Change search
ReferencesLink to record
Permanent link

Direct link
SEARCH for EXTENDED GAMMA-RAY EMISSION from the VIRGO GALAXY CLUSTER with FERMI-LAT
KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. Oskar Klein Ctr Cosmoparticle Phys, SE-10691 Stockholm, Sweden.
Number of Authors: 121
2015 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 812, no 2, 159Article in journal (Refereed) Published
Abstract [en]

Galaxy clusters are one of the prime sites to search for dark matter (DM) annihilation signals. Depending on the substructure of the DM halo of a galaxy cluster and the cross sections for DM annihilation channels, these signals might be detectable by the latest generation of gamma-ray telescopes. Here we use three years of Fermi-Large Area Telescope data, which are the most suitable for searching for very extended emission in the vicinity of the nearby Virgo galaxy cluster. Our analysis reveals statistically significant extended emission which can be well characterized by a uniformly emitting disk profile with a radius of 3 degrees that moreover is offset from the cluster center. We demonstrate that the significance of this extended emission strongly depends on the adopted interstellar emission model (IEM) and is most likely an artifact of our incomplete description of the IEM in this region. We also search for and find new point source candidates in the region. We then derive conservative upper limits on the velocity-averaged DM pair annihilation cross section from Virgo. We take into account the potential gamma-ray flux enhancement due to DM sub-halos and its complex morphology as a merging cluster. For DM annihilating into b (b) over bar, assuming a conservative sub-halo model setup, we find limits that are between 1 and 1.5 orders of magnitude above the expectation from the thermal cross section for m(DM) <= 100 GeV. In a more optimistic scenario, we exclude <sigma v > similar to 3 x 10(-26)cm(3)s(-1) for m(DM)less than or similar to 40 GeV for the same channel. Finally, we derive upper limits on the gamma-ray-flux produced by hadronic cosmic-ray interactions in the inter cluster medium. We find that the volume-averaged cosmic-ray-to-thermal pressure ratio is less than similar to 6%.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2015. Vol. 812, no 2, 159
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
URN: urn:nbn:se:kth:diva-180338DOI: 10.1088/0004-637X/812/2/159ISI: 000365206600071ScopusID: 2-s2.0-84946110462OAI: oai:DiVA.org:kth-180338DiVA: diva2:892819
Note

QC 20160111

Available from: 2016-01-11 Created: 2016-01-11 Last updated: 2016-01-11Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Larsson, Stefan
By organisation
Particle and Astroparticle Physics
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: 36 hits
ReferencesLink to record
Permanent link

Direct link