Title:	Detection of a cyclotron line in the Be X-ray pulsar IGR J06074+2205
Authors:	Roy, Kinjal Sharma, Rahul Manikantan, Hemanth Paul, Biswajit
Keywords:	pulsars individual (IGR J0607.4+2205) — X-rays binaries — X-rays bursts
Issue Date:	15-Feb-2024
Publisher:	EDP Sciences
Citation:	Astronomy and Astrophysics, 2024
Abstract:	Context. IGR J0607.4+2205 is a transient Be X-ray binary discovered two decades ago. IGR J0607.4+2205 underwent an outburst in 2023 during which it was observed twice with NuSTAR. Aims. The main goal of this work is to model the broadband X-ray spectrum of IGR J0607.4+2205 during the outburst and to study the variations of the spectral and timing features at di erent intensities. Methods. We extracted the light curve and spectrum of the source from the two NuSTAR observations carried out during the recent outburst in the energy range of 3􀀀78 keV. We used the epoch folding technique to find pulsation from the source and to study the changes in emission characteristics from the source with energy across an order of magnitude variation in source luminosity. Results. IGR J0607.4+2205 shows pulsations with a period of 347.6 s during both the observations, with a pulse fraction of 50%. The broadband spectrum of the source was modelled using a power-law continuum with a high-energy cuto . During the first observation, a cyclotron absorption line at 51 keV was also present in the source with an optical depth of 1.3. However, no cyclotron line feature was detected in the second observation when the source was an order of magnitude fainter. Additionally, soft excess was detected in the second observation, which was modelled with a black body component emerging from close to the neutron star (NS). Conclusions. We report the first ever detection of a cyclotron line in the broadband spectrum of IGR J0607.4+2205 centred at 51 1 keV. The magnetic field strength of the NS is estimated to be 4 1012 G from the centroid energy of the absorption line. A significant change is observed in the pulse profile with luminosity during the decay of the outburst, indicating an associated change in the beaming pattern.
Description:	Restricted Access
URI:	http://hdl.handle.net/2289/8278
Alternative Location:	https://ui.adsabs.harvard.edu/abs/2024arXiv240217382R/abstract https://arxiv.org/abs/2402.17382 https://doi.org/10.1051/0004-6361/202348998
Copyright:	2024,The Author(s)
Appears in Collections:	Research Papers (A&A)

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