2001/04/30 by Peter G. Jonker, Michiel van der Klis · 3 citations
Earth and Planetary Sciences · Physics and Astronomy · #Astrophysical Phenomena and Observations #Earth Systems and Cosmic Evolution #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.1086/320510
6 pages long, including 4 figures, uses emulateapj5, accepted for ApJL, Replaced figure 1
arxiv created 2001/05/10 · openalex publication_date 2001/05/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We report the discovery of 0.59 s X-ray pulsations from the low-mass X-ray binary, 5.57 hr dipping and eclipsing accretion disk corona source 2A 1822-371. Pulse arrival time analysis indicates a circular orbit with e < 0.03 (95% confidence) and an a sin i for the neutron star of 1.006(5) lt-s, implying a mass function of (2.03 ± 0.03) × 10 -2 M ☉ . The barycentric pulse period was 0.59325(2) s in 1996.270 and 0.59308615(5) s in 1998.205, indicating an average spin-up with / P = (-1.52 ± 0.02) × 10 -4 yr -1 . For a magnetic field strength of ~(1-5) × 10 12 G as derived from the X-ray spectrum, the implied intrinsic X-ray luminosity is ~(2-4) × 10 37 ergs s -1 . The pulse amplitude is low but increases steeply as a function of energy from a sinusoidal amplitude of 0.25% in 2-5.4 keV to ~3% above 20 keV. We discuss the constraints on the masses of the companion star and the fact that several aspects of the energy spectrum are in qualitative accordance with that of a strongly magnetized neutron star.