Renewed activity of X-ray binary pulsar A 0535+262 detected by Swift/BAT, MAXI/GSC, and Fermi/GBM

ATel #14392; Manoj Mandal (MCC), Sabyasachi Pal (ICSP/MCC), Mangal Hazra (MCC), Bikram Bhunia (MCC)
on 15 Feb 2021; 12:07 UT
Credential Certification: Sabyasachi Pal (sabya.pal@gmail.com)

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We report renewed activity from the accreting transient X-ray pulsar A 0535+262 (V725 Tau) using Swift/BAT (15-50 keV) and MAXI/GSC (2-20 keV). The source was earlier reported to be in X-ray outburst several times (viz. ATel #504, #2142, #2161, #2324, #2541, #2970, #6043, #6569, #7015, #14157). Recently the source went through a giant outburst in November-December, 2020 and reached a record high value of ~12 Crab (ATel #14157, #14170). The observed spin period of the X-ray pulsar during the giant outburst was ~103.58 s (Mandal & Pal, 2020, arXiv:2012.15839).

The X-ray flux from the source started to increase from MJD 59249 (4th February 2021) and it is still increasing as detected in hard X-ray by Swift/BAT (15-50 keV) and reached a value of 70±6.3 mCrab on MJD 59259. The enhanced X-ray activity is also detected by MAXI/GSC (2-20 keV) from MJD 59248.5 and continues to rise. On MJD 59257.5, the Flux in MAXI/GSC in 2-20 keV is 44.4±8.2 mCrab and in 4-10 keV is 56.10±11.6 mCrab. The hardness ratio (4-10 keV/2-4 keV) varies between 0.6-1.5 during time-range MJD 59247-59257.

The enhanced X-ray activity from the source was also detected by Fermi/GBM (12-50 keV). The pulsed flux has started to increase from MJD 59252 and reached a maximum value of ~0.23 keV/cm²/s on MJD 59256. The spin period is ~103.507 s on MJD 59256 as measured by Fermi/GBM.

We encourage further multi-wavelength observations.

This research has made use of the MAXI data provided by RIKEN, JAXA, and the MAXI team.

Light Curve of A 0535+262