A<i>CHANDRA X-RAY OBSERVATORY</i>STUDY OF PSR J1740-5340 AND CANDIDATE MILLISECOND PULSARS IN THE GLOBULAR CLUSTER NGC 6397

Bogdanov, Slavko; Berg, M. van den; Heinke, C. O.; Cohn, H. N.; Lugger, P. M.; Grindlay, Jonathan E.

doi:10.1088/0004-637x/709/1/241

Cited by 73 publications

(109 citation statements)

References 60 publications

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“…It then measures the brightness of each star in each exposure, both individually and simultaneously, using a spatially variable library of PSFs. This analysis did not detect any star within the error circle of U24, the qLMXB in NGC 6397, although there are two relatively bright stars only ∼0.6" away from the center of the error circle, which has radius 0.285" (at 95% confidence; Bogdanov et al 2010). However, Cohn et al (2010) did note a "hint of detection in R only" for U24 in their Table 1 owing to the presence of "a small 'blip' near the center of the error circle in the stacked R image."…”

Section: Ngc 6397: Hst Datamentioning

confidence: 84%

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Improved mass and radius constraints for quiescent neutron stars in ω Cen and NGC 6397

Heinke¹,

Cohn²,

Lugger³

et al. 2014

Monthly Notices of the Royal Astronomical Society

113

155

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We use Chandra and XMM-Newton observations of the globular clusters ω Cen and NGC 6397 to measure the spectrum of their quiescent neutron stars (NSs), and thus to constrain the allowed ranges of mass and radius for each. We also use Hubble Space Telescope photometry of NGC 6397 to identify a potential optical companion to the quiescent NS, and find evidence that the companion lacks hydrogen. We carefully consider a number of systematic problems, and show that the choices of atmospheric composition, interstellar medium abundances, and cluster distances can have important effects on the inferred NS mass and radius. We find that for typical NS masses, the radii of both NSs are consistent with the 10 − 13 km range favored by recent nuclear physics experiments. This removes the evidence suggested by Guillot and collaborators for an unusually small NS radius, which relied upon the small inferred radius of the NGC 6397 NS.

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Section: Ngc 6397: Hst Datamentioning

confidence: 84%

“…There are five available Chandra observations of NGC 6397 (Table 1); one 48 ks ACIS-I observation taken in 2000 (Grindlay et al 2001), and pairs of ACIS-S observations in 2002 (totaling 55 ks) and in 2007 (totalling 237 ks; Bogdanov et al 2010). All of these observations were analyzed by Guillot, Rutledge & Brown (2011).…”

Section: Ngc 6397: Chandra Datamentioning

confidence: 99%

Improved mass and radius constraints for quiescent neutron stars in ω Cen and NGC 6397

Heinke¹,

Cohn²,

Lugger³

et al. 2014

Monthly Notices of the Royal Astronomical Society

113

155

View full text Add to dashboard Cite

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“…In the case of NGC 6752 we have transformed the X-ray luminosities given by Forestell et al (2014) in the band 0.5-8 keV to luminosities in the band 0.5-6 keV by multiplying for the appropriate factor (0.95) assuming a 2 keV bremsstrahlung model. For NGC 6397 we have converted the X-ray fluxes reported in Bogdanov et al (2010) into X-ray luminosities assuming a distance of 2.2 kpc. In Figure 14 we show a histogram of X-ray luminosities of the CVs.…”

Section: X-ray and Optical Properties Of The CV Populationmentioning

confidence: 99%

“…* Luminosities in the 0.5-6 keV band were calculated by taking the fluxes from Bogdanov et al (2010), and assuming a distance to NGC 6397 of 2.2 kpc. Errors are not provided by the authors.…”

Section: Appendix C: Cataclysmic Variables In Other Globular Clustersmentioning

confidence: 99%

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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“…Grindlay et al 2001a,b;Pooley et al 2002;Edmonds et al 2003a,b;Heinke et al 2003a,b;Hannikainen et al 2005;Lugger et al 2007;Elsner et al 2008;Bogdanov et al 2010;Cohn et al 2010;Forestell et al 2014). The combination of both X-ray and FUV observations is thus an ideal approach to detect and study the interacting CBs in GCs.…”

mentioning

confidence: 99%

Far-ultraviolet observation of the globular cluster NGC 6397

Dieball

Rasekh

Knigge

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present an observational far-UV (FUV) and near-UV (NUV) study of the core region of the globular cluster NGC 6397. The observations were obtained with the Space Telescope Imaging Spectrograph (STIS, FUV), and the Wide Field Camera 3 (WFC3, NUV) on board the Hubble Space Telescope. Here, we focus on the UV bright stellar populations such as blue stragglers (BSs), white dwarfs (WDs) and cataclysmic variables (CVs). We present the first FUV − NUV color-magnitude diagram (CMD) for this cluster. To support our classification of the stellar populations, we compare our FUV − NUV CMD with optical data from the ACS Survey of Galactic Globular Clusters. The FUV − NUV CMD indicates 16 sources located in the WD area, and ten BSs within the 25 ′′ × 25 ′′ of the STIS FUV data. Eighteen Chandra X-ray sources are located within the FUV field of view. Thirteen of those have a NUV counterpart, of which nine sources also have a FUV counterpart. Out of those, five sources are previously suggested CVs, and indeed all five are located in the WD/CV region in our FUV − NUV CMD. Another CV only has a FUV but no NUV counterpart. We also detect a NUV (but no FUV) counterpart to the MSP located in the core of this cluster. The NUV lightcurves of the CVs and MSP show flickering behaviour typical of CVs. We found that the BSs and CVs are the most centrally concentrated population. This might be an effect of mass segregation or indicate the preferred birth place of BSs and CVs via dynamical interactions in the dense core region of GCs. HB stars are the least centrally concentrated population and absent in the innermost area of the core.

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ACHANDRA X-RAY OBSERVATORYSTUDY OF PSR J1740-5340 AND CANDIDATE MILLISECOND PULSARS IN THE GLOBULAR CLUSTER NGC 6397

Cited by 73 publications

References 60 publications

Improved mass and radius constraints for quiescent neutron stars in ω Cen and NGC 6397

Improved mass and radius constraints for quiescent neutron stars in ω Cen and NGC 6397

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

Far-ultraviolet observation of the globular cluster NGC 6397

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