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 Supernovae and Gamma-ray Bursts

2011 ◽  
Vol 7 (S279) ◽  
pp. 75-82
Author(s):  
Paolo A. Mazzali
Keyword(s):  
Black Hole ◽  
Massive Star ◽  
Gamma Ray ◽  
Massive Stars ◽  
Observational Evidence ◽  
Gamma Ray Bursts ◽  
Core Collapse ◽  
Broad Absorption ◽  
X Ray ◽  
Long Duration

AbstractThe properties of the Supernovae discovered in coincidence with long-duration Gamma-ray Bursts and X-Ray Flashes are reviewed, and compared to those of SNe for which GRBs are not observed. The SNe associated with GRBs are of Type Ic, they are brighter than the norm, and show very broad absorption lines in their spectra, indicative of high expansion velocities and hence of large explosion kinetic energies. This points to a massive star origin, and to the birth of a black hole at the time of core collapse. There is strong evidence for gross asymmetries in the SN ejecta. The observational evidence seems to suggest that GRB/SNe are more massive and energetic than XRF/SNe, and come from more massive stars. While for GRB/SNe the collapsar model is favoured, XRF/SNe may host magnetars.

scholarly journals On the Relation Between GRB Classes and X-ray Flashes

10.14311/1496 ◽  
2012 ◽  
Vol 52 (1) ◽  
Author(s):  
Z. Bagoly ◽  
P. Veres ◽  
I. Horváth ◽  
A. Mészáros ◽  
L. G. Balázs
Keyword(s):  
Physical Properties ◽  
Short Duration ◽  
Classification Scheme ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
The Other ◽  
X Ray ◽  
Intermediate Group ◽  
Long Duration

Gamma-ray bursts are usually classified into either short-duration or long-duration bursts. Going beyond the short-long classification scheme, it has been shown on statistical grounds that a third, intermediate population is needed in this classification scheme. We are looking for physical properties which discriminate the intermediate duration bursts from the other two classes. As the intermediate group is the softest, we argue that we have related them with X-ray flashes among the GRBs. We give a new, probabilistic definition for this class of events.

scholarly journals Gamma-ray Bursts

2005 ◽  
Vol 192 ◽  
pp. 459-466
Author(s):  
Alberto J. Castro-Tirado
Keyword(s):  
Gamma Ray ◽  
Massive Stars ◽  
Gamma Ray Bursts ◽  
Compact Objects ◽  
X Ray ◽  
Long Duration ◽  
Multi Wavelength ◽  
New Generation ◽  
Short Grbs

SummarySince their discovery in 1967 Gamma-ray bursts (GRBs) have been puzzling to astrophysicists. With the advent of a new generation of X–ray satellites in the late 90’s, it was possible to carry out deep multi-wavelength observations of the counterparts associated with the long duration GRBs class just within a few hours of occurrence, thanks to the observation of the fading X-ray emission that follows the more energetic gamma-ray photons once the GRB event has ended. The fact that this emission (the afterglow) extends at longer wavelengths, led to the discovery of optical/IR/radio counterparts in 1997-2003, greatly improving our understanding of these sources. The classical, long duration GRBs, have been observed to originate at cosmological distances in a range of redshifts with 0.1685 ≤ z ≤ 4.50 implying energy releases of ~ 1051 ergs. The recent results on GRB 021004 and GRB 030329 confirm that the central engines that power these extraordinary events are due to be collapse of massive stars rather than the merging of compact objects as previously also suggested. Short GRBs still remain a mystery as no counterparts have been detected so far.

scholarly journals Can we quickly flag ultra-long gamma-ray bursts?

2019 ◽  
Vol 486 (2) ◽  
pp. 2471-2476 ◽  
Author(s):  
B Gendre ◽  
Q T Joyce ◽  
N B Orange ◽  
G Stratta ◽  
J L Atteia ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
Wide Field ◽  
Exact Nature ◽  
X Ray ◽  
Central Engine ◽  
Long Duration ◽  
Limited Coverage

Abstract Ultra-long gamma-ray bursts are a class of high-energy transients lasting several hours. Their exact nature is still elusive, and several models have been proposed to explain them. Because of the limited coverage of wide-field gamma-ray detectors, the study of their prompt phase with sensitive narrow-field X-ray instruments could help in understanding the origin of ultra-long GRBs. However, the observers face a true problem in rapidly activating follow-up observations, due to the challenging identification of an ultra-long GRB before the end of the prompt phase. We present here a comparison of the prompt properties available after a few tens of minutes of a sample of ultra-long GRBs and normal long GRBs, looking for prior indicators of the long duration. We find that there is no such clear prior indicator of the duration of the burst. We also found that statistically, a burst lasting at least 10 and 20 minutes has respectively $28{{\ \rm per\ cent}}$ and $50{{\ \rm per\ cent}}$ probability to be an ultralong event. These findings point towards a common central engine for normal long and ultra-long GRBs, with the collapsar model privileged.

