Related papers: The Eddington Limit and Soft Gamma Repeaters
Bursts from soft gamma repeaters have been shown to be super-Eddington by a factor of 1000 and have been persuasively associated with compact objects. Here, a model of super-Eddington radiation transfer on the surface of a strongly magnetic…
Soft Gamma Repeaters (SGRs) are a class of rare, high-energy galactic transients that have episodes of short (~0.1 sec), soft (~30 keV), intense (~100 Crab), gamma-ray bursts. We report an analysis of the x-ray emission from 95 SGR1806-20…
In this letter we suggest a scenario for simultaneous emission of gravitational-wave and $\gamma$-ray bursts (GRBs) from soft gamma-ray repeaters (SGRs). we argue that both of the radiations can be generated by a super-Eddington accreting…
Emission of two short hard X-ray bursts on 2009 June 5 disclosed the existence of a new soft gamma-ray repeater, now catalogued as SGR 0418+5729. After a few days, X-ray pulsations at a period of 9.1 s were discovered in its persistent…
I summarize the recent advances in our understanding of the Soft Gamma Repeaters: in particular their spin behavior, persistent emission and hyper-Eddington outbursts. The giant flares on 5 March 1979 and 27 August 1998 provide compelling…
The sky region containing the soft gamma-ray repeater SGR 1627-41 has been observed three times with XMM-Newton in February and September 2004. SGR 1627-41 has been detected with an absorbed flux of ~9x10^{-14} erg cm^{-2} s^{-1} (2-10…
All the confirmed Soft Gamma-ray Repeaters have been observed with the EPIC instrument on the XMM-Newton satellite. We review the results obtained in these observations, providing the most accurate spectra on the persistent X-ray emission…
An optical spectroscopy of an unusual fast transient V4641 Sgr constrains its mass to 8.7-11.7M_sun (9.6M_sun is the best fit value) and the distance to 7.4--12.3 kpc (Orosz et al. 2001). At this distance the peak flux of 12 Crab in the…
A ~50 ks XMM-Newton observation of SGR 1900+14 has been carried out in September 2005, after almost three years during which no bursts were detected from this soft gamma-ray repeater. The 0.8-10 keV spectrum was well fit by a power law plus…
The spectra of soft gamma-ray repeaters (SGRs), with the exception of the March 5, 1979 main burst, are characterized by high-energy cutoffs around 30 keV and low-energy turnovers that are much steeper than a Wien spectrum. Baring (1995)…
Four Soft Gamma Repeaters (SGRs) have now been identified with certainty, and a fifth has possibly been detected. I will review their X-ray and gamma-ray properties in both outburst and quiescence. The magnetar model accounts fairly well…
Soft gamma repeaters and anomalous x-ray pulsars form a rapidly increasing group of x-ray sources exhibiting sporadic emission of short bursts. They are believed to be magnetars, i.e. neutron stars powered by extreme magnetic fields,…
Recent study of gamma rays originating from the region of galactic centre has confirmed an anomalous $\gamma$-ray excess within the energy range 1-3 GeV. This can be explained as the consequence of pair annihilation of a 31-40 GeV dark…
The low energy (<10 keV) X-ray emission of the Soft Gamma-ray Repeater SGR1806-20 has been studied by means of four XMM-Newton observations carried out in the last two years, the latter performed in response to a strong sequence of hard…
We report on two observations of a soft bursting source in 1997 June, whose time histories and energy spectra are consistent with those of the soft gamma repeaters. The source can only be localized to an ~3.8 degree long error box in the…
The public data from the EGRET space telescope on diffuse galactic gamma rays in the energy range from 0.1 to 10 GeV show an excess for energies above 1 GeV in comparison with the expectations from conventional galactic models. This excess…
The luminosity range at and just below the 10^39 erg/s cut-off for defining ultraluminous X-ray sources (ULXs) is a little-explored regime. It none-the-less hosts a large number of X-ray sources, and has great potential for improving our…
In this paper we investigate the relation between the maximal luminosity of X-ray outburst and the orbital period in transient low mass X-ray binaries (or soft X-ray transients) observed by the Rossi X-ray Timing Explorer (RXTE) in the past…
Here is reviewed our current understanding of Galactic and extragalactic diffuse gamma-ray emission. The spectrum of the extragalactic gamma-ray background above 30 MeV can be well described by a power law with photon index s=2.1. In the…
I review some recent developments in our understanding of the environments of soft gamma-ray repeaters. I pay particular attention to the apparent association betwwen SGR 1900+14 and SGR 1806-20 and embedded clusters of stars.