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Measuring the diffuse Galactic gamma-ray flux in the TeV range is difficult for ground-based gamma-ray telescopes because of the residual cosmic-ray background, which is higher than the gamma-ray flux by several orders of magnitude. Its…

High Energy Astrophysical Phenomena · Physics 2020-01-22 A. Neronov , D. V. Semikoz

A wealth of new data from upgraded and new radio interferometers are rapidly improving and transforming our understanding of the faint extra-galactic radio sky. Indeed the mounting statistics at sub-mJy and uJy flux levels is finally…

Astrophysics of Galaxies · Physics 2018-10-15 Isabella Prandoni

We present an overview of unbiased studies of diffuse extragalactic radio sources. We use a previously developed filtering technique to remove compact sources from large surveys such as WENSS, WISH, and NVSS and examine the residual diffuse…

Astrophysics · Physics 2009-11-11 Lawrence Rudnick , Kisha M. Delain , Jeffrey A. Lemmerman

Extra-galactic radio sources are a significant contaminant in cosmic microwave background and Sunyaev-Zel'dovich effect experiments. Deep interferometric observations with the BIMA and OVRO arrays are used to characterize the spatial,…

We show the existence of a statistically significant, robust detection of a gamma-ray source in the Milky Way Galactic Center that is consistent with a spatially extended signal using about 4 years of Fermi-LAT data. The gamma-ray flux is…

High Energy Astrophysical Phenomena · Physics 2013-05-23 Kevork N. Abazajian , Manoj Kaplinghat

We present the results of a 8.4 GHz Very Large Array radio survey of early-type galaxies extracted from the ACS Virgo Cluster Survey. The aim of this survey is to investigate the origin of radio emission in early-type galaxies and its link…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Alessandro Capetti , Preeti Kharb , David J. Axon , David Merritt , Ranieri D. Baldi

We construct a large sample of gamma-ray blazars with low-frequency radio data using the recent released TGSS AD1 catalog at 150 MHz. The radio/gamma connections of blazars are compared from 143 GHz to 150 MHz. The radio flux density at all…

High Energy Astrophysical Phenomena · Physics 2018-12-26 Xu-Liang Fan , Qingwen Wu

We describe the properties of the blazars detected by EGRET and summarize the results on the calculations of the evolution and luminosity function of these sources. Of the large number of possible origins of extragalactic diffuse gamma-ray…

Astrophysics · Physics 2009-10-31 R. Mukherjee , J. Chiang

We study the capabilities of the Fermi-LAT instrument on board of the Fermi mission to constrain particle dark matter properties, as annihilation cross section, mass and branching ratio into dominant annihilation channels, with gamma-ray…

High Energy Astrophysical Phenomena · Physics 2017-02-22 Nicolas Bernal , Sergio Palomares-Ruiz

We present a catalog of gamma-ray sources at energies above 10 GeV based on data from the Large Area Telescope (LAT) accumulated during the first three years of the Fermi Gamma-ray Space Telescope mission. The first Fermi-LAT catalog of…

Instrumentation and Methods for Astrophysics · Physics 2015-06-16 LAT Collaboration

To fully exploit the scientific potential of the Fermi mission, we initiated the F-GAMMA program. Between 2007 and 2015 it was the prime provider of complementary multi-frequency monitoring in the radio regime. We quantify the radio…

The radio properties of hard (2-8keV) X-ray selected sources are explored by combining a single 50ks XMM-Newton pointing with the ultra-deep and homogeneous Phoenix radio (1.4GHz) survey (Hopkins et al. 2003). A total of 43 sources are…

Astrophysics · Physics 2009-11-10 A. Georgakakis , A. M. Hopkins , J. Afonso , M. Sullivan , B. Mobasher , L. E. Cram

Photons produced in the annihilations of dark matter particles can be detected by gamma-ray telescopes; this technique of indirect detection serves as a cornerstone of the upcoming assault on the dark matter paradigm. The main obstacle to…

Cosmology and Nongalactic Astrophysics · Physics 2011-07-08 Eric J. Baxter , Scott Dodelson

Cosmic rays travel throughout the Galaxy, leaving traces from radio to ultra-high-energy gamma rays due to interactions with the interstellar gas, radiation field and magnetic field. Therefore, it is necessary to utilize multi-wavelength…

High Energy Astrophysical Phenomena · Physics 2024-03-15 Xin-Yu He , Pei-Pei Zhang , Qiang Yuan , Yi-Qing Guo

We measured the dipole of the diffuse $\gamma$-ray background (DGB) identifying a highly significant time-independent signal coincidental with that of the Pierre Auger UHECR. The DGB dipole is determined from flux maps in narrow energy…

High Energy Astrophysical Phenomena · Physics 2024-01-10 A. Kashlinsky , F. Atrio-Barandela , C. S. Shrader

Several cosmic ray experiments have measured excesses in electrons and positrons, relative to standard backgrounds, for energies from ~ 10 GeV - 1 TeV. These excesses could be due to new astrophysical sources, but an explanation in which…

High Energy Astrophysical Phenomena · Physics 2014-11-20 Spencer Chang , Lisa Goodenough

The origin of the hard (2-10 keV) X-ray background has remained mysterious for over 35 years. Most of the soft (0.5-2 keV) X-ray background has been resolved into discrete sources, which are primarily quasars; however, these sources do not…

Astrophysics · Physics 2017-05-10 R. F. Mushotzky , L. L. Cowie , A. J. Barger , K. A. Arnaud

Star-forming galaxies which are too faint to be detected individually produce intensity fluctuations in the cosmic background light. This contribution needs to be taken into account as a foreground when using the primordial signal to…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Han-Seek Kim , C. G. Lacey , S. Cole , C. M. Baugh , C. S. Frenk , G. Efstathiou

We use the GALPROP model for cosmic-ray propagation to obtain a new estimate of the Galactic component of gamma rays, and show that away from the Galactic plane it gives an accurate prediction of the observed EGRET intensities in the energy…

Astrophysics · Physics 2009-11-10 A. W. Strong , I. V. Moskalenko , O. Reimer

A thorough study of radio emission in Active Galactic Nuclei (AGN) is of fundamental importance to understand the physical mechanisms responsible for the emission and the interplay between accretion and ejection processes. High frequency…

Astrophysics of Galaxies · Physics 2020-05-27 E. Chiaraluce , F. Panessa , G. Bruni , R. D. Baldi , E. Behar , F. Vagnetti , F. Tombesi , I. McHardy