High-resolution X-ray imaging of M33

Schulman, Eric; Bregman, Joel N.

doi:10.1086/175383

Cited by 43 publications

(51 citation statements)

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“…A special case is IC 133 due to its extraordinarily high F 60 value. Schulman & Bregman (1995) found it associated with a bright X-ray source located in a hole in the H layer of the galaxy, indicating energetic stellar winds and supernovae from massive stars. The average F 60 /F 170 ratio for the 20 bright star-forming regions is 0.32, with a dispersion of 0.05, and 0.165 for the interarm regions with a scatter of 0.03.…”

Section: Spatial Distribution Of the Warm Dustmentioning

confidence: 97%

The spiral galaxy M 33 mapped in the FIR by ISOPHOT

Hippelein

Haas

Tuffs

et al. 2003

A&A

119

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Abstract. The Sc galaxy M 33 has been mapped with ISOPHOT in the far-infrared, at 60, 100, and 170 µm. The spatial resolution of these FIR maps allows the separation of spiral arms and interarm regions and the isolation of a large number of star-forming regions. The spectral energy distribution in the FIR indicates a superposition of two components, a warm one originating from dust at ∼45 K, and a cold one, at ∼16 K. The warm component is concentrated towards the spiral arms and the star-forming regions, and is likely heated by the UV radiation from OB stars. The cold component is more smoothly distributed over the disk, and heated by the diffuse interstellar radiation. For the about 60 star-forming regions detected the Hα/FIR flux ratio increases significantly with the distance from the galaxy center, probably due to decreasing extinction. An anti-correlation of F Ha /F 60 with F 170 suggests the intrinsic extinction to be related to the cold dust surface brightness according to A V /S 170 ∼ 0.03 mag MJy −1 sr. For the total galaxy the star formation rate (SFR) derived from the FIR is in agreement with that derived from the de-extincted Hα emission. For individual star-forming regions, a consistency between SFRs derived from the optical and from the FIR requires only a fraction of the UV radiation to be absorbed locally. The individual star-forming regions also show a local radio-FIR correlation. This local correlation is, however, due to quite different components than to those that lead to the well-known global radio-FIR correlation for entire galaxies.

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Section: Spatial Distribution Of the Warm Dustmentioning

confidence: 97%

The spiral galaxy M 33 mapped in the FIR by ISOPHOT

Hippelein

Haas

Tuffs

et al. 2003

A&A

119

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“…7. Column 11 lists all cross-correlations with sources detected in earlier X-ray surveys of M 33 (Long et al 1981;Trinchieri et al 1988b;Schulman & Bregman 1995;Long et al 1996;Haberl & Pietsch 2001), including X-ray variability and other information presented in these catalogues. The detected USNO-B1 counterparts and corresponding X-ray to optical flux ratio (see Sect.…”

Section: Description Of the Cataloguementioning

confidence: 99%

“…Appendices A and B are only available in electronic form at http://www.edpsciences.org also revealed a number of new point-like sources (Schulman & Bregman 1995;Long et al 1996). Combining all ROSAT data, Haberl & Pietsch (2001) compiled a catalogue of 184 sources in the direction of M 33, and classified the brightest objects using their X-ray properties and identification with optical and radio counterparts.…”

Section: Introductionmentioning

confidence: 99%

An XMM-Newton survey of the Local Group galaxy M 33 – variability of the detected sources

Misanovic

Pietsch

Haberl

et al. 2006

A&A

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We present an analysis of the individual observations of a deep XMM-Newton survey of the Local Group spiral galaxy M 33. We detected a total of 350 sources with fluxes (in the 0.2-4.5 keV energy band) in the range 6.7 × 10 −16 −1.5 × 10 −11 erg s −1 . This comprehensive study considers flux variability, spectral characteristics, and classification of the detected objects. Thirty-nine objects in our catalogue are new sources, while 311 were already detected in a previous analysis of most of the same data using combined images. We present improved positions of these sources and the X-ray parameters of each source in each individual observation that covers the source. We then used these parameters to systematically search for flux variability on time scales of hours to months or years. The long-term light-curves were generated for the 61 sources showing a significant variability of the (0.2-4.5) keV flux, by a factor of 1.2 to 144. The detected variability was then used to classify 8 new X-ray binary candidates in M 33. Together with the hardness ratio method and cross-correlation with optical, infrared, and radio data, we also classify or confirm previous classification of 25 supernova remnants and candidates, 2 X-ray binaries, and 11 super-soft source candidates (7 of which are new SSS candidates). In addition, we classify 13 active galactic nuclei and background galaxies, 6 stars, and 23 foreground star candidates in the direction of M 33. Further 206 objects are classified as "hard", approximately half of which are sources intrinsic to M 33. The relative contribution of the classified XRB and SSS in M 33 is now comparable to M 31. The luminosity distribution of SNRs in both spiral galaxies is almost the same, although the number of the detected SNRs in M 33 remains much higher.

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“…The best-fit model was composed of a multicolour disc (MCD) plus a power law at high energies, Schulman & Bregman (1995), based on ROSAT observations, conclude that the probability of such an unusual X-ray binary close to the centre of M 33 is very small. Another point which makes M 33 X-8 an unusual source is the steadiness of its flux, except for a modulation of ∼20% with a period of 106 days (Dubus et al 1997).…”

Section: To Increasementioning

confidence: 99%

“…In past observations, intrinsic absorption was never mandatory: Schulman & Bregman (1995) with ROSAT and Table 2. Results from the fit of the X-ray data.…”

Section: Spectral Analysismentioning

confidence: 99%

XMM–Newtonobservations of the ultraluminous nuclear X-ray source in M 33

Foschini¹,

Rodríguez²,

Fuchs³

et al. 2004

A&A

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Abstract. We present observations with XMM-Newton of M 33 X-8, the ultraluminous X-ray source (L 0.5−10 keV ≈ 2×10 39 erg/s) closest to the centre of the galaxy. The best-fit model is similar to the typical model of Galactic black holes in very high state. Comparison with previous observations indicates that the source is still in a very high state after about 20 years of observations. No state transition has been observed even during the present set of XMM-Newton observations. We estimate the lower limit of the mass of the black hole >6 M , but with proper parameters taking into account different effects, the best estimate becomes 12 M . Our analysis favours the hypothesis that M 33 X-8 is a stellar mass black hole candidate, in agreement with the findings of other authors. In addition, we propose a different model where the high luminosity of the source is likely to be due to orientation effects of the accretion disc and anisotropies in the Comptonized emission.

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High-resolution X-ray imaging of M33

Cited by 43 publications

References 0 publications

The spiral galaxy M 33 mapped in the FIR by ISOPHOT

The spiral galaxy M 33 mapped in the FIR by ISOPHOT

An XMM-Newton survey of the Local Group galaxy M 33 – variability of the detected sources

XMM–Newtonobservations of the ultraluminous nuclear X-ray source in M 33

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