Related papers: Soft gamma-ray repeaters and anomalous X-ray pulsa…
We show that the period clustering of anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs), their X-ray luminosities, ages and statistics can be explained with fallback disks with large initial specific angular momentum. The…
Double degenerate white dwarf (WD) mergers can exhibit extreme magnetic fields exceeding $10^{8}$ G and rapid rotation, but their spectral-energy distributions and high-energy emission mechanisms remain poorly characterised. ZTF J1901+1458…
The energy source of the anomalous X-ray pulsars is not well understood, hence their designation as anomalous. Unlike binary X-ray pulsars, no companions are seen, so the energy cannot be supplied by accretion of matter from a companion…
The magnetic fields of white dwarfs distort their shape generating an anisotropic moment of inertia. A magnetized white dwarf which rotates obliquely relative to the symmetry axis has a mass quadrupole moment which varies in time, so it…
Low mass axion-like particles could be produced in abundance within the cores of hot, compact magnetic white dwarf (MWD) stars from electron bremsstrahlung and converted to detectable X-rays in the strong magnetic fields surrounding these…
The recent discovery of the "weak field, old magnetar", the soft gamma repeater SGR 0418+5729, whose dipole magnetic field is less than 7.5 \times 10^{12} G, has raised perplexing questions: How can the neutron star produce SGR-like bursts…
The anomalous X-ray pulsars (AXPs) represent a growing class of neutron stars discovered at X-ray energies. While the nature of their multi-wavelength emission mechanism is still under debate, evidence has been recently accumulating in…
A number of Anomalous X-ray Pulsars (AXPs) have recently been detected in the optical/IR wavelengths. We use their inferred brightness to place general constraints on any model for this emission within the magnetar framework. We find that…
Marsden, Lingenfelter, Rothschild & Higdon have given arguments against the magnetar model for Soft Gamma Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs), as forcefully advocated by R. Rothschild at this meeting. We critique these…
Besides being among the most promising sources of gravitational waves, merging neutron star binaries also represent a leading scenario to explain the phenomenology of short gamma-ray bursts (SGRBs). Recent observations have revealed a large…
Supersoft X-ray sources (SSSs) host white dwarfs (WDs) accreting at rates that sustain steady nuclear burning, driving rapid mass growth, radial contraction, and magnetic field amplification. Angular-momentum transfer from the accretion…
We discuss some aspects of Sousa et al.(2020a, 2020b) concerning two mechanisms of gravitational wave (GW) emission in fast-spinning white dwarfs (WDs): accretion of matter and magnetic deformation. In both cases, the GW emission is…
Recent observations with the Imaging X-ray Polarimetry Explorer (IXPE) of two anomalous X-ray pulsars provided evidence that X-ray emission from magnetar sources is strongly polarized. Here we report on the joint IXPE and XMM-Newton…
Strong magnetic field of accreting neutron stars ($10^{14}$ G) is hard to probe by X-ray spectroscopy but can be indirectly inferred from spin-up/spin-down measurement in X-ray pulsars. The existing observations of slowly rotating X-ray…
Over the past couple of decades, researchers have predicted more than a dozen super-Chandrasekhar white dwarfs from the detections of over-luminous type Ia supernovae. It turns out that magnetic fields and rotation can explain such massive…
A neutron star with mass close to the lower limit might be a reasonable model for some anomalous pulsars. Emission is thermal. X-ray luminosity is high. Spatial velocity can be high. Since the radius is predicted to be large, the magnetic…
X-ray pulsars shine thanks to the conversion of the gravitational energy of accreted material to X-ray radiation. The accretion rate is modulated by geometrical and hydrodynamical effects in the stellar wind of the pulsar companions and/or…
The nature of AXPs/SGRs (anomalous X-ray pulsars/soft $\gamma$-ray repeaters) and high field radio pulsars is still unclear even in the magnetar and/or accretion models. The detection of radio emission from AXP XTE J1810$-$197 and the…
We make use of the high photometric precision of Kepler to search for periodic modulations among 14 normal (DA- and DB-type, likely non-magnetic) hot white dwarfs (WDs). In five, and possibly up to seven of the WDs, we detect periodic, ~2…
Anomalous X-ray Pulsars and Soft-Gamma Repeaters groups are magnetar candidates featuring low characteristic ages ($\tau = {P\over{2 {\dot P}}}$). At least some of them they should still be associated with the remnants of the explosive…