Download or read book Fermi Large Area Telescope Observation of a Gamma Ray Source at the Position of Eta Carinae written by and published by . This book was released on 2013 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Handbook of X ray and Gamma ray Astrophysics written by Cosimo Bambi and published by Springer Nature. This book was released on with total page 5912 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Multiple Messengers and Challenges in Astroparticle Physics written by Roberto Aloisio and published by Springer. This book was released on 2018-02-27 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book, designed as a tool for young researchers and graduate students, reviews the main open problems and research lines in various fields of astroparticle physics: cosmic rays, gamma rays, neutrinos, cosmology, and gravitational physics. The opening section discusses cosmic rays of both galactic and extragalactic origin, examining experimental results, theoretical models, and possible future developments. The basics of gamma-ray astronomy are then described, including the detection methods and techniques. Galactic and extragalactic aspects of the field are addressed in the light of recent discoveries with space-borne and ground-based detectors. The review of neutrinos outlines the status of the investigations of neutrino radiation and brings together relevant formulae, estimations, and background information. Three complementary issues in cosmology are examined: observable predictions of inflation in the early universe, effects of dark energy/modified gravity in the large-scale structure of the universe, and neutrinos in cosmology and large-scale structures. The closing section on gravitational physics reviews issues relating to quantum gravity, atomic precision tests, space-based experiments, the strong field regime, gravitational waves, multi-messengers, and alternative theories of gravity.
Download or read book Gamma ray Large Area Space Telescope written by and published by . This book was released on 1998 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fermi Large Area Telescope Bright Gamma ray Source List written by and published by . This book was released on 2009 with total page 55 pages. Available in PDF, EPUB and Kindle. Book excerpt: Following its launch in 2008 June, the Fermi Gamma-ray Space Telescope (Fermi) began a sky survey in August. The Large Area Telescope (LAT) on Fermi in three months produced a deeper and better resolved map of the [gamma]-ray sky than any previous space mission. We present here initial results for energies above 100 MeV for the 205 most significant (statistical significance greater than ≈10[sigma]) [gamma]-ray sources in these data. These are the best characterized and best localized point-like (i.e., spatially unresolved) [gamma]-ray sources in the early mission data.
Download or read book Proceedings of the Third Workshop on Science with the New Generation of High Energy Gamma ray Experiments written by Alessandro De Angelis and published by World Scientific. This book was released on 2006 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction -- I. Detectors for high-energy gamma-rays. First results from the MAGIC experiment / D. Bastieri for the MAGIC collaboration. H.E.S.S. / P. Vincent for the H.E.S.S. collaboration. CANGAROO / M. Mori for the CANGAROO-II, III Team. The status of VERITAS / M.K. Daniel on behalf of the VERITAS collaboration. Gamma ray bursts: recent results obtained by the SWIFT mission / G. Chinearini on behalf of the SWIFT team. Functional tests and performance characterization during the assembly phase of the modules of the AGILE silicon tracker / M. Basset [und weitere]. Status of GLAST, the gamma-ray large-area space telescope / L. Rochester on behalf of the GLAST team. Status of the ARGO-YBJ experiment / P. Camarri for the ARGO-YBJ collaboration. Gamma Air Watch (GAW) - an imaging atmospheric Cherenkov telescope large with large field of view / T. Mineo [und weitere] -- II. Topics in fundamental physics. Frontiers of high energy cosmic rays / M. Pimenta. Measurement of cosmological parameters / A. Balbi. The present and the future of cosmology with gamma ray bursts / G. Ghirlanda, G. Ghisellini. Supersymmetry breaking, extra dimensions and neutralino dark matter / A.M. Lionetto. Dark matter at [symbol]-rays / L. Pieri. Populations of subhalos in cold dark matter halos / E. Bisesi -- III. Multiwavelength observations. WEBT multifrequency support to space observations / C.M. Raiteri and M. Villata for the WEBT collaboration. REM - The Remote Observatory for GRB et al. / E. Molinari on behalf of the REM/ROSS team. Planck-LFI: operation of the scientific ground segment / F. Pasian [und weitere]. INTEGRAL three years later / L. Foschini, G. Di Cocco, G. Malaguti. XMM observations of Geminga, PSR B1055-52 and PSR B0656+14: phase resolved spectroscopy as a tool to investigate the X-[symbol] connection / P.A. Caraveo [und weitere] -- IV. Poster session. Software time-calibration of the ARGO-YBJ detector / A.K. Calabrese Melcarne for the ARGO-YBJ collaboration. Gamma-ray burst physics with GLAST / N. Omodei. Observations of blazars and EGRET sources with INTEGRAL / V. Vitale [und weitere]. A third level trigger programmable on FPGA for the gamma/hadron separation in a Cherenkov telescope using Pseudo-Zernike moments and the SVM classifier / M. Frailis [und weitere]. PulsarSpectrum: simulating gamma-ray pulsars for the GLAST mission / M. Razzano [und weitere]
Download or read book Gamma Ray Large Area Space Telescope written by and published by . This book was released on 1998 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fermi Large Area Telescope Observations of the Cosmic Ray Induced written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We report on measurements of the cosmic-ray induced?-ray emission of Earth's atmosphere by the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope. The LAT has observed the Earth during its commissioning phase and with a dedicated Earth-limb following observation in September 2008. These measurements yielded H"6.4 x 106 photons with energies> 100 MeV and H"250 hours total livetime for the highest quality data selection. This allows the study of the spatial and spectral distributions of these photons with unprecedented detail. The spectrum of the emission - often referred to as Earth albedo gamma-ray emission - has a power-law shape up to 500 GeV with spectral index? = 2.79 ± 0.06.
