Distances to Anomalous X-ray Pulsars using Red Clump Stars
نویسنده
چکیده
We identify “red clump stars” – core helium-burning giants – among 2MASS stars and use them to measure the run of reddening with distance in the direction of each of the Galactic Anomalous X-ray Pulsars (AXP). We combine this with extinction estimates from X-ray spectroscopy to infer distances and find that the locations of all AXP are consistent with being in Galactic spiral arms. We also find that the 2–10 keV luminosities implied by our distances are remarkably similar for all AXP, being all around ∼ 1.3 × 10 erg s. Furthermore, using our distances to estimate effective black-body emitting radii, we find that the radii are tightly anti-correlated with pulsed fraction, and somewhat less tightly anti-correlated with black-body temperature. We find no obvious relationship of any property with the dipole magnetic field strength inferred from the spin-down rate. Subject headings: pulsars: anomalous X-ray pulsars, distance measurement, ISM, reddening
منابع مشابه
To appear in ApJL The distance to the Fornax dwarf galaxy using red clump stars, and the discrepancy between red clump and tip of the red giant branch distances
The distance to the Fornax dwarf galaxy using red clump stars, and the discrepancy between red clump and tip of the red giant branch distances ABSTRACT I determine a distance to the Fornax dwarf galaxy using stars in the red clump and at the tip of the red giant branch. They are in very good agreement, with µ 0 = 20.66 mag. Comparing the magnitudes of the tip of the red giant branch and of the ...
متن کاملA Glitch in an Anomalous X-ray Pulsar
We report the detection of a sudden spin-up of the 11 s anomalous X-ray pulsar 1RXS J170849.0−4000910 in regular timing observations made with the Rossi X-ray Timing Explorer. The event, which occurred between MJD 51446 (1999 September 25) and 51472 (1999 October 21), is well characterized by an increase in the rotational frequency of magnitude |∆ν/ν| = (6.2±0.3)×10−7 and an increase in the rat...
متن کاملPulsars and quark stars
Members of the family of pulsar-like stars are distinguished by their different manifestations observed, i.e., radio pulsars, accretion-driven X-ray pulsars, X-ray bursts, anomalous X-ray pulsars/soft gamma-ray repeaters, compact center objects, and dim thermal neutron stars. Though one may conventionally think that these stars are normal neutron stars, it is still an open issue whether they ar...
متن کاملForty Years of X-Ray Binaries
In 2012 it was forty years ago that the discovery of the first X-ray binary Centaurus X-3 became known. That same year it was discovered that apart from the High-Mass X-ray Binaries (HMXBs) there are also Low-Mass X-ray Binaries (LMXBs), and that Cygnus X-1 is most probably a black hole. By 1975 also the new class of Be/X-ray binaries was discovered. After this it took 28 years before ESAs INTE...
متن کاملNeutron Stars in X-ray Pulsars and Their Magnetic Fields
Estimates of the magnetic field of neutron stars in X-ray pulsars are obtained using the hypothesis of the equilibrium period for disk and wind accretion and also from the BATSE data on timing of X-ray pulsars using the observed maximum spin-down rate. Cyclotron lines at energies ≥ 100 keV in several Be-transient are predicted for future observations. We suggest a new method of estimating dista...
متن کامل