Anomalous X-ray pulsar

Highly magnetized neutron star

Anomalous X-ray pulsars (AXPs) are an observational manifestation of magnetars—young, isolated, highly magnetized neutron stars. These energetic X-ray pulsars are characterized by slow rotation periods of ~2–12 seconds and large magnetic fields of ~10¹³–10¹⁵ gauss (1 to 100 gigateslas). As of 2017^[update], there were 12 confirmed and 2 candidate AXPs known.^[1] The identification of AXPs with magnetars was motivated by their similarity to soft gamma repeaters.

The AXP candidates and their estimated rotation period in seconds, as of 2003^[update], were:
AXP 1E 2259+586	6.98
AXP 1E 1048-59	6.45
AXP 4U 0142+61	8.69
AXP 1RXS 1708-40	11.0
AXP 1E 1841-045	11.8
AXP AXJ1844-0258	6.97
AXP CXJ0110-7211	5.44
The second, fourth, and last names have been abbreviated.

References

^ SGR/AXP Online Catalog (An online catalog of SGR/AXP properties maintained by the pulsar group at McGill University)

Sources

Van Paradijs, J.; Taam, R. E.; Van Den Heuvel, E. P. J. (1995). "On the nature of the 'anomalous' 6-s X-ray pulsars". Astronomy and Astrophysics. 299: L41. Bibcode:1995A&A...299L..41V.
Duncan, Robert C.; Thompson, Christopher (1996). "Magnetars". AIP Conference Proceedings. Vol. 366. p. 111. doi:10.1063/1.50235.
Kouveliotou, Chryssa; Duncan, Robert C.; Thompson, Christopher (2003). "Magnetars". Scientific American. 288 (2): 34. Bibcode:2003SciAm.288b..34K. doi:10.1038/scientificamerican0203-34. PMID 12561456.