Ultra-high Energy Cosmic Rays from Blazars

dc.contributor.author Dermer, Charles en_US
dc.contributor.corporatename Naval Research Laboratory (U.S.) en_US
dc.contributor.corporatename Georgia Institute of Technology. School of Physics en_US
dc.date.accessioned 2013-01-25T20:54:07Z
dc.date.available 2013-01-25T20:54:07Z
dc.date.issued 2012-12-10
dc.description Presented on December 10, 2012 from 3:00 to 4:00 pm in Marcus Nanotechnology Conference room 1116. en_US
dc.description Runtime: 57:51 minutes. en_US
dc.description.abstract Blazar astronomy is rapidly progressing thanks in large part to the successes of the Fermi Gamma-ray Space Telescope and the ground-based gamma-ray telescopes. More than 1000 active galaxies have been detected at GeV energies, and nearly 50 at Very-High Energies (VHE, > 100 GeV). We can now explore multiwavelength and multi-messenger connections in unprecedented detail, and derive the astroparticle implications of those results. In this presentation, leptonic and hadronic spectral modeling of blazars is reviewed with the intent of identifying ultra-high energy cosmic rays (UHECRs) in the spectral energy distributions of these objects. We consider a number of unusual results that could be explained by UHECRs in blazars: (1) distinct spectral components revealed by deabsorption of blazar VHE spectra; (2) flattening at moderate redshift in the Stecker-Scully relation showing the GeV - TeV spectral index difference versus redshift; (3) conflicting results for the location of the gamma-ray emission site in blazars; (4) the unusually short variability times of luminous blazars. The arguments for and against radio galaxies and blazars being the sources of the UHECRs are reviewed, and predictions for UHECR composition is made if BL Lac objects accelerate most of the UHECRs. Unusual effects of UHECR acceleration in blazars is illustrated by the strange case of 4C +21.35. We also discuss effects of hypothetical axions, a dark matter candidate, in the interpretation of unusual blazar behavior, and a recent Fermi-LAT search for axions in occultations of bright AGNs by the Sun. en_US
dc.format.extent 57:51 minutes
dc.identifier.uri http://hdl.handle.net/1853/46015
dc.language.iso en_US en_US
dc.publisher Georgia Institute of Technology en_US
dc.relation.ispartofseries Physics Colloquium
dc.subject Blazars en_US
dc.subject Ultra-high energy cosmic rays en_US
dc.subject Gamma ray astronomy en_US
dc.subject Axions en_US
dc.title Ultra-high Energy Cosmic Rays from Blazars en_US
dc.type Moving Image
dc.type.genre Lecture
dspace.entity.type Publication
local.contributor.corporatename College of Sciences
local.contributor.corporatename School of Physics
local.relation.ispartofseries Physics Colloquium
relation.isOrgUnitOfPublication 85042be6-2d68-4e07-b384-e1f908fae48a
relation.isOrgUnitOfPublication 2ba39017-11f1-40f4-9bc5-66f17b8f1539
relation.isSeriesOfPublication 5fcf4984-0912-45ae-91c5-2c6de98772b0
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