Echoes from an irradiated disc in GRO J1655-40

RI Hynes, K O'Brien, Keith Douglas Horne, W Chen, CA Haswell

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)


We demonstrate correlated rapid variability between the optical/UV and X-ray emission for the first time in a soft X-ray transient, GRO J1655-40: Hubble Space Telescope (HST) light curves show similar features to those seen by the Rossi X-my Timing Explorer (RXTE), but with mean delay of up to 10-20 s. We interpret the correlations as the result of reprocessing of X-rays into optical and UV emission, with a delay owing to finite light travel time, and thus perform echo mapping of the system. The time-delay distribution has a mean of 14.6 +/- 1.4 s and dispersion (i.e. the standard deviation of the distribution) of 10.5 +/- 1.9 s at binary phase 0.4. Hence we identify the reprocessing region as the accretion disc rather than the mass donor star.

Original languageEnglish
Pages (from-to)pp.L37-L41.
Number of pages5
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Publication statusPublished - 1 Oct 1998


  • accretion, accretion discs
  • binaries : close
  • stars : individual : Nova Sco 1994
  • (GRO J1655-40)
  • ultraviolet : stars
  • X-rays : stars


Dive into the research topics of 'Echoes from an irradiated disc in GRO J1655-40'. Together they form a unique fingerprint.

Cite this