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Related papers: Unidentified sources in the Fermi-LAT second sourc…

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Very recently, it was pointed out that there exists a population of gamma-ray sources without associations at other wavelengths which exhibit spectral features consistent with mono-energetic lines at energies of approximately 111 and 129…

High Energy Astrophysical Phenomena · Physics 2013-05-30 Dan Hooper , Tim Linden

The Galactic Center region is expected to host the largest density of Dark Matter (DM) particles within the Milky Way. Then a relatively large gamma-ray signal would be expected from the possible DM particles annihilation (or decay). We are…

High Energy Astrophysical Phenomena · Physics 2019-08-14 Vincenzo Vitale , Aldo Morselli

BL Lac objects are an extreme type of active galactic nuclei (AGNs) that belong to the largest population of $\gamma$-ray sources: blazars. This class of AGNs shows a double-bumped spectral energy distribution that is commonly described in…

High Energy Astrophysical Phenomena · Physics 2020-04-08 E. J. Marchesini , A. Paggi , F. Massaro , N. Masetti , R. D'Abrusco , I. Andruchow , R. de Menezes

We selected a sample of 437 BL Lac objects, taken from the RomaBZCat catalogue, for which spectroscopic information and SDSS photometry is available. We propose a new classification of BL Lacs in which the sources' type is not defined only…

High Energy Astrophysical Phenomena · Physics 2015-06-04 Enrico Massaro , Roberto Nesci , Silvia Piranomonte

We recently started a systematic search of low-energy counterparts of the unidentified gamma-ray sources (UGSs) listed in the Fermi-Large Area Telescope (LAT) First Source Catalog (1FGL) and the Fermi-LAT 2-Year Source Catalog (2FGL).} The…

High Energy Astrophysical Phenomena · Physics 2015-06-24 F. Massaro , M. Landoni , R. D'Abrusco , D. Milisavljevic , A. Paggi , N. Masetti , Howard A. Smith , G. Tosti

The LAT instrument on the Fermi Gamma-Ray Space Telescope is performing an all-sky survey from 20 MeV to 300 GeV with unprecedented statistics and angular resolution. This is providing a wealth of new information on the non-thermal emission…

High Energy Astrophysical Phenomena · Physics 2019-08-14 A. W. Strong

We search for spectral features in Fermi-LAT gamma-rays coming from regions corresponding to eighteen brightest nearby galaxy clusters determined by the magnitude of their signal line-of-site integrals. We observe a double peak-like excess…

High Energy Astrophysical Phenomena · Physics 2015-06-05 Andi Hektor , Martti Raidal , Elmo Tempel

Very high-energy (VHE; E > 100 GeV) gamma-rays have been detected from a wide range of astronomical objects, such as SNRs, pulsars and pulsar wind nebulae, AGN, gamma-ray binaries, molecular clouds, and possibly star-forming regions as…

High Energy Astrophysical Phenomena · Physics 2010-01-19 P. H. Thomas Tam , Stefan Wagner , Omar Tibolla , Ryan Chaves

Stellar streams are remnants of globular clusters or dwarf galaxies that have been tidally disrupted by the gravitational potential of their host galaxy. Streams originating from dwarfs can be particularly compelling targets for indirect…

High Energy Astrophysical Phenomena · Physics 2025-02-24 Cristina Fernandez-Suarez , Miguel A. Sanchez-Conde

A large fraction of Fermi-Large Area Telescope (LAT) sources in the fourth Fermi-LAT 14 yr catalog (4FGL) still remain unidentified (unIDed). We continued to improve our machine-learning pipeline and used it to classify 1206 X-ray sources…

High Energy Astrophysical Phenomena · Physics 2024-08-20 Hui Yang , Jeremy Hare , Oleg Kargaltsev

The {\it Fermi} Large Area Telescope (LAT) has been routinely gathering science data since August 2008, surveying the full sky every three hours. The first Fermi-LAT catalog of sources detected above 10 GeV (1FHL) relied on three years of…

High Energy Astrophysical Phenomena · Physics 2019-08-14 M. Ajello , A. Domínguez , D. Gasparrini , S. Cutini

We report on our second-year campaign of X-ray follow-up observations of unidentified Fermi-LAT \gamma-ray sources at high Galactic latitudes (|b|>10 degree) using the X-ray Imaging Spectrometer onboard the Suzaku X-ray Observatory. In this…

The extragalactic gamma-ray sky is dominated by relativistic jets aligned to the observer's line of sight, i.e., blazars. A few of their misaligned counterparts, e.g., radio galaxies, are also detected with the Fermi-Large Area Telescope…

High Energy Astrophysical Phenomena · Physics 2024-10-15 Vaidehi S. Paliya , D. J. Saikia , Alberto Domínguez , C. S. Stalin

Searching for as yet undetected gamma-ray sources is a major target of the Fermi LAT Collaboration. We present an algorithm capable of identifying such type of sources by non-parametrically clustering the directions of arrival of the…

Instrumentation and Methods for Astrophysics · Physics 2023-01-30 Anna Montin , Alessandra R. Brazzale , Giovanna Menardi

Dark matter (DM) constitutes around a 25% of the Universe, while baryons only a 4%. DM can be reasonably assumed to be made of particles, and many theories (Super-symmetry, Universal Extra Dimensions, etc.) predict Weakly Interacting…

High Energy Astrophysical Phenomena · Physics 2022-03-02 A. Morselli , B. Canadas , V. Vitale

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

In our previous work in Xiao et al. (2019), we suggested that 6 superluminal sources could be gamma-ray candidates, and in fact 5 of them have been confirmed in the fourth Fermi-LAT source catalogue (4FGL). In this work, based on the 4FGL,…

High Energy Astrophysical Phenomena · Physics 2020-07-15 Hubing Xiao , Junhui Fan , Riccardo Rando , Jingtian Zhu , Liangjun Hu

We present Chandra ACIS-I X-ray observations of 0FGL J1311.9-3419 and 0FGL J1653.4-0200, the two brightest high Galactic latitude (|b|>10 deg) gamma-ray sources from the 3 month Fermi-LAT bright source list that are still unidentified. Both…

High Energy Astrophysical Phenomena · Physics 2015-06-05 C. C. Cheung , D. Donato , N. Gehrels , K. V. Sokolovsky , M. Giroletti

Here we report the results of searching millisecond pulsar (MSP) candidates from the Fermi LAT second source catalog (2FGL). Seven unassociated $\gamma-$ray sources in this catalog are identified as promising MSP candidates based on their…

High Energy Astrophysical Phenomena · Physics 2015-08-19 C. Y. Hui , S. M. Park , C. P. Hu , L. C. C. Lin , K. L. Li , A. K. H. Kong , P. H. T. Tam , J. Takata , K. S. Cheng , Ruolan Jin , T. -C. Yen , Chunglee Kim

We present a systematic reassessment of 5,062 high-Galactic latitude gamma-ray sources from the Fermi-LAT 4FGL-DR4 catalog using Firmamento, a web-based platform for multi-frequency source discovery and analysis. Our goal is to provide an…

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