X-Ray Afterglows of Short Gamma-Ray Bursts: Magnetar or Fireball?

Sarin, N.; Lasky, P. D.; Ashton, G.

doi:10.3847/1538-4357/aaf9a0

Cited by 32 publications

(34 citation statements)

References 61 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(12) with (µ 1 , σ 1 ) = (1.32, 0.11), (µ 2 , σ 2 ) = (1.80, 0.21), and let be a free parameter which we infer through our hierarchical model. Following Sarin et al [20], one can derive the post-merger remnant mass distribution having the same functional form as Eq. (12) with (µ 1 , σ 1 ) = (2.42, 0.09), (µ 2 , σ 2 ) = (3.21, 0.25) assuming ≈ 0.07M of dynamical ejecta is produced in the merger, consistent with observations of GW170817 [e.g., 49].…”

Section: Methodsmentioning

confidence: 99%

“…Although a sharp drop in luminosity cannot be adequately explained within the fireball-shock model, we perform Bayesian model selection between our collapsing magnetar model and an agnostic fireball-shock model as described in [20] to ensure the data is best explained by a collapsing magnetar model. The Bayes factors comparing the fireball-shock and magnetar model for these 18 gamma-ray bursts are shown in Table II likely 1 , the collapsing magnetar model is significantly favoured over the fireball-shock model indicating that the X-ray afterglow observations here are best explained by the presence of a long-lived neutron star which collapses at some time.…”

Section: Neutron Star Collapse Timesmentioning

confidence: 99%

“…Bayes factor ln BF M/F for the collapsing magnetar model introduced here (Eq. 1) and fireball-shock model as introduced in [20].…”

Section: Neutron Star Collapse Timesmentioning

confidence: 99%

See 2 more Smart Citations

Gravitational waves or deconfined quarks: What causes the premature collapse of neutron stars born in short gamma-ray bursts?

2020

Self Cite

View full text Add to dashboard Cite

We infer the collapse times of long-lived neutron stars into black holes using the X-ray afterglows of 18 short gamma-ray bursts. We then apply hierarchical inference to infer properties of the neutron star equation of state and dominant spin-down mechanism. We measure the maximum nonrotating neutron star mass MTOV = 2.31 +0.36 −0.21 M and constrain the fraction of remnants spinning down predominantly through gravitational-wave emission to η = 0.69 +0.21 −0.39 with 68% uncertainties. In principle, this method can determine the difference between hadronic and quark equation of states. In practice, however, the data is not yet informative with indications that these neutron stars do not have hadronic equation of states at the 1σ level. These inferences all depend on the underlying progenitor mass distribution for short gamma-ray bursts produced by binary neutron star mergers. The recently announced gravitational-wave detection of GW190425 suggests this underlying distribution is different from the locally-measured population of double neutron stars. We show that MTOV and η constraints depend on the fraction of binary mergers that form through a distribution consistent with the locally-measured population and a distribution that can explain GW190425. The more binaries that form from the latter distribution, the larger MTOV needs to be to satisfy the X-ray observations. Our measurements above are marginalised over this unknown fraction. If instead, we assume GW190425 is not a binary neutron star merger, i.e the underlying mass distribution of double neutron stars is the same as observed locally, we measure MTOV = 2.26 +0.31 −0.17 M . arXiv:2001.06102v2 [astro-ph.HE]1 In reality, both models are not equally likely as the fireball is always believed to be present. Here, the correct metric to compare the two models is the Odds (see Sarin et al. [20] for details), however model selection with the Odds requires knowing M TOV and the neutron star mass distribution.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Neutron Star Collapse Timesmentioning

confidence: 99%

See 1 more Smart Citation

Gravitational waves or deconfined quarks: What causes the premature collapse of neutron stars born in short gamma-ray bursts?

