Seminars
Our seminars take place in the lecture room of the building at
Praha–Sporilov.
Next seminar:
(none)
Previous seminar:
22.10.2013 15:00
Jiri Svoboda
Astronomical Institute, Academy of Sciences, Prague
Spectral states of active galactic nuclei from simultaneous X-ray and UV measurements by XMM-Newton
Abstract
Jiri Svoboda
Spectral states of active galactic nuclei from simultaneous X-ray and UV measurements by XMM-Newton
It is generally believed that the black holes in active galactic nuclei
(AGNs) and X-ray binaries (XRBs) work in a similar way. While XRBs evolve
rapidly and several sources have undergone a few complete cycles from
quiescence to an outburst and back, AGNs remain in the same state due to
their larger characteristic time-scale, proportional to their size.
However, the study of AGN spectral states is still possible with a large
sample of sources. Multiwavelength observations are needed for this purpose
since the AGN thermal disc-emission dominates in the ultraviolet energy
range while the up-scattered hot-corona emission is detected in X-rays.
Based on ROSAT All-Sky Survey and SDSS database, Koerding et al. (2006)
constructed the disc-fraction/luminosity diagrams of AGNs that revealed the
analogy with the state diagrams of XRBs. I would like to present our
results that are based on the comparison of strictly simultaneous UV and
X-ray measurements of AGNs obtained with the XMM-Newton satellite.
If you would like to give a seminar in our group, please contact Vladimir Karas or Jaroslav Hamersky.
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