2021MNRAS.504..974G -
Mon. Not. R. Astron. Soc., 504, 974-982 (2021/June-2)
Super-Eddington accretion on to a stellar mass ultraluminous X-ray source NGC 4190 ULX1.
GHOSH T. and RANA V.
Abstract (from CDS):
We present the results of high-quality XMM-NEWTON observations of a ultraluminous X-ray source (ULX) in the galaxy NGC 4190. The detection of spectral cutoff in NGC 4190 ULX1 spectra rules out the interpretation of the ULX to be in a standard low/hard canonical accretion state. We report that the high quality EPIC spectra can be better described by broad thermal component, such as a slim disc. In addition we found long-term spectral and flux variability in the source using several XMM-NEWTON and Swift data. A clear anticorrelation between flux and power-law photon index is found which further confirms the unusual spectral state evolution of the ULX. Spectral properties of the ULX suggest that the source is in a broadened disc state with luminosities [≃(3 - 10) x 1039 erg s–1] falling in the ultraluminous regime. The positive luminosity-temperature relation further suggests that the multicolour disc model follows the L ∝ T4 relation that is expected for a blackbody disc emission from a constant area and the slim disc model seems to favour L ∝ T2 relation consistent with an advection-dominated disc emission. From the broadened disc-like spectral feature at such luminosity, we estimated the upper limit of the mass of the central compact object from the inner disc radius and found that the ULX hosts a stellar mass black hole.
Abstract Copyright:
© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society
Journal keyword(s):
accretion, accretion discs - X-rays: binaries - X-rays: individual: (NGC 4190 ULX1)
Errata:
erratum vol. 522, p. 1183 (2023)
Simbad objects:
4
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