Discovery of a 26.2 day period in the long-term X-ray light curve of the Be/X-ray pulsar SXP 1323
Abstract
SXP 1323 is one of the longest-period Be/X-ray pulsars known in the Small Magellanic Cloud. Analysing systematically the large set of calibration observations available for the source from Suzaku, XMM-Newton and Chandra, we discovered a 26.188+-0.045d period which confirms the optical period derived from OGLE data and that we therefore interpret as the orbital period. This period is short with respect to what is expected from the spin/orbital period relationship. We furthermore study the long term evolution of the pulse period and report a very rapid spin-up with a period decreasing from 1340s to 1100s in a time range from 2006 to end 2016. SXP 1323 is therefore a peculiar Be/X-ray binary for either the long pulse period and corresponding short orbital period, and for the rapid spin-up for several years. It is necessary to continue to monitor the source in the next years to establish the long-term behaviour of the spin period.
- Publication:
-
The X-ray Universe 2017
- Pub Date:
- October 2017
- Bibcode:
- 2017xru..conf...52C