9,580 research outputs found
Fermi Paper Model (Formerly GLAST Paper Model)
This paper model provides a short description of the scientific instruments on board GLAST as well as links to other resources about the GLAST instruments. There is also a short description of how GLAST detects gamma-rays with the Large Area Telescope as well as the GLAST Burst Monitor detectors. The product includes three pages of parts that can be cut out and easily assembled using common household items. Note: In 2008, the Gamma-ray Large Area Space Telescope (GLAST) was renamed Fermi, for the physicist Enrico Fermi. Educational levels: Informal education, General public
Jets, Blazars and the EBL in the GLAST-EXIST Era
The synergy of GLAST and the proposed EXIST mission as the Black Hole Finder
Probe in the Beyond Einstein Program is remarkable. With its full-sky per orbit
hard X-ray imaging (3-600 keV) and "nuFnu" sensitivity comparable to GLAST,
EXIST could measure variability and spectra of Blazars in the hard X-ray
synchrotron component simultaneous with GLAST (~10-100GeV) measures of the
inverse Compton component, thereby uniquely constraining intrinsic source
spectra and allowing measured high energy spectral breaks to measure the cosmic
diffuse extra-galactic background light (EBL) by determining the intervening
diffuse IR photon field required to yield the observed break from photon-photon
absorption. Such studies also constrain the physics of jets (and parameters and
indeed the validity of SSC models) and the origin of the >100 MeV gamma-ray
diffuse background likely arising from Blazars and jet-dominated sources. An
overview of the EXIST mission, which could fly in the GLAST era, is given
together with a synopsis of other key synergies of GLAST-EXIST science.Comment: 3 pages, 2 Figs., to appear in Proc. First GLAST Symp. (Stanford,
Feb. 5-8, 2007), eds. S.Ritz, P.F.Michelson, and C.Meegan, AIP Conf. Pro
Simultaneous Radio to (Sub-) mm-Monitoring of Variability and Spectral Shape Evolution of potential GLAST Blazars
The Large Area Telescope (LAT) instrument onboard GLAST offers a tremendous
opportunity for future blazar studies. In order to fully benefit from its
capabilities and to maximize the scientific return from the LAT, it is of great
importance to conduct dedicated multi-frequency monitoring campaigns that will
result comprehensive observations. Consequently, we initiated an effort to
conduct a GLAST-dedicated, quasi-simultaneous, broad-band flux-density (and
polarization) monitoring of potential GLAST blazars with the Effelsberg and
OVRO radio telescopes (11cm to 7mm wavelength). Here, we present a short
overview of these activities which will complement the multi-wavelengths
activities of the GLAST/LAT collaboration towards the 'low-energy' radio bands.
Further we will give a brief outlook including the extension of this
coordinated campaign towards higher frequencies and future scientific aims.Comment: 3 pages, to appear in the Proceedings of the First GLAST Symposium,
Stanford University, February 200
Angular power spectrum of gamma-ray sources for GLAST: blazars and clusters of galaxies
Blazars, a beamed population of active galactic nuclei, radiate high-energy
gamma-rays, and thus are a good target for the Gamma Ray Large Area Space
Telescope (GLAST). As the blazars trace the large-scale structure of the
universe, one may observe spatial clustering of blazars. We calculate the
angular power spectrum of blazars that would be detected by GLAST. We show that
we have the best chance of detecting their clustering at large angular scales,
\theta >~ 10 deg, where shot noise is less important, and the dominant
contribution to the correlation comes from relatively low redshift, z <~ 0.1.
The GLAST can detect the correlation signal, if the blazars detected by GLAST
trace the distribution of low-z quasars observed by optical galaxy surveys,
which have the bias of unity. If the bias of blazars is greater than 1.5, GLAST
will detect the correlation signal unambiguously. We also find that GLAST may
detect spatial clustering of clusters of galaxies in gamma-rays. The shape of
the angular power spectrum is different for blazars and clusters of galaxies;
thus, we can separate these two contributions on the basis of the shape of the
power spectrum.Comment: 14 pages, 10 figures; added references; accepted by MNRA
Studies of EGRET sources with a novel image restoration technique
We have developed an image restoration technique based on the Richardson-Lucy
algorithm optimized for GLAST-LAT image analysis. Our algorithm is original
since it utilizes the PSF (point spread function) that is calculated for each
event. This is critical for EGRET and GLAST-LAT image analysis since the PSF
depends on the energy and angle of incident gamma-rays and varies by more than
one order of magnitude. EGRET and GLAST-LAT image analysis also faces Poisson
noise due to low photon statistics. Our technique incorporates wavelet
filtering to minimize noise effects. We present studies of EGRET sources using
this novel image restoration technique for possible identification of extended
gamma-ray sources.Comment: 5 pages, 3 figures. Presented at First GLAST Symposium, Stanford
University, Stanford, CA, USA, February 5-8, 200
Finding (or not) New Gamma-ray Pulsars with GLAST
Young energetic pulsars will likely be the largest class of Galactic sources
observed by GLAST, with many hundreds detected. Many will be unknown as radio
pulsars, making pulsation detection dependent on radio and/or x-ray
observations or on blind periodicity searches of the gamma-rays. Estimates for
the number of pulsars GLAST will detect in blind searches have ranged from tens
to many hundreds. I argue that the number will be near the low end of this
range, partly due to observations being made in a scanning as opposed to a
pointing mode. This paper briefly reviews how blind pulsar searches will be
conducted using GLAST, what limits these searches, and how the computations and
statistics scale with various parameters.Comment: 3 pages, 2 figures, for the Proceedings of the First GLAST Symposium
(5-8 Feb 2007
Simulation of prompt emission from GRBs with a photospheric component and its detectability by GLAST
The prompt emission from gamma-ray bursts (GRBs) still requires a physical
explanation. Studies of time-resolved GRB spectra, observed in the keV-MeV
range, show that a hybrid model consisting of two components, a photospheric
and a non-thermal component, in many cases fits bright, single-pulsed bursts as
well as, and in some instances even better than, the Band function. With an
energy coverage from 8 keV up to 300 GeV, GLAST will give us an unprecedented
opportunity to further investigate the nature of the prompt emission. In
particular, it will give us the possibility to determine whether a photospheric
component is the determining feature of the spectrum or not. Here we present a
short study of the ability of GLAST to detect such a photospheric component in
the sub-MeV range for typical bursts, using simulation tools developed within
the GLAST science collaboration.Comment: 12 pages, 5 figures; submitted proceeding for GRB Symposium in
Stockholm, Sweden : "Gamma-Ray Bursts: Prospects for GLAST
GLAST Tracker
The Large Area Telescope (LAT) on board the Gamma-ray Large-Area Space
Telescope (GLAST) is a pair-conversion gamma-ray detector designed to explore
the gamma-ray universe in the 20 MeV-300 GeV energy band. The Tracker subsystem
of the LAT will perform tracking of electron and positrons to determine the
origin of the gamma-ray. The design and performance of the GLAST LAT Tracker
are described in this paper.Comment: 5 pages, 5 figues, Invited talk at Vertex 2005, Chuzenji Lake, Nikko,
Japan, November 7-November 11, 2005, To be published in Nuclear Instruments
and Methods
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