Resolving white dwarf binaries within globular clusters with LISA

Astronomy and Astrophysics, vol. 705, pp. A259

Abstract

Context . Globular clusters (GCs) around the Milky Way (MW) are expected to host white dwarf (WD) binaries emitting gravitational waves that could be detectable by LISA. Aims . Our aim is to investigate whether LISA has the capacity to resolve WD binaries in GCs well enough in terms of sky location and distance that they can be distinguished from binaries in the MW disc. Methods . We used a sample of 20 of the most massive GCs around the MW and simulated LISA’s sky location and distance measurement errors for WD binaries in these GCs using the software package GWT oolbox . We did this in the context of a model of the LISA-detectable binaries in the MW from the population synthesis code S e B a . Results . We find that for five of the GCs in our sample, binaries in the GC could be easily distinguished from MW disc binaries using the sky location alone; for another five, binaries in the GCs could be distinguished using a combination of LISA’s sky location and distance measurements; and for the final ten, binaries in the GCs could not be distinguished from overlapping MW disc binaries. The results depend strongly on the sky locations of the GCs, with GCs far away from the Galactic plane being easy to resolve, while GCs close to the Galactic centre overlap with many MW disc binaries. The most promising GC with respect to the potential of locating a WD binary that could be resolved to that specific GC (based on sky location and GC mass) is 47 Tucanae.

Authors 4

1. Wouter G. J. van Zeist Aachen Leiden Observatory

   Leiden University · Radboud University Nijmegen · University of Auckland · Leiden Observatory

   Affiliation as printed

   Department of Astrophysics/IMAPP, Radboud University

   Department of Physics, University of Auckland

   Leiden Observatory, Leiden University

2. Gijs Nelemans Aachen Netherlands Institute for Space Research

   Radboud University Nijmegen · Space Research Organisation Netherlands · KU Leuven

   Affiliation as printed

   Department of Astrophysics/IMAPP, Radboud University

   Institute of Astronomy, KU Leuven

   SRON, Netherlands Institute for Space Research

3. Shu-Xu Yi

   Chinese Academy of Sciences · Institute of High Energy Physics · University of Chinese Academy of Sciences

   Affiliation as printed

   Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences

   University of Chinese Academy of Sciences, Chinese Academy of Sciences

4. Simon Portegies Zwart Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory, Leiden University