Open AccessCorrelated optical and X‐ray variability in LMC X‐2
Author(s) -
McGowan K. E.,
Charles P. A.,
O'Donoghue D.,
Smale A. P.
Publication year - 2003
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2003.07029.x
Subject(s) - physics , photometry (optics) , astrophysics , x ray , time lag , lag , astronomy , light curve , high resolution , optics , stars , remote sensing , computer network , computer science , geology
We have obtained high time resolution (seconds) photometry of LMC X‐2 in 1997 December, simultaneously with the Rossi X‐ray Timing Explorer ( RXTE ), in order to search for correlated X‐ray and optical variability on time‐scales from seconds to hours. We find that the optical and X‐ray data are correlated only when the source is in a high, active X‐ray state. Our analysis shows evidence for the X‐ray emission leading the optical with a mean delay of <20 s. The time‐scale for the lag can be reconciled with disc reprocessing, driven by the higher‐energy X‐rays, only by considering the lower limit for the delay. The results are compared with a similar analysis of archival data of Sco X‐1.