scholarly journals The binary progenitors of short and long GRBs and their gravitational-wave emission

2018 ◽  
Vol 168 ◽  
pp. 01006
Author(s):  
J. A. Rueda ◽  
R. Ruffini ◽  
J. F. Rodriguez ◽  
M. Muccino ◽  
Y. Aimuratov ◽  
...  
Keyword(s):  
Neutron Star ◽  
Gravitational Wave ◽  
Gamma Ray ◽  
Critical Mass ◽  
Compact Object ◽  
Annual Number ◽  
Black Hole Binaries ◽  
Nuclear Equation Of State ◽  
Long Duration ◽  
Wave Emission

We have sub-classified short and long-duration gamma-ray bursts (GRBs) into seven families according to the binary nature of their progenitors. Short GRBs are produced in mergers of neutron-star binaries (NS-NS) or neutron star-black hole binaries (NS-BH). Long GRBs are produced via the induced gravitational collapse (IGC) scenario occurring in a tight binary system composed of a carbon-oxygen core (COcore) and a NS companion. The COcore explodes as type Ic supernova (SN) leading to a hypercritical accretion process onto the NS: if the accretion is sufficiently high the NS reaches the critical mass and collapses forming a BH, otherwise a massive NS is formed. Therefore long GRBs can lead either to NS-BH or to NS-NS binaries depending on the entity of the accretion. We discuss for the above compact-object binaries: 1) the role of the NS structure and the nuclear equation of state; 2) the occurrence rates obtained from X and gamma-rays observations; 3) the predicted annual number of detections by the Advanced LIGO interferometer of their gravitational-wave emission.

scholarly journals The binary systems associated with short and long gamma-ray bursts and their detectability

2017 ◽  
Vol 26 (09) ◽  
pp. 1730016 ◽  
Author(s):  
Jorge A. Rueda ◽  
Y. Aimuratov ◽  
U. Barres de Almeida ◽  
L. Becerra ◽  
C. L. Bianco ◽  
...  
Keyword(s):  
Neutron Star ◽  
Gravitational Collapse ◽  
Binary Systems ◽  
Gamma Ray ◽  
Critical Mass ◽  
Compact Object ◽  
Gamma Ray Bursts ◽  
Black Hole Binaries ◽  
Long Duration

Short and long-duration gamma-ray bursts (GRBs) have been recently sub-classified into seven families according to the binary nature of their progenitors. For short GRBs, mergers of neutron star binaries (NS–NS) or neutron star-black hole binaries (NS-BH) are proposed. For long GRBs, the induced gravitational collapse (IGC) paradigm proposes a tight binary system composed of a carbon–oxygen core (CO[Formula: see text]) and a NS companion. The explosion of the CO[Formula: see text] as supernova (SN) triggers a hypercritical accretion process onto the NS companion which might reach the critical mass for the gravitational collapse to a BH. Thus, this process can lead either to a NS-BH or to NS–NS depending on whether or not the accretion is sufficient to induce the collapse of the NS into a BH. We shall discuss for the above compact object binaries: (1) the role of the NS structure and the equation-of-state on their final fate; (2) their occurrence rates as inferred from the X and gamma-ray observations; (3) the expected number of detections of their gravitational wave (GW) emission by the Advanced LIGO interferometer.

scholarly journals Gravitational waves from mountains in newly born millisecond magnetars

2021 ◽  
Vol 502 (4) ◽  
pp. 4680-4688
Author(s):  
Ankan Sur ◽  
Brynmor Haskell
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Massive Star ◽  
Gamma Ray ◽  
Dipole Radiation ◽  
X Ray ◽  
Binary Neutron Star ◽  
Spin Period ◽  
Lower Maximum ◽  
Wave Emission

ABSTRACT In this paper, we study the spin-evolution and gravitational-wave luminosity of a newly born millisecond magnetar, formed either after the collapse of a massive star or after the merger of two neutron stars. In both cases, we consider the effect of fallback accretion; and consider the evolution of the system due to the different torques acting on the star, namely the spin-up torque due to accretion and spin-down torques due to magnetic dipole radiation, neutrino emission, and gravitational-wave emission linked to the formation of a ‘mountain’ on the accretion poles. Initially, the spin period is mostly affected by the dipole radiation, but at later times, accretion spin the star up rapidly. We find that a magnetar formed after the collapse of a massive star can accrete up to 1 M⊙, and survive on the order of 50 s before collapsing to a black hole. The gravitational-wave strain, for an object located at 1 Mpc, is hc ∼ 10−23 at kHz frequencies, making this a potential target for next-generation ground-based detectors. A magnetar formed after a binary neutron star merger, on the other hand, accretes at the most 0.2 M⊙ and emits gravitational waves with a lower maximum strain of the order of hc ∼ 10−24, but also survives for much longer times, and may possibly be associated with the X-ray plateau observed in the light curve of a number of short gamma-ray burst.

