THE RELATION OF OPTICAL/ULTRAVIOLET AND X-RAY EMISSION IN LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI

We study the relation of optical/UV and X-ray emission in the low luminosity active galactic nuclei (LLAGNs), using a sample of 49 sources including 28 local Seyfert galaxies and 21 low-ionization nuclear emission-line regions with optical/UV spectral luminosity at wavelength {lambda} = 2500 A, 23.0...

Full description

Saved in:
Bibliographic Details
Published inThe Astrophysical journal Vol. 739; no. 2
Main Author Xu Yadi
Format Journal Article
LanguageEnglish
Published United States 01.10.2011
Subjects
ACCRETION DISKS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CORRELATIONS
ELECTROMAGNETIC RADIATION
EMISSION
GALAXIES
GALAXY NUCLEI
IONIZING RADIATIONS
LUMINOSITY
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS
SEYFERT GALAXIES
ULTRAVIOLET RADIATION
X RADIATION
Online AccessGet full text

Cover

More Information
Summary:We study the relation of optical/UV and X-ray emission in the low luminosity active galactic nuclei (LLAGNs), using a sample of 49 sources including 28 local Seyfert galaxies and 21 low-ionization nuclear emission-line regions with optical/UV spectral luminosity at wavelength {lambda} = 2500 A, 23.0 {<=} log L{sub {nu}(2500A)}(erg s{sup -1} Hz{sup -1}) {<=} 27.7, and X-ray spectral luminosity at 2 keV, 20.5 {<=} log L{sub {nu}(2keV)} {<=} 25.3. Strong correlations are found between the X-ray luminosity and the optical/UV-to-X-ray index, {alpha}{sub ox}, with the optical/UV luminosity, with slopes very similar to the findings for the luminous AGNs in previous works. The correlation between {alpha}{sub ox} and L{sub {nu}(2keV)} is very weak, as is that found for the luminous AGNs in the majority of previous similar works. We also study the relation between {alpha}{sub ox} and the Eddington ratio L{sub bol}/L{sub Edd} for our sample and find a significant anti-correlation for the sources with L{sub bol}/L{sub Edd} {approx}< 10{sup -3}, which is opposite to the correlation between the two variables for the luminous AGNs. Using the advection-dominated accretion flow (ADAF) model, we roughly reproduce this anti-correlationship for the two variables for the LLAGNs. This result strongly supports the ADAF as a candidate for the accretion mode in LLAGNs.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/739/2/64;COUNTRYOFINPUT:INTERNATIONALATOMICENERGYAGENCY(IAEA)