Volume 602, June 2017
|Number of page(s)||7|
|Section||Stellar structure and evolution|
|Published online||22 June 2017|
Swift monitoring of the massive X-ray binary SAX J0635.2+0533
INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, via E. Bassini 15, 20133 Milano, Italy
Received: 29 March 2017
Accepted: 6 May 2017
SAX J0635.2+0533 is a binary pulsar with a very short pulsation period (P = 33.8 ms) and a high long-term spin down (Ṗ> 3.8 × 10-13 s s-1), which suggests a rotation-powered (instead of an accretion-powered) nature for this source. While it was discovered at a flux level around 10-11 erg cm-2 s-1, between 2003 and 2004, this source was detected with XMM–Newton at an average flux of about 10-13 erg cm-2 s-1; moreover, the flux varied by over one order of magnitude on timescales of a few days, sometimes decreasing to below 3 × 10-14 erg cm-2 s-1. Since both the rotation-powered and the accretion-powered scenarios have difficulties to explain these properties, the nature of SAX J0635.2+0533 is still unclear. Here we report on our recent long-term monitoring campaign on SAX J0635.2+0533 carried out with Swift, and on a systematic reanalysis of all the RXTE observations performed between 1999 and 2001. We found that during this time interval, the source remained almost always active at a flux level above 10-12 erg cm-2 s-1.
Key words: stars: individual: SAX J0635+0533 / X-rays: binaries
© ESO, 2017
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.