<i>CHANDRA</i>AND<i>HST</i>STUDIES OF THE X-RAY SOURCES IN GALACTIC GLOBULAR CLUSTER M92

Lu, T.; Kong, Albert; Verbunt, F.; Lewin, W. H. G.; Anderson, Scott F.; Pooley, David

doi:10.1088/0004-637x/736/2/158

Cited by 9 publications

(6 citation statements)

References 38 publications

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“…Clusters where multiple identifications of CVs in GCs have been made as counterparts to X-ray sources include 47 Tuc (E03a; E03b; Beccari et al 2014), NGC 6752 (Pooley et al 2002;Thomson et al 2012), NGC 6397 Cohn et al 2010), M30 (Lugger et al 2007), NGC 2808 (Servillat et al 2008), M71 (Huang et al 2010), M80 (Dieball et al 2010), M92 (Lu et al 2011), NGC 6388 (Maxwell et al 2012), and ω Cen (Cool et al 2013). These studies have shown the effectiveness of this technique and have revealed different characteristics of CVs in GCs.…”

Section: Introductionmentioning

confidence: 93%

New cataclysmic variables and other exotic binaries in the globular cluster 47 Tucanae*

Sandoval

Berg

Heinke

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We present 22 new (+3 confirmed) cataclysmic variables (CVs) in the non corecollapsed globular cluster 47 Tucanae (47 Tuc). The total number of CVs in the cluster is now 43, the largest sample in any globular cluster so far. For the identifications we used near-ultraviolet (NUV) and optical images from the Hubble Space Telescope, in combination with X-ray results from the Chandra X-ray Observatory. This allowed us to build the deepest NUV CV luminosity function of the cluster to date. We found that the CVs in 47 Tuc are more concentrated towards the cluster center than the main sequence turnoff stars. We compared our results to the CV populations of the core-collapsed globular clusters NGC 6397 and NGC 6752. We found that 47 Tuc has fewer bright CVs per unit mass than those two other clusters. That suggests that dynamical interactions in core-collapsed clusters play a major role creating new CVs. In 47 Tuc, the CV population is probably dominated by primordial and old dynamically formed systems. We estimated that the CVs in 47 Tuc have total masses of ∼ 1.4 M . We also found that the X-ray luminosity function of the CVs in the three clusters is bimodal. Additionally, we discuss a possible double degenerate system and an intriguing/unclassified object. Finally, we present four systems that could be millisecond pulsar companions given their X-ray and NUV/optical colors. For one of them we present very strong evidence for being an ablated companion. The other three could be CO-or He-WDs.

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Section: Introductionmentioning

confidence: 93%

New cataclysmic variables and other exotic binaries in the globular cluster 47 Tucanae*

Sandoval

Berg

Heinke

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…A number of studies have looked for accreting binaries through emission lines searches in GCs (e.g. Pooley et al 2002;Kong et al 2006;Bassa et al 2008;Cohn et al 2010;Lu et al 2011). The GC 47 Tucanae is definitely one of the most promising targets for this kind of investigation, since it harbours a crowded zoo of stellar exotica, including BSSs, LMXBs and candidate CVs (e.g.…”

Section: Introductionmentioning

confidence: 99%

Hα photometry of low-mass stars in 47 Tucanae: chromospheric activity and exotica

Beccari

Marchi

Panagia

et al. 2013

Monthly Notices of the Royal Astronomical Society

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We have used archival Hubble Space Telescope observations obtained with the Advanced Camera for Surveys to study the Hα emission properties of main sequence stars in the globular cluster 47 Tucanae. Using a combination of multi-band observations in the F606W, F814W and F658N bands, we search for stars showing Hα excess emission. An accurate photometric measurement of their Hα equivalent width allows us to identify objects with large Hα emission, which we attribute to mass accretion rather than enhanced chromospheric activity. The spatial position of some of these stars is coincident with that of known X-ray sources and their location in the colour-magnitude diagram allows us to classify them as active binaries or cataclysmic variables (CVs). We show that this method, commonly adopted to study accreting discs in young stellar objects, can be successfully used to identify and characterise candidate CVs.

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“…These methods have been used to identify numerous optical/UV counterparts in 47 Tuc (references above) and in numerous other clusters (e.g. Grindlay et al 2001a;Pooley et al 2002b;Kong et al 2006;Bassa et al 2008;Lu et al 2011;Cohn et al 2010;Cool et al 2013).…”

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confidence: 99%

Chandra studies of the globular cluster 47 Tucanae: a deeper X-ray source catalogue, five new X-ray counterparts to millisecond radio pulsars and new constraints to r-mode instability window

Bhattacharya

Heinke

Chugunov

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We combined Chandra ACIS observations of the globular cluster 47 Tucanae (hereafter, 47 Tuc) from 2000, 2002, and 2014-15 to create a deeper X-ray source list, and study some of the faint radio millisecond pulsars (MSPs) present in this cluster. We have detected 370 X-ray sources within the half-mass radius (2 .79) of the cluster, 81 of which are newly identified, by including new data and using improved source detection techniques. The majority of the newly identified sources are in the crowded core region, indicating cluster membership. We associate five of the new X-ray sources with chromospherically active BY Dra or W UMa variables identified by Albrow et al. (2001). We present alternative positions derived from two methods, centroiding and image reconstruction, for faint, crowded sources. We are able to extract X-ray spectra of the recently discovered MSPs 47 Tuc aa, 47 Tuc ab, the newly timed MSP 47 Tuc Z, and the newly resolved MSPs 47 Tuc S and 47 Tuc F. Generally, they are well fit by black body or neutron star atmosphere models, with temperatures, luminosities and emitting radii similar to those of other known MSPs in 47 Tuc, though 47 Tuc aa and 47 Tuc ab reach lower X-ray luminosities. We limit X-ray emission from the full surface of the rapidly spinning (542 Hz) MSP 47 Tuc aa, and use this limit to put an upper bound for amplitude of r-mode oscillations in this pulsar as α < 2.5 × 10 −9 and constrain the shape of the r-mode instability window.

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CHANDRAANDHSTSTUDIES OF THE X-RAY SOURCES IN GALACTIC GLOBULAR CLUSTER M92

Cited by 9 publications

References 38 publications

New cataclysmic variables and other exotic binaries in the globular cluster 47 Tucanae*

New cataclysmic variables and other exotic binaries in the globular cluster 47 Tucanae*

Hα photometry of low-mass stars in 47 Tucanae: chromospheric activity and exotica

Chandra studies of the globular cluster 47 Tucanae: a deeper X-ray source catalogue, five new X-ray counterparts to millisecond radio pulsars and new constraints to r-mode instability window

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