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 Quark-Nova Explosion inside a Collapsar: Application to Gamma Ray Bursts

2009 ◽  
Vol 2009 ◽  
pp. 1-10 ◽  
Author(s):  
Rachid Ouyed ◽  
Denis Leahy ◽  
Jan Staff ◽  
Brian Niebergal
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Prompt Gamma ◽  
Stellar Envelope ◽  
X Ray ◽  
Star Forming ◽  
Star Forming Regions ◽  
Long Duration ◽  
Model Features ◽  
Prompt Emission

If a quark-nova occurs inside a collapsar, the interaction between the quark-nova ejecta (relativistic iron-rich chunks) and the collapsar envelope leads to features indicative of those observed in Gamma Ray Bursts. The quark-nova ejecta collides with the stellar envelope creating an outward moving cap (Γ∼1–10) above the polar funnel. Prompt gamma-ray burst emission from internal shocks in relativistic jets (following accretion onto the quark star) becomes visible after the cap becomes optically thin. Model features include (i) precursor activity (optical, X-ray,γ-ray), (ii) promptγ-ray emission, and (iii) afterglow emission. We discuss SN-less long duration GRBs, short hard GRBs (including association and nonassociation with star forming regions), dark GRBs, the energetic X-ray flares detected in Swift GRBs, and the near-simultaneous optical andγ-ray prompt emission observed in GRBs in the context of our model.

scholarly journals Broad-line type Ic SN 2020bvc

2020 ◽  
Vol 639 ◽  
pp. L11 ◽  
Author(s):  
L. Izzo ◽  
K. Auchettl ◽  
J. Hjorth ◽  
F. De Colle ◽  
C. Gall ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Optical Spectra ◽  
Gamma Ray Bursts ◽  
Archival Data ◽  
Broad Line ◽  
X Ray ◽  
Long Duration ◽  
Gamma Ray Emission ◽  
Very High ◽  
Line Type

Long-duration gamma-ray bursts (GRBs) are almost unequivocally associated with very energetic, broad-line supernovae of Type Ic-BL. While the gamma-ray emission is emitted in narrow jets, the SN emits radiation isotropically. Therefore, it has been hypothesized that some SN Ic-BL not associated with GRBs arise from events with inner engines such as off-axis GRBs or choked jets. Here we present observations of the nearby (d = 120 Mpc) SN 2020bvc (ASAS-SN 20bs) that support this scenario. Swift-UVOT observations reveal an early decline (up to two days after explosion), while optical spectra classify it as a SN Ic-BL with very high expansion velocities (≈70 000 km s−1), similar to that found for the jet-cocoon emission in SN 2017iuk associated with GRB 171205A. Moreover, the Swift X-Ray Telescope and CXO X-ray Observatory detected X-ray emission only three days after the SN and decaying onward, which can be ascribed to an afterglow component. Cocoon and X-ray emission are both signatures of jet-powered GRBs. In the case of SN 2020bvc, we find that the jet is off axis (by ≈23 degrees), as also indicated by the lack of early (≈1 day) X-ray emission, which explains why no coincident GRB was detected promptly or in archival data. These observations suggest that SN 2020bvc is the first orphan GRB detected through its associated SN emission.

scholarly journals LONG-DURATION X-RAY FLASH AND X-RAY-RICH GAMMA-RAY BURSTS FROM LOW-MASS POPULATION III STARS

2012 ◽  
Vol 759 (2) ◽  
pp. 128 ◽  
Author(s):  
Daisuke Nakauchi ◽  
Yudai Suwa ◽  
Takanori Sakamoto ◽  
Kazumi Kashiyama ◽  
Takashi Nakamura
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
X Ray ◽  
Long Duration ◽  
Low Mass ◽  
Population Iii Stars ◽  
Population Iii

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

scholarly journals Population III Gamma-Ray Burst

2011 ◽  
Vol 7 (S279) ◽  
pp. 301-304 ◽  
Author(s):  
Kunihito Ioka ◽  
Yudai Suwa ◽  
Hiroki Nagakura ◽  
Rafael S. de Souza ◽  
Naoki Yoshida
Keyword(s):  
Mass Loss ◽  
First Generation ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Gamma Ray Burst ◽  
X Ray ◽  
The Core ◽  
Long Duration ◽  
The Future ◽  
Bright Phase

AbstractGamma-ray bursts (GRBs) are unique probes of the first generation (Pop III) stars. We show that a relativistic gamma-ray burst (GRB) jet can potentially pierce the envelope of a very massive Pop III star even if the Pop III star has a supergiant hydrogen envelope without mass loss, thanks to the long-lived powerful accretion of the envelope itself. While the Pop III GRB is estimated to be energetic (Eγ,iso ~ 1055 erg), the supergiant envelope hides the initial bright phase in the cocoon component, leading to a GRB with a long duration ~1000 (1 + z) s and an ordinary isotropic luminosity ~ 1052 erg s−1 (~ 10−9 erg cm−2 s−1 at redshift z ~ 20), although these quantities are found to be sensitive to the core and envelope mass. We also show that Pop III.2 GRBs (which are primordial but affected by radiation from other stars) occur >100 times more frequently than Pop III.1 GRBs, and thus should be suitable targets for future X-ray and radio missions. The radio transient surveys are already constraining the Pop III GRB rate and promising in the future.

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