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1976-05 with total page 912 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fermi LAT Discovery of GeV Gamma ray Emission from the Young Supernova Remnant Cassiopeia A written by and published by . This book was released on 2011 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Gamma ray Burst Observations at High energy with the Fermi Large Area Telescope written by Aurélien Philippe Bouvier and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Fermi Gamma-ray Space Telescope recently celebrated its two-years anniversary in space. With the Large Area Telescope (LAT), its main instrument onboard, Fermi opened a new era in high-energy astrophysics and in particular for the study of Gamma-Ray Bursts (GRBs), which are short flashes of -rays associated with the brightest and most distant events ever observed in our universe after the Big Bang. My thesis work focused primarily on the observations of this phenomenon with the LAT (20 MeV - 300 GeV) and the Gamma-ray Burst Monitor (10 keV - 40 MeV) onboard the Fermi satellite. After describing the procedure used for detection and analysis of LAT GRBs, I will provide an overview of the temporal and spectral features observed during the prompt emission of these events after one year and a half of operation for Fermi. GRBs can also be used as a tool to probe interesting physics. My focus will be on the detection of very high energy photons (typically above 10 GeV) associated with LAT GRBs and which were used to set significant constraints both on a possible violation of Lorentz invariance - which postulates that all observers measure exactly the same speed of light in vacuum, independently of photon energy - and on the Optical-Ultraviolet extragalactic background light in the Universe.
Download or read book Fermi Large Area Telescope Observations of the Cygnus Loop Supernova Remnant written by and published by . This book was released on 2011 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present an analysis of the gamma-ray measurements by the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope in the region of the supernova remnant (SNR) Cygnus Loop (G74.0-8.5). We detect significant gamma-ray emission associated with the SNR in the energy band 0.2-100 GeV. The gamma-ray spectrum shows a break in the range 2-3 GeV. The gamma-ray luminosity is ≈ 1 x 1033 erg s−1 between 1-100 GeV, much lower than those of other GeV-emitting SNRs. The morphology is best represented by a ring shape, with inner/outer radii 0{sup o}.7 ± 0{sup o}.1 and 1{sup o}.6 ± 0{sup o}.1. Given the association among X-ray rims, H[alpha] filaments and gamma-ray emission, we argue that gamma rays originate in interactions between particles accelerated in the SNR and interstellar gas or radiation fields adjacent to the shock regions. The decay of neutral pions produced in nucleon-nucleon interactions between accelerated hadrons and interstellar gas provides a reasonable explanation for the gamma-ray spectrum.
Download or read book Variability of Point Sources of Gamma Rays Detected by the Fermi Large area Telescope written by Eric Wallace and published by . This book was released on 2016 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Large Area Telescope (LAT) aboard the Fermi Gamma-Ray Space Telescope has revolutionized gamma-ray astronomy, allowing the detection of thousands of point sources of gamma rays. Variability studies are of significant interest as a potential source of information about the emission mechanisms, and as a means to identify gamma-ray sources with known sources in other wavelengths and to improve detection sensitivity in searches for new sources. The inclusion of temporal resolution, however, adds to the already considerable complexity of the required analysis, and as a result, variability studies have generally been limited either in scope or in detail, or both, compared to time-integrated spectral analyses. Pointlike is a software package designed for fast maximum likelihood analysis of LAT data, allowing for interactive and large-scale analyses. Here, we present an application of pointlike to the characterization of the variability of the full sample of known gamma-ray point sources. We describe the construction of light curves in one-month time bins, spanning the first 42 months of the Fermi mission, for a sample of 2652 sources. We discuss the use of the detection significance in individual months to improve the significance of detection of marginal sources, and show that including that measure of significance increases the set of significantly detected sources by nearly 20% compared to using only the average significance. We describe a statistical measure of the significance of variability in a light curve, and examine the variability of the sample as whole, and of subsets associated with particular source types, especially pulsars. We discuss the use of pulsars, which are generally non-variable on long timescales, to calibrate variability statistics, and to assess the importance of systematic errors in estimates of variability. Finally, we discuss the potential to extend the method to produce light curves of longer duration and finer time binning, and to search for transient sources.
