Spectral study of neutron star low mass X-ray binary source 1A 1744-361

Abstract

We present X-ray observations of the recent outburst of 2022 from the neutron star low mass X-ray binary (LMXB) source 1A 1744-361. Spectral properties of the source have been analyzed using joint NuSTAR and NICER observations. During our observations, the source happens to be in the banana state (soft state) of the hardness intensity diagram (HID). In addition to a power-law with a high energy cutoff, the spectrum is found to exhibit broad iron $K_{\alpha}$ emission along with distinct absorption features. A prominent absorption feature observed at 6.92 keV may be interpreted as $K_{\alpha}$ absorption line from hydrogen-like iron. The absorption feature observed at 7.98 keV may be interpreted as a blend of Fe XXV and Ni XXVII transitions. We have summarized the evidence of variability of the spectral features observed in the X-ray continuum by time-resolved spectroscopy.