NuSTAR observation of X-ray pulsar 1E 1145.1-6141

Abstract

In this paper, we report on the hard X-ray observation of the X-ray pulsar 1E 1145.1-6141 performed with the Nuclear Spectroscopic Telescope Array mission (NuSTAR). The coherent pulsation of the source with a period of $\sim296.653\;\pm\;0.021\;s $ is detected. The source may be in the equilibrium phase, according to the most recent measurements of its pulse period. The pulse profile reveals a mild energy dependence and generally hints at a pencil-beam pattern. The pulse profile have evolved with time. The Pulse fraction is found to depend on energy with a fall in the value at $\sim 32\; keV$. The NuSTAR spectra can be approximated by a composite model with two continuum components, a blackbody emission, cut-off powerlaw, and a discrete component in the form of gaussian to account for the emission line of iron. The estimated absorbed flux of the source is $\sim6\times10^{-10}\;erg\;cm^{-2}\;s^{-1}$ which corresponds to a luminosity of $\sim5\times 10^{36}\;erg\;s^{-1}$. Pulse phase-resolved spectroscopy were performed to understand the evolution of spectral parameters with pulse phase. The estimated blackbody radius is found to be consistent with the size of the theoretical prediction.