The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope discovered a rapid (about 5 days duration), high-energy (E >100 MeV) gamma-ray outburst from a source identified with the blazar PKS 1502+106 (OR 103, S3 1502+10, z=1.839) starting on August 05, 2008 and followed by bright and variable flux over the next few months. Results on the gamma-ray localization and identification, as well as spectral and temporal behavior during the first months of the Fermi all-sky survey are reported here in conjunction with a multi-waveband characterization as a result of one of the first Fermi multi-frequency campaigns. The campaign included a Swift ToO (followed up by 16-day observations on August 07-22, MJD 54685-54700), VLBA (within the MOJAVE program), Owens Valley (OVRO) 40m, Effelsberg-100m, Metsahovi-14m, RATAN-600 and Kanata-Hiroshima radio/optical observations. Results from the analysis of archival observations by INTEGRAL, XMM-Newton and Spitzer space telescopes are reported for a more complete picture of this new gamma-ray blazar.

/pdf/pks-1502-106-a-new-and-distant-gamma-ray-blazar-in-outburst-e6a7kyj2ux.pdf

PKS 1502+106: A New and Distant Gamma-ray Blazar in Outburst Discovered by the Fermi Large Area Telescope

Results of a phenomenological model to estimate the gamma-ray burst (GRB) detection rate by the Fermi Gamma-Ray Space Telescope are reported. This estimate is based on the Burst and Transient Source Experiment (BATSE) 4B GRB fluence distribution, the mean ratio of fluences measured at 100 MeV-5 GeV with Energetic Gamma-Ray Experiment Telescope (EGRET) and at 20 keV-2 MeV with BATSE, and the mean EGRET GRB spectrum for the five EGRET spark-chamber GRBs. For a 10% fluence ratio and a number spectral index α1 = –2 at 100 MeV- 5 GeV energies, we estimate a rate of ≈20 and 4 GRBs yr–1 in the Fermi Large Area Telescope field of view (FOV) with at least five photons with energy E>100 MeV and E>1 GeV, respectively. We also estimate ≈1.5 GRBs yr–1 in the Fermi FOV where at least one photon with energy E>10 GeV is detected. For these parameters, we estimate ≈1-2 GRBs yr–1 detected with the Fermi telescope with more than 100 γ-rays with E 100 MeV. Comparison predictions for α1 = –2.2, different fluence ratios, and the AGILE γ-ray satellite are made. Searches for different classes of GRBs using a diagram plotting 100 MeV-10 GeV fluence versus 20 keV- 20 MeV fluence is considered as a way to search for separate classes of GRBs and, specifically, spectral differences between the short-hard and long-duration GRB classes, and for hard components in GRBs.

pdf/gamma-ray-burst-predictions-for-the-fermi-gamma-ray-space-3yrkelvopz.pdf

Gamma-ray burst predictions for the fermi gamma ray space telescope

The detection of gamma-rays, antiprotons and positrons due to pair annihilation of dark matter particles in the Milky Way halo is a viable techniques to search for supersymmetric dark matter candidates. In particular the EGRET team has seen a convincing signal for a strong excess of emission from the Galactic center that has no simple explanation with standard processes. We will review the limits achievable with the experiment GLAST and we will compare this method with the antiproton and positrons experiments.

pdf/search-for-dark-matter-with-glast-4aang8fd6k.pdf

Search for Dark Matter with GLAST

Results of a phenomenological model to estimate the GRB detection rate by the Fermi Gamma ray Space Telescope are reported. This estimate is based on the BATSE 4B GRB fluence distribution, the mean ratio of fluences measured at 100 MeV - 5 GeV with EGRET and at 20 keV - 2 MeV with BATSE, and the mean EGRET GRB spectrum for the 5 EGRET spark-chamber GRBs. For a 10% fluence ratio and a number spectral index alpha_1 = -2 at 100 MeV - 5 GeV energies, we estimate a rate of ~ 20 and 4 GRBs per yr in the Fermi Large Area Telescope field of view with at least 5 photons with energy E > 100 MeV and E > 1 GeV, respectively. We also estimate ~ 1.5 GRBs per yr in the Fermi FoV where at least 1 photon with energy E > 10 GeV is detected. For these parameters, we estimate = 1 - 2 GRBs per year detected with the Fermi telescope with more than 100 gamma rays with E >~ 100$ MeV. Comparison predictions for alpha_1 = -2.2, different fluence ratios, and the AGILE gamma-ray satellite are made. Searches for different classes of GRBs using a diagram plotting 100 MeV - 10 GeV fluence vs. 20 keV - 20 MeV fluence is considered as a way to search for separate classes of GRBs and, specifically, spectral differences between the short-hard and long duration GRB classes, and for hard components in GRBs.

Gamma Ray Burst Predictions for the Fermi Gamma Ray Space Telescope

Measurements of the cosmic ray electron spectrum have received much attention over the last decade as anomalies in both electron and positron observations have been detected independently by several experiments. The profound possible implications in the fields of high energy astrophysics and particle physics have allowed for many interpretations on the origin of these inconsistencies in the spectra. This research focuses on two space-borne cosmic radiation experiments at different stages in their mission lifetimes: the Calorimetric Electron Telescope (CALET) and the Fermi Large Area Telescope (LAT). We explore the proton-electron discriminating capabilities of the CALET instrument through Monte Carlo simulations. Additionally, we present our efforts in electron identification using dedicated information of the tracking region of the LAT, exploiting calibration data from the beam test campaign. Within both studies, we employ multivariate techniques to improve the identification of cosmic ray electrons from the vast background.

Identification of High Energy Cosmic Ray Electrons using Advanced Techniques in CALET and Fermi LAT

The Gamma-ray Large Area Space Telescope (GLAST) is an international and multi-agency space mission that will study the cosmos in the energy range 20 MeV – 1 TeV. GLAST is an imaging gamma-ray telescope more much capable than instruments flown previously. The main instrument on board of the spacecraft is the Large Area Telescope (LAT), a high energy pair conversion telescope consisting of three major subsystems: a precision silicon tracker/converter, a CsI electromagnetic calorimeter and a segmented anti-coincidence system. In this article, we present the status of the construction and tests of the silicon tracker.

http://people.roma2.infn.it/~glast/A79Glast_tracker.pdf

The GLAST tracker design and construction

GLAST is a next generation high-energy gamma-ray observatory designed for making observations of celestial gamma-ray sources in the energy band extending from 10 KeV to more than 300 GeV. Respect to the previous instrument EGRET, GLAST will have a higher effective area (six times more), higher field of view, energy range and resolution, providing an unprecedented advance in sensitivity (a factor 30 or more). The main scientific goals are the study of all gamma-ray sources such as blazars, gamma-ray bursts, supernova remnants, pulsars, diffuse radiation, and unidentified high-energy sources. The construction and test of the Large Area Telescope (LAT) tracker, has been a great effort during the past years, involving tens of people from many Italian INFN sections and industrial partners. Environmental and performance tests of the hardware, detectors and reading electronics, have been carried on during all the steps of the LAT construction. The resulting LAT performance are better than the ones required by the original science proposal, demonstrating the quality of the italian group effort. In this article we summarize the LAT construction and test workflow, presenting its main results.

/pdf/the-glast-lat-tracker-construction-and-test-2p1doxh6cn.pdf

The GLAST LAT tracker construction and test

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The GLAST tracker design and construction

The GLAST LAT tracker construction and test