scholarly journals Gamma-ray Bursts Progress and Problems

2016 ◽  
Vol 12 (S324) ◽  
pp. 49-53
Author(s):  
N. R. Tanvir
Keyword(s):  
Galaxy Evolution ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Compact Binary ◽  
Distant Galaxies ◽  
Long Duration ◽  
Massive Neutron Star ◽  
Binary Mergers ◽  
The Impact ◽  
The Universe

AbstractOur understanding of gamma-ray bursts (GRBs) has come a long way in the past fifty years since their first detection. We now know that GRBs arise in distant galaxies and that there are at least two distinct sub-classes, the long-duration class being produced by some rare massive star core collapse and the short-duration class likely by compact binary mergers involved neutron stars. In both cases, the final remnant will be a stellar-mass black-hole or a massive neutron star. The bursts themselves are associated with ultra-relativistic jetted outflows created by these events, and their afterglows by the impact of these outflows on the surrounding circumburst material. Increasingly GRBs are also being used as probes of the universe, both for understanding galaxy evolution back to the era of reionization, and for the physics of gravitational wave sources. However, many aspects of GRBs remain poorly understood, some pointers to which are given here.

scholarly journals The Swift satellite lives up to its name, revealing cosmic explosions as they happen

2008 ◽  
Vol 366 (1884) ◽  
pp. 4393-4404 ◽  
Author(s):  
Rhaana L.C Starling
Keyword(s):  
Gamma Radiation ◽  
Gamma Ray ◽  
Massive Stars ◽  
Gamma Ray Bursts ◽  
Electromagnetic Spectrum ◽  
Distant Galaxies ◽  
The 1960S ◽  
Cosmic Explosions ◽  
The Universe

Gamma-ray bursts are the most powerful objects in the Universe. Discovered in the 1960s as brief flashes of gamma radiation, we now know that they emit across the entire electromagnetic spectrum, are located in distant galaxies and comprise two distinct populations, one of which may originate in the deaths of massive stars. The launch of the Swift satellite in 2004 brought a flurry of new discoveries, advancing our understanding of these sources and the galaxies that host them. I highlight a number of important results from the Swift era thus far.

scholarly journals Precessing magnetars as central engines in short gamma-ray bursts

2021 ◽  
Vol 502 (2) ◽  
pp. 2482-2494
Author(s):  
A G Suvorov ◽  
K D Kokkotas
Keyword(s):  
Gamma Ray ◽  
Magnetic Energy ◽  
Information Criterion ◽  
Gamma Ray Bursts ◽  
Internal Stresses ◽  
X Ray ◽  
Compact Binary ◽  
Long Duration ◽  
Hydrodynamic Evolution ◽  
Data Points

ABSTRACT Short gamma-ray bursts that are followed by long-duration X-ray plateaus may be powered by the birth, and hydrodynamic evolution, of magnetars from compact binary coalescence events. If the rotation and magnetic axes of the system are not orthogonal to each other, the star will undergo free precession, leading to fluctuations in the luminosity of the source. In some cases, precession-induced modulations in the spin-down power may be discernible in the X-ray flux of the plateau. In this work, 25 X-ray light curves associated with bursts exhibiting a plateau are fitted to luminosity profiles appropriate for precessing, oblique rotators. Based on the Akaike Information Criterion, 16 $(64{{\ \rm per\ cent}})$ of the magnetars within the sample display either moderate or strong evidence for precession. Additionally, since the precession period of the star is directly tied to its quadrupolar ellipticity, the fits allow for an independent measure of the extent to which the star is deformed by internal stresses. Assuming these deformations arise due to a mixed poloidal–toroidal magnetic field, we find that the distribution of magnetic-energy ratios is bimodal, with data points clustering around energetically equal and toroidally dominated partitions. Implications of this result for gravitational-wave emission and dynamo activity in newborn magnetars are discussed.

scholarly journals Gamma-ray bursts associating with gravitational waves from compact binary mergers

2020 ◽  
Vol 50 (12) ◽  
pp. 129502
Author(s):  
TAN Wei-Wei ◽  
YU Yun-Wei ◽  
DAI Zi-Gao ◽  
LI Yong-Sen
Keyword(s):  
Gravitational Waves ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Compact Binary ◽  
Binary Mergers

Binary progenitor models for long-duration gamma-ray bursts

2007 ◽  
Vol 365 (1854) ◽  
pp. 1163-1169 ◽  
Author(s):  
Philipp Podsiadlowski
Keyword(s):  
Gamma Ray ◽  
Rare Events ◽  
Gamma Ray Bursts ◽  
Constant Density ◽  
New Model ◽  
Common Envelope ◽  
Long Duration ◽  
Binary Mergers

While it is well established that long-duration gamma-ray bursts (LGRBs) are intrinsically rare events, requiring a special evolutionary channel, the nature of the most important channels still has to be established. Here, we review some of the main binary models that have been proposed, specifically tidal spin-up models and binary mergers of various types, and then present a new model involving the recently discovered mechanism of explosive common-envelope ejection. The latter model naturally explains why LGRB-related supernovae have not observed helium and may also explain a constant-density medium around LGRBs, as has been deduced in some cases. LGRB rates as well as their metallicity dependence is also discussed for the various models.

scholarly journals The Life and Death of Massive Stars in the Starburst Galaxy I Zw 18

2015 ◽  
Vol 11 (A29B) ◽  
pp. 215-216
Author(s):  
Dorottya Szécsi ◽  
Norbert Langer
Keyword(s):  
Stellar Evolution ◽  
Gamma Ray ◽  
Massive Stars ◽  
Gamma Ray Bursts ◽  
Starburst Galaxy ◽  
Life And Death ◽  
Long Duration ◽  
Low Metallicity ◽  
The Universe ◽  
Evolution Proceeds

AbstractMassive stars at low metallicity are strong candidates for two of the most energetic explosions in the Universe: long duration gamma-ray bursts and superluminous supernovae. But what is the reason these explosions prefer low metallicity environments? To answer this question, we investigate how massive stellar evolution proceeds in low metallicity environments.

Short gamma-ray bursts near and far

2007 ◽  
Vol 365 (1854) ◽  
pp. 1315-1321 ◽  
Author(s):  
Andrew J Levan
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Compact Binary ◽  
Binary Mergers ◽  
Short Grbs

Progress in understanding the nature of short gamma-ray bursts (GRBs) has been rapid since the discovery of the first afterglows in mid-2005. The emerging picture appears to be of short GRBs, which originate at moderate redshift (a few tenths) and appear in galaxies of all ages. This discovery has been used to argue for their origin in compact binary mergers. However, this population does not describe all short bursts. Here, I will present results of observations of several short GRBs, which challenge the conclusions drawn from the early observations. The observations show that some short GRBs originate in the very low redshift Universe (below 100 Mpc), while some may also lie at redshifts comparable with the long GRBs (i.e. z >2). I will discuss the properties of these bursts and the implications they have for the progenitors of short GRBs.

scholarly journals SOFT X-RAY EXTENDED EMISSIONS OF SHORT GAMMA-RAY BURSTS AS ELECTROMAGNETIC COUNTERPARTS OF COMPACT BINARY MERGERS: POSSIBLE ORIGIN AND DETECTABILITY

2014 ◽  
Vol 796 (1) ◽  
pp. 13 ◽  
Author(s):  
Takashi Nakamura ◽  
Kazumi Kashiyama ◽  
Daisuke Nakauchi ◽  
Yudai Suwa ◽  
Takanori Sakamoto ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
X Ray ◽  
Compact Binary ◽  
Binary Mergers
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