 570–1 830, 270–630, 200–420, and 100–200 mJy beam–1, respectively. We also performed a dedispersion search for prompt signals at the position of the SGRB with a temporal and spectral resolution of 0.5 s and 1.28 MHz, respectively, resulting in a $6\sigma$ fluence upper-limit range from 570 Jy ms at DM $=3\,000$ pc cm–3 ( $z\sim 2.5$ ) to 1 750 Jy ms at DM $=200$ pc cm–3 ( $z\sim 0.1)$ , corresponding to the known redshift range of SGRBs. We compare the fluence prompt emission limit and the persistent upper limit to SGRB coherent emission models assuming the merger resulted in a stable magnetar remnant. Our observations were not sensitive enough to detect prompt emission associated with the alignment of magnetic fields of a binary neutron star just prior to the merger, from the interaction between the relativistic jet and the interstellar medium (ISM) or persistent pulsar-like emission from the spin-down of the magnetar. However, in the case of a more powerful SGRB (a gamma-ray fluence an order of magnitude higher than GRB 180805A and/or a brighter X-ray counterpart), our MWA observations may be sensitive enough to detect coherent radio emission from the jet-ISM interaction and/or the magnetar remnant. Finally, we demonstrate that of all current low- frequency radio telescopes, only the MWA has the sensitivity and response times capable of probing prompt emission models associated with the initial SGRB merger event.

Some Recent Developments in γ-ray Burst Afterglow and Prompt Emission Models

2003 ◽  
Vol 214 ◽  
pp. 311-320
Author(s):  
Bing Zhang ◽  
Peter Mészáros ◽  
Junfeng Wang
Keyword(s):  
Gamma Ray ◽  
Current Data ◽  
Spectral Domain ◽  
Gamma Ray Burst ◽  
Temporal Domain ◽  
Global View ◽  
Recent Developments ◽  
Emission Models ◽  
Γ Ray ◽  
Prompt Emission

Extensive observational campaigns of afterglow hunting have greatly enriched our understanding of the gamma-ray burst (GRB) phenomenon. Efforts have been made recently to explore some afterglow properties or signatures that will be tested by the on-going or the future observational campaigns yet come. These include the properties of GRB early afterglows in the temporal domain; the GeV-TeV afterglow signatures in the spectral domain; as well as a global view about the GRB universal structured jet configuration. These recent efforts are reviewed. Within the standard cosmological fireball model, the very model(s) responsible for the GRB prompt emission is (are) not identified. These models are critically reviewed and confronted with the current data.

scholarly journals The radio/gamma-ray connection from 120 MHz to 230 GHz

2016 ◽  
Author(s):  
Marcello Giroletti ◽  
Filippo D'Ammando ◽  
Monica Orienti ◽  
Rocco Lico
Keyword(s):  
Radio Emission ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Low Frequency ◽  
High Energy ◽  
Physical Parameters ◽  
Radiation Emission ◽  
Spatial Features ◽  
Murchison Widefield Array ◽  
Radio Band

Radio loud active galactic nuclei are composed of different spatial features, each one characterized by different spectral properties in the radio band. Among them, blazars are the most common class of sources detected at gamma-rays by \fermi, and their radio emission is dominated by the flat spectrum compact core. In this contribution, we explore the connection between emission at high energy revealed by \fermi\ and at radio frequency. Taking as a reference the strong and very highly significant correlation found between gamma rays and cm-$\lambda$ radio emission, we explore different behaviours found as we change the energy range in gamma rays and in radio, therefore changing the physical parameters of the zones involved in the radiation emission. We find that the correlation weakens when we consider (1) gamma rays of energy above 10 GeV (except for high synchrotron peaked blazars) or (2) low frequency radio data taken by the Murchison Widefield Array; on the other hand, the correlation strengthens when we consider mm-$\lambda$ data taken by ALMA.

scholarly journals Constraining coherent low-frequency radio flares from compact binary mergers

2019 ◽  
Vol 489 (3) ◽  
pp. 3316-3333 ◽  
Author(s):  
A Rowlinson ◽  
G E Anderson
Keyword(s):  
Neutron Star ◽  
Radio Emission ◽  
Gamma Ray ◽  
Low Frequency ◽  
Binary Neutron Star ◽  
Compact Binary ◽  
Binary Mergers ◽  
Wave Emission ◽  
Murchison Widefield Array ◽  
Response Modes

ABSTRACT The presence and detectability of coherent radio emission from compact binary mergers (containing at least one neutron star) remains poorly constrained due to large uncertainties in the models. These compact binary mergers may initially be detected as short gamma-ray bursts or via their gravitational wave emission. Several radio facilities have developed rapid response modes enabling them to trigger on these events and search for this emission. For this paper, we constrain this coherent radio emission using the deepest available constraints for GRB 150424A, which were obtained via a triggered observation with the Murchison Widefield Array. We then expand this analysis to determine the properties of magnetar merger remnants that may be formed via a general population of binary neutron star mergers. Our results demonstrate that many of the potential coherent emission mechanisms that have been proposed for such events can be detected or very tightly constrained by the complementary strategies used by the current generation of low-frequency radio telescopes.

scholarly journals LOFAR detectability of prompt low-frequency radio emission during gamma-ray burst X-ray flares

2020 ◽  
Vol 494 (4) ◽  
pp. 5787-5792
Author(s):  
R L C Starling ◽  
A Rowlinson ◽  
A J van der Horst ◽  
R A M J Wijers
Keyword(s):  
Radio Emission ◽  
Gamma Ray ◽  
Low Frequency ◽  
Light Curves ◽  
Wind Model ◽  
X Ray ◽  
Poynting Flux ◽  
Scattering Effects ◽  
Flux Model ◽  
Prompt Emission

