Publications by Year: 2015

2015
Vasilopoulos G. Measuring the spin period of XMMU J004855.5-734946 during a large outburst. [Internet]. 2015:4825. WebsiteAbstract
Spin periods of Be/X-ray binary (BeXRB) pulsars are important for probing their formation channels and the connection between orbital period and pulsar spin in XRBs (Knigge+ 2011). From the 120 BeXRBs in the SMC only 50% have known spin periods, with the majority of them measured during outburst with ToOs. From the remaining systems only 6 have a known orbital period. XMMU J004855.5-734946 is a BeXRB in the SMC (Haberl & Sturm 2016, XMM Lx (0.03-1)x10^35 erg/s) with a 36.43d orbital period (Atel#9198), but with no X-ray pulsations detected so far. On 06/24 a 37s Swift/XRT observation detected the system at Lx 10^37 erg/s (Atel#9197) following a marginal detection on 06/16 (Lx<5x10^36 erg/s) confirming the onset of a large outburst. A follow-up 1ks Swift ToO on 06/29 measures an Lx = 8.3x10^36 erg/s. This is a unique opportunity to measure the spin period of one of the few BeXRBs in the SMC with known orbital period but unknown spin period.
Haberl F, Vasilopoulos G, Sturm R, Maggi P. Identification of IGR J01217-7257 with the transient pulsar XTE J0119-731 (SXP2.16) using XMM-Newton. [Internet]. 2015;8305:1. WebsiteAbstract
We report first results from our XMM-Newton observation of IGR J01217-7257 performed on November 7, 2015. This transient in the Small Magellanic Cloud (Coe et al. 2014, ATel #5806) was found to be in a new outburst during Integral observations end of October 2015 (Coe et al. 2015, ATel #8246).
Gazeas K, Vasilopoulos G, Petropoulou M, Sapountzis K. Optical follow-up of V404 Cyg during the current enhanced activity. [Internet]. 2015;7650:1. WebsiteAbstract
V404 Cyg is a known black hole Low mass X-ray binary with a late G-type companion, having a ~6.5 d orbital period. On June 15 18:32 UT Swift Burst Alert Telescope (BAT) was triggered due to the high X-ray activity of the system (Barthelmy et al.