Change search
ReferencesLink to record
Permanent link

Direct link
Show others and affiliations
2010 (English)In: ASTROPHYS J LETT, ISSN 2041-8205, Vol. 717, no 1, l71-L78 p.Article in journal (Refereed) Published
Abstract [en]

The detection of diffuse radio emission associated with clusters of galaxies indicates populations of relativistic leptons infusing the intracluster medium (ICM). Those electrons and positrons are either injected into and accelerated directly in the ICM, or produced as secondary pairs by cosmic-ray ions scattering on ambient protons. Radiation mechanisms involving the energetic leptons together with the decay of neutral pions produced by hadronic interactions have the potential to produce abundant GeV photons. Here, we report on the search for GeV emission from clusters of galaxies using data collected by the Large Area Telescope on the Fermi Gamma-ray Space Telescope from 2008 August to 2010 February. Thirty-three galaxy clusters have been selected according to their proximity and high mass, X-ray flux and temperature, and indications of non-thermal activity for this study. We report upper limits on the photon flux in the range 0.2-100 GeV toward a sample of observed clusters (typical values (1-5) x 10(-9) photon cm(-2) s(-1)) considering both point-like and spatially resolved models for the high-energy emission and discuss how these results constrain the characteristics of energetic leptons and hadrons, and magnetic fields in the ICM. The volume-averaged relativistic-hadron-to-thermal energy density ratio is found to be <5%-10% in several clusters.

Place, publisher, year, edition, pages
2010. Vol. 717, no 1, l71-L78 p.
Keyword [en]
cosmic rays, galaxies: clusters: general, gamma rays: galaxies: clusters, radiation mechanisms: non-thermal
National Category
Natural Sciences
URN: urn:nbn:se:su:diva-48945DOI: 10.1088/2041-8205/717/1/L71ISI: 000279430600015OAI: diva2:376177
authorCount :169Available from: 2010-12-10 Created: 2010-12-10 Last updated: 2010-12-10Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Conrad, JanRipken, JoachimYang, Zhaoyu
By organisation
Department of Physics
Natural Sciences

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