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http://hdl.handle.net/20.500.12386/27739
Title: | The two ultraluminous X-ray sources in the galaxy NGC 925 | Authors: | Pintore, Fabio ZAMPIERI, Luca MEREGHETTI, Sandro WOLTER, Anna Luisa Maria RODRIGUEZ CASTILLO, Guillermo Andres ISRAEL, Gian Luca Esposito, P. PAIANO, Simona TRINCHIERI, Ginevra Ochner, P. |
Issue Date: | 2018 | Journal: | MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | Number: | 479 | Issue: | 3 | First Page: | 4271 | Abstract: | NGC 925 ULX-1 and ULX-2 are two ultraluminous X-ray sources (ULXs) in the galaxy NGC 925, at a distance of 8.5 Mpc. For the first time, we analysed high quality, simultaneous XMM-Newton and NuSTAR data of both sources. Although at a first glance ULX-1 resembles an intermediate mass black hole candidate (IMBH) because of its high X-ray luminosity [(2-4) × 10<SUP>40</SUP> erg s<SUP>-1</SUP>] and its spectral/temporal features, a closer inspection shows that its properties are more similar to those of a typical super-Eddington accreting stellar black hole and we classify it as a `broadened disc' ULX. Based on the physical interpretation of this spectral state, we suggest that ULX-1 is seen at small inclination angles, possibly through the evacuated cone of a powerful wind originating in the accretion disc. The spectral classification of ULX-2 is less certain, but we disfavour an IMBH accreting at sub-Eddington rates as none of its spectral/temporal properties can be associated with either the soft or the hard state of Galactic accreting black hole binaries. | URI: | http://hdl.handle.net/20.500.12386/27739 | URL: | https://academic.oup.com/mnras/article/479/3/4271/5049028 | ISSN: | 0035-8711 | DOI: | 10.1093/mnras/sty1766 | Bibcode ADS: | 2018MNRAS.479.4271P | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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