scholarly journals A Powerful e ± Outflow Driven by a Proto-strange Quark Star

2021 ◽  
Vol 922 (2) ◽  
pp. 214
Author(s):  
Shao-Ze Li ◽  
Yun-Wei Yu ◽  
He Gao ◽  
Zi-Gao Dai ◽  
Xiao-Ping Zheng
Keyword(s):  
Strange Quark ◽  
Initial Temperature ◽  
Gamma Ray ◽  
Thermal Evolution ◽  
Quark Star ◽  
Plateau Phase ◽  
Electron Positron ◽  
Temperature Plateau ◽  
Prompt Emission ◽  
Extended Emission

Abstract An electron–positron layer can cover the surface of a bare strange star (SS), the electric field in which can excite the vacuum and drive a pair wind by taking away the heat of the star. In order to investigate the pair-emission ability of a proto-SS, we establish a toy model to describe its early thermal evolution, where the initial trapping of neutrinos is specially taken into account. It is found that the early cooling of the SS is dominated by the neutrino diffusion rather than the conventional Urca processes, which leads to the appearance of an initial temperature plateau. During this plateau phase, the surface e ± pair emission can maintain a constant luminosity of 1048 − 1050erg s−1 for about a few to a few tens of seconds, which is dependent on the value of the initial temperature. The total energy released through this e ± wind can reach as high as ∼1051 erg. In principle, this pair wind could be responsible for the prompt emission or extended emission of some gamma-ray bursts.

scholarly journals The properties of prompt emission in short gamma-ray bursts with extended emission observed by Fermi/GBM

2020 ◽  
Vol 492 (3) ◽  
pp. 3622-3630
Author(s):  
Lin Lan ◽  
Rui-Jingi Lu ◽  
Hou-Jun Lü ◽  
Jun Shen ◽  
Jared Rice ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Large Scatter ◽  
Intrinsic Properties ◽  
Temporal Properties ◽  
Peak Energy ◽  
Peak Flux ◽  
Short Grbs ◽  
Prompt Emission ◽  
Extended Emission

ABSTRACT Short gamma-ray bursts (GRB) with extended emission (EE) that are composed of an initial short hard spike followed by a long-lasting EE are thought to comprise a sucategory of short GRBs. The narrow energy band available during the Swift era, combined with a lack of spectral information, prevented the discovery of the intrinsic properties of these events. In this paper, we perform a systematic search of short GRBs with EE using all available Fermi/GBM data. The search identified 26 GBM-detected short GRBs with EE that are similar to GRB 060614 observed by Swift/BAT. We focus on investigating the spectral and temporal properties of both the hard spike and the EE component of all 26 GRBs, and explore differences and possible correlations between them. We find that while the peak energy (Ep) of the hard spikes is slightly harder than that of the EE, their fluences are comparable. The harder Ep seems to correspond to a larger fluence and peak flux, with a large scatter for both the hard spike and the EE component. Moreover, the Ep of both the hard spike and the EE are compared with other short GRBs. Finally, we also compare the properties of GRB 170817A with those of short GRBs with EE and find no significant statistical differences between them. We find that GRB 170817A has the lowest Ep, probably because it is off-axis.

scholarly journals A THREE-STAGE MODEL FOR THE INNER ENGINE OF GRBs: PROMPT EMISSION AND EARLY AFTERGLOW

2008 ◽  
Vol 17 (09) ◽  
pp. 1383-1389 ◽  
Author(s):  
J. STAFF ◽  
B. NIEBERGAL ◽  
R. OUYED
Keyword(s):  
Black Hole ◽  
Gamma Ray ◽  
Surrounding Medium ◽  
Core Collapse ◽  
Stage Model ◽  
Quark Star ◽  
X Ray ◽  
Core Collapse Supernova ◽  
Stage 1 ◽  
Prompt Emission

We describe a model within the "quark-nova" scenario to interpret the recent observations of early X-ray afterglows of long gamma-ray bursts (GRBs) with the Swift satellite. This is a three-stage model within the context of a core-collapse supernova. STAGE 1 is an accreting (proto-) neutron star leading to a possible delay between the core collapse and the GRB. STAGE 2 is accretion onto a quark star, launching an ultrarelativistic jet generating the prompt GRB. This jet also creates the afterglow as the jet interacts with the surrounding medium creating an external shock. Slower shells ejected from the quark star (during accretion), can re-energize the external shock leading to a flatter segment in the X-ray afterglow. STAGE 3, which occurs only if the quark star collapses to form a black hole, consists of an accreting black hole. The jet launched in this accretion process interacts with the preceding quark star jet, and could generate the flaring activity frequently seen in early X-ray afterglows. Alternatively, a STAGE 2b can occur in our model if the quark star does not collapse to a black hole. The quark star in this case can then spin down due to magnetic braking, and the spin down energy may lead to flattening in the X-ray afterglow as well. This model seems to account for both the energies and the timescales of GRBs, in addition to the newly discovered early X-ray afterglow features.

