X-ray reverberation modelling of the observed UV/optical power spectra of quasars

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F25%3A00639689" target="_blank" >RIV/67985815:_____/25:00639689 - isvavai.cz</a>

Result on the web

<a href="https://hdl.handle.net/11104/0370245" target="_blank" >https://hdl.handle.net/11104/0370245</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/202554220" target="_blank" >10.1051/0004-6361/202554220</a>

Result language

angličtina

Original language name

X-ray reverberation modelling of the observed UV/optical power spectra of quasars

Original language description

Context. Over the past decade, a significant amount of effort has been put into investigating the ultraviolet (UV) and optical variability of active galactic nuclei (AGNs). Comprehensive studies of intensive multi-wavelength monitoring and surveys of local and high-redshift AGNs have shown that X-ray illumination of AGN accretion discs is a potential explanation for the observed variability. Aims. Our main objective is to study the UV/optical power spectra of AGNs under the assumption of X-ray reverberation and to test whether this model can explain the observed power spectra of distant quasars. Methods. We computed the disc transfer function in the case of X-ray reverberation using a recent physical model and studied its dependence on the parameters of the model. This model allows us to explore the variability of X-ray illuminated discs under the scenario in which the X-ray corona is powered by the accretion process or by an external source. We then calculated UV/optical power spectra using the disc transfer function and assuming a bending power law for the X-ray power spectrum. We fitted our models to the observed power spectra of quasars determined by a recent power spectrum analysis of the SDSS Stripe-82 light curves. Results. We demonstrate that X-ray reverberation can fit the power spectra of quasars in our sample well at all wavelengths, from similar to 1300 Å up to 4000 Å. Our best-fit models imply that the X-ray corona is powered by the accretion disc, and that the black hole spin is probably lower than 0.7, while the X-ray corona height is in the range of 20 60 R-g. This is in agreement with previous findings from the application of the X-ray reverberation model to the quasar micro-lensing disc size problem, as well as recent time-lag measurements.

Czech name

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Czech description

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Type

J_imp - 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

—

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2025

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Astronomy & Astrophysics

ISSN

0004-6361

e-ISSN

1432-0746

Volume of the periodical

701

Issue of the periodical within the volume

Sept.

Country of publishing house

FR - FRANCE

Number of pages

13

Pages from-to

A295

UT code for WoS article

001579007600009

EID of the result in the Scopus database

2-s2.0-105017370060