ABSTRACT The prompt emission in long gamma-ray bursts (GRBs) arises from within relativistic outflows created during the collapse of massive stars, and the mechanism by which radiation is produced may be either magnetically or matter dominated. In this work, we suggest an observational test of a magnetically dominated Poynting flux model that predicts both γ-ray and low-frequency radio pulses. A common feature among early light curves of long GRBs are X-ray flares, which have been shown to arise from sites internal to the jet. Ascribing these events to the prompt emission, we take an established Swift XRT flare sample and apply a magnetically dominated wind model to make predictions for the timing and flux density of corresponding radio pulses in the ∼100–200 MHz band observable with radio facilities such as LOFAR. We find that 44 per cent of the X-ray flares studied would have had detectable radio emission under this model, for typical sensitivities reached using LOFAR’s rapid response mode and assuming negligible absorption and scattering effects in the interstellar and intergalactic medium. We estimate the rate of Swift GRBs displaying X-ray flares with detectable radio pulses, accessible to LOFAR, of order seven per year. We determine that LOFAR triggered observations can play a key role in establishing the long debated mechanism responsible for GRB prompt emission.

scholarly journals Strategies for Finding Prompt Radio Counterparts to Gravitational Wave Transients with the Murchison Widefield Array

2016 ◽  
Vol 33 ◽  
Author(s):  
D. L. Kaplan ◽  
T. Murphy ◽  
A. Rowlinson ◽  
S. D. Croft ◽  
R. B. Wayth ◽  
...  
Keyword(s):  
Neutron Star ◽  
Radio Emission ◽  
Gravitational Wave ◽  
Radio Signal ◽  
Low Frequency ◽  
Field Of View ◽  
Optimal Conditions ◽  
Murchison Widefield Array ◽  
Complicated Geometry ◽  
Prompt Emission

AbstractWepresent and evaluate several strategies to search for prompt, low-frequency radio emission associated with gravitational wave transients using the Murchison Widefield Array. As we are able to repoint the Murchison Widefield Array on timescales of tens of seconds, we can search for the dispersed radio signal that has been predicted to originate along with or shortly after a neutron star-neutron star merger. We find that given the large, 600 deg2 instantaneous field of view of the Murchison Widefield Array, we can cover a significant fraction of the predicted gravitational wave error region, although due to the complicated geometry of the latter, we only cover > 50% of the error region for approximately 5% of events, and roughly 15% of events will be located < 10° from the Murchison Widefield Array pointing centre such that they will be covered in the radio images. For optimal conditions, our limiting flux density for a 10-s long transient would be 0.1 Jy, increasing to about 1 Jy for a wider range of events. This corresponds to luminosity limits of 1038−39 erg s−1 based on expectations for the distances of the gravitational wave transients, which should be sufficient to detect or significantly constrain a range of models for prompt emission.

The GLEAM 4-Jy Sample: The brightest radio-sources in the southern sky

2019 ◽  
Vol 15 (S356) ◽  
pp. 375-375
Author(s):  
Sarah White
Keyword(s):  
Radio Emission ◽  
Active Galactic Nuclei ◽  
Visual Inspection ◽  
Low Frequency ◽  
Galactic Nuclei ◽  
Radio Sources ◽  
Relativistic Jets ◽  
The Galaxy ◽  
Murchison Widefield Array ◽  
Past Activity

AbstractLow-frequency radio emission allows powerful active galactic nuclei (AGN) to be selected in a way that is unaffected by dust obscuration and orientation of the jet axis. It also reveals past activity (e.g. radio lobes) that may not be evident at higher frequencies. Currently, there are too few “radio-loud” galaxies for robust studies in terms of redshift-evolution and/or environment. Hence our use of new observations from the Murchison Widefield Array (the SKA-Low precursor), over the southern sky, to construct the GLEAM 4-Jy Sample (1,860 sources at S151MHz > 4 Jy). This sample is dominated by AGN and is 10 times larger than the heavily relied-upon 3CRR sample (173 sources at S178MHz > 10 Jy) of the northern hemisphere. In order to understand how AGN influence their surroundings and the way galaxies evolve, we first need to correctly identify the galaxy hosting the radio emission. This has now been completed for the GLEAM 4-Jy Sample – through repeated visual inspection and extensive checks against the literature – forming a valuable, legacy dataset for investigating relativistic jets and their interplay with the environment.

scholarly journals Prompt emission from the counter jet of a short gamma-ray burst

2018 ◽  
Vol 2018 (3) ◽  
Author(s):  
Ryo Yamazaki ◽  
Kunihito Ioka ◽  
Takashi Nakamura
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Burst ◽  
Prompt Emission

scholarly journals GAMMA-RAY BURSTS: PROGRESS, PROBLEMS & PROSPECTS

2004 ◽  
Vol 19 (15) ◽  
pp. 2385-2472 ◽  
Author(s):  
BING ZHANG ◽  
PETER MÉSZÁROS
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Current Understanding ◽  
Shock Model ◽  
Gamma Ray Burst ◽  
Prompt Emission

The cosmological gamma-ray burst (GRB) phenomenon is reviewed. The broad observational facts and empirical phenomenological relations of the GRB prompt emission and afterglow are outlined. A well-tested, successful fireball shock model is introduced in a pedagogical manner. Several important uncertainties in the current understanding of the phenomenon are reviewed, and prospects of how future experiments and extensive observational and theoretical efforts may address these problems are discussed.

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