XMM-Newton Detection of Type I X-ray burst and Spectral Features Of EXO 0748-676
ATel #16703; Sayantan Bhattacharya (Umass Lowell), Sudip Bhattacharyya (TIFR, Mumbai)
on 11 Jul 2024; 18:56 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Sayantan Bhattacharya (sayantan34@gmail.com)
Subjects: X-ray, Binary, Neutron Star, Transient
EXO 0748-676 is a Low Mass X-ray Binary (LMXB) system with a neutron star as a compact object. It recently went into an outburst after 16 years of quiescence. EXO 0748-676 was discovered in 1985 by the EXOSAT satellite (Parmar et al. 1986) and remained X-ray active until August 2008. The source was detected recently by Swift/BAT & MAXI with enhanced X-ray activity (ATel#16646,#16655). NuSTAR recently observed the source in hard X-rays (ATel#16673). Optical observations have confirmed that this object has entered the outburst phase (ATel#16646, #16648, #16649).
XMM-Newton observed EXO 0748-676 on 2024-06-30 14:30:35 UTC (DDT-TOO Obsid: 0935191701, PI: Dr. Norbert Schartel). A type I x-ray burst is observed in the combined EPIC lightcurve at MJD 60492.311. The MOS spectra fitted with pcfabs and cutoffpl model (nH = 19.8+-0.9x10^22 cm-2, coverfrac = 0.919+-0.007, photon Index = 1.89+-0.09, HighECut=0.98+-0.02, norm=1.6+-0.2). This gives a 0.2 - 10 KeV flux in the range of 3.878e-09 - 4.187e-09 ergs/cm^2/s. The RGS (1+2) high-resolution spectrum shows a broad O VII x,y emission feature at 21.8 Angstrom, this is also mentioned in Cottam et. al. 2008 (J. Cottam et al 2008 ApJ 672 504), this feature was present in the early burst phase and then disappeared in the late burst phase. We observe it reappear now, further analysis is in progress and will be published soon. Multiwavelength monitoring of this ongoing outburst is encouraged.