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Spectral study of X-ray sources in some galaxies recently observed by Chandra

  • Amom Lanchenbi Chanu,
  • Anoubam Senorita Devi

摘要

With the aim to study the spectral properties of some X-ray sources from recently observed Chandra data, 9 galaxies which have been observed by Chandra ACIS-S during the year 2018 to 2022 have been considered for the present work. 27 sources with net source counts \( \ge 100\) 100 have been considered. The spectra of all the sources were fitted using two empirical models-an absorbed powerlaw and an absorbed disk blackbody. Based on their estimated bolometric luminosities, the 27 X-ray sources have been classified into 6 X-ray binaries (XRBs) and 21 Ultraluminous X-ray sources (ULXs). All the six XRBs are found to be in the spectrally hard state ( \(\Gamma \sim 1.52-2.29\) Γ 1.52 - 2.29 ) which indeed may be due to thermal comptonization. Only one ULX-CXOUJ032251.2-370950 (X-5) was found to be spectrally soft while the remaining 20 ULXs were spectrally hard. The spectral parameters of X-5 with an inner disk temperature (kT \(_\textrm{in}\) in ) \(\sim \) 0.5 keV and an estimated bolometric luminosity, L \(_X \sim 3.26 \times 10^{39}\) X 3.26 × 10 39 erg s \(^{-1} \) - 1 requires a black hole of mass, \( M_\textrm{BH} \sim 137.86^{+66.62}_{-47.41} M_\odot \) M BH 137 . 86 - 47.41 + 66.62 M accreting at \( \sim 0.19 \) 0.19 times its Eddington limit. 8 ULXs-X-4, X-8, X-9, X-10, X-11, X-12, X-20 and X-21 were found to be in the Extremely luminous X-ray sources (ELXs) regime with even their lower limit of luminosity \(> 10^{40}\) > 10 40 erg s \(^{-1}\) - 1 . Softening/Hardening of spectra with or without changes in the luminosity were also observed in some ULXs/ELXs. In the hard ELX, X-8, spectral softening with almost consistent luminosity was observed. While in the ULXs-X-20 and X-25 spectral softening with increasing luminosity was observed. However, spectral hardening with increase in luminosity were observed in the ULXs-X-21 and X-26.