Change search
ReferencesLink to record
Permanent link

Direct link
Long-term monitoring of PKS2155-304 with ATOM and HESS:investigation of optical/gamma-ray correlations in different spectral states
Show others and affiliations
2014 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 571, A39Article in journal (Refereed) Published
Abstract [en]

In this paper we report on the analysis of all the available optical and very high-energy gamma-ray (> 200 GeV) data for the BL Lac object PKS 2155-304, collected simultaneously with the ATOM and H.E.S.S. telescopes from 2007 until 2009. This study also includes X-ray (RXTE, Swift) and high-energy gamma-ray (Fermi-LAT) data. During the period analysed, the source was transitioning from its flaring to quiescent optical states, and was characterized by only moderate flux changes at different wavelengths on the timescales of days and months. A flattening of the optical continuum with an increasing optical flux can be noted in the collected dataset, but only occasionally and only at higher flux levels. We did not find any universal relation between the very high-energy gamma-ray and optical flux changes on the timescales from days and weeks up to several years. On the other hand, we noted that at higher flux levels the source can follow two distinct tracks in the optical flux-colour diagrams, which seem to be related to distinct gamma-ray states of the blazar. The obtained results therefore indicate a complex scaling between the optical and gamma-ray emission of PKS 2155 304, with different correlation patterns holding at different epochs, and a gamma-ray flux depending on the combination of an optical flux and colour rather than a flux alone.

Place, publisher, year, edition, pages
2014. Vol. 571, A39
Keyword [en]
radiation mechanisms: non-thermal, galaxies: active, black hole physics, BL Lacertae objects: individual: PKS 2155-304, galaxies: jets, gamma rays: galaxies
National Category
Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:su:diva-115642DOI: 10.1051/0004-6361/201424142ISI: 000345282600058OAI: diva2:800122


Available from: 2015-04-01 Created: 2015-03-27 Last updated: 2015-04-01Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Conrad, JanFarnier, ChristianMeyer, ManuelMorå, KnutSpengler, GerritWagner, Robert M.
By organisation
Department of PhysicsThe Oskar Klein Centre for Cosmo Particle Physics (OKC)
In the same journal
Astronomy and Astrophysics
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: 278 hits
ReferencesLink to record
Permanent link

Direct link