ROSAT HRI observations of the globular clusters M13 and M92

Fox, D. B.; Lewin, W. H. G.; Margon, B.; Paradijs, J.A. van; Verbunt, F.

doi:10.1093/mnras/282.3.1027

Cited by 12 publications

(24 citation statements)

References 16 publications

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“…In 47 Tuc, of the candidate counterparts suggested by a variety of authors, Verbunt & Hasinger (1998) only retain three, on the basis of more accurate positions of the X-ray sources; these were also confirmed with Chandra. Ferraro et al (1997) suggested ultraviolet stars as counterparts for two sources found by Fox et al (1996) in NGC 6205 (see also ). An ultraviolet counterpart suggested by Ferraro et al (2000) for a source in NGC 6341 is incompatible with the position of that source (Geffert 1998).…”

Section: Some Information On the Luminous X-ray Sources In Globularmentioning

confidence: 81%

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Globular cluster X-ray sources

Verbunt

Lewin

2006

Compact Stellar X-Ray Sources

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Two new bright X-ray sources in globular clusters, and many less luminous ones in globular clusters and in old open clusters, have been discovered with ROSAT. Accurate positions obtained with ROSAT help identification with optical objects, which however is still very incomplete in globular clusters. One dim globular cluster source has been identified with a recycled radio pulsar; several others may be cataclysmic variables. The four brightest X-ray sources identified in the old open cluster M 67 are puzzling, as we do not understand why they emit X-rays. In comparison with the two old open clusters studied so far, globular clusters are remarkably underluminous in X-rays. FirstI am grateful to the organizers of this meeting for the opportunity to contribute to this celebration of the 65 th birthday of Joachim Trümper. During my years (1985)(1986)(1987)(1988)(1989) at the Max Planck Institut für extraterrestrische Physik, I have always felt very much at home, as if an 'honorary German', and I thank Joachim and my other colleagues for this. I was impressed with the width and depth of Joachim Trümper's interests, and thoroughly enjoyed my many discussions with him.The deadline for the first Announcement of Opportunity for observing with ROSAT was on a Sunday evening, at midnight (in checking the date, I find it was on my birthday!). Joachim Trümper was in his office that night, to sign proposals until just before the deadline, or almost, as 11 copies needed to be made for submission. Some of the proposals he signed that night contributed to the results discussed in this review.

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Section: Some Information On the Luminous X-ray Sources In Globularmentioning

confidence: 81%

“…by Fox et al (1996) in NGC 6341 and NGC 6205. However, it is fair to say that the actual plethora of sources shown by the Chandra observations in virtually every cluster that it observed (Tables 8.2, 8.4) was unpredicted.…”

Section: Some Information On the Luminous X-ray Sources In Globularmentioning

confidence: 93%

Globular cluster X-ray sources

Verbunt

Lewin

2006

Compact Stellar X-Ray Sources

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“…ROSAT HRI and PSPC observations (Fox et al 1996;Verbunt 2001), revealed several dim X-ray sources in M 13. The HRI observations showed two core sources, whose unresolved PSPC spectrum could be fitted with a 0.9 keV thermal bremsstrahlung model (L 0.5−2.5 keV ∼ 2.5 × 10 32 ergs s −1 ).…”

Section: Introductionmentioning

confidence: 99%

Discovery of a quiescent neutron star binary in the globular cluster M 13

Gendre

Barret

Webb

2003

A&A

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Abstract.We have discovered with XMM-Newton an X-ray source in the core of the globular cluster M 13, whose X-ray spectral properties suggest that it is a quiescent neutron star X-ray binary. The spectrum can be well fitted with a pure hydrogen atmosphere model, with T ∞ = 76 ± 3 eV, R ∞ = 12.8 ± 0.4 km and an X-ray luminosity of 7.3 ± 0.6 × 10 32 ergs s −1 . In the light of this result, we have discovered a strong correlation between the stellar encounter rate and the number of quiescent neutron stars found in the ten globular clusters observed so far by either XMM-Newton or Chandra. This result lends strong support to the idea that these systems are primarily produced by stellar encounters in the core of globular clusters.

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“…Searching the SIMBAD database, none of the X-ray sources have an optical counterpart that lies within the error box of the X-ray determined coordinates. We have therefore tried to evaluate whether we see an overdensity of sources within the core of the cluster, in a similar manner to Fox et al (1996). We have used the log N -log S relation derived from XMM-Newton observations of the Lockman Hole (Hasinger et al 2001).…”

Section: Cluster Membershipmentioning

confidence: 99%

First XMM-Newton observations of the globular cluster M 22

Webb

Gendre

Barret

2002

A&A

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Abstract.We have examined preliminary data of the globular cluster, M 22, from the EPIC MOS detectors on board XMM-Newton. We have detected 27 X-ray sources within the centre of the field of view, 24 of which are new detections. Three sources were found within the core of the cluster. From spectral analysis of the X-ray sources, it is possible that the object at the centre of the core is a quiescent X-ray transient and those lying further out are maybe cataclysmic variables.

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ROSAT HRI observations of the globular clusters M13 and M92

Cited by 12 publications

References 16 publications

Globular cluster X-ray sources

Globular cluster X-ray sources

Discovery of a quiescent neutron star binary in the globular cluster M 13

First XMM-Newton observations of the globular cluster M 22

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