Monitoring the Very-Long-Term Variability of X-ray Sources in the Giant Elliptical Galaxy M87
arXiv:1303.6968 · doi:10.1093/mnras/stt557
Abstract
We report on our search for very-long-term variability (weeks to years) in X-ray binaries (XRBs) in the giant elliptical galaxy M87. We have used archival Chandra imaging observations to characterise the long-term variability of 8 of the brightest members of the XRB population in M87. The peak brightness of some of the sources exceeded the ultra luminous X-ray source (ULX) threshold luminosity of ~ 10^{39} erg/s, and one source could exhibit dips or eclipses. We show that for one source, if it has similar modulation amplitude as in SS433, then period recoverability analysis on the current data would detect periodic modulations, but only for a narrow range of periods less than 120 days. We conclude that a dedicated monitoring campaign, with appropriately defined sampling, is essential if we are to investigate properly the nature of the long-term modulations such as those seen in Galactic sources.
19 pages, 19 figures, 1 table, Accepted for publication in MNRAS. Updated to correct typos in previous version
References in corpus (10)
- Evidence for an Intermediate Mass Black Hole in NGC 5408 X-1
- The Long-Term Variability of the X-Ray Sources in NGC 6946 and NGC 4485/4490
- A Close Look at the Population of Supersoft and Quasi-Soft X-Ray Sources Observed in M31 with XMM-Newton
- The ultraluminous X-ray source population of NGC 4485/4490
- 12 years of X-ray variability in M31 globular clusters, including 8 black hole candidates, as seen by Chandra
- Interpretation of the 115 Day Periodic Modulation in the X-ray Flux of NGC 5408 X-1
- An ultraluminous supersoft source with a 4 hour modulation in NGC 4631
- The Remarkable Stability of Probable Black Hole Low-Mass X-ray Binaries in Nearby Galaxies
- A period distribution of X-ray binaries observed in the central region of M31 with Chandra and HST
- Monitoring Variable X-ray Sources in Nearby Galaxies