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The detection of Fermi AGN above 100 GeV using clustering analysis

Armstrong, Thomas; Brown, Anthony M.; Chadwick, Paula; Nolan, Sam

The detection of Fermi AGN above 100 GeV using clustering analysis Thumbnail


Thomas Armstrong

Sam Nolan


The density-based clustering algorithm DBSCAN has been applied to the Fermi Large Area Telescope (LAT) data set of Eγ ≥ 100 GeV events with |b| > 10°, in order to search for new very high energy (VHE) γ-ray sources. The clustering analysis returned 49 clusters, of which 21 correspond to already known VHE-emitting active galactic nuclei (AGN) within the TeVCat catalogue and a further 11 were found to be significant in a full Fermi analysis. Of these, two are previously detected Fermi VHE AGN, and nine represent new VHE sources consisting of six BL Lac objects, one blazar of unknown type and two unassociated sources. Comparing these, along with the VHE AGN RBS 0679 and RBS 0970 previously detected with Fermi-LAT, to the current populations of AGN detected with ground-based instruments and Fermi suggests that the VHE-emitting AGN discovered in this study are very similar to the TeVCat AGN and therefore further observations with ground-based imaging atmospheric Cherenkov telescopes are recommended.


Armstrong, T., Brown, A. M., Chadwick, P., & Nolan, S. (2015). The detection of Fermi AGN above 100 GeV using clustering analysis. Monthly Notices of the Royal Astronomical Society, 452(3), 3159-3166.

Journal Article Type Article
Acceptance Date Jun 19, 2015
Publication Date Sep 21, 2015
Deposit Date Apr 10, 2015
Publicly Available Date Aug 7, 2015
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 452
Issue 3
Pages 3159-3166
Keywords Radiation mechanisms: non-thermal, Methods: statistical, Galaxies: active, BL Lacertae objects: general, Gamma-rays: galaxies.


Published Journal Article (912 Kb)

Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society. ©: 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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