X-ray emission from the Sculptor galaxy NGC 300

Read, A. M.; Pietsch, W.

doi:10.1051/0004-6361:20010636

Cited by 41 publications

(62 citation statements)

References 31 publications

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“…The mean absorbed luminosity in the 0.2-10 keV energy band is 1.5 × 10 38 erg s −1 , which is close to that found from the XMM-Newton data, L 0.2−10 keV ∼ 2×10 38 erg s −1 (Carpano et al 2007) and close to the ROSAT value, L 0.1−2.4 keV ∼ 2.2 × 10 38 erg s −1 (Read & Pietsch 2001). …”

Section: Time Analysis Of Swift Light Curvesupporting

confidence: 86%

A 33 hour period for the Wolf-Rayet/black hole X-ray binary candidate NGC 300 X-1

Carpano

Pollock

Prestwich

et al. 2007

A&A

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Context. NGC 300 X-1 is the second extragalactic candidate, after IC 10 X-1, in the rare class of Wolf-Rayet/compact object X-ray binary systems exemplified in the Galaxy by Cyg X-3. From a theoretical point of view, accretion onto a black hole in a detached system is possible for large orbital periods only if the mass of the relativistic object is high or the velocity of the accreted wind is low. Aims. We analysed a 2 week SWIFT XRT light curve of NGC 300 X-1 and searched for periodicities. Methods. Period searches were made using Lomb-Scargle periodogram analysis. We evaluated the confidence level using Monte Carlo simulations. Results. A period of 32.8 ± 0.4 h (3σ error) was found for NGC 300 X-1 with a confidence level >99%. Furthermore, we confirm the high irregular variability during the high flux level, as already observed in the XMM-Newton observations of the source. A folded XMM-Newton light curve is shown, with a profile that is in agreement with SWIFT. The mean absorbed X-ray luminosity in the SWIFT observations was 1.5 × 10 38 erg s −1 , close to the value derived from the XMM-Newton data. Conclusions. While Cyg X-3 has a short period of 4.8 h, the period of NGC 300 X-1 is very close to that of IC 10 X-1 (34.8 ± 0.9 h). These are likely orbital periods. Possibility of formation of accretion disk for such high orbital periods strongly depends on the terminal velocity of the Wolf-Rayet star wind and black-hole mass. While low masses are possible for wind velocities 1000 km s −1 , these increase to several tens of solar masses for velocities >1600 km s −1 and no accretion disk may form for terminal velocities larger than 1900 km s −1 .

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Section: Time Analysis Of Swift Light Curvesupporting

confidence: 86%

A 33 hour period for the Wolf-Rayet/black hole X-ray binary candidate NGC 300 X-1

Carpano

Pollock

Prestwich

et al. 2007

A&A

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“…Nor do we find a X-ray counterpart for clump "A" in the source list of Read & Pietsch (2001), who observed the NGC 300 field for 46 ksec with ROSAT PSPC. Clump "C" is slightly outside the ROSAT field of view.…”

Section: X-ray Observations Of the Ngc 300 Fieldcontrasting

confidence: 77%

GaBoDS: The Garching-Bonn Deep Survey

Schirmer

Erben

Schneider

et al. 2003

A&A

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Abstract. The Garching-Bonn Deep Survey (GaBoDS) is a virtual 12 square degree cosmic shear and cluster lensing survey, conducted with the WFI@2.2 m MPG/ESO telescope at La Silla. It consists of shallow, medium and deep random fields taken in R-band in subarcsecond seeing conditions at high galactic latitude. A substantial amount of the data was taken from the ESO archive, by means of a dedicated ASTROVIRTEL program. In the present work we describe the main characteristics and scientific goals of GaBoDS. Our strategy for mining the ESO data archive is introduced, and we comment on the Wide Field Imager data reduction as well. In the second half of the paper we report on clusters of galaxies found in the background of NGC 300, a random archival field. We use weak gravitational lensing and the red cluster sequence method for the selection of these objects. Two of the clusters found were previously known and already confirmed by spectroscopy. Based on the available data we show that there is significant evidence for substructure in one of the clusters, and an increasing fraction of blue galaxies towards larger cluster radii. Two other mass peaks detected by our weak lensing technique coincide with red clumps of galaxies. We estimate their redshifts and masses, and check for possible X-ray counterparts in deep XMM observations.

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“…(iv) NGC 300 SSS1. Originally found in a ROSAT observation from 1992 (Read & Pietsch 2001), this source exhibits bright and dim states. For example, it was not seen by ROSAT in later observations but was seen by XMM-Newton in a bright state in 2000 December and became an order of magnitude dimmer in another XMM-Newton observation only 6 days later .…”

Section: Definition Of Our Target Samplementioning

confidence: 92%

Optically thick outflows in ultraluminous supersoft sources

Urquhart¹,

Soria²

2015

Mon. Not. R. Astron. Soc.

108

181

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Ultraluminous supersoft sources (ULSs) are defined by a thermal spectrum with colour temperatures ∼0.1 keV, bolometric luminosities ∼ a few 10 39 erg s −1 , and almost no emission above 1 keV. It has never been clear how they fit into the general scheme of accreting compact objects. To address this problem, we studied a sample of seven ULSs with extensive Chandra and XMM-Newton coverage. We find an anticorrelation between fitted temperatures and radii of the thermal emitter, and no correlation between bolometric luminosity and radius or temperature. We compare the physical parameters of ULSs with those of classical supersoft sources, thought to be surfacenuclear-burning white dwarfs, and of ultraluminous X-ray sources (ULXs), thought to be super-Eddington stellar-mass black holes. We argue that ULSs are the sub-class of ULXs seen through the densest wind, perhaps an extension of the soft-ultraluminous regime. We suggest that in ULSs, the massive disk outflow becomes effectively optically thick and forms a large photosphere, shrouding the inner regions from our view. Our model predicts that when the photosphere expands to 10 5 km and the temperature decreases below ≈50 eV, ULSs become brighter in the far-UV but undetectable in X-rays. Conversely, we find that harder emission components begin to appear in ULSs when the fitted size of the thermal emitter is smallest (interpreted as a shrinking of the photosphere). The observed short-term variability and absorption edges are also consistent with clumpy outflows. We suggest that the transition between ULXs (with a harder tail) and ULSs (with only a soft thermal component) occurs at blackbody temperatures of ≈150 eV.

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X-ray emission from the Sculptor galaxy NGC 300

Cited by 41 publications

References 31 publications

A 33 hour period for the Wolf-Rayet/black hole X-ray binary candidate NGC 300 X-1

A 33 hour period for the Wolf-Rayet/black hole X-ray binary candidate NGC 300 X-1

GaBoDS: The Garching-Bonn Deep Survey

Optically thick outflows in ultraluminous supersoft sources

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