Publications (32)
The Blazar Hadronic Code Comparison Project
Matteo Cerruti, Michael Kreter, Maria Petropoulou +15
Blazar hadronic models have been developed in the past decades as an alternative to leptonic ones. In hadronic models the gamma-ray emission is associated with synchrotron emission…
Recent results from the Pierre Auger Observatory
Andreas Zech
The goal of the Pierre Auger Observatory is to determine the still unknown nature and origin of ultra-high energy cosmic rays. The study of these elusive particles probes astrophys…
Gammapy: high level data analysis for extragalactic science cases with the Cherenkov Telescope Array
Julien Lefaucheur, Catherine Boisson, Zeljka Bosnjak +5
The Cherenkov Telescope Array (CTA) observatory will probe the non-thermal universe above 20 GeV up to several hundreds of TeV with a significant improvement in sensitivity and ang…
Blazar flares from plasma blobs crossing the broad-line region
Sébastien Le Bihan, Anton Dmytriiev, Andreas Zech
The blazar 3C 279 is well known for its rapid and large-amplitude variability. On 20 December 2013, the source exhibited an orphan γ-ray flare characterized by a flux-doubling tim…
An orphan flare from a plasma blob crossing the broad-line region ?
Sébastien Le Bihan, Anton Dmytriiev, Andreas Zech
The blazar 3C 279 is well known for its prolific emission of rapid flares. A particular event occurred on 12/20/2013, exhibiting a large flux increase with a doubling time scale of…
The variety of extreme blazars in the AstroSat view
Pranjupriya Goswami, Michael Zacharias, Andreas Zech +3
Extreme blazars have exceptionally hard intrinsic X-ray/TeV spectra and extreme peak energies in their spectral energy distribution (SED). Observational evidence suggests that the…
ExHaLe-jet: Modeling blazar jets with an extended hadro-leptonic radiation code
Michael Zacharias, Anita Reimer, Catherine Boisson +1
Blazars emit across all electromagnetic wavelengths. While the so-called one-zone model has described well both quiescent and flaring states, it cannot explain the radio emission a…
A mixed lepto-hadronic scenario for PKS 2155-304
Matteo Cerruti, Andreas Zech, Catherine Boisson +1
The models developed to describe the spectral energy distribution (SED) of blazars can be divided into leptonic or hadronic scenarios, according to the particles responsible for th…
Particle acceleration signatures in the time-dependent one-zone synchrotron self-Compton model of blazar flares
Paloma Thevenet, Andreas Zech, Catherine Boisson +1
The study of multiwavelength flux and spectral variations during rapid flares from blazars provides strong constraints on the physical parameters of the compact emission regions re…
H.E.S.S. searches for TeV gamma rays associated to high-energy neutrinos
Fabian Schüssler, Halim Ashkar, Michael Backes +12
The detection of an astrophysical flux of high-energy neutrinos by IceCube is a major step forward in the search for the origin of cosmic rays, as this emission is expected to orig…
The Giant Radio Array for Neutrino Detection (GRAND): Science and Design
GRAND Collaboration, Jaime Alvarez-Muniz, Rafael Alves Batista +48
The Giant Radio Array for Neutrino Detection (GRAND) is a planned large-scale observatory of ultra-high-energy (UHE) cosmic particles, with energies exceeding 10^8 GeV. Its goal is…
Expected signatures from hadronic emission processes in the TeV spectra of BL Lac objects
Andreas Zech, Matteo Cerruti, Daniel Mazin
The wealth of recent data from imaging air Cherenkov telescopes (IACTs), ultra-high energy cosmic-ray experiments and neutrino telescopes have fuelled a renewed interest in hadroni…
Equipartition Gamma-Ray Blazars and the Location of the Gamma-Ray Emission Site in 3C 279
Charles D. Dermer, Matteo Cerruti, Benoit Lott +2
Blazar spectral models generally have numerous unconstrained parameters, leading to ambiguous values for physical properties like Doppler factor delta or fluid magnetic field B'. T…
Modelling the variable emission states of -ray emitting Narrow-Line Seyfert 1 galaxies
Anna Luashvili, Catherine Boisson, Andreas Zech +2
-ray-emitting narrow-line Seyfert 1 galaxies (-NLS1) constitute an intriguing small population of Active Galactic Nuclei with -ray emission resembling low power flat-sp…
The relativistic jet of the gamma-ray emitting narrow-line Seyfert 1 galaxy 1H 0323+342
Daniel Kynoch, Hermine Landt, Martin J. Ward +7
The detection of several radio-loud narrow-line Seyfert 1 (NLS1) galaxies by the Fermi Gamma-Ray Space Telescope hints at the existence of a rare, new class of gamma-ray emitting a…
Monte Carlo Studies of the GCT Telescope for the Cherenkov Telescope Array
Thomas Armstrong, Heide Costantini, Cameron Rulten +2
The GCT is an innovative dual-mirror solution proposed for the small-size telescopes for CTA, capable of imaging primary cosmic gamma-rays from below a TeV to hundreds of TeV. The…
