Some problems of gamma-astronomy

Dogiel, V. A.; Ginzburg, V. L.

doi:10.1007/bf00241870

Cited by 10 publications

(6 citation statements)

References 88 publications

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“…High-energy photons can be produced in collisions of accelerated particles with the ambient medium. There are several processes which could accelerate particles in young supernova remnants (see, e.g., Dogiel and Ginzburg 1989, for a review). Gaisser, Harding and Stanev (1989) discuss the acceleration of particles at the pulsar wind shock.…”

Section: Discussionmentioning

confidence: 99%

A Search for TeV Gamma Rays from SN 1987A in 2001

Enomoto

Ksenofontov

Tsuchiya

et al. 2003

ApJ

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We searched for TeV gamma-rays from the remnant of SN 1987A around 5400 days after the supernova. The observations were carried out in 2001, from November 16 to December 11, using the CANGAROO-II Imaging Atmospheric Cherenkov Telescope. In total, 708 minutes of ON-and 1019 minutes of OFF-source data were obtained under good conditions. The detection threshold was estimated to be 1 TeV, due to the mean zenith angle of 39 • . The upper limits for the gamma-ray flux were obtained and compared with the previous observations and theoretical models. The observations indicate that the gamma-ray luminosity is lower than 1 × 10 37 erg s −1 at ∼ 10 TeV.

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Section: Discussionmentioning

confidence: 99%

A Search for TeV Gamma Rays from SN 1987A in 2001

Enomoto

Ksenofontov

Tsuchiya

et al. 2003

ApJ

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“…However, in the energy range above 10 MeV, the in-flight annihilation emission is quite significant and gives the main contribution at ∼ 30 MeV. It is interesting to note that at this energy the in-flight flux exceeds the contribution from inverse Compton scattering of relativistic electrons which is essential in the Galaxy especially at relatively high latitudes (Dogiel & Ginzburg 1989;Strong et al 2000).…”

Section: Mev-gev Gamma-raysmentioning

confidence: 97%

Diffuse gamma-ray emission from the Galactic center – a multiple energy injection model

Cheng

Chernyshov

Dogiel

2007

A&A

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We suggest that the energy source of the observed diffuse gamma-ray emission from the direction of the Galactic center is the Galactic black hole Sgr A*, which becomes active when a star is captured at a rate of ∼ 10 −5 yr −1 . Subsequently the star is tidally disrupted and its matter is accreted into the black hole. During the active phase relativistic protons with a characteristic energy ∼ 6 × 10 52 erg per capture are ejected. Over 90% of these relativistic protons disappear due to protonproton collisions on a timescale τ pp ∼ 10 4 years in the small central bulge region with radius ∼ 50 pc within Sgr A*, where the density is ≥ 10 3 cm −3 . The gamma-ray intensity, which results from the decay of neutral pions produced by proton-proton collisions, decreases according to e −t/τpp , where t is the time after last stellar capture. Less than 5% of relativistic protons escaped from the central bulge region can survive and maintain their energy for > 10 7 years due to much lower gas density outside, where the gas density can drop to ∼ 1 cm −3 . They can diffuse to a ∼ 500 pc region before disappearing due to proton-proton collisions. The observed diffuse GeV gamma-rays resulting from the decay of neutral pions produced via collision between these escaped protons and the gas in this region is expected to be insensitive to time in the multi-injection model with the characteristic injection rate of 10 −5 yr −1 . Our model calculated GeV and 511 keV gamma-ray intensities are consistent with the observed results of EGRET and INTEGRAL, however, our calculated inflight annihilation rate cannot produce sufficient intensity to explain the COMPTEL data.

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“…This is going to be GAMMA-400, which will be installed onboard the Russian space observatory [14][15][16][17][18].…”

Section: The Gamma-400 Gamma-ray Telescopementioning

confidence: 99%

New stage in high-energy gamma-ray studies with GAMMA-400 after Fermi-LAT

et al. 2017

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Abstract. Fermi-LAT has made a significant contribution to the study of high-energy gamma-ray diffuse emission and the observations of 3000 discrete sources. However, one third of all gamma-ray sources (both galactic and extragalactic) are unidentified, the data on the diffuse gamma-ray emission should be clarified, and signatures of dark matter particles in the high-energy gamma-ray range are not observed up to now. GAMMA-400, the currently developing gamma-ray telescope, will have angular (∼ 0.01• at 100 GeV) and energy (∼ 1% at 100 GeV) resolutions in the energy range of 10-1000 GeV which are better than Fermi-LAT (as well as ground gamma-ray telescopes) by a factor of 5-10. It will observe some regions of the Universe (such as the Galactic Center, Fermi Bubbles, Crab, Cygnus, etc.) in a highly elliptic orbit (without shading the telescope by the Earth) continuously for a long time. It will allow us to identify many discrete sources, to clarify the structure of extended sources, to specify the data on the diffuse emission, and to resolve gamma rays from dark matter particles.

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Some problems of gamma-astronomy

Cited by 10 publications

References 88 publications

A Search for TeV Gamma Rays from SN 1987A in 2001

A Search for TeV Gamma Rays from SN 1987A in 2001

Diffuse gamma-ray emission from the Galactic center – a multiple energy injection model

New stage in high-energy gamma-ray studies with GAMMA-400 after Fermi-LAT

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