Searches for millisecond pulsations in low-mass X-ray binaries, 2

Abstract

view Abstract Citations (161) References (34) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Searches for Millisecond Pulsations in Low-Mass X-Ray Binaries. II. Vaughan, B. A. ; van der Klis, M. ; Wood, K. S. ; Norris, J. P. ; Hertz, P. ; Michelson, P. F. ; van Paradijs, J. ; Lewin, W. H. G. ; Mitsuda, K. ; Penninx, W. Abstract Coherent millisecond X-ray pulsations are expected from low-mass X-ray binaries (LMXBs), but remain undetected. Using the single-parameter Quadratic Coherence Recovery Technique (QCRT) to correct for unknown binary orbit motion, we have performed Fourier transform searches for coherent oscillations in all long, continuous segments of data obtained at 1 ms time resolution during Ginga observations of LMXB. We have searched the six known Z sources (GX 5-1, Cyg X-2, Sco X-1, GX 17+2, GX 340+0, and GX 349+2), seven of the 14 known atoll sources (GX 3+1. GX 9+1, GX 9+9, 1728-33. 1820-30, 1636-53 and 1608-52), the 'peculiar' source Cir X-1, and the high-mass binary Cyg X-3. We find no evidence for coherent pulsations in any of these sources, with 99% confidence limits on the pulsed fraction between 0.3% and 5.0% at frequencies below the Nyquist frequency of 512 Hz. A key assumption made in determining upper limits in previous searches is shown to be incorrect. We provide a recipe for correctly setting upper limits and detection thresholds. Finally we discuss and apply two strategies to improve sensitivity by utilizing multiple, independent, continuous segments of data with comparable count rates. Publication: The Astrophysical Journal Pub Date: November 1994 DOI: 10.1086/174818 Bibcode: 1994ApJ...435..362V Keywords: Neutron Stars; Orbit Calculation; Pulsed Radiation; Stellar Models; Stellar Oscillations; X Ray Astronomy; X Ray Binaries; Ginga Satellite; Mathematical Models; Nyquist Frequencies; Stellar Magnetic Fields; Stellar Mass; Stellar Rotation; Astronomy; METHODS: NUMERICAL; STARS: BINARIES: CLOSE; STARS: NEUTRON; STARS: OSCILLATIONS; X-RAYS: STARS full text sources ADS | data products SIMBAD (15)