Resolved atomic lines reveal outflows in two ultraluminous X-ray sources

Pinto, C.; Middleton, M.; Fabian, A. C.

doi:10.1038/nature17417

Cited by 239 publications

(380 citation statements)

References 29 publications

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“…Even if we allow for the possibility of < p 0.6 in a sub-Eddington disk, the presence of strong line residuals in the soft X-ray band is another, stronger piece of evidence against the standard disk model. It is instead indicative of Eddington accretion and associated outflows (Middleton et al 2015b;Pinto et al 2016a). For these reasons, we disfavor the sub-Eddington standard disk model for ULX-1.…”

Section: Spectral Models For Ulx-1mentioning

confidence: 99%

Two Eclipsing Ultraluminous X-Ray Sources in M51

Urquhart

Soria

2016

ApJ

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We present the discovery, from archival Chandra and XMM-Newton data, of X-ray eclipses in two ultraluminous X-ray sources (ULXs), located in the same region of the galaxy M51: CXOM51 J132940.0+471237 (ULX-1, for simplicity) and CXOM51 J132939.5+471244 (ULX-2). Three eclipses were detected for ULX-1 and two for ULX-2. The presence of eclipses puts strong constraints on the viewing angle, suggesting that both ULXs are seen almost edge-on and are certainly not beamed toward us. Despite the similar viewing angles and luminosities ( »Ĺ 2 10 X 39 erg s −1 in the 0.3-8 keV band for both sources), their X-ray properties are different. ULX-1 has a soft spectrum, well fitted by Comptonization emission from a medium with electron temperature » kT 1 keV e . ULX-2 is harder, well fitted by a slim disk with » kT 1.5 in -1.8 keV and normalization consistent with a ∼10 M e black hole. ULX-1 has a significant contribution from multi-temperature thermal-plasma emission ( »Ĺ 2 10 X,mekal 38 erg s −1 ). About 10% of this emission remains visible during the eclipses, proving that the emitting gas comes from a region slightly more extended than the size of the donor star. From the sequence and duration of the Chandra observations in and out of eclipse, we constrain the binary period of ULX-1 to be either »6.3 days, or ≈12.5-13 days. If the donor star fills its Roche lobe (a plausible assumption for ULXs), both cases require an evolved donor, most likely a blue supergiant, given the young age of the stellar population in that Galactic environment.

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Section: Spectral Models For Ulx-1mentioning

confidence: 99%

Two Eclipsing Ultraluminous X-Ray Sources in M51

Urquhart

Soria

2016

ApJ

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“…Observationally, the detection of soft X-ray spectral residuals (Middleton et al 2014(Middleton et al , 2015b and emission/absorption lines (Pinto et al 2016) in ULXs have been argued as a signature of outflows associated with supercritical accretion. An absorption edge near 1 keV is detected in the 2009 XMM-Newton observation of NGC 247 ULX, and is also detected from several other soft ULXs (Antennae, M51, M101, and NGC 4631; see Table 4 in Urquhart & Soria 2016).…”

Section: Signatures Of Outflowsmentioning

confidence: 99%

Nature of the Soft Ulx in NGC 247: Super-Eddington Outflow and Transition Between the Supersoft and Soft Ultraluminous Regimes

Feng

Tao

Kaaret

et al. 2016

ApJ

100

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We report on XMM-Newton/Chandra/Swift/Hubble Space Telescope observations of the ultraluminous X-ray source (ULX) in NGC 247, which is found to make transitions between the supersoft ultraluminous (SSUL) regime with a spectrum dominated by a cool (∼0.1 keV) blackbody component and the soft ultraluminous (SUL) regime with comparable luminosities shared by the blackbody and power-law components. Multi-epoch observations revealed an anti-correlation between the blackbody radius and temperature, µ - R T bb bb 2.8 0.3 , ruling out a standard accretion disk as the origin of the soft X-ray emission. The soft X-ray emission is much more variable on both short and long timescales in the SSUL regime than in the SUL regime. We suggest that the SSUL regime may be an extension of the ultraluminous state toward the high accretion end, being an extreme case of the SUL regime, with the blackbody emission arising from the photosphere of thick outflows and the hard X-rays being emission leaked from the embedded accretion disk via the central low-density funnel or advected through the wind. However, the scenario that the supersoft ULXs are standard ULXs viewed nearly edge-on cannot be ruled out. Flux dips on a timescale of 200 s were observed. The dips cannot be explained by an increase of absorption, but could be due to the change of accretion rate or related to thermal fluctuations in the wind or disk. The optical emission of NGC 247 ULX exhibits a blackbody spectrum at a temperature of 19,000K with a radius of 20  R , likely arising from an OB supergiant companion star.

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“…From Figure 4 it is clear that the strongest spectral change is observed in p. At super-Eddington accretion rates, it is expected that the accretion disk is flared up due to radiation pressure, i.e., itbecomes geometrically thick and increases in size with radius. In addition, a strong wind is launched, which is also largely optically thick (Poutanen et al 2007;Dotan & Shaviv 2011) and for which observational evidence has recently been found in NGC 1313X-1 and NGC 5408X-1 (Pinto et al 2016;Walton et al 2016b). The observed temperature profile, therefore, depends on which parts and with what angle we observe the accretion disk.…”

Section: Connection Between the Super-orbital Period And Spectral Chamentioning

confidence: 99%

Spectral Changes in the Hyperluminous Pulsar in NGC 5907 as a Function of Super-Orbital Phase

Fürst

Walton

Stern

et al. 2017

ApJ

103

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We present broadband, multi-epoch X-ray spectroscopy of the pulsating ultra-luminous X-ray source (ULX) in NGC 5907. Simultaneous XMM-Newton and NuSTAR data from 2014 are best described by a multicolor blackbody model with a temperature gradient as a function of accretion disk radius significantly flatter than expected for a standard thin accretion disk ( µ -T r r p ( ) , with = -+ p 0.608 0.012 0.014 ). Additionally, we detect a hard power-law tail at energies above 10 keV, which we interpret as being due to Comptonization. We compare this observation to archival XMM-Newton, Chandra, and NuSTAR data from 2003, 2012, and 2013, and investigate possible spectral changes as a function of phase over the 78-daysuper-orbital period of this source. We find that observations taken around phases 0.3-0.4 show very similar temperature profiles, even though the observed flux varies significantly, while one observation taken around phase 0 has a significantly steeper profile. We discuss these findings in light of the recent discovery that the compact object is a neutron star and show that precession of the accretion disk or the neutron star can self-consistently explain most observed phenomena.

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Resolved atomic lines reveal outflows in two ultraluminous X-ray sources

Cited by 239 publications

References 29 publications

Two Eclipsing Ultraluminous X-Ray Sources in M51

Two Eclipsing Ultraluminous X-Ray Sources in M51

Nature of the Soft Ulx in NGC 247: Super-Eddington Outflow and Transition Between the Supersoft and Soft Ultraluminous Regimes

Spectral Changes in the Hyperluminous Pulsar in NGC 5907 as a Function of Super-Orbital Phase

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