Cataclysmic Variables in Globular Clusters, the Galactic Center, and Local Space

Heinke, Craig; Ruiter, Ashley J.; Muno, M. P.; Belczyński, Krzysztof; Bandyopadhyay, Reba M.; Wachter, Stefanie; Gelino, Dawn; Gelino, Christopher R.

doi:10.1063/1.2945021

Cited by 8 publications

(3 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, low accretion rate polars corresponding to magnetic white dwarfs in detached systems (which capture a substantial fraction of the stellar wind of its detached companion) may be a viable population each contributing at a level of ∼10 30 erg s −1 (see Webbink & Wickramasinghe 2005). On the other hand, the white dwarfs in binaries known as polars or intermediate polars, where the mass transfer is accomplished via Roche lobe overflow, which are generally characterized by a hard spectrum with a photon indices near unity (see Heinke et al 2008), are sufficiently luminous (> 10 31 erg s −1 ) that they would have been detected as resolved point sources.…”

Section: Discussionmentioning

confidence: 99%

Diffuse X-Ray Emission in Globular Cluster Cores

Hui¹,

Cheng²,

Taam³

2009

ApJ

View full text Add to dashboard Cite

The unresolved X-ray emission in the cores of 10 globular clusters hosting millisecond pulsars is investigated. Subtraction of the known resolved point sources leads to detectable levels of unresolved emission in the core region of M28, NGC 6440, M62, and NGC 6752. The X-ray luminosities in the 0.3-8 keV energy band of this emission component were found to lie in the range ∼1.5 × 10 31 erg s −1 (NGC 6752) to ∼2.2 × 10 32 erg s −1 (M28). The lowest limiting luminosity for X-ray source detections amongst these four clusters was 1.1 × 10 30 erg s −1 for NGC 6752. The spectrum of the unresolved emission can be fit equally well by a power law, a thermal bremsstrahlung model, a blackbody plus power law, or a thermal bremsstrahlung model plus blackbody component. The unresolved emission is considered to arise from the cumulative contribution of active binaries, cataclysmic variables, and faint millisecond pulsars with their associated pulsar wind nebulae. In examining the available X-ray data, no evidence for any pulsar wind nebular emission in globular clusters is found. It is shown that the X-ray luminosity contribution of a faint source population based on an extrapolation of the luminosity function of detected point sources is compatible with the unresolved X-ray emission in the cores of NGC 6440 and NGC 6752. Adopting the same slope for the luminosity function for M62 as for NGC 6440 and NGC 6752 leads to a similar result for M62. For M28, the contribution from faint sources in the core can attain a level comparable with the observed value if a steeper slope is adopted. The characteristics on the faint source population as constrained by the properties of the unresolved X-ray emission are briefly discussed.

show abstract

Section: Discussionmentioning

confidence: 99%

Diffuse X-Ray Emission in Globular Cluster Cores

Hui¹,

Cheng²,

Taam³

2009

ApJ

View full text Add to dashboard Cite

show abstract

“…However, the CV samples in GCs tend to be X-ray selected (Heinke et al 2008) which, in turn, favours the detection of magnetic CVs (brighter in X-ray than the non-magnetic counterpart). Unfortunately, few investigations went deep enough to detect the non-magnetic CVs ( 10 30 erg s −1 ) in the X-ray and more efforts should be put in this direction.…”

Section: Nature Of Cvs In Gcsmentioning

confidence: 99%

MOCCA-SURVEY database I. Accreting white dwarf binary systems in globular clusters – I. Cataclysmic variables – present-day population

Belloni

Giersz

Askar

et al. 2016

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

In this paper, which is the first in a series of papers associated with cataclysmic variables and related objects, we introduce the CATUABA code, a numerical machinery written for analysis of the MOCCA simulations, and show some first results by investigating the present-day population of cataclysmic variables in globular clusters. Emphasis was given on their properties and the observational selection effects when observing and detecting them. In this work we analysed in this work six models, including three with Kroupa distributions of the initial binaries. We found that for models with Kroupa initial distributions, considering the standard value of the efficiency of the common envelope phase adopted in BSE, no single cataclysmic variable was formed only via binary stellar evolution, i.e. in order to form them, strong dynamical interactions have to take place. We show and explain why this is inconsistent with observational and theoretical results. Our results indicate that the population of cataclysmic variables in globular clusters is, mainly, in the last stage of their evolution and observational selection effects can drastically change the expected number of observed cataclysmic variables. We show that the probability of observing them during the outbursts is extremely small and conclude that the best way of looking for cataclysmic variables in globular clusters is by searching for variabilities during quiescence, instead of during outbursts. For that, one would need a very deep observation which could reach magnitudes 27 mag. Finally, we argue that cataclysmic variables in globular clusters are not necessarily magnetic.

show abstract

“…Our best-fitting power-law spectrum is relatively hard, with photon index Γ = 1.51±0.11. Heinke et al (2008) investigated the relationship between CV subtype and X-ray spectrum and luminosity for a sample of CVs comprising confirmed magnetic CVs (IPs and polars), quiescent DN and nova-like CVs (NL) and globular cluster CVs. They found the distribution of photon index differed significantly between magnetic CVs, which are harder X-ray sources (mean Γ = 1.22, σ = 0.33), and non-magnetic CVs (mean Γ = 1.97, σ = 0.20), but was fairly consistent within either group.…”

Section: X-ray Properties: CV or Lmxb? Magnetic Or Non-magnetic?mentioning

confidence: 99%

Ground and space-based study of two globular cluster CVs: M22 CV1 and M5 V101

Hourihane,

Callanan,

Cool

et al. 2011

Preprint

View full text Add to dashboard Cite

As a class of compact binaries with large binding energy, cataclysmic variables formed through close encounters play an important role in the dynamical evolution of globular clusters. As part of a systematic search for CVs undergoing dwarf nova eruptions in globular clusters, our 2004 monitoring programme of M22 detected an outburst of the dwarf nova candidate CV1 during May. We implement the ISIS image subtraction routine to obtain a light curve for an outburst of CV1. We present the outburst light curve as well as HST /WFPC2 photometry in the V, U and near ultra-violet (nUV ) bands and a Chandra/ACIS-S spectrum of the object. Our results confirm the DN nature of the outburst and the CV status of the object. We also present the results of a ground-based study of another globular cluster CV, M5 V101 -including quiescent medium-resolution WHT/ISIS spectroscopy in the B and R bands, displaying prominent Balmer and He I emission, and R-band photometry.

show abstract

Cataclysmic Variables in Globular Clusters, the Galactic Center, and Local Space

Cited by 8 publications

References 20 publications

Diffuse X-Ray Emission in Globular Cluster Cores

Diffuse X-Ray Emission in Globular Cluster Cores

MOCCA-SURVEY database I. Accreting white dwarf binary systems in globular clusters – I. Cataclysmic variables – present-day population

Ground and space-based study of two globular cluster CVs: M22 CV1 and M5 V101

Contact Info

Product

Resources

About