ISDC Science Results
Probing the cosmic-ray content of galaxy clusters by stacking Fermi-LAT count maps|
2013-10-02 | Fermi, VHE, Galaxy cluster
The cosmic-ray content of galaxy clusters is expected to produce a gamma-ray signal that could be detected by the Fermi Gamma-ray Space Telescope. We show here that even by stacking the Fermi observations at the position of 53 known galaxy clusters we still cannot detect such an emission.
Introducing the CTA concept|
2013-03-01 | VHE
The Cherenkov Telescope Array (CTA) is a new observatory for very high-energy (VHE) gamma rays. CTA has ambitions science goals, for which it is necessary to achieve full-sky coverage, to improve the sensitivity by about an order of magnitude, to span about four decades of energy, from a few tens of GeV to above 100 TeV with enhanced angular and energy resolutions over existing VHE gamma-ray observatories.
A stacking method to study the gamma-ray emission of source samples based on the co-adding of Fermi LAT count maps|
2012-09-13 | Fermi, VHE
Objects with low integrated gamma-ray fluxes that are not detected individually may become detectable when their corresponding count maps are added. This paper describes a method that can be used to analyze stacked data obtained with the Fermi Large Area Telescope.
Fermi/LAT observations of 1ES 0229+200: implications for extragalactic magnetic fields and background light|
2012-01-25 | Fermi, VHE
New data from the Fermi/LAT instrument allow us to measure the GeV spectrum of a prominent TeV blazar 1ES 0229+200. Being one of the hardest TeV sources on the sky, 1ES 0229+200 provides the best constraints for the Extragalactic magnetic field and Extragalactic background light. The new observations permit us to measure these two quantities simultaneously.
Stochastic Acceleration and the Evolution of Spectral Distributions in SSC Sources: A Self Consistent Modeling of Blazars' Flares |
2011-07-12 | AGN, VHE
We investigated the role of the stochastic acceleration on the evolution of the particle energy distribution in relativistic jet, taking into account radiative losses in a SSC scenario. We find that in the acceleration dominated stage the distribution is well described by a log-parabolic shape, and that the predicted trends among synchrotron curvature (bs), peak energy (Es), and peak luminosities (Ls), match those observed in a sample of 6 TeV detected BL Lacs.
12 hours spikes from the Crab Pevatron|
2010-12-15 | INTEGRAL, Fermi, VHE | Press Release
The Crab nebula featured 3 gamma-ray spikes in the GeV band in September 2010. These γ-ray flares are due to synchrotron emission from a very compact Pevatron located closer to the pulsar than the equatorial termination shock between the supersonic wind and the surrounding nebula. The spectral and timing properties of the flare are interpreted in the framework of a relativistically moving emitter. The flare duration is of the order of the synchrotron cooling time scale for electrons at an energy larger than 1015 eV, the highest electron energy ever measured in a cosmic accelerator.
HESS J1632-478: An Energetic Relic|
2010-07-04 | VHE, Fermi
The unidentified very high energy source HESS J1632-478 is very likely an old (104 years) Pulsar Wind Nebula with a size of several parsecs containing very high energy electrons cooling slowly mostly through Inverse Compton scattering. Its spectrum is made of a faint synchrotron component (from the radio to the X-rays) emitted by electrons accelerated up to very high energies and of a bright high-energy gamma-ray component emitted by inverse Compton scatering against infrared photons.
Evidence for strong extragalactic magnetic fields from Fermi observations of TeV blazars|
2010-04-04 | Fermi, AGN, VHE | Press Release
FERMI/LAT observations of distant blazars together with theoretical modeling provide us with the first clue about the parameters of primordial magnetic field, survived up to nowadays in the voids of the Large-Scale Structure.