scholarly journals On the gamma-ray burst – gravitational wave association in GW150914

2016 ◽  
Vol 12 (S324) ◽  
pp. 291-294
Author(s):  
Agnieszka Janiuk ◽  
Szymon Charzynski ◽  
Michal Bejger
Keyword(s):  
Black Hole ◽  
Gravitational Wave ◽  
Gamma Ray ◽  
Photon Emission ◽  
Close Binary ◽  
Wave Source ◽  
Compact Binary ◽  
Electron Positron ◽  
Wave Emission ◽  
Prompt Emission

AbstractHyperaccreting disks around black holes are the engines that drive outflows and jets in gamma ray bursts (GRBs). The torus formed after the core collapse or a compact binary merger is composed of free nucleons, Helium, electron-positron pairs, and is cooled by neutrinos rather than photon emission. Hyperaccretion powers the ultra-relativistic jets, where the GRB prompt emission originates. The neutrons produced in the disk and also in the outflowing material are necessary for the production of heavier nuclei. We discuss here the observable consequences of nucleosynthesis and we also apply the scenario of hyperaccretion to the gravitational wave source, GW150914. Temporal coincidence reported by the Fermi satellite suggested that the black hole merger might be accompanied with a GRB. We propose that a collapsing massive star and a black hole in a close binary could lead to such event. Gravitational wave emission due to the merger of collapsed core and the companion black hole might then coincide with a weak GRB.

The late X-ray afterglow of gamma-ray bursts

2007 ◽  
Vol 365 (1854) ◽  
pp. 1189-1195 ◽  
Author(s):  
Richard Willingale ◽  
Paul T O'Brien
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Spectral Indices ◽  
Plateau Phase ◽  
Start Time ◽  
X Ray ◽  
Temporal Decay ◽  
Decay Parameters ◽  
Steep Decay ◽  
Prompt Emission

We have developed a functional fit which can be used to represent the entire temporal decay of the X-ray afterglow of gamma-ray bursts (GRBs). The fit delineates and parameterizes well-defined phases for the decay: the prompt emission; an initial steep decay; a shallow plateau phase; and finally, a powerlaw afterglow. For 20% of GRBs, the plateau phase is weak, or not seen, and the initial powerlaw decay becomes the final afterglow. We compare the temporal decay parameters and X-ray spectral indices for 107 GRBs discovered by Swift with the expectations of the standard fireball model including a search for possible jet breaks. For approximately 50% of GRBs, the observed afterglow is in accord with the model, but for the rest the temporal and spectral properties are not as expected. We identify a few possible jet breaks, but there are many examples where such breaks are predicted but are absent. We also find that the start time of the final afterglow decay, T a , is associated with the peak of the prompt γ -ray emission spectrum, E peak , just as optical jet-break times, t j , are associated with E peak in the Ghirlanda relation.

scholarly journals Linking extended and plateau emissions of short gamma-ray bursts

2020 ◽  
Vol 493 (1) ◽  
pp. 783-791 ◽  
Author(s):  
Tatsuya Matsumoto ◽  
Shigeo S Kimura ◽  
Kohta Murase ◽  
Peter Mészáros
Keyword(s):  
Gamma Ray ◽  
Lorentz Factor ◽  
Gamma Ray Bursts ◽  
Radiation Efficiency ◽  
High Radiation ◽  
Average Value ◽  
Forward Shock ◽  
Compactness Arguments ◽  
Prompt Emission ◽  
Extended Emission

ABSTRACT Some short gamma-ray bursts (SGRBs) show a longer lasting emission phase, called extended emission (EE) lasting ${\sim}10^{2\!-\!3}\, \rm s$, as well as a plateau emission (PE) lasting ${\sim}10^{4\!-\!5}\, \rm s$. Although a long-lasting activity of the central engines is a promising explanation for powering both emissions, their physical origin and their emission mechanisms are still uncertain. In this work, we study the properties of the EEs and their connection with the PEs. First, we constrain the minimal Lorentz factor Γ of the outflows powering EEs, using compactness arguments and find that the outflows should be relativistic, Γ ≳ 10. We propose a consistent scenario for the PEs, where the outflow eventually catches up with the jet responsible for the prompt emission, injecting energy into the forward shock formed by the prior jet, which naturally results in a PE. We also derive the radiation efficiency of EEs and the Lorentz factor of the outflow within our scenario for 10 well-observed SGRBs accompanied by both EE and PE. The efficiency has an average value of ${\sim}3\, {{\ \rm per\ cent}}$ but shows a broad distribution ranging from ∼0.01 to ${\sim}100{{\ \rm per\ cent}}$. The Lorentz factor is ∼20–30, consistent with the compactness arguments. These results suggest that EEs are produced by a slower outflow via more inefficient emission than the faster outflow that causes the prompt emission with a high radiation efficiency.

