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Excess of gamma rays around the Galactic center (GC) observed in the Fermi Large Area Telescope (LAT) data is one of the most intriguing features in the gamma-ray sky. The spherical morphology and the spectral energy distribution with a…

High Energy Astrophysical Phenomena · Physics 2025-03-13 Dmitry V. Malyshev

Recent observations of the diffuse Galactic gamma-ray emission by the Fermi-LAT satellite have shown significant deviations from models which assume the same diffusion properties for cosmic rays (CR) throughout the Galaxy. We explore the…

High Energy Astrophysical Phenomena · Physics 2017-08-17 G. Morlino , M. D'Angelo , P. Blasi , E. Amato

With a decade of gamma-ray data from the Fermi-LAT telescope, we can now hope to answer how well we know the local Universe at gamma-ray frequencies. On the other hand, with gamma-ray data alone it is not possible to directly access the…

Cosmology and Nongalactic Astrophysics · Physics 2018-11-27 Simone Ammazzalorso , Nicolao Fornengo , Shunsaku Horiuchi , Marco Regis

Static gamma-ray detector systems that are deployed outdoors for radiological monitoring purposes experience time- and spatially-varying natural backgrounds and encounters with man-made nuisance sources. In order to be sensitive to illicit…

Instrumentation and Detectors · Physics 2023-09-11 M. S. Bandstra , N. Abgrall , R. J. Cooper , D. Hellfeld , T. H. Y. Joshi , V. Negut , B. J. Quiter , M. Salathe , R. Sankaran , Y. Kim , S. Shahkarami

Approximately one-third of existing $\gamma$-ray sources identified by the $\textit{Fermi Gamma-Ray Space Telescope}$ are considered to be unassociated, with no known counterpart at other frequencies/wavelengths. These sources have been the…

High Energy Astrophysical Phenomena · Physics 2023-02-01 S. Bruzewski , F. K. Schinzel , G. B. Taylor

We describe a method for deriving the position and flux of point and compact sources observed by a scanning survey mission. Results from data simulated to test our method are presented, which demonstrate that at least a 10-fold improvement…

Instrumentation and Methods for Astrophysics · Physics 2015-05-13 F. van Leeuwen , A. N. Morgan , D. L. Harrison

A novel method for localization and estimation of compact sources of gamma radiation for Micro Aerial Vehicles (MAVs) is presented in this paper. The method is developed for a novel single-detector Compton camera, developed by the authors.…

We present the second catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of…

High Energy Astrophysical Phenomena · Physics 2015-05-30 LAT Collaboration

A Galactic cosmic-ray transport model featuring non-homogeneous transport has been developed over the latest years. This setup is aimed at reproducing gamma-ray observations in different regions of the Galaxy (with particular focus on the…

High Energy Astrophysical Phenomena · Physics 2022-10-18 Pedro De la Torre Luque , Daniele Gaggero , Dario Grasso

Image coaddition is one of the most basic operations that astronomers perform. In Paper~I, we presented the optimal ways to coadd images in order to detect faint sources and to perfrom flux measurements under the assumption that the noise…

Instrumentation and Methods for Astrophysics · Physics 2018-03-28 Barak Zackay , Eran O. Ofek

A list of 205 gamma-ray strong objects was reported recently as a result of a 3-month integration with the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope. We attempted identification of these objects, cross-correlating…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Y. Y. Kovalev

There is an extensive set of methods to determine sparse sources from mixtures where the mixing coefficients are unknown. Each method involves plotting N sets of mixed data against each other in N-dimensional space. In the approach adopted…

Signal Processing · Electrical Eng. & Systems 2021-08-27 Malcolm Woolfson

The total anisotropy of a diffuse background composed of two or more sources, such as the Fermi-LAT--measured gamma-ray background, is set by the anisotropy of each source population and the contribution of each population to the total…

Cosmology and Nongalactic Astrophysics · Physics 2013-08-14 Brandon S. Hensley , Vasiliki Pavlidou , Jennifer M. Siegal-Gaskins

We present nested sampling for factor graphs (NSFG), a novel nested sampling approach to approximate inference for posterior distributions expressed over factor-graphs. Performing such inference is a key step in simultaneous localization…

Robotics · Computer Science 2022-08-10 Qiangqiang Huang , Alan Papalia , John J. Leonard

In observations of diffuse emissions like, e.g., the Lyman-$\alpha$ heliospheric glow, contributions to the observed signal from point sources (e.g., stars) are considered as a contamination. There are relatively few brightest point sources…

Solar and Stellar Astrophysics · Physics 2020-08-19 Marek Strumik , Maciej Bzowski , Izabela Kowalska-Leszczynska , Marzena A. Kubiak

The second Fermi-LAT source catalog (2FGL) is the deepest survey of the gamma-ray sky ever compiled, containing 1873 sources that constitute a very complete sample down to an energy flux of about 10^(-11) erg cm^(-2) s^(-1). While…

High Energy Astrophysical Phenomena · Physics 2013-07-01 M. Doert , M. Errando

We present the starblade algorithm, a method to separate superimposed point sources from auto-correlated, diffuse flux using a Bayesian model. Point sources are assumed to be independent from each other and to follow a power-law brightness…

Instrumentation and Methods for Astrophysics · Physics 2018-08-07 Jakob Knollmüller , Philipp Frank , Torsten A. Enßlin

All-sky explorations by Fermi-LAT have revolutionized our view of the gamma-ray sky. While its ongoing all-sky survey counts thousands of sources, essential issues related to the nature of unassociated sources call for sensitive all-sky…

High Energy Astrophysical Phenomena · Physics 2016-06-22 Eugenio Bottacini , Marco Ajello

Recent studies have found a positive correlation between the star-formation rate of galaxies and their gamma-ray luminosity. Galaxies with a high star-formation rate are expected to produce a large amount of high-energy cosmic rays, which…

High Energy Astrophysical Phenomena · Physics 2016-08-17 Cesar Rojas-Bravo , Miguel Araya

From the launch of the Fermi Gamma-ray Space Telescope to July 9, 2010, the Gamma-ray Burst Monitor (GBM) has detected 497 probable GRB events. Twenty-two of these satisfy the simultaneous requirements of an estimated burst direction within…

High Energy Astrophysical Phenomena · Physics 2015-05-20 C. W. Akerlof , W. Zheng , S. B. Pandey , T. A. McKay