THE NOISE IN THE 35-D CYCLE OF HER X-1

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BAYKAL A., BOYNTON P., DEETER J., SCOTT D.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, vol.265, no.2, pp.347-350, 1993 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 265 Issue: 2
  • Publication Date: 1993
  • Doi Number: 10.1093/mnras/265.2.347
  • Journal Name: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Applied Science & Technology Source, Communication Abstracts, INSPEC, Metadex, zbMATH, DIALNET, Civil Engineering Abstracts
  • Page Numbers: pp.347-350
  • Open Archive Collection: AVESIS Open Access Collection
  • Middle East Technical University Affiliated: Yes

Abstract

We calculate the power density spectrum of fluctuations in the X-ray turn-on times of Her X-1, including new data which extend the X-ray and optical flux observations to a span of over 20 yr with 221 distinct 35-d high-low flux cycles. If we assume that turn-on times define the period of the 35-d clock, this statistical interpretation of turn-on behaviour is consistent with a white-noise process in the first derivative of the 35-d phase fluctuations (or a random walk in clock phase). We discuss the implications of considering the 35-d clock mechanism as a noise process.