ICRC2015

Session

Parallel GA08 EGAL

1 Aug 2015, 11:00

World Forum

927. Detection of very-high-energy gamma rays from the most distant and gravitationally lensed blazar S3 0218+35 using the MAGIC telescope system

Julian Sitarek (University of Łódź)

01/08/2015, 11:00

GA-EX

Oral contribution

S3 0218+35 is a blazar located at a cosmological redshift of z=0.944. It is gravitationally lensed by a spiral galaxy at a redshift of z=0.68. The blazar and its lens are well studied in the radio through X-ray bands, and several blazar outbursts were detected by Fermi-LAT at energies above 100 MeV. Strong gravitational lensing was invoked to explain the two components apparent in the...

879. The extreme environment in the center of Mrk 876 and the switch on of its AGN activity

Dr Eugenio Bottacini (Stanford University)

01/08/2015, 11:15

GA-EX

Oral contribution

Results from surveys show that most galaxies underwent one or more eras of Active Galactic Nucleus (AGN) activity throughout their existence. During the AGN era the central region of the galaxy becomes very bright up to soft gamma-ray energies due to inverse-Comptonization by relativistic electrons. However, survey studies can not draw definite conclusions on what switches on the AGN activity...

762. VERITAS detection of gamma-ray flaring activity from the BL Lac object 1ES1727+502 during bright moonlight observations

Matteo Cerruti (Harvard-Smithsonian Center for Astrophysics)

01/08/2015, 11:30

GA-EX

Oral contribution

During May 2013, a gamma-ray flare from the BL Lac object 1ES 1727+502 (z=0.055) has been detected with the VERITAS Cherenkov telescopes. This detection represents the first evidence of very-high-energy (E>100 GeV) variability from this blazar and has been achieved using a reduced-high-voltage configuration which allows observations under bright moonlight. The integral flux is about five times...

742. Discovery of VHE gamma-rays from the radio galaxy PKS 0625-354 with H.E.S.S.

Michal Dyrda (Institute of Nuclear Physics PAS)

01/08/2015, 11:45

GA-EX

Oral contribution

Most of the extragalactic objects detected so far in the very high energy (VHE) regime are blazars, but detected nearby radio galaxies: M87, Cen A and NGC 1275 of type FRI seem to constitute a new class of VHE emitters. The radio galaxy PKS 0625-354 was observed with the H.E.S.S. phase I telescopes in 2012, above the energy threshold of 250 GeV. The time-averaged TeV energy spectrum is well...

668. The Detection of Fermi AGN above 100 GeV using Clustering Analysis

Mr Thomas Armstrong (Department of Physics, University of Durham, South Road, Du rham, DH1 3LE, UK)

01/08/2015, 12:00

GA-EX

Oral contribution

The 6-year *Fermi* data set contains some 8000 extragalactic events with E > 100GeV. To search fo the sources of these events, we applied a clustering algorithm (DBSCAN), using a search radius based on the *Fermi*-LAT point spread function, to events from > 10 degrees above and below the Galactic plane. This analysis revealed 49 significant clusters. Of these, 21 correspond to known Very High...

591. A Bright Gamma-ray flare from the Blazar B2 1215+30 Detected by VERITAS and Fermi-LAT

Floriana Zefi (LLR - Ecole Polytechnique)

01/08/2015, 12:15

GA-EX

Oral contribution

We report on evidence of correlated gamma-ray variability from the BL Lac source B2 1215+30, detected by VERITAS (E > 100 GeV) and the Fermi Large Area Telescope (100 MeV < E <100 GeV). The source was observed by VERITAS during an exceptional flaring state in February 2014. Further investigations of flux variability in the energy range covered by Fermi-LAT, quasi-simultaneous with VERITAS...