Transient low-mass X-ray binary populations in elliptical galaxies NGC3379 and NGC4278

T. Fragos*, V. Kalogera, B. Willems, K. Belczynski, G. Fabbiano, N. J. Brassington, D. W. Kim, L. Angelini, R. L. Davies, J. S. Gallagher, A. R. King, S. Pellegrini, G. Trinchieri, S. E. Zepf, A. Zezas

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


We propose a physically motivated and self-consistent prescription for the modeling of transient neutron star low-mass X-ray binary (LMXB) properties, such as duty cycle (DC), outburst duration, and recurrence time. We apply this prescription to the population synthesis models of field LMXBs presented by Fragos etal., and compare the transient LMXB population to the Chandra X-ray survey of the two elliptical galaxies NGC3379 and NGC4278, which revealed several transient sources. We are able to exclude models with a constant DC for all transient systems, while models with a variable DC based on the properties of each system are consistent with the observed transient populations. We predict that the majority of the observed transient sources in these two galaxies are LMXBs with red giant donors. Finally, our comparison suggests that transient LMXBs are very rare in globular clusters (GCs), and thus the number of identified transient LMXBs may be used as a tracer of the relative contribution of field and GC LMXB populations.

Original languageEnglish (US)
Pages (from-to)L143-L147
JournalAstrophysical Journal
Issue number2 PART 2
StatePublished - 2009


  • Binaries: close
  • Galaxies: elliptical and lenticular, cD
  • Stars: evolution
  • X-rays: binaries

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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