Change search
ReferencesLink to record
Permanent link

Direct link
Show others and affiliations
2012 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 747, no 2, 104- p.Article in journal (Refereed) Published
Abstract [en]

We report on a systematic investigation of the gamma-ray properties of 120 hard X-ray-selected Seyfert galaxies classified as radio-quiet objects, utilizing the three-year accumulation of Fermi Large Area Telescope (LAT) data. Our sample of Seyfert galaxies is selected using the Swift Burst Alert Telescope 58 month catalog, restricting the analysis to the bright sources with average hard X-ray fluxes F14-195 keV >= 2.5 x 10(-11) erg cm(-2) s(-1) at high Galactic latitudes (|b| > 10 degrees). In order to remove radio-loud objects from the sample, we use the hard X-ray radio loudness parameter, RrX, defined as the ratio of the total 1.4 GHz radio to 14-195 keV hard X-ray energy fluxes. Among 120 X-ray bright Seyfert galaxies with RrX < 10(-4), we did not find a statistically significant g-ray excess (TS > 25) positionally coincident with any target Seyferts, with possible exceptions of ESO 323-G077 and NGC 6814. The mean value of the 95% confidence level gamma-ray upper limit for the integrated photon flux above 100 MeV from the analyzed Seyferts is similar or equal to 4 x 10(-9) photons cm(-2) s(-1), and the upper limits derived for several objects reach similar or equal to 1 x 10(-9) photons cm(-2) s(-1). Our results indicate that no prominent gamma-ray emission component related to active galactic nucleus activity is present in the spectra of Seyferts around GeV energies. The Fermi-LAT upper limits derived for our sample probe the ratio of gamma-ray to X-ray luminosities L-gamma/L-X < 0.1, and even <0.01 in some cases. The obtained results impose novel constraints on the models for high-energy radiation of radio-quiet Seyfert galaxies.

Place, publisher, year, edition, pages
2012. Vol. 747, no 2, 104- p.
Keyword [en]
accretion, accretion disks, galaxies: active, galaxies: Seyfert, gamma rays: galaxies, X-rays: galaxies
National Category
Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:su:diva-80156DOI: 10.1088/0004-637X/747/2/104ISI: 000302856400020OAI: diva2:552310


Available from: 2012-09-13 Created: 2012-09-12 Last updated: 2012-09-13Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Conrad, JanGarde, Maja LlenaYang, ZhaoyuZimmer, Stephan
By organisation
Department of PhysicsThe Oskar Klein Centre for Cosmo Particle Physics (OKC)
In the same journal
Astrophysical Journal
Astronomy, Astrophysics and Cosmology

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 30 hits
ReferencesLink to record
Permanent link

Direct link