Change search
ReferencesLink to record
Permanent link

Direct link
Constraints on the gamma ray emission from the cluster scale agn outburst in the hydra a galaxy cluster
Show others and affiliations
2012 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 545, A103- p.Article in journal (Refereed) Published
Abstract [en]

Context. In some galaxy clusters, powerful active galactic nuclei (AGN) have blown bubbles with cluster scale extent into the ambient medium. The main pressure support of these bubbles is not known to date, but cosmic rays are a viable possibility. For such a scenario copious gamma-ray emission is expected as a tracer of cosmic rays from these systems. Aims. Hydra A, the closest galaxy cluster hosting a cluster scale AGN outburst, located at a redshift of 0.0538, is investigated for being a gamma-ray emitter with the High Energy Stereoscopic System (H.E.S.S.) array and the Fermi Large Area Telescope (Fermi-LAT). Methods. Data obtained in 20.2 h of dedicated H. E. S. S. observations and 38 months of Fermi-LAT data, gathered by its usual all-sky scanning mode, have been analyzed to search for a gamma-ray signal. Results. No signal has been found in either data set. Upper limits on the gamma-ray flux are derived and are compared to models. These are the first limits on gamma-ray emission ever presented for galaxy clusters hosting cluster scale AGN outbursts. Conclusions. The non-detection of Hydra A in gamma-rays has important implications on the particle populations and physical conditions inside the bubbles in this system. For the case of bubbles mainly supported by hadronic cosmic rays, the most favorable scenario, which involves full mixing between cosmic rays and embedding medium, can be excluded. However, hadronic cosmic rays still remain a viable pressure support agent to sustain the bubbles against the thermal pressure of the ambient medium. The largest population of highly-energetic electrons, which are relevant for inverse-Compton gamma-ray production is found in the youngest inner lobes of Hydra A. The limit on the inverse-Compton gamma-ray flux excludes a magnetic field below half of the equipartition value of 16 mu G in the inner lobes.

Place, publisher, year, edition, pages
2012. Vol. 545, A103- p.
Keyword [en]
gamma rays: galaxies: clusters, galaxies: clusters: individual: Hydra A, galaxies: active
National Category
Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:su:diva-83987DOI: 10.1051/0004-6361/201219655ISI: 000309254900103OAI: diva2:577975


Available from: 2012-12-17 Created: 2012-12-17 Last updated: 2012-12-17Bibliographically approved

Open Access in DiVA

Fulltext(335 kB)92 downloads
File information
File name FULLTEXT01.pdfFile size 335 kBChecksum SHA-512
Type fulltextMimetype application/pdf

Other links

Publisher's full text

Search in DiVA

By author/editor
Conrad, JanDickinson, H. J.Ripken, Joachim
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
Total: 92 downloads
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: 90 hits
ReferencesLink to record
Permanent link

Direct link