Bibcode
Durant, Martin
Bibliographical reference
40 YEARS OF PULSARS: Millisecond Pulsars, Magnetars and More. AIP Conference Proceedings, Volume 983, pp. 280-282 (2008).
Advertised on:
2
2008
Citations
0
Refereed citations
0
Description
Finding distances in astronomy is notoriously difficult. With accurate
optical spectroscopy, both the distance to and extinction (reddening) of
normal stars can be found, but this is not possible for X-ray sources.
It is possible, however, to measure the extincting column from an X-ray
spectrum from photoelectric ionisation edges. It is also possible to
construct the function of reddening along the line of sight using field
red-clump (helium-burning giants) stars in the infrared. I will
demonstrate this method to derive distances for the Anomalous X-ray
Pulsars (AXPs). With these new distances, it turns out that all the AXPs
have remarkably similar 2-10 keV luminosities, a clue to their internal
processes.
Our method succeeds for the AXPs, despite its many-step nature and
poorly defined conversions. This hints that the two measurables
involved-soft-X-ray extinction and infrared reddening-are far better
correlated than the separate relations linking them would initially
suggest. Such a correlation would be very useful, and the observational
resources exist to be able to establish it.