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.

scholarly journals Gravitational wave emission from a magnetically deformed non-barotropic neutron star

2011 ◽  
Vol 417 (3) ◽  
pp. 2288-2299 ◽  
Author(s):  
A. Mastrano ◽  
A. Melatos ◽  
A. Reisenegger ◽  
T. Akgün
Keyword(s):  
Neutron Star ◽  
Gravitational Wave ◽  
Wave Emission

Gravitational-wave astrophysics from neutron star inspiral and coalescence

2018 ◽  
Vol 27 (11) ◽  
pp. 1843018 ◽  
Author(s):  
John L. Friedman
Keyword(s):  
Neutron Star ◽  
Gravitational Wave ◽  
Gamma Ray ◽  
Hubble Constant ◽  
Gamma Ray Bursts ◽  
Nuclear Density ◽  
Independent Measurement ◽  
Process Elements ◽  
Heaviest Elements ◽  
Cold Matter

Prior to the observation of a double neutron star inspiral and merger, its possible implications were striking. Events whose light and gravitational waves are simultaneously detected could resolve the 50-year mystery of the origin of short gamma-ray bursts; they might provide strong evidence for (or against) mergers as the main source of half the heaviest elements (the [Formula: see text]-process elements); and they could give an independent measurement of the Hubble constant. The closest events can also address a primary goal of gravitational-wave astrophysics: From the imprint of tides on inspiral waveforms, one can find the radius and tidal distortion of the inspiraling stars and infer the behavior of cold matter above nuclear density. Remarkably, the first observation of the inspiral and coalescence of a double neutron star system was accompanied by a gamma-ray burst and then an array of electromagnetic counterparts, and the combined effort of the gravitational-wave and astronomy communities has led to dramatic advances along all of these anticipated avenues of multimessenger astrophysics.

scholarly journals Measuring the eccentricity of GW170817 and GW190425

2020 ◽  
Vol 497 (2) ◽  
pp. 1966-1971 ◽  
Author(s):  
Amber K Lenon ◽  
Alexander H Nitz ◽  
Duncan A Brown
Keyword(s):  
Parameter Estimation ◽  
Neutron Star ◽  
Gravitational Wave ◽  
Matched Filter ◽  
Wave Frequency ◽  
Limited Information ◽  
Binary Neutron Star ◽  
Wave Emission

ABSTRACT Two binary neutron star mergers, GW170817 and GW190425, have been detected by Advanced LIGO and Virgo. These signals were detected by matched-filter searches that assume that the star’s orbit has circularized by the time their gravitational-wave emission is observable. This suggests that their eccentricity is low, but full parameter estimation of their eccentricity has not yet been performed. We use gravitational-wave observations to measure the eccentricity of GW170817 and GW190425. We find that the eccentricity at a gravitational-wave frequency of 10 Hz is e ≤ 0.024 and e ≤ 0.048 for GW170817 and GW190425, respectively (90 per cent confidence). This is consistent with the binaries being formed in the field, as such systems are expected to have circularized to e ≤ 10−4 by the time they reach the LIGO–Virgo band. Our constraint is a factor of 2 smaller that an estimate based on GW170817 being detected by searches that neglect eccentricity. However, we caution that we find significant prior dependence in our limits, suggesting that there is limited information in the signals. We note that other techniques used to constrain binary neutron star eccentricity without full parameter estimation may miss degeneracies in the waveform, and that for future signals, it will be important to perform full parameter estimation with accurate waveform templates.

scholarly journals Constraint on Hybrid Stars with Gravitational Wave Events

Universe ◽  
2020 ◽  
Vol 6 (12) ◽  
pp. 231
Author(s):  
Kilar Zhang ◽  
Feng-Li Lin
Keyword(s):  
Black Hole ◽  
Dark Matter ◽  
Neutron Star ◽  
Gravitational Wave ◽  
Compact Object ◽  
Compact Objects ◽  
Compact Stars ◽  
Hybrid Star ◽  
Hybrid Stars

Motivated by the recent discoveries of compact objects from LIGO/Virgo observations, we study the possibility of identifying some of these objects as compact stars made of dark matter called dark stars, or the mix of dark and nuclear matters called hybrid stars. In particular, in GW190814, a new compact object with 2.6 M⊙ is reported. This could be the lightest black hole, the heaviest neutron star, and a dark or hybrid star. In this work, we extend the discussion on the interpretations of the recent LIGO/Virgo events as hybrid stars made of various self-interacting dark matter (SIDM) in the isotropic limit. We pay particular attention to the saddle instability of the hybrid stars which will constrain the possible SIDM models.

VACUUM DISCHARGE AS A POSSIBLE SOURCE OF GAMMA-RAY BURSTS

2000 ◽  
Vol 09 (02) ◽  
pp. 185-192
Author(s):  
G. MAO ◽  
S. CHIBA ◽  
W. GREINER ◽  
K. OYAMATSU
Keyword(s):  
Neutron Star ◽  
Gamma Ray ◽  
Ambient Medium ◽  
Critical Density ◽  
Compact Object ◽  
Dense Matter ◽  
Initial Energy ◽  
Strong Interactions ◽  
Γ Ray ◽  
The Impact

We propose that spontaneous particle–anti-particle pair creations from the discharged vacuum caused by the strong interactions in dense matter are major sources of γ-ray bursts. Two neutron star collisions or black-hole-neutron star mergers at cosmological distance could produce a compact object with its density exceeding the critical density for pair creations. The emitted anti-particles annihilate with corresponding particles at the ambient medium. This releases a large amount of energy. We discuss the spontaneous [Formula: see text] pair creations within two neutron star collision and estimate the exploded energy from [Formula: see text] annihilation processes. The total energy could be around 1051–1053 erg depending on the impact parameter of colliding neutron stars. This value fits well into the range of the initial energy of the most energetic γ-ray bursts.

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