Download or read book Early Fermi Gamma ray Space Telescope Observations of the Quasar 3C454 3 written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first report of Fermi Gamma-ray Space Telescope observations of the quasar 3C 454.3, which has been undergoing pronounced long-term outbursts since 2000. The data from the Large Area Telescope (LAT), covering 2008 July 7-October 6, indicate strong, highly variable [gamma]-ray emission with an average flux of H"3 x 10−6 photons cm−2 s−1, for energies> 100 MeV. The [gamma]-ray flux is variable, with strong, distinct, symmetrically-shaped flares for which the flux increases by a factor of several on a time scale of about three days. This variability indicates a compact emission region, and the requirement that the source is optically thin to pair-production implies relativistic beaming with Doppler factor [delta]> 8, consistent with the values inferred from VLBI observations of superluminal expansion ([delta] H"25). The observed [gamma]-ray spectrum is not consistent with a simple power-law, but instead steepens strongly above H"2 GeV, and is well described by a broken power-law with photon indices of H"2.3 and H"3.5 below and above the break, respectively. This is the first direct observation of a break in the spectrum of a high luminosity blazar above 100 MeV, and it is likely direct evidence for an intrinsic break in the energy distribution of the radiating particles. Alternatively, the spectral softening above 2GeV could be due to -ray absorption via photonphoton pair production on the soft X-ray photon field of the host AGN, but such an interpretation would require the dissipation region to be located very close (H" 100 gravitational radii) to the black hole, which would be inconsistent with the X-ray spectrum of the source.
Download or read book Fermi LAT Discovery of Extended Gamma Ray Emission in the Direction of Supernova Remnant W51C written by and published by . This book was released on 2012 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: The discovery of bright gamma-ray emission coincident with supernova remnant (SNR) W51C is reported using the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope. W51C is a middle-aged remnant (≈104 yr) with intense radio synchrotron emission in its shell and known to be interacting with a molecular cloud. The gamma-ray emission is spatially extended, broadly consistent with the radio and X-ray extent of SNR W51C. The energy spectrum in the 0.2-50 GeV band exhibits steepening toward high energies. The luminosity is greater than 1 x 1036 erg s−1 given the distance constraint of D> 5.5 kpc, which makes this object one of the most luminous gamma-ray sources in our Galaxy. The observed gamma-rays can be explained reasonably by a combination of efficient acceleration of nuclear cosmic rays at supernova shocks and shock-cloud interactions. The decay of neutral p mesons produced in hadronic collisions provides a plausible explanation for the gamma-ray emission. The product of the average gas density and the total energy content of the accelerated protons amounts to {bar n}{sub H} W{sub p} ≃ 5 x 1051 (D/6 kpc)2 erg cm−3. Electron density constraints from the radio and X-ray bands render it difficult to explain the LAT signal as due to inverse Compton scattering. The Fermi LAT source coincident with SNR W51C sheds new light on the origin of Galactic cosmic rays.
Download or read book Diffuse ray Emission Observed by the Fermi Large Telescope written by Luigi Tibaldo and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Galactic diffuse gamma-ray emission is produced by interactions of cosmic rays with interstellar gas and low-energy radiation fields is the brightest component of the high-energy gamma-ray sky, surveyed since 2008 with unprecedented sensitivity and angular resolution by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. Galactic diffuse emission constitutes not on bright and structured background which needs to be modeled in order to study individual sources and fainter diffuse components, but it can be used also as a probe of the interstellar environment of the Milky Way. We present in-depth studies of LAT g-ray observations of selected regions in the local and outer Galaxy. LAT data are compared v multiwavelength tracers of the interstellar medium, including radio/mm-wave lines of gas and infrared emission/extinction from dust On one hand, we discuss the constraints provided by the gamma-ray data on the census of the interstellar gas. We determine the ratio X(CO)=N(H2)/W(CO) for several clouds and we also find evidence for an ubiquitous dark phase of interstellar gas which does not shine; at other wavelengths. On the other hand, we use the emissivity per hydrogen atom to infer the distribution of cosmic rays in distant locations not accessible by direct measurements. A remarkably hard and extended excess of gamma-rays is detected in the innermost 100 pc of the massive-star forming region in Cygnus.
Download or read book Utilizing Swift XRT Data to Identify Source Classes in Fermi Unassociated Objects written by Matthew Pryal and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Large Area Telescope on board the Fermi Gamma-Ray Space Telescope has revolutionized the detection and identification of gamma-ray emitting astrophysical objects since the launch of Fermi in 2008. Gamma-rays are the highest energy photons observed in the universe and our understanding of objects that emit gamma-rays is essential to our understanding of physics at its greatest limits. The 1FGL, 2FGL, and 3FGL Fermi catalogs outline the identification of over 2000 gamma-ray emitting objects such as blazars and pulsars, but there still remains many unassociated objects in the Fermi catalogs. In this thesis we attempt to statistically show associations of these Fermi unassociated objects in the 1FGL and 2FGL catalogs by utilizing data mining and machine learning techniques to find distinct separations in the properties of known blazars and pulsars. Our analysis is unique in that we will be utilizing known X-ray fluxes for the unassociated objects observed by the Swift X-ray Telescope in addition to the gamma-ray properties available in the Fermi catalogs. Our analysis shows distinct separations in the gamma-ray properties of known blazars and pulsars when compared to X-ray flux and we were able to suggest possible associations to 136 previously unassociated Fermi objects.
