Sco X‐1: Hints of Periodic Variability at Radio Frequencies

Open Access
Publisher Website
Google Scholar
Abstract
We present the results of the flux density variability observations of Sco X-1 obtained during six VLA observing sessions between 1981 and 1990. The light curves indicate three timescales of flux density variation: slow, intermediate, and rapid. The rapidity of the variations sets a conservative upper limit on size of ~6 mas, assuming a distance of 200 pc, from light travel arguments for the radio-emitting regions. The corresponding brightness temperature of greater than 107 K indicates a nonthermal origin for the radio emission. A detailed analysis of the light curves suggests that the radio emission may exhibit true periodicity on timescales of ~3 hr. We also provide a prescription for accurate signal recovery and image restoration of point and extended sources when an object of varying signal is present in the synthesized beam.

This publication has 19 references indexed in Scilit: