2002/09/19 by Dae‐Sik Moon, Dae-Sik Moon, S. S. Eikenberry +3 · 1 citation
Physics and Astronomy · #Astrophysical Phenomena and Observations #Gamma-ray bursts and supernovae #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.1086/367782
published as Astrophys.J. 582 (2003) L91-L94 · 14 pages (5 figures), To appear in ApJ Letters
arxiv created 2002/09/19 · openalex publication_date 2003/01/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We present Rossi X-Ray Timing Explorer observations of the X-ray pulsar SMC X-1. The source is highly variable on short timescales (<1 hr), exhibiting apparent flares occupying a significant fraction (~3%) of the total observing time. The flares seem to occur over all binary orbital phases and correlate with the overall variability in the light curve. We find a total of 323 discrete flares having a mean FWHM of ~18 s. The detailed properties of SMC X-1 do not vary significantly between the flares and the normal state, suggesting that the flare may be an extension of the normal state persistent emission with increased accretion rates. The flares resemble type II X-ray bursts from GRO J1744-28. We discuss the origin of the SMC X-1 flares in terms of a viscous instability near the inner edge of the accretion disk around a weakly magnetized X-ray pulsar and find this is consistent with the interpretation that SMC X-1 is in fact an intermediate-stage source like GRO J1744-28.