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

Abstract

With the aim to study the spectral properties of some X-ray sources from recently observed {\it Chandra} data, 9 galaxies which have been observed by {\it Chandra} ACIS-S during the year 2018 to 2022 have been considered for the present work. 27 sources with net source counts $\ge$ 100 have been considered. The spectra of all the sources were fitted using two empirical models -- an absorbed powerlaw and an absorbed disk blackbody. From their estimated bolometric luminosities, the 27 X-ray sources are categorized as 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) 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${}_{in}$) $\sim$ 0.5 keV and an estimated bolometric luminosity, L${}_X\sim$ 3.26 $\times$ 10${}^{39}$ erg s${}^{-1}$ requires a black hole of mass, M${}_{BH}\sim$ 137.86${}_{-47.41}^{+66.62}$ M${}_{\odot }$ accreting at $\sim$ 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${}^{40}$ erg s${}^{-1}$. 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.

arXiv commentPublished in Indian Journal of Physics

References in corpus (45)

• HI4PI: A full-sky HI survey based on EBHIS and GASS
• GW190521: A Binary Black Hole Merger with a Total Mass of $150M_{\odot }$
• An Ultraluminous X-ray Source Powered by An Accreting Neutron Star
• Ultraluminous X-Ray Sources in External Galaxies
• Ultraluminous X-Ray Sources
• The Ultra-Luminous X-ray Source Population from the Chandra Archive of Galaxies
• Missing Link Found? --- The ``runaway'' path to supermassive black holes
• Discovery of pulsations from NGC 300 ULX1 and its fast period evolution
• A mass of less than 15 solar masses for the black hole in an ultraluminous X-ray source
• The Transition from Inspiral to Plunge for a Compact Body in a Circular Equatorial Orbit Around a Massive, Spinning Black Hole
• Puzzling accretion onto a black hole in the ultraluminous X-ray source M101 ULX-1
• X-ray observations of ultraluminous X-ray sources
• The discovery of weak coherent pulsations in the ultraluminous X-ray source NGC 1313 X-2
• Ultraluminous X-ray sources
• Discovery of a 2.8 s pulsar in a 2 d orbit High-Mass X-ray Binary powering the Ultraluminous X-ray source ULX-7 in M51
• The most extreme ultraluminous X-ray sources: evidence for intermediate-mass black holes?
• Diagnosing the accretion flow in ultraluminous X-ray sources using soft X-ray atomic features
• Spitzer Observations of White Dwarfs: the Missing Planetary Debris Around DZ Stars
• A census of ultraluminous X-ray sources in the local Universe
• Investigating slim disk solutions for HLX-1 in ESO 243-49
• Spectral State Transitions of the Ultraluminous X-ray Sources X-1 and X-2 in NGC 1313
• A new, clean catalogue of extragalactic non-nuclear X-ray sources in nearby galaxies
• A Hard X-Ray Study of Ultraluminous X-ray Source NGC 5204 X-1 with NuSTAR and XMM-Newton
• The Long-Term Variability of the X-Ray Sources in NGC 6946 and NGC 4485/4490
• Spectral state transitions in low-mass X-ray binaries - the effect of hard and soft irradiation
• A bright ultraluminous X-ray source in NGC 5907
• The K-band luminosity functions of super star clusters in luminous infrared galaxies, their slopes, and the effects of blending
• Multiband counterparts of two eclipsing ultraluminous X-ray sources in M 51
• The ultraluminous X-ray source population of NGC 4485/4490
• X-Ray Spectral Variability of Ultraluminous X-Ray Sources in Extragalactic Globular Clusters
• Disentangling the ISM phases of the dwarf galaxy NGC 4214 using [CII] SOFIA/GREAT observations
• Compact radio emission in Ultraluminous X-ray sources
• The Chandra Local Volume Survey I: The X-ray Point Source Populations of NGC 55, NGC 2403, and NGC 4214
• The dependence of the estimated luminosities of ULX on spectral models
• Broadband X-ray spectral variability of the pulsing ULX NGC 1313 X-2
• The Luminous X-Ray Halos of Two Compact Elliptical Galaxies
• Discovery of a 3.6-hr Eclipsing Luminous X-Ray Binary in the Galaxy NGC 4214
• NGC1600 - Cluster or Field Elliptical?
• The spectral and temporal properties of an Ultra-Luminous X-ray source in NGC 6946
• Long-term Spectral Variability of the Ultra-luminous X-ray source Holmberg IX X--1
• Optical Counterparts of ULXs and Their Host Environments in NGC 4490/4485
• X-ray spectral and optical properties of a ULX in NGC 4258 (M106)
• First characterization of Swift J1845.7-0037 with NuSTAR
• Ultra-luminous X-ray sources: extreme accretion and feedback
• Constraints on accretion in Ultraluminous X-ray Sources from Spitzer IRS observations of NGC 4485/90: Infrared diagnostic diagrams