2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…Both fireball models and central engine models are capable of explaining some (but not all) features of X-ray plateaux. Sarin et al (2019) demonstrated that GRB140903A and GRB130603B favour a simple magnetar model, making these two sGRBs particularly suited to investigating the plerion-inspired model in this paper.…”

Section: Introductionmentioning

confidence: 85%

Inferring properties of neutron stars born in short gamma-ray bursts with a plerion-like X-ray plateau

Strang,

Melatos,

Sarin

et al. 2021

Preprint

View full text Add to dashboard Cite

Time-resolved spectra of six short gamma-ray bursts (sGRBs), measured by the Swift telescope, are used to estimate the parameters of a plerion-like model of the X-ray afterglow. The unshrouded, optically thin component of the afterglow is modelled as emanating from an expanding bubble of relativistic, shock-accelerated electrons fuelled by a central object. The electrons are injected with a power-law distribution and cool mainly by synchrotron losses. We compute posteriors for model parameters describing the central engine (e.g. spin frequency at birth, magnetic field strength) and shock acceleration (e.g. power-law index, minimum injection energy). It is found that the central engine is compatible with a millisecond magnetar, and the shock physics is compatible with what occurs in Galactic supernova remnants, assuming standard magnetic field models for the magnetar wind. Separately, we allow the magnetic field to vary arbitrarily and infer that it is roughly constant and lower in magnitude than the wind-borne extension of the inferred magnetar field. This may be due to the expansion history of the bubble, or the magnetization of the circumstellar environment of the sGRB progenitor.

show abstract

“…Due to the complexity of the coalescence stages, i.e., inspiralling, merging, and ringdown, multi-stage measurements have been made for some SGRBs, including precursor flares, main episodes, and afterglows. Each delivers different information on NS physics, such as the equation of state (EOS) and the central engine of emissions from both the progenitors (Giacomazzo et al 2013;Ascenzi et al 2019) and the remnants (Lasky et al 2014;Sarin, Lasky, & Ashton 2019;Suvorov & Kokkotas 2020b). In particular, precursor flares have been observed for a few SGRBs with some of them likely occuring before the merger (Tsang et al 2012).…”

Section: Introductionmentioning

confidence: 99%

General-relativistic treatment of tidal $g$-mode resonances in coalescing binaries of neutron stars. II. As triggers for precursor flares of short gamma-ray bursts

Kuan,

Suvorov,

Kokkotas

2021

Preprint

View full text Add to dashboard Cite

In some short gamma-ray bursts, precursor flares occurring ∼ seconds prior to the main episode have been observed. These flares may then be associated with the last few cycles of the inspiral when the orbital frequency is a few hundred Hz. During these final cycles, tidal forces can resonantly excite quasi-normal modes in the inspiralling stars, leading to a rapid increase in their amplitude. It has been shown that these modes can exert sufficiently strong strains onto the neutron star crust to instigate yieldings. Due to the typical frequencies of g-modes being ∼ 100 Hz, their resonances with the orbital frequency match the precursor timings and warrant further investigation. Adopting realistic equations of state and solving the general-relativistic pulsation equations, we study g-mode resonances in coalescing quasi-circular binaries, where we consider various stellar rotation rates, degrees of stratification, and magnetic field structures. We show that for some combination of stellar parameters, the resonantly excited g 1and g 2 -modes may lead to crustal failure and trigger precursor flares.

show abstract

X-Ray Afterglows of Short Gamma-Ray Bursts: Magnetar or Fireball?

Cited by 32 publications

References 61 publications

Gravitational waves or deconfined quarks: What causes the premature collapse of neutron stars born in short gamma-ray bursts?

Gravitational waves or deconfined quarks: What causes the premature collapse of neutron stars born in short gamma-ray bursts?

Inferring properties of neutron stars born in short gamma-ray bursts with a plerion-like X-ray plateau

General-relativistic treatment of tidal $g$-mode resonances in coalescing binaries of neutron stars. II. As triggers for precursor flares of short gamma-ray bursts

Contact Info

Product

Resources

About