A1 Refereed original research article in a scientific journal
X-ray dips and a complex UV/X-ray cross-correlation function in the black hole candidate MAXI J1820+070
Authors: Kajava J.J.E., Motta S.E., Sanna A., Veledina A., Del Santo M., Segreto A.
Publisher: OXFORD UNIV PRESS
Publication year: 2019
Journal: Monthly Notices of the Royal Astronomical Society: Letters
Journal name in source: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Journal acronym: MON NOT R ASTRON SOC
Volume: 488
Issue: 1
First page : L18
Last page: L23
Number of pages: 6
ISSN: 0035-8711
DOI: https://doi.org/10.1093/mnrasl/slz089
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/42009766
MAXI J1820+070, a black hole candidate first detected in early 2018 March, was observed by XMM-Newton during the outburst rise. In this letter we report on the spectral and timing analysis of the XMM-Newton X-ray and UV data, as well as contemporaneous X-ray data from the Swift satellite. The X-ray spectrum is well described by a hard thermal Comptonization continuum. The XMM-Newton X-ray light curve shows a pronounced dipping interval, and spectral analysis indicates that it is caused by a moderately ionized partial covering absorber. The XMM-Newton/OM U-filter data do not reveal any signs of the 17 h orbital modulation that was seen later on during the outburst decay. The UV/X-ray cross-correlation function shows a complex shape, with a peak at positive lags of about 4 s and a precognition dip at negative lags, which is absent during the X-ray dipping episode. Such shape could arise if the UV emission comes partially from synchrotron self-Compton emission near the black hole, as well as from reprocessing of the X-rays in the colder accretion disc further out.
Downloadable publication This is an electronic reprint of the original article. |  |
