Last moments in the life of a compact binary system: gravitational waves, gamma-ray bursts and magnetar formation

Mergers of double neutron stars are considered the most likely progenitors for short gamma-ray bursts. Indeed such a merger can produce a black hole with a transient accreting torus of nuclear matter (Lee & Ramirez-Ruiz 2007, Oechslin & Janka 2006), and the conversion of a fraction of the torus mass-energy to radiation can power a gamma-ray burst (Nakar 2006). Using available binary pulsar observations supported by our extensive evolutionary calculations of double neutron sta...

Discovered over forty years ago, Gamma-Ray Bursts (GRBs) remain a forefront topic in modern astrophysics. Perhaps the most fundamental question associated with GRBs is the nature of the astrophysical agent (or agents) that ultimately powers them: the central engine. In this review, I focus on the possible central engines of long-duration GRBs, and the constraints that present observations place on these models. Long GRBs are definitively associated with the deaths of massive ...

The central engine that powers gamma-ray bursts (GRBs), the most powerful explosions in the universe, is still not identified. Besides hyper-accreting black holes, rapidly spinning and highly magnetized neutron stars, known as millisecond magnetars, have been suggested to power both long and short GRBs. The presence of a magnetar engine following compact star mergers is of particular interest as it would provide essential constraints on the poorly understood equation of state...

Two types of Gamma-ray bursts (GRBs) are observed: short duration hard spectrum GRBs and long duration soft spectrum GRBs. For many years long GRBs were the focus of intense research while the lack of observational data limited the study of short-hard GRBs (SHBs). In 2005 a breakthrough occurred following the first detections of SHB afterglows, longer wavelength emission that follows the burst of gamma-rays. Similarly to long GRBs, afterglow detections led to the identificati...

The fraction of long duration gamma ray bursts (GRBs) without an associated bright supernovae (SNe) at small redshifts $(z<0.15)$ is comparable to that of GRBs associated with SNe. We show, that their X-ray afterglow and the X-ray afterglow of most of the nearby $(z<1)$ GRBs without a confirmed association with SNe, are well reproduced by the launch of highly relativistic jets in the SN-less birth of millisecond pulsars in neutron star mergers or through phase transition of n...

The recent detections of the $\sim10$-s long $\gamma$-ray bursts (GRBs) 211211A and 230307A followed by softer temporally extended emission (EE) and kilonovae, point to a new GRB class. Using state-of-the-art first-principles simulations, we introduce a unifying theoretical framework that connects binary neutron star (BNS) and black hole-NS (BH-NS) merger populations with the fundamental physics governing compact-binary GRBs (cbGRBs). For binaries with large total masses $M_{...

We consider gamma--ray bursts produced by the merger of a massive white dwarf with a neutron star. We show that these are likely to produce long--duration GRBs, in some cases definitely without an accompanying supernova, as observed recently. This class of burst would have a strong correlation with star formation, and occur close to the host galaxy. However rare members of the class need not be near star--forming regions, and could have any type of host galaxy. Thus a long--d...

Gamma-ray bursts (GRBs) display a bimodal duration distribution, with a separation between the short- and long-duration bursts at about 2 sec. The progenitors of long GRBs have been identified as massive stars based on their association with Type Ic core-collapse supernovae, their exclusive location in star-forming galaxies, and their strong correlation with bright ultraviolet regions within their host galaxies. Short GRBs have long been suspected on theoretical grounds to ar...

[Abridged] The study of short-duration gamma-ray bursts (GRBs) experienced a complete revolution in recent years thanks to the discovery of the first afterglows and host galaxies in May 2005. These observations demonstrated that short GRBs are cosmological in origin, reside in both star forming and elliptical galaxies, are not associated with supernovae, and span a wide isotropic-equivalent energy range of ~10^48-10^52 erg. However, a fundamental question remains unanswered: ...

The first X-ray afterglow for a short (~30 ms), hard gamma-ray burst was detected by Swift on 9 May 2005 (GRB 050509b). No optical or radio counterpart was identified in follow-up observations. The tentative association of the GRB with a nearby giant elliptical galaxy at redshift z=0.2248 would imply a total energy release E(gamma, isotropic) ~3 x 10**48 erg, and that the progenitor had traveled several tens of kpc from its point of origin, in agreement with expectations link...