ICRC2015

Session

Parallel GA18 EGAL

5 Aug 2015, 11:00

World Forum

375. Gamma-ray cosmology and fundamental physics with TeV blazars: results from 20 years of observations

Jonathan Biteau (UC Santa Cruz)

05/08/2015, 11:00

GA-EX

Oral contribution

Gamma rays from TeV blazars have been detected by ground-based experiments for more than two decades. We have collected the most extensive set of archival spectra from these sources in order to constrain the processes affecting gamma-ray propagation on cosmological distances. We discuss our results on the diffuse photon field that populates universe, called the extragalactic background light,...

309. MAGIC observations of the February 2014 flare of 1ES 1011+496 and measurement of the Extragalactic Background Light density

Priyadarshini Bangale (Max planck Institute for physics)

05/08/2015, 11:15

GA-EX

Oral contribution

1ES 1011+496 is a blazar located at a redshift z=0.212, revealed as a very-high-energy gamma-ray emitter by MAGIC in 2007. In February 2014 the source underwent an unprecedented flaring episode. Following a flare alert issued by VERITAS, the MAGIC telescopes carried out an observation campaign for a total of 17 nights between February 6 and March 7, during which the source reached a peak flux...

641. Update on the determination of the extragalactic background light spectral energy distribution with H.E.S.S.

Matthias Lorentz (IRFU CEA Saclay)

05/08/2015, 11:30

GA-EX

Oral contribution

When very high-energy photons (VHE, E>100 GeV) travel over cosmological distances, they interact with background light by pair production. In the Earth reference frame it turns out the threshold of the reaction with photons from IR to UV falls in the energy range where the H.E.S.S. array of Cherenkov telescopes is the most sensitive. Observations of spectral features in the VHE band of...

832. VERITAS Search for Magnetically Broadened Emission From Blazars

Elisa Kay Pueschel (University College Dublin)

05/08/2015, 11:45

GA-EX

Oral contribution

A non-zero intergalactic magnetic field (IGMF) would potentially produce detectable effects on cascade emission from blazars. Depending on the strength of the IGMF, the cascade emission may be time delayed or angularly broadened compared to the blazar’s primary, unscattered emission. Ground-based imaging atmospheric-Cherenkov telescopes, such as VERITAS, have the precise angular resolution...

239. Results from monitoring TeV blazars with HAWC

Dr Robert Lauer (University of New Mexico)

05/08/2015, 12:00

GA-EX

Oral contribution

The recently completed High Altitude Water Cherenkov (HAWC) gamma-ray observatory has been taking data in a partial configuration with >95% duty cycle for more than one year. With an instantaneous field of view of 2 sr, two-thirds of the sky is surveyed every day at gamma-ray energies between 100 GeV and 100 TeV. Any source location in the field of view can be monitored each day, with an...

149. FACT - TeV Flare Alerts Triggering Multi-Wavelength Observations

Daniela Dorner

05/08/2015, 12:15

GA-EX

Oral contribution

Active galactic nuclei show variability on time scales ranging from minutes to decades. The radiation from these extreme objects spans many orders of magnitude along the whole electromagnetic spectrum. It shows two peaks, where for the subgroup of blazars the first peak is in the radio to x-ray regime, while the second peak is in the gamma-ray regime. Due to the extreme variability and the...