Sources of GeV Photons and the Fermi Results

Dermer, C. D.

doi:10.1007/978-3-642-36134-0_3

Cited by 14 publications

(11 citation statements)

References 294 publications

(335 reference statements)

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“…On the other hand, luminous gamma-ray sources have been observed up to ∼ 100 TeV for Milky Way sources and ∼ 10 TeV for extragalactic sources, but it is not yet known if these are the cosmic-ray production sites. In the GeV range, the Large Area Telescope (LAT) onboard the Fermi satellite has detected extragalactic gamma rays from active galactic nuclei (AGN), star-burst galaxies, and gamma-ray bursts (GRBs) [e.g., 4,6,8,33]. But only a small fraction of the sky has been covered at energies above the typical maximum energy of the Fermi gamma-ray telescope, ∼ 300 − 1000 GeV, because of the small fields of view of ground-based imaging atmospheric Cherenkov telescopes (IACTs).…”

Section: Introductionmentioning

confidence: 99%

“…The diffuse gamma-ray background (DGB) was measured by LAT above 200 MeV [5], and it turned out that its flux at ∼ 1 − 10 GeV is much lower than that obtained by EGRET [84,86]. The origin of the DGB is still under debate, and many theoretical attempts have been made in order to explain it (see [33] and references therein). However, none are universally accepted although guaranteed contributors such as undetected AGN and starburst galaxy populations are widely accepted.…”

Section: Introductionmentioning

confidence: 99%

“…Hence, unaccounted-for Galactic components (e.g., millisecond pulsars [40,81], dark matter [72], debris at the outer frontier of the solar system [66], IC scattering of solar photons with local CRs [67]) and/or unaccounted-for CR-induced detector backgrounds could potentially contribute. In particular, an unresolved population of millisecond pulsars is difficult to explain the VHE DGB since its typical spectrum shows a cutoff around a few × GeV [33].…”

Section: Introductionmentioning

confidence: 99%

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Gamma-ray and neutrino backgrounds as probes of the high-energy universe: hints of cascades, general constraints, and implications for TeV searches

Murase

Beacom

Takami³

2012

J. Cosmol. Astropart. Phys.

113

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Recent observations of isotropic diffuse backgrounds by Fermi and IceCube allow us to get more insight into distant very-high-energy (VHE) and ultra-high-energy (UHE) gamma-ray/neutrino emitters, including cosmic-ray accelerators/sources. First, we investigate the contribution of intergalactic cascades induced by gamma-rays and/or cosmic rays (CRs) to the diffuse gamma-ray background (DGB) in view of the latest Fermi data. We identify a possible "VHE Excess" from the fact that the Fermi data are well above expectations for an attenuated power law, and show that cascades induced by VHE gamma rays (above ∼ 10 TeV) and/or VHECRs (below ∼ 10 19 eV) may significantly contribute to the DGB above ∼ 100 GeV. The relevance of the cascades is also motivated by the intergalactic cascade interpretations of extreme TeV blazars such as 1ES 0229+200, which suggest very hard intrinsic spectra. This strengthens the importance of future detailed VHE DGB measurements. Then, more conservatively, we derive general constraints on the cosmic energy budget of high-energy gamma rays and neutrinos based on recent Fermi and IceCube observations of extragalactic background radiation. We demonstrate that these multi-messenger constraints are useful and the neutrino limit is very powerful for VHE/UHE hadronic sources. Furthermore, we show the importance of constraints from individual source surveys by future imaging atmospheric Cherenkov telescopes such as Cherenkov Telescope Array, and demonstrate that the cascade hypothesis for the VHE DGB can be tested by searching for distant emitters of cascaded gamma rays.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Gamma-ray and neutrino backgrounds as probes of the high-energy universe: hints of cascades, general constraints, and implications for TeV searches

Murase

Beacom

Takami³

2012

J. Cosmol. Astropart. Phys.

113

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“…The Fermi-LAT data (Abdo & et al 2010a) are interpreted as the superposition of inverse Compton with CMB and EBL photon fields and hadronic interactions. The typical values of CMB and EBL photon densities and energies were used from Dermer (2013), and the values of electron Lorentz factors from Fraija (2014). The contribution of pion decay products from hadronic interactions were calculated considering the photopion efficiency based on spectral arguments and the CR luminosities normalized with the number of UHECRs, and extrapolated to energies as low as 1 TeV.…”

Section: High-energy γ-Ray Photonsmentioning

confidence: 99%

Study of the PeV neutrino, γ-rays, and UHECRs around the lobes of Centaurus A

Fraija

Aguilar-Ruiz

Galván-Gaméz

et al. 2018

Monthly Notices of the Royal Astronomical Society

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Pierre Auger observatory reported the distribution of arrival directions of the highest energy cosmic rays. These events were collected in 10 years of operations with declinations between -90 • and +45 • . The IceCube neutrino telescope reported the detection of 82 extraterrestrial neutrinos in the High-Energy Starting Events catalog. The highest-energy neutrino event (IC35) reported in this catalog had an energy of 2004 +236 −262 TeV and its reconstruction was centered at RA=208.4 • and DEC=−55.8 • (J2000). Being Centaurus A the nearest radioloud active Galactic nucleus and one of the potential candidates for accelerating cosmic rays up to ∼ 10 20 eV, we show that the ultra-high-energy cosmic rays (UHECRs) around the direction of Centaurus A (15 • radius) could be accelerated inside the giant lobes. Studying the composition of UHECRs through the photo-disintegration processes, the maximum energy that these can reach in the giant lobes and the average deflecting angles that nuclei undergo due to Galactic and extragalactic magnetic fields, it is shown that the most promise candidates of UHECR composition are light nuclei such as carbon/nitrogen nuclei. Considering the interactions of the relativistic carbon nuclei with photon fields (extragalactic background light and synchrotron) and materials (inside and outside the lobes), we do not find enough evidence to associate the IC35 event with the UHECRs reported by Pierre Auger observatory.

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“…Important discoveries include the observation of the pion-decay cutoff in the spectra of supernova remnants (SNRs), and multi-GeV components of gamma-ray bursts (GRBs), etc (see e.g. a review article by 19). The LAT also significantly enhanced our knowledge on the diffuse gamma-ray backgrounds.…”

Section: Introductionmentioning

confidence: 99%

Ground- and Space-Based Gamma-Ray Astronomy

Funk

2015

Annu. Rev. Nucl. Part. Sci.

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In recent years, observational γ-ray astronomy has seen a remarkable range of exciting new results in the high-energy and very-high energy regimes. Coupled with extensive theoretical and phenomenological studies of non-thermal processes in the Universe these observations have provided a deep insight into a number of fundamental problems of high energy astrophysics and astroparticle physics. Although the main motivations of γ-ray astronomy remain unchanged, recent observational results have contributed significantly towards our understanding of many related phenomena. This article aims to review the most important results in the young and rapidly developing field of γ-ray astrophysics.

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Sources of GeV Photons and the Fermi Results

Cited by 14 publications

References 294 publications

Gamma-ray and neutrino backgrounds as probes of the high-energy universe: hints of cascades, general constraints, and implications for TeV searches

Gamma-ray and neutrino backgrounds as probes of the high-energy universe: hints of cascades, general constraints, and implications for TeV searches

Study of the PeV neutrino, γ-rays, and UHECRs around the lobes of Centaurus A

Ground- and Space-Based Gamma-Ray Astronomy

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