1998/09/24 by G. G. Pooley, R. P. Fender, C. Brocksopp · 69 citations
Engineering · Physics and Astronomy · #Amplitude #Astronomical Observations and Instrumentation #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Flux (metallurgy) #Modulation (music) #Optics #Orbital period #Physics #Superconducting Materials and Applications #Wavelength #astro-ph
paper · pdf · doi:10.1046/j.1365-8711.1999.02225.x
published in Monthly Notices of the Royal Astronomical Society 302(1), L1-L5 (Oxford University Press) · Accepted for publication in MNRAS
arxiv created 1998/09/24 · openalex publication_date 1999/01/01 · arxiv updated 2009/12/01 · openalex created_date 2020/11/23 · openalex updated_date 2026/08/05
20 months of observations of the radio emission at 15 GHz from Cygnus X-1, starting in 1996 October, show variations at the binary period of 5.6 d, but with a phase offset from those at X-ray wavelengths. There are also longer term variations on a time-scale of 150 d, which are only loosely related to the soft X-ray flux. The source was in the hard/low X-ray state throughout this period. The mean 15-GHz flux density is 13 mJy, the radio spectrum is flat and the semi-amplitude of the orbital modulation is about 2 mJy. We discuss the possible origins of the modulation and the relationship to the soft X-ray emission.