Related papers: Thin Disk Models of Anomalous X-ray Pulsars
We present new models for the X-ray photoevaporation of circumstellar discs which suggest that the resulting mass loss (occurring mainly over the radial range 10-40 AU) may be the dominant dispersal mechanism for gas around low mass…
Collapsar disks have been proposed to be rich factories of heavy elements, but the major question of whether their outflows are neutron-rich, and could therefore represent significant sites of the rapid neutron-capture (r-) process, or…
An analysis of ablation processes is made for a fall-back disk with inner and outer radii external to the neutron-star light cylinder. The calculated ablation rate leads, with certain other assumptions, to a simple expression relating the…
The long term (~1.5 years) X-ray enhancement and the accompanying infrared enhancement light curves of the anomalous X-ray pulsar 1E 2259+58 following the major bursting epoch can be accounted for by the relaxation of a fall back disk that…
The magnetar model and a solid quark star model for anomalous X-ray pulsars/soft gamma-ray repeaters (AXPs/SGRs) are discussed. Different manifestations of pulsar-like stars are speculated to be due to both their nature (e.g., mass and…
Many astrophysical sources, e.g., cataclysmic variables, X-ray binaries, active galactic nuclei, exhibit a wind outflow, when they reveal a multicolor blackbody spectrum, hence harboring a geometrically thin Keplerian accretion disk. Unlike…
We revisit the apparent correlation between soft X-ray band photon index and spin-down rate nudot previously reported for Anomalous X-ray Pulsars (AXPs) and Soft Gamma Repeaters (SGRs) by Marsden & White (2001). Our analysis, improved…
We report the serendipitous discovery of a 7-s X-ray pulsar using data acquired with the Advanced Satellite for Cosmology and Astrophysics. The pulsar is detected as an unresolved source located towards a region of the Galactic plane (l,b ~…
I review of the observational properties of Soft Gamma Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs), two unusual manifestations of neutron stars. I summarize the reasoning for SGRs being "magnetars," neutron stars powered by the…
Anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs) are magnetar candidates, i.e., neutron stars powered by strong magnetic field. If they are indeed magnetars, they will emit high-energy gamma-rays which are detectable by…
We compute mass outflow rates from advective accretion disks around compact objects, such as neutron stars and black holes. These computations, for the first time, are done using combinations of exact transonic inflow and outflow solutions…
Several observations obtained in the last few years indicate that Soft Gamma-ray Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs) are basically a single class of isolated neutron stars. Their properties are well explained by the magnetar…
The paradigm for Anomalous X-ray Pulsars (AXPs) has evolved recently with the discovery by INTEGRAL and RXTE of flat, hard X-ray components in three AXPs. These non-thermal spectral components differ dramatically from the steeper…
We model gas inflow patterns onto circumstellar disks and the evolution of the pseudodisk using three-dimensional resistive MHD simulations. Starting from a prestellar core without turbulence and with a misalignment between the initial…
In this article we treat the non-adiabatic photon-to-axion resonant conversion of curvature radiation, synchrotron emission and inverse Compton scattering dominating the spectral density function of pulsars. First, we introduce emission…
The NuSTAR experiment detected a hard X-ray emission (10-70 keV) with a period of 8.68917 s and a pulse-phase modulation at 55 ks, or half this value, from the anomalous X-ray pulsar (AXP) 4U 0142+61. It is shown here that this evidence is…
We present an analysis of five X-ray Multi-Mirror Mission (XMM) observations of the anomalous X-ray pulsar (AXP) 1E 2259+586 taken in 2004 and 2005 during its relaxation following its 2002 outburst. We compare these data with those of five…
Fallback disks are expected to form around young neutron stars. The presence of these disks can be revealed by their blackbody spectrum in the infrared, optical and UV bands. We present a re-reduction of the archival optical and infrared…
The launching process of a magnetically driven outflow from an accretion disk is investigated in a local, shearing box model which allows a study of the feedback between accretion and angular momentum loss. The mass-flux instability found…
AXPs and SGRs constitute a special population of young neutron stars, which are thought to be magnetars, i.e., neutron stars with super-strong magnetic fields (10^14 - 10^15 G). Assuming that AXPs and SGRs accrete matter from a fallback…