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Title: Super-Eddington accretion on to a stellar mass ultraluminous X-ray source NGC 4190 ULX1
Authors: Ghosh, Tanuman
Rana, Vikram
Keywords: accretion
accretion discs
X-rays: binaries
X-rays: individual (NGC 4190 ULX1)
Issue Date: Jun-2021
Publisher: Oxford University Press on behalf of the Royal Astronomical Society
Citation: Monthly Notices of the Royal Astronomical Society, 2021, Vol. 504, p974–982
Abstract: 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) × 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.
Description: Restricted Access. An open-access version is available at (one of the alternative locations)
ISSN: 0035-8711
1365-2966 (Online)
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Copyright: 2021 The Author(s)
Appears in Collections:Research Papers (A&A)

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