Swift-BAT results on the prompt emission of short bursts

2007 ◽  
Vol 365 (1854) ◽  
pp. 1281-1291 ◽  
Author(s):  
Scott D Barthelmy
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Extended Phase ◽  
Hardness Ratio ◽  
Prompt Emission ◽  
Extended Emission

This is a brief review of short hard bursts (SHBs) from previous missions and from Swift-BAT; in particular, a review of the developing class of gamma-ray bursts which are similar to SHBs in that they have the short hard initial spike (0.1 to a few seconds), but that they also have a long extended phase of soft emission (50–200 s). Further, we suggest that a class of events discovered by Horvath in the T90 versus hardness ratio plane is this SHB with extended emission.

scholarly journals Evolution of an electron-positron plasma produced by induced gravitational collapse in binary-driven hypernovae

2018 ◽  
Vol 168 ◽  
pp. 04009 ◽  
Author(s):  
J. D. Melon Fuksman ◽  
L. Becerra ◽  
C. L. Bianco ◽  
M. Karlica ◽  
M. Kovacevic ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Gravitational Collapse ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Relativistic Hydrodynamics ◽  
X Ray ◽  
The Past ◽  
Electron Positron ◽  
Prompt Emission

The binary-driven hypernova (BdHN) model has been introduced in the past years, to explain a subfamily of gamma-ray bursts (GRBs) with energies Eiso ≥ 1052 erg associated with type Ic supernovae. Such BdHNe have as progenitor a tight binary system composed of a carbon-oxigen (CO) core and a neutron star undergoing an induced gravitational collapse to a black hole, triggered by the CO core explosion as a supernova (SN). This collapse produces an optically-thick e+e- plasma, which expands and impacts onto the SN ejecta. This process is here considered as a candidate for the production of X-ray flares, which are frequently observed following the prompt emission of GRBs. In this work we follow the evolution of the e+e- plasma as it interacts with the SN ejecta, by solving the equations of relativistic hydrodynamics numerically. Our results are compatible with the Lorentz factors estimated for the sources that produce the flares, of typically Γ ≲ 4.

scholarly journals Was GW190814 a Black Hole–Strange Quark Star System?

2021 ◽  
Vol 126 (16) ◽  
Author(s):  
I. Bombaci ◽  
A. Drago ◽  
D. Logoteta ◽  
G. Pagliara ◽  
I. Vidaña
Keyword(s):  
Black Hole ◽  
Strange Quark ◽  
Quark Star ◽  
Star System

scholarly journals Strange quark star in dilaton gravity

2019 ◽  
Vol 19 (6) ◽  
pp. 078
Author(s):  
Alireza Peivand ◽  
Kazem Naficy ◽  
Gholam Hossein Bordbar
Keyword(s):  
Strange Quark ◽  
Quark Star ◽  
Dilaton Gravity

scholarly journals Interpreting the X-ray afterglows of gamma-ray bursts with radiative losses and millisecond magnetars

2020 ◽  
Vol 499 (4) ◽  
pp. 5986-5992
Author(s):  
Nikhil Sarin ◽  
Paul D Lasky ◽  
Gregory Ashton
Keyword(s):  
Gravitational Wave ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Dipole Radiation ◽  
X Ray ◽  
Radiative Efficiency ◽  
Central Engine ◽  
Radiative Losses ◽  
Wave Emission ◽  
Prompt Emission

ABSTRACT The spin-down energy of millisecond magnetars has been invoked to explain X-ray afterglow observations of a significant fraction of short and long gamma-ray bursts. Here, we extend models previously introduced in the literature, incorporating radiative losses with the spin-down of a magnetar central engine through an arbitrary braking index. Combining this with a model for the tail of the prompt emission, we show that our model can better explain the data than millisecond-magnetar models without radiative losses or those that invoke spin-down solely through vacuum dipole radiation. We find that our model predicts a subset of X-ray flares seen in some gamma-ray bursts. We can further explain the diversity of X-ray plateaus by altering the radiative efficiency and measure the braking index of newly born millisecond magnetars. We measure the braking index of GRB061121 as $n=4.85^{+0.11}_{-0.15}$ suggesting the millisecond-magnetar born in this gamma-ray burst spins down predominantly through gravitational-wave emission.

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