Dynamical Formation of Close Binary Systems in Globular Clusters

By D. Pooley, W. Lewin, S. Anderson, H. Baumgardt, A. Filippenko, B. Gaensler, L. Homer, P. Hut, Victoria Kaspi, J. Makino and 5 more. 2003

262 citations recorded by the source corpus.

We know from observations that globular clusters are very efficient catalysts in forming unusual short-period binary systems or their offspring, such as low-mass X-ray binaries (LMXBs; neutron stars accreting matter from low-mass stellar companions), cataclysmic variables (white dwarfs accreting matter from stellar companions), and millisecond pulsars (rotating neutron stars with spin periods of a few milliseconds). Although there has been little direct evidence, the overabundance of these objects in globular clusters has been attributed by numerous authors to the high densities in the cores, which leads to an increase in the formation rate of exotic binary systems through close stellar encounters. Many such close binary systems emit X-radiation at low luminosities (LX ≲ 1034 ergs s-1) and are being found in large numbers through observations with the Chandra X-Ray Observatory. Here we present conclusive observational evidence of a link between the number of close binaries observed in X-rays in a globular cluster and the stellar encounter rate of the cluster. We also make an estimate of the total number of LMXBs in globular clusters in our Galaxy.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/589a472f5edbe553e49dc70d9d3770e0f032bd60

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Citations in the corpus

Formation and evolution of compact binaries in globular clusters – II. Binaries with neutron stars (2007, methodology): “A strong dependence of LMXB production on cluster density has been inferred observationally, both in Galactic globular clusters (e.g., Verbunt & Hut 1987; Pooley et al. 2003; Heinke et al. 2003) and in extragalactic globular clusters (e.g., Jordán et al. 2004; Sivakoff et al. 2007).”
N-body modelling of globular clusters: masses, mass-to-light ratios and intermediate-mass black holes (2016, background): “…and high stellar encounter rates, globular clusters are also unique environments for the creation of exotic stars like blue stragglers (Bailyn 1995; Davies, Piotto & de Angeli 2004), low-mass X-ray binaries (Verbunt 1993; Pooley et al. 2003) and millisecond pulsars (Manchester et al. 1991).”
A Deep Chandra Survey of the Globular Cluster 47 Tucanae: Catalog of Point Sources (2005, unknown): “We choose this radius for easy comparison with analyses of other clusters (e.g., Pooley et al. 2002a, 2002b, 2003; Heinke et al. 2003a; Bassa et al. 2004) and because it strikes a balance between inclusion of almost all real cluster sources and exclusion of most foreground and background sources at…”
Eight New Millisecond Pulsars in NGC 6440 and NGC 6441 (2007, background): “Pooley et al. (2003) provide a simple way of calculating the stellar interaction rate at the core of any GC: c / 1:50 r 2 c ; ð1Þ where 0 is the central mass density and rc is the core radius.”
A complete N-body model of the old open cluster M67 (2005, background): “X-ray observations of old open clusters (van den Berg et al. 2004) and globular clusters (Pooley et al. 2003) have proved to be very efficient at detecting short-period interacting binaries.”
Young Massive Star Clusters (2010, background): “Much of this excess is attributed to the dynamical environment in dense cluster cores (Fabian, Pringle & Rees 1975; Pooley et al. 2003).”
THE DYNAMICAL EVOLUTION OF STELLAR BLACK HOLES IN GLOBULAR CLUSTERS (2014, background): “It is well known that the formation rate per unit mass of XRBs is orders of magnitude larger in massive clusters than it is in the field (e.g., Pooley et al. 2003), which suggests that stellar dynamics must play an essential role in producing XRBs in present-day clusters.”
A catalogue of masses, structural parameters, and velocity dispersion profiles of 112 Milky Way globular clusters (2018, background): “In addition, their high stellar densities make them unique environments for the creation of exotic stars like blue stragglers (Bailyn 1995; Davies, Piotto & de Angeli 2004), low-mass X-ray binaries (Verbunt 1993; Pooley et al. 2003) and millisecond pulsars (Manchester et al. 1991).”
An Overabundance of Transient X-Ray Binaries within 1 Parsec of the Galactic Center (2004, background): “In the cores of globular clusters, three-body interactions produce this excess of LMXBs (e.g., Rasio et al. 2000; Pooley et al. 2003).”
Analysis of the Quiescent Low-Mass X-Ray Binary Population in Galactic Globular Clusters (2003, methodology): “NGC 6397, the densest globular cluster yet studied, has an apparent excess of X-ray sources (Table 1, and Pooley et al. 2003b), which suggests the opposite conclusion.”