Spectral and polarization properties of black hole accretion disc emission: including absorption effects
Identifikátory výsledku
Kód výsledku v IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F21%3A00549680" target="_blank" >RIV/67985815:_____/21:00549680 - isvavai.cz</a>
Výsledek na webu
<a href="https://doi.org/10.1093/mnras/staa3859" target="_blank" >https://doi.org/10.1093/mnras/staa3859</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1093/mnras/staa3859" target="_blank" >10.1093/mnras/staa3859</a>
Alternativní jazyky
Jazyk výsledku
angličtina
Název v původním jazyce
Spectral and polarization properties of black hole accretion disc emission: including absorption effects
Popis výsledku v původním jazyce
The study of radiation emitted from black hole (BH) accretion discs represents a crucial way to understand the main physical properties of these sources, and in particular the BH spin. Beside spectral analysis, polarimetry is becoming more and more important, motivated by the development of new techniques which will soon allow to perform measurements also in the X- and gamma-rays. Photons emitted from BH accretion discs in the soft state are indeed expected to be polarized, with an energy dependence which can provide an estimate of the BH spin. Calculations performed so far, however, considered scattering as the only process to determine the polarization state of the emitted radiation, implicitly assuming that the temperatures involved are such that material in the disc is entirely ionized. In this work, we generalize the problem by calculating the ionization structure of a surface layer of the disc with the public code cloudy, and then by determining the polarization properties of the emerging radiation using the Monte Carlo code stokes. This allows us to account for absorption effects alongside scattering ones. We show that including absorption can deeply modify the polarization properties of the emerging radiation with respect to what is obtained in the pure-scattering limit. As a general rule, we find that the polarization degree is larger when absorption is more important, which occurs, for example, for low accretion rates and/or spins when the ionization of the matter in the innermost accretion disc regions is far from complete.
Název v anglickém jazyce
Spectral and polarization properties of black hole accretion disc emission: including absorption effects
Popis výsledku anglicky
The study of radiation emitted from black hole (BH) accretion discs represents a crucial way to understand the main physical properties of these sources, and in particular the BH spin. Beside spectral analysis, polarimetry is becoming more and more important, motivated by the development of new techniques which will soon allow to perform measurements also in the X- and gamma-rays. Photons emitted from BH accretion discs in the soft state are indeed expected to be polarized, with an energy dependence which can provide an estimate of the BH spin. Calculations performed so far, however, considered scattering as the only process to determine the polarization state of the emitted radiation, implicitly assuming that the temperatures involved are such that material in the disc is entirely ionized. In this work, we generalize the problem by calculating the ionization structure of a surface layer of the disc with the public code cloudy, and then by determining the polarization properties of the emerging radiation using the Monte Carlo code stokes. This allows us to account for absorption effects alongside scattering ones. We show that including absorption can deeply modify the polarization properties of the emerging radiation with respect to what is obtained in the pure-scattering limit. As a general rule, we find that the polarization degree is larger when absorption is more important, which occurs, for example, for low accretion rates and/or spins when the ionization of the matter in the innermost accretion disc regions is far from complete.
Klasifikace
Druh
J<sub>imp</sub> - Článek v periodiku v databázi Web of Science
CEP obor
—
OECD FORD obor
10308 - Astronomy (including astrophysics,space science)
Návaznosti výsledku
Projekt
<a href="/cs/project/GA18-00533S" target="_blank" >GA18-00533S: Reverberace akrečních disků černých děr</a><br>
Návaznosti
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Ostatní
Rok uplatnění
2021
Kód důvěrnosti údajů
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Údaje specifické pro druh výsledku
Název periodika
Monthly Notices of the Royal Astronomical Society
ISSN
0035-8711
e-ISSN
1365-2966
Svazek periodika
501
Číslo periodika v rámci svazku
3
Stát vydavatele periodika
GB - Spojené království Velké Británie a Severního Irska
Počet stran výsledku
13
Strana od-do
3393-3405
Kód UT WoS článku
000610549500022
EID výsledku v databázi Scopus
2-s2.0-85100290645