NuSTAR detection of a broad absorption line in IGR J06074+2205

Abstract

BeXRB pulsar IGR J06074+2205 using NuSTAR observations. The temporal and spectral characteristics of the source are investigated. We detect coherent X-ray pulsations of the source and determine the spin period evolution. Using the current spin period data of the source, we show that the source is spinning down at 0.0202(2) s $da{y}^{-1}$. The pulse profiles are found to evolve with energy and luminosity. Another interesting feature of the source is that the pulse profiles are dual peaked. The dual-peaked pulse profile is characterized by a decreasing secondary peak amplitude with increasing energy. We also observed a proportionate increase in the primary peak amplitude as the energy increases. The pulse fraction exhibits an overall increasing trend with the energy. The X-ray continuum of the source indicates the existence of a characteristic absorption feature with a centroid energy ∼55 keV, which may be interpreted as a cyclotron line. We estimate the corresponding magnetic field strength to be $\sim 4.74\times {10}^{12}$ G. A peculiar ‘10 keV’ absorption feature is observed in the X-ray spectra of the second observation. The luminosity measurements predict that the source may be accreting in the sub-critical regime.