Minimum X-ray source size of the on-axis corona in AGN
Result description
The "lamppost" model is often used to describe the X-ray source geometry in AGN, where an infinitesimal point source is located on the black hole spin axis. This is especially invoked for narrow line Seyfert 1 (NLS1) galaxies, where an extremely broad iron line seen in episodes of low X-ray flux can both be explained by extremely strong relativistic effects as the source approaches the black hole horizon. The most extreme spectrum seen from the NLS1 1H0707-495 requires that the source is less than 1GM/c(2) above the event horizon in this geometry. However, the source must also be large enough to intercept sufficient seed photons from the disc to make the hard X-ray Compton continuum which produces the observed iron line/reflected spectrum. We use a fully relativistic ray tracing code to show that this implies that the source must be substantially larger than 1GM/c(2) in 1H0707-495 if the disc is the source of seed photons. Hence the source cannot fit as close as 1GM/c(2) to the horizon, so the observed spectrum and variability are not formed purely by effects of strong gravity but probably also by changes in corona and inner accretion flow geometry
Keywords
The result's identifiers
Result code in IS VaVaI
Result on the web
DOI - Digital Object Identifier
Alternative languages
Result language
angličtina
Original language name
Minimum X-ray source size of the on-axis corona in AGN
Original language description
The "lamppost" model is often used to describe the X-ray source geometry in AGN, where an infinitesimal point source is located on the black hole spin axis. This is especially invoked for narrow line Seyfert 1 (NLS1) galaxies, where an extremely broad iron line seen in episodes of low X-ray flux can both be explained by extremely strong relativistic effects as the source approaches the black hole horizon. The most extreme spectrum seen from the NLS1 1H0707-495 requires that the source is less than 1GM/c(2) above the event horizon in this geometry. However, the source must also be large enough to intercept sufficient seed photons from the disc to make the hard X-ray Compton continuum which produces the observed iron line/reflected spectrum. We use a fully relativistic ray tracing code to show that this implies that the source must be substantially larger than 1GM/c(2) in 1H0707-495 if the disc is the source of seed photons. Hence the source cannot fit as close as 1GM/c(2) to the horizon, so the observed spectrum and variability are not formed purely by effects of strong gravity but probably also by changes in corona and inner accretion flow geometry
Czech name
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Czech description
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Classification
Type
Jx - Unclassified - Peer-reviewed scientific article (Jimp, Jsc and Jost)
CEP classification
BN - Astronomy and celestial mechanics, astrophysics
OECD FORD branch
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Result continuities
Project
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Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Others
Publication year
2016
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Astronomische Nachrichten
ISSN
0004-6337
e-ISSN
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Volume of the periodical
337
Issue of the periodical within the volume
4-5
Country of publishing house
DE - GERMANY
Number of pages
7
Pages from-to
441-447
UT code for WoS article
000375725600017
EID of the result in the Scopus database
2-s2.0-84964793148
Basic information
Result type
Jx - Unclassified - Peer-reviewed scientific article (Jimp, Jsc and Jost)
CEP
BN - Astronomy and celestial mechanics, astrophysics
Year of implementation
2016