scholarly journals On the Central Engine of Short Gamma-ray Bursts

2005 ◽  
Vol 192 ◽  
pp. 503-508
Author(s):  
Stephan Rosswog ◽  
Enrico Ramírez-Ruiz
Keyword(s):  
Neutron Star ◽  
Kinetic Energy ◽  
Gamma Ray ◽  
Rotation Axis ◽  
Gamma Ray Bursts ◽  
Relativistic Jets ◽  
Dynamo Action ◽  
Neutron Star Mass ◽  
Central Engine ◽  
Star Binary

SummaryWe assess the ability of neutron star binary coalescence to produce short gamma-ray bursts (GRBs). We find that the neutrino annihilation above the merged remnant will drive bipolar, relativistic jets along the initial binary rotation axis. This outflow can be collimated by the energetic, neutrino-driven baryonic wind that is blown off the remnant. Despite the narrow neutron star mass distribution the apparent luminosities will be spread over a broad range from ~ 1049 to ~ 1052erg s−1, typical jet opening half-angles are around 5 degrees. If the central core of the merger remnant does not collapse immediately convective dynamo action will set in and the available kinetic energy can be transformed into magnetic fields in excess of 1017 G. The corresponding spin-down time scale is ~ 0.2 s, just about the duration of a short GRB.

Anatomy of a merger

2019 ◽  
pp. 541-580
Author(s):  
Nils Andersson
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Binary System ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Late Time ◽  
Tidal Effects ◽  
Gamma Ray Burst ◽  
Love Numbers ◽  
Star Binary

This chapter discusses the different stages of an inspiralling neutron star binary system, through the formation of a black hole and the possible emergence of a gamma-ray burst. Tidal effects and the information encoded in the so-called Love numbers are explored. The violent dynamics of the merger is considered and models of gamma-ray bursts and the late time kilonova emission are also explored.

Induced gravitational collapse in FeCO Core–Neutron star binaries and Neutron star–Neutron star binary mergers

2015 ◽  
Vol 30 (28n29) ◽  
pp. 1545023
Author(s):  
R. Ruffini ◽  
Y. Aimuratov ◽  
C. L. Bianco ◽  
M. Enderli ◽  
M. Kovacevic ◽  
...  
Keyword(s):  
Neutron Star ◽  
Gravitational Collapse ◽  
Binary Systems ◽  
Recent Progress ◽  
Gamma Ray ◽  
Critical Mass ◽  
Gamma Ray Bursts ◽  
New Paradigm ◽  
Binary Mergers ◽  
Star Binary

We review the recent progress in understanding the nature of gamma-ray bursts (GRBs). The occurrence of GRB is explained by the Induced Gravitational Collapse (IGC) in FeCO Core–Neutron star binaries and Neutron star–Neutron star binary mergers, both processes occur within binary system progenitors. Making use of this most unexpected new paradigm, with the fundamental implications by the neutron star (NS) critical mass, we find that different initial configurations of binary systems lead to different GRB families with specific new physical predictions confirmed by observations.

scholarly journals Reverse shocks in the relativistic outflows of gravitational wave-detected neutron star binary mergers

2019 ◽  
Vol 489 (2) ◽  
pp. 1820-1827 ◽  
Author(s):  
Gavin P Lamb ◽  
Shiho Kobayashi
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Gravitational Wave ◽  
Strong Magnetic Field ◽  
Gamma Ray ◽  
Reverse Shock ◽  
Central Engine ◽  
Forward Shock ◽  
Binary Mergers ◽  
Star Binary

ABSTRACT The afterglows to gamma-ray bursts (GRBs) are due to synchrotron emission from shocks generated as an ultrarelativistic outflow decelerates. A forward and a reverse shock will form, however, where emission from the forward shock is well studied as a potential counterpart to gravitational wave-detected neutron star mergers the reverse shock has been neglected. Here, we show how the reverse shock contributes to the afterglow from an off-axis and structured outflow. The off-axis reverse shock will appear as a brightening feature in the rising afterglow at radio frequencies. For bursts at ∼100 Mpc, the system should be inclined ≲20° for the reverse shock to be observable at ∼0.1–10 d post-merger. For structured outflows, enhancement of the reverse shock emission by a strong magnetic field within the outflow is required for the emission to dominate the afterglow at early times. Early radio photometry of the afterglow could reveal the presence of a strong magnetic field associated with the central engine.

scholarly journals Long-Term Evolution of (Short) Gamma-Ray Burst Central Engines

2004 ◽  
Vol 194 ◽  
pp. 132-133
Author(s):  
William H. Lee
Keyword(s):  
Black Holes ◽  
Neutron Star ◽  
Accretion Disks ◽  
Gamma Ray ◽  
Dynamical Evolution ◽  
Gamma Ray Bursts ◽  
Term Evolution ◽  
Star Binary ◽  
Short Grbs

AbstractCosmological gamma ray bursts (GRBs) possibly originate from accretion disks around stellar mass black holes. These could be formed after the merger of a double neutron star or black hole-neutron star binary. The dynamical evolution of the disk is important if one wishes to relate characteristic timescales with the observed duration and variability. We show here the results of such a set of calculations, relevant for short GRBs.

scholarly journals Magnetized Hypermassive Neutron-Star Collapse: A Central Engine for Short Gamma-Ray Bursts

2006 ◽  
Vol 96 (3) ◽  
Author(s):  
Masaru Shibata ◽  
Matthew D. Duez ◽  
Yuk Tung Liu ◽  
Stuart L. Shapiro ◽  
Branson C. Stephens
Keyword(s):  
Neutron Star ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Central Engine

scholarly journals Central-engine-powered Bright X-Ray Flares in Short Gamma-Ray Bursts: A Hint of a Black Hole–Neutron Star Merger?

2018 ◽  
Vol 858 (1) ◽  
pp. 34 ◽  
Author(s):  
Hui-Jun Mu ◽  
Wei-Min Gu ◽  
Jirong Mao ◽  
Shu-Jin Hou ◽  
Da-Bin Lin ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
X Ray ◽  
Central Engine

scholarly journals Can we constrain the aftermath of binary neutron star mergers with short gamma-ray bursts?

2020 ◽  
Vol 499 (1) ◽  
pp. L96-L100
Author(s):  
B Patricelli ◽  
M G Bernardini
Keyword(s):  
Neutron Star ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Binary Neutron Star ◽  
The Poor ◽  
Central Engine ◽  
Novel Method ◽  
Merger Rate ◽  
The Masses ◽  
Jet Structure

ABSTRACT The joint observation of GW170817 and GRB170817A proved that binary neutron star (BNS) mergers are progenitors of short gamma-ray bursts (SGRBs): this established a direct link between the still unsettled SGRB central engine and the outcome of BNS mergers, whose nature depends on the equation of state (EOS) and on the masses of the NSs. We propose a novel method to probe the central engine of SGRBs based on this link. We produce an extended catalogue of BNS mergers by combining recent theoretically predicted BNS merger rate as a function of redshift and the NS mass distribution inferred from measurements of Galactic BNSs. We use this catalogue to predict the number of BNS systems ending as magnetars (stable or supramassive NS) or BHs (formed promptly or after the collapse of a hypermassive NS) for different EOSs, and we compare these outcomes with the observed rate of SGRBs. Despite the uncertainties mainly related to the poor knowledge of the SGRB jet structure, we find that for most EOSs the rate of magnetars produced after BNS mergers is sufficient to power all the SGRBs, while scenarios with only BHs as possible central engine seem to be disfavoured.

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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