Fermi Gamma-ray Space Telescope

Résumé

Le Fermi Gamma-ray Space Telescope (anciennement Gamma-ray Large Area Space Telescope, ou GLAST) est un télescope spatial de l'agence spatiale américaine destiné à l'étude des rayons gamma de haute énergie émis par les objets célestes. Ce satellite a été lancé le 11 juin 2008 et placé sur une orbite basse terrestre circulaire de pour une durée d'au moins 5 ans. L'instrument principal LAT permet d'observer des rayons gamma de à . Un deuxième instrument, le GBM, est réservé à l'étude des sursauts gamma. Le télescope Fermi a pour objectif l'étude des phénomènes les plus violents observés dans l'univers tels que les blazars jets relativistes produits par des trous noirs supermassifs, les sursauts gamma et doit contribuer à une meilleure compréhension de phénomènes tels que les pulsars, les éruptions solaires et l'origine des rayons cosmiques. Cette mission spatiale est financée conjointement par la NASA, le Département de l'Énergie américaine avec la participation de laboratoires de re

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https://fr.wikipedia.org/wiki/Fermi_Gamma-ray_Space_Telescope

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Publications associées (19)

We report on simultaneous broadband observations of the TeV-emitting blazar Markarian 501 between 2013 April 1 and August 10, including the first detailed characterization of the synchrotron peak with Swift and NuSTAR. During the campaign, the nearby BL Lac object was observed in both a quiescent and an elevated state. The broadband campaign includes observations with NuSTAR, MAGIC, VERITAS, the Fermi Large Area Telescope, Swift X-ray Telescope and UV Optical Telescope, various ground-based optical instruments, including the GASP-WEBT program, as well as radio observations by OVRO, Metsahovi, and the F-Gamma consortium. Some of the MAGIC observations were affected by a sand layer from the Saharan desert, and had to be corrected using event-by-event corrections derived with a Light Detection and Ranging (LIDAR) facility. This is the first time that LIDAR information is used to produce a physics result with Cherenkov Telescope data taken during adverse atmospheric conditions, and hence sets a precedent for the current and future ground-based gamma-ray instruments. The NuSTAR instrument provides unprecedented sensitivity in hard X-rays, showing the source to display a spectral energy distribution (SED) between 3 and 79 keV consistent with a log-parabolic spectrum and hard X-ray variability on hour timescales. None (of the four extended NuSTAR observations) show evidence of the onset of inverse-Compton emission at hard X-ray energies. We apply a single-zone equilibrium synchrotron self-Compton (SSC) model to five simultaneous broadband SEDs. We find that the SSC model can reproduce the observed broadband states through a decrease in the magnetic field strength coinciding with an increase in the luminosity and hardness of the relativistic leptons responsible for the high-energy emission.

Iop Publishing Ltd2015

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Teraelectronvolt pulsed emission from the Crab Pulsar detected by MAGIC

Thomas Günther Bretz

Aims. We investigate the extension of the very high-energy spectral tail of the Crab Pulsar at energies above 400 GeV. Methods. We analyzed similar to 320 h of good-quality Crab data obtained with the MAGIC telescope from February 2007 to April 2014. Results. We report the most energetic pulsed emission ever detected from the Crab Pulsar reaching up to 1.5 TeV. The pulse profile shows two narrow peaks synchronized with those measured in the GeV energy range. The spectra of the two peaks follow two different power-law functions from 70GeV up to 1.5 TeV and connect smoothly with the spectra measured above 10GeV by the Large Area Telescope (LAT) on board the Fermi satellite. When making a joint fit of the LAT and MAGIC data above 10 GeV the photon indices of the spectra differ by 0.5 +/- 0.1. Conclusions. Using data from the MAGIC telescopes we measured the most energetic pulsed photons from a pulsar to date. Such TeV pulsed photons require a parent population of electrons with a Lorentz factor of at least 5x10(6). These results strongly suggest IC scattering off low-energy photons as the emission mechanism and a gamma-ray production region in the vicinity of the light cylinder.

Edp Sciences S A2016

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Limits to dark matter annihilation cross-section from a combined analysis of MAGIC and Fermi-LAT observations of dwarf satellite galaxies

Thomas Günther Bretz

We present the first joint analysis of gamma-ray data from the MAGIC Cherenkov telescopes and the Fermi Large Area Telescope (LAT) to search for gamma-ray signals from dark matter annihilation in dwarf satellite galaxies. We combine 158 hours of Segue 1 observations with MAGIC with 6-year observations of 15 dwarf satellite galaxies by the Fermi-LAT. We obtain limits on the annihilation cross-section for dark matter particle masses between 10 GeV and 100 TeV - the widest mass range ever explored by a single gamma-ray analysis. These limits improve on previously published Fermi-LAT and MAGIC results by up to a factor of two at certain masses. Our new inclusive analysis approach is completely generic and can be used to perform a global, sensitivity-optimized dark matter search by combining data from present and future gamma-ray and neutrino detectors.

Iop Publishing Ltd2016

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