Space detectors for gamma rays (100 MeV–100 GeV): From EGRET to Fermi LAT

Thompson, D. J.

doi:10.1016/j.crhy.2015.07.002

Cited by 21 publications

(9 citation statements)

References 44 publications

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“…The launch of the Fermi-LAT satellite in 2008, with a gain of about a factor of five in effective area and in field of view with respect to EGRET, triggered a tremendous growth in the number of extragalactic gamma-ray sources detected above 100 MeV. With an angular resolution (68% containment angle) better than a degree above 1 GeV [16], cross-identification with radio, optical and X-ray catalogs established the prominence of blazars in the gamma-ray sky, although with marked differences with the emerging population uncovered by ground-based telescopes at higher energies. About half of the blazars categorized in the first Fermi-LAT catalog ( [17], 1FGL in Figure 1) were found to be flat-spectrum radio quasars (FSRQs), at variance with the prevalence of BLLs at higher energies.…”

Section: The Extragalactic Gamma-ray Skymentioning

confidence: 99%

Gamma-ray Cosmology and Tests of Fundamental Physics

Biteau,

Meyer

2022

Preprint

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The propagation of gamma-rays over cosmological distances is the subject of extensive theoretical and observational research at GeV and TeV energies. The mean free path of gamma-rays in the cosmic web is limited above 100 GeV due to the production of electrons and positrons on the cosmic optical and infrared backgrounds. Electrons and positrons cool in the intergalactic medium while gyrating in its magnetic fields, which could cause either its global heating or the production of lowerenergy secondary gamma-rays. The energy distribution of gamma-rays surviving the cosmological journey carries observed absorption features that gauge the emissivity of baryonic matter over cosmic time, constrain the distance scale of ΛCDM cosmology, and limit the alterations of the interaction cross section. Competitive constraints are in particular placed on the cosmic star-formation history as well as on phenomena expected from quantum gravity and string theory, such as the coupling to hypothetical axion-like particles or the violation of Lorentz invariance. Recent theoretical and observational advances offer a glimpse of the multi-wavelength and multi-messenger path that the new generation of gamma-ray observatories is about to open.

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Section: The Extragalactic Gamma-ray Skymentioning

confidence: 99%

Gamma-ray Cosmology and Tests of Fundamental Physics

Biteau,

Meyer

2022

Preprint

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“…Currently, ground-based gamma-ray detectors are classified into two categories, namely the Imaging Atmospheric Cherenkov Telescope (IACT) and Extensive Air Shower (EAS) arrays based on the detection techniques. We refer to [25,26] for a review of gamma-ray detection techniques. We discuss below briefly two upcoming detectors, namely CTA and LHAASO, in each of these categories and for which we estimate the sensitivities to the FBs.…”

Section: Ground-based Gamma-ray Observatoriesmentioning

confidence: 99%

Constraints on very high energy gamma-ray emission from the Fermi bubbles with future ground-based experiments

Yang

Razzaque

2019

Phys. Rev. D

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The origin of sub-TeV gamma rays detected by the Fermi-Large Area Telescope (LAT) from the Fermi Bubbles (FBs) at the Galactic center is still uncertain. In a hadronic model, acceleration of protons and/or nuclei and their subsequent interactions with gas in the bubble volume can produce the observed gamma rays. Recently the High Altitude Water Cherenkov (HAWC) observatory reported an absence of gamma-ray excess from the Northern FB at b 6 • Galactic latitude, which resulted in flux upper limits in the energy range of 1.2 − 126 TeV. These upper limits are consistent with the gamma-ray spectrum measured by Fermi-LAT at |b| ≥ 10 • , where an exponential cutoff at energies 100 GeV is evident. However, the FB gamma-ray spectrum at |b| ≤ 10 • , without showing any sign of cutoff up to around 1 TeV in the latest results, remains unconstrained. The upcoming Cherenkov Telescope Array (CTA) will perform a Galactic center survey with unprecedented sensitivity in the energy between 20 GeV and 300 TeV. In this work, we perform both morphological and classic on/off analyses with planned CTA deep central and extended survey and estimate the sensitivity of CTA to the FB hadronic gamma-ray flux models that best fit the spectrum at |b| ≤ 10 • and whose counterpart neutrino flux model best fits the optimistic neutrino spectrum from IceCube Neutrino Observatory. We also perform sensitivity analysis with a future ground-based Cherenkov detector the Large High Altitude Air Shower Observatory (LHAASO). We find that CTA will be able to discover or constrain the FB gamma-ray flux at |b| ≤ 10 • in the ≈ 200 GeV -100 TeV range with planned observation strategy, while LHAASO may constrain emission in the ≈ 100 GeV -100 TeV range if 10% systematic uncertainties can be achieved.

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“…The launch of the Fermi-LAT satellite in 2008, with a gain of about a factor of five in effective area and in field of view with respect to EGRET, triggered a tremendous growth in the number of extragalactic gamma-ray sources detected above 100 MeV. With an angular resolution (68% containment angle) better than a degree above 1 GeV [23], cross-identification with radio, optical and X-ray catalogs established the prominence of blazars in the gamma-ray sky, although with marked differences with the emerging population uncovered by ground-based telescopes at higher energies. About half of the blazars categorized in the first Fermi-LAT catalog ( [16], 1FGL in Figure 1) were found to be flat-spectrum radio quasars (FSRQs), at variance with the prevalence of BLLs at higher energies.…”

Section: The Extragalactic Gamma-ray Skymentioning

confidence: 99%

Gamma-Ray Cosmology and Tests of Fundamental Physics

Biteau

Meyer

2022

Galaxies

View full text Add to dashboard Cite

The propagation of gamma-rays over cosmological distances is the subject of extensive theoretical and observational research at GeV and TeV energies. The mean free path of gamma-rays in the cosmic web is limited above 100 GeV due to the production of electrons and positrons on the cosmic optical and infrared backgrounds. Electrons and positrons cool in the intergalactic medium while gyrating in its magnetic fields, which could cause either its global heating or the production of lower-energy secondary gamma-rays. The energy distribution of gamma-rays surviving the cosmological journey carries observed absorption features that gauge the emissivity of baryonic matter over cosmic time, constrain the distance scale of ΛCDM cosmology, and limit the alterations of the interaction cross section. Competitive constraints are, in particular, placed on the cosmic star-formation history as well as on phenomena expected from quantum gravity and string theory, such as the coupling to hypothetical axion-like particles or the violation of Lorentz invariance. Recent theoretical and observational advances offer a glimpse of the multi-wavelength and multi-messenger path that the new generation of gamma-ray observatories is about to open.

show abstract

Space detectors for gamma rays (100 MeV–100 GeV): From EGRET to Fermi LAT

Cited by 21 publications

References 44 publications

Gamma-ray Cosmology and Tests of Fundamental Physics

Gamma-ray Cosmology and Tests of Fundamental Physics

Constraints on very high energy gamma-ray emission from the Fermi bubbles with future ground-based experiments

Gamma-Ray Cosmology and Tests of Fundamental Physics

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