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Related papers: Investigating source confusion in PMN J1603$-$4904

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We have investigated a number of factors that can have significant impacts on the classification performance of $\gamma$-ray sources detected by Fermi Large Area Telescope (LAT) with machine learning techniques. We show that a framework of…

Instrumentation and Methods for Astrophysics · Physics 2020-01-29 Shengda Luo , Alex P. Leung , C. Y. Hui , K. L. Li

We present 1 - 12 GHz Karl G. Jansky Very Large Array observations of 9 off-nuclear persistent radio sources (PRSs) in nearby (z < 0.055) dwarf galaxies, along with high-resolution European very-long baseline interferometry (VLBI) Network…

In this letter we present the result of the cross correlation between the 4th INTEGRAL/IBIS soft gamma-ray catalog, in the range 20-100 keV, and the Fermi LAT bright source list of objects emitting in the 100 MeV - 100 GeV range. The main…

High Energy Astrophysical Phenomena · Physics 2014-11-20 P. Ubertini , V. Sguera , J. B. Stephen , L. Bassani , A. Bazzano , A. J. Bird

Radio and gamma-ray emission from active galactic nuclei (AGN) are thought to share a common origin, related to the ejection phenomena in the vicinity of supermassive black holes. Thanks to its sensitivity, surveying capability, and broad…

Cosmology and Nongalactic Astrophysics · Physics 2010-01-29 M. Giroletti , A. Reimer , L. Fuhrmann , V. Pavlidou , J. L. Richards

MAXI J1744$-$294, likely a low-mass X-ray binary system, is a Galactic-center transient source, detected at radio and X-ray wavelengths, located approximately $19''$ southeast of Sgr A*. We report the first detection of its variable linear…

We report the detection of pulsed gamma-rays for PSRs J0631+1036, J0659+1414, J0742-2822, J1420-6048, J1509-5850 and J1718-3825 using the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (formerly known as GLAST).…

Solar and Stellar Astrophysics · Physics 2010-01-06 The Fermi LAT collaboration , the Fermi Pulsar Timing Consortium

We investigate faint radio emission from low- to high-luminosity Active Galactic Nuclei (AGN) selected from the Sloan Digital Sky Survey (SDSS). Their radio properties are inferred by co-adding large ensembles of radio image cut-outs from…

Astrophysics · Physics 2008-11-26 W. H. de Vries , J. A. Hodge , R. H. Becker , R. L. White , D. J. Helfand

We present the discovery of a very extended (550 kpc) and low-surface-brightness ($ 3.3 \mu \mathrm{Jy} \, arcsec^{-2} $ at 144 MHz) radio emission region in Abell 1318. These properties are consistent with its characterisation as an active…

Following our work presented in Dai et al. (2016), we report our detailed data analysis for another 38 Fermi gamma-ray un-associated sources. These sources are selected from the Fermi Large Area Telescope (LAT) third source catalog on the…

High Energy Astrophysical Phenomena · Physics 2021-06-03 Xuejie Dai , Zhongxiang Wang , V. Jithesh , Yi Xing

The microquasar V404 Cygni (also known as GS 2023+338) was previously reported to have weak GeV gamma-ray emission in sub-day time periods during its 2015 outburst. In order to provide more detailed information at the high energy range for…

High Energy Astrophysical Phenomena · Physics 2021-12-08 Yi Xing , Zhongxiang Wang

We use nine years of gamma-ray data provided by the Fermi Large Area Telescope (LAT) to systematically study the light curves of more than two thousand active galactic nuclei (AGN) included in recent Fermi-LAT catalogs. Ten different…

High Energy Astrophysical Phenomena · Physics 2020-07-01 P. Peñil , A. Domínguez , S. Buson , M. Ajello , J. Otero-Santos , J. A. Barrio , R. Nemmen , S. Cutini , B. Rani , A. Franckowiak , E. Cavazzuti

We used the Karl G. Jansky Very Large Array (VLA) to image one primary beam area at 3 GHz with 8 arcsec FWHM resolution and 1.0 microJy/beam rms noise near the pointing center. The P(D) distribution from the central 10 arcmin of this…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 J. J. Condon , W. D. Cotton , E. B. Fomalont , K. I. Kellermann , N. Miller , R. A. Perley , D. Scott , T. Vernstrom , J. V. Wall

We present a multi-epoch, multi-observatory X-ray analysis for 2FHL J1745.1-3035, a newly discovered very high energy Galactic source detected by the Fermi Large Area Telescope (LAT) located in close proximity to the Galactic Center…

We calculate the diffuse $\gamma$-ray emission due to the population of misaligned AGN (MAGN) unresolved by the Large Area Telescope (LAT) on the {\it Fermi} Gamma-ray Space Telescope ({\it Fermi}). A correlation between the $\gamma$-ray…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-21 M. Di Mauro , F. Donato , F. Calore

The extragalactic sources of ultra-high-energy (E > 4x10^19 eV) cosmic rays that make a small contribution to the flux of particles recorded by ground-based arrays are discussed. We show that cosmic rays from such sources can produce a…

High Energy Astrophysical Phenomena · Physics 2019-01-09 Anna Uryson

The detection of very-high-energy (VHE; $>$100 GeV) $\gamma$-ray radiation from misaligned jetted Active Galactic Nuclei (AGN) challenges the emission models that primarily explain VHE emissions from beamed AGN, i.e., blazars. Using over 16…

High Energy Astrophysical Phenomena · Physics 2025-08-25 Gunjan Tomar , Vaidehi S. Paliya , D. J. Saikia , C. S. Stalin

Based on the first 13.4 yr of Fermi science data in the energy range from 300 MeV to 500 GeV, we discovered a bright GeV gamma-ray source with a $\sim$5.64 $\sigma$ detection, named Fermi J1242.5+3236, which has an offset of about 0fdg0996…

High Energy Astrophysical Phenomena · Physics 2023-01-31 Xiu-Rong Mo , Ming-Hong Luo , Hong-bin Tan , Qing-Wen Tang , Ruo-Yu Liu

A well-known calibrator source in radio astronomy, 3C 286 ($z=0.85$), is a compact steep-spectrum (CSS) radio source and spectroscopically classified as a narrow-line Seyfert 1 (NLS1) galaxy. It is also known for its damped Ly$\alpha$…

High Energy Astrophysical Phenomena · Physics 2024-07-29 Su Yao , S. Komossa , A. Kraus , D. Grupe

The third INTEGRAL/IBIS survey has revealed several new hard X-ray sources, which are still unclassified. To identify these sources, we need to find their counterparts at other wavelengths and then study their nature. The capability of XRT…

Astrophysics · Physics 2009-11-13 R. Landi , J. B. Stephen , N. Masetti , D. Grupe , F. Capitanio , A. J. Bird , A. J. Dean , M. Fiocchi , N. Gehrels

We report our detailed data analysis for 39 $\gamma$-ray sources selected from the 992 unassociated sources in the \textit{Fermi} Large Area Telescope (LAT) third source catalog. The selection criteria, which were set for finding candidate…

High Energy Astrophysical Phenomena · Physics 2021-06-03 Xuejie Dai , Zhongxiang Wang , V. Jithesh , Yi Xing