Estimating the size of X-ray lamppost coronae in active galactic nuclei

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F20%3A00538501" target="_blank" >RIV/67985815:_____/20:00538501 - isvavai.cz</a>
Result on the web
<a href="https://doi.org/10.1051/0004-6361/202039158" target="_blank" >https://doi.org/10.1051/0004-6361/202039158</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1051/0004-6361/202039158" target="_blank" >10.1051/0004-6361/202039158</a>

Result language
angličtina
Original language name
Estimating the size of X-ray lamppost coronae in active galactic nuclei
Original language description
We report estimates of the X-ray coronal size of active galactic nuclei in the lamppost geometry. In this commonly adopted scenario, the corona is assumed for simplicity to be a point-like X-ray source located on the axis of the accretion disc. However, the corona must intercept a number of optical/UV seed photons from the disc consistent with the observed X-ray flux, which constrains its size. At least for the sources accreting below the Eddington limit, we find that a Comptonizing lamppost corona can generally exist, but with constraints on its size and height above the event horizon of the black hole depending on the spin. For a maximally spinning black hole, a solution can almost always be found at any height, while for a non-spinning black hole the height must generally be higher than 5 gravitational radii. This is because, for a given luminosity, a higher spin implies more seed photons illuminating the corona, which is due to a larger and hotter inner disc area. The maximal spin solution is favoured, as it predicts an X-ray photon index in better agreement with the observations.
Czech name
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Czech description
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Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
—
OECD FORD branch
10308 - Astronomy (including astrophysics,space science)

Project
<a href="/en/project/GA17-02430S" target="_blank" >GA17-02430S: Geometrical properties of the accretion disc corona in Active Galactic Nuclei</a><br>
Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year
2020
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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