NICER follow-up of the Be/X-ray binary pulsar IGR J06074+2205 in outburst

ATel #16401; M. Nakajima, H. Negoro (Nihon U.), T. Mihara (RIKEN), M. Sugizaki (NAOC), W. Iwakiri (Chiba U.), K. Gendreau, Z. Arzoumanian (NASA/GSFC)
on 12 Jan 2024; 00:37 UT
Credential Certification: Motoki Nakajima (nakajima.motoki@nihon-u.ac.jp)

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We report on observational results for the Be/X-ray binary pulsar IGR J06074+2205 by NICER. Following the outburst report made by MAXI/GSC (ATel#16394), NICER observations were performed from 2023-12-28T01:35(UT) to 2023-12-29T22:45(UT). We analyzed the first 3.6 ksec of exposure. A clear periodic variation was seen in the 0.5-10 keV light curve. A pulsation search shows that there is a strong periodicity of 374.6 seconds, which is comparable to the previous result reported by Reig et al. (2018). The 0.5-10 keV light curve was folded with this pulse period to obtain the pulse profile. The folded light curve above 1 keV showed a double-peak profile, whereas below 1 keV it became a single-peak profile. The pulse fraction increased from 50% to 70% with increasing energy. The NICER 0.5-10 keV spectrum can be fitted with an absorbed cutoff power-law model (hydrogen column density 0.76±0.02×10²² cm^-2; photon index 0.58±0.07; cutoff energy=8.7^+1.8_-1.2 keV). The absorbed source flux in 0.5-10 keV is 2.1×10^-10 ergs cm^-2 s^-1. The observed flux value is consistent with the MAXI/GSC observations on average from December 24 to December 31, 2023.

NICER is a 0.2-12 keV X-ray telescope operating on the International Space Station. The NICER mission and portions of the NICER science team activities are funded by NASA.