2002/09/13 by D. M. Smith, David M. Smith, W. A. Heindl +1 · 1 citation
Engineering · Physics and Astronomy · #Astronomical Observations and Instrumentation #Astrophysical Phenomena and Observations #Gamma-ray bursts and supernovae #astro-ph
paper · pdf · doi:10.1086/344701
published as Astrophys.J. 578 (2002) L129-L132 · 13 pages, 5 figures, accepted by The Astrophysical Journal Letters
arxiv created 2002/09/13 · openalex publication_date 2002/10/08 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
Five years of Rossi X-Ray Timing Explorer ( RXTE ) observations of the Galactic black hole candidates 1E 1740.7-2942 and GRS 1758-258 show a periodic modulation with an amplitude of 3%-4% in each source at 12.73 ± 0.05 and 18.45 ± 0.10 days, respectively. We interpret the modulations as orbital, suggesting that the objects have red giant companions. Combining the RXTE data with earlier data (Zhang, Harmon, & Liang) from the Burst and Transient Source Experiment on the Compton Gamma Ray Observatory , we find a long period or quasi-period of about 600 days in 1E 1740.7-2942 and a suggestion of a similar 600 day period in GRS 1758-258. These timescales are longer than any yet found for either precessing systems like Hercules X-1 and SS 433 or binaries like LMC X-3 and Cygnus X-1 with more irregular long periods.