Flux variability from ejectas in structured relativistic jets with large-scale magnetic fields
Gaëtan Fichet de Clairfontaine, Zakaria Meliani, Andreas Zech +1
Using the relativistic MHD code MPI-AMRVAC and a radiative transfer code in post-processing, we explore the influence of the magnetic-field configuration and transverse stratificat…
Progress in unveiling extreme particle acceleration in persistent astrophysical jets
Jonathan Biteau, Elisa Prandini, Luigi Costamante +7
The most powerful persistent accelerators in the Universe are jetted active galaxies. Blazars, galaxies whose jets are directed towards Earth, dominate the extragalactic gamma-ray…
News from the very-high-energy sky seen with H.E.S.S
Andreas Zech, H. E. S. S. Collaboration
The H.E.S.S. experiment, the largest Cherenkov telescope array to date, has been observing the sky at TeV energies for the past 16 years. Its location in the Southern hemisphere pr…
Studies of Systematic Uncertainties in the HiRes-II Measurement of the UHECR Spectrum
Andreas Zech
We present studies of systematic uncertainties in the measurement of the ultra-high energy cosmic ray (UHECR) spectrum with the FADC detector of the High Resolution Fly's Eye exper…
Constraining the parameter space of the one-zone synchrotron-self-Compton model for GeV-TeV detected BL Lac objects
Matteo Cerruti, Catherine Boisson, Andreas Zech
The one-zone synchrotron-self-Compton (SSC) model aims to describe the spectral energy distribution (SED) of BL Lac objects via synchrotron emission by a non-thermal population of…
A Measurement of the UHECR Spectrum with the HiRes FADC Detector
Andreas Zech
We have measured the energy spectrum of ultra-high energy cosmic rays (UHECR) with the HiRes FADC detector (HiRes-2) in monocular mode. A detailed Monte Carlo simulation of the det…
Electron-proton co-acceleration on relativistic shocks in extreme-TeV blazars
Andreas Zech, Martin Lemoine
The multi-wavelength emission from a newly identified population of `extreme-TeV' blazars, with Compton peak frequencies around 1 TeV, is difficult to interpret with standard one-z…
Gamma-ray blazars near equipartition and the origin of the GeV spectral break in 3C 454.3
Matteo Cerruti, Charles D. Dermer, Benoit Lott +2
Observations performed with the Fermi-LAT telescope have revealed the presence of a spectral break in the GeV spectrum of flat-spectrum radio quasars (FSRQs) and other low- and int…
Flare echos from relaxation shocks in perturbed relativistic jets
Gaëtan Fichet de Clairfontaine, Zakaria Meliani, Andreas Zech
One of the main scenarios to account for the multi-wavelength flux variability observed in relativistic jets of AGNs is based on diffusive shock acceleration of a population of rel…
The Giant Radio Array for Neutrino Detection (GRAND): Present and Perspectives
Ke Fang, Jaime Ãlvarez-Muñiz, Rafael Alves Batista +33
The Giant Radio Array for Neutrino Detection (GRAND) aims at detecting ultra-high energy extraterrestrial neutrinos via the extensive air showers induced by the decay of tau lepton…
ExHaLe-jet: An extended hadro-leptonic jet model for blazars. I. Code description and initial results
Michael Zacharias, Anita Reimer, Catherine Boisson +1
The processes operating in blazar jets are still an open question. Modeling the radiation emanating from an extended part of the jet allows one to capture these processes on all sc…
The imprint of protons on the emission of extended blazar jets
Michael Zacharias, Anita Reimer, Andreas Zech
Blazars - active galaxies with the jet pointing at Earth - emit across all electromagnetic wavelengths. The so-called one-zone model has described well both quiescent and flaring s…
Blazars at Very High Energies: Emission Modelling
Hélène Sol, Andreas Zech
Blazars are very broadband cosmic sources with spectra spanning over twenty orders of magnitude in frequency, down to the 100 MHz regime in the radio range, up to VHE at several te…
Lepto-hadronic modelling of blazar emission
Matteo Cerruti, Andreas Zech, Catherine Boisson +1
The characteristic double-bumped spectral energy distribution (SED) of blazars is explained by either leptonic or hadronic models. In the former, Inverse Compton emission dominates…
A Comprehensive Hadronic Code Comparison for Active Galactic Nuclei
Matteo Cerruti, Annika Rudolph, Maria Petropoulou +14
We perform the first dedicated comparison of five hadronic codes (AM, ATHEA, B13, LeHa-Paris, and LeHaMoC) that have been extensively used in modeling of the spectral energ…
Chasing Gravitational Waves with the Cherenkov Telescope Array
Jarred Gershon Green, Alessandro Carosi, Lara Nava +563
The detection of gravitational waves from a binary neutron star merger by Advanced LIGO and Advanced Virgo (GW170817), along with the discovery of the electromagnetic counterparts…