Chapter 2 Galactic Gamma-ray Sources

2021 ◽  
Author(s):  
Yang Chen ◽  
Xiao Zhang

Abstract In the gamma-ray sky, the highest fluxes come from Galactic sources: supernova remnants (SNRs), pulsars and pulsar wind nebulae, star forming regions, binaries and micro-quasars, giant molecular clouds, Galactic center, and the large extended area around the Galactic plane. The radiation mechanisms of -ray emission and the physics of the emitting particles, such as the origin, acceleration, and propagation, are of very high astrophysical significance. A variety of theoretical models have been suggested for the relevant physics and emission with energies E_1014 eV are expected to be crucial in testing them. In particular, this energy band is a direct window to test at which maximum energy a particle can be accelerated in the Galactic sources and whether the most probable source candidates such as Galactic center and SNRs are “PeVatrons”. Designed aiming at the very high energy (VHE, >100 GeV) observation, LHAASO will be a very powerful instrument in these astrophysical studies. Over the past decade, great advances have been made in the VHE -ray astronomy. More than 170 VHE -ray sources have been observed, and among them, 42 Galactic sources fall in the LHAASO field-of-view. With a sensitivity of 10 milli-Crab, LHAASO can not only provide accurate spectrum for the known -ray sources, but also search new TeV -ray sources. In the following sub-sections, the observation of all the Galactic sources with LHAASO will be discussed in details.

2007 ◽  
Vol 22 (29) ◽  
pp. 2167-2174
Author(s):  
H. BARTKO

The MAGIC telescope with its 17m diameter mirror is today the largest operating single-dish Imaging Air Cherenkov Telescope (IACT). It is located on the Canary Island La Palma, at an altitude of 2200 m above sea level, as part of the Roque de los Muchachos European Northern Observatory. The MAGIC telescope detects celestial very high energy γ-radiation in the energy band between about 50 GeV and 10 TeV. Since the autumn of 2004 MAGIC has been taking data routinely, observing various objects, like supernova remnants (SNRs), γ-ray binaries, Pulsars, Active Galactic Nuclei (AGN) and Gamma-ray Bursts (GRB). We briefly describe the observational strategy, the procedure implemented for the data analysis, and discuss the results of observations of Galactic Sources.


2018 ◽  
Vol 612 ◽  
pp. A1 ◽  
Author(s):  
◽  
H. Abdalla ◽  
A. Abramowski ◽  
F. Aharonian ◽  
F. Ait Benkhali ◽  
...  

We present the results of the most comprehensive survey of the Galactic plane in very high-energy (VHE) γ-rays, including a public release of Galactic sky maps, a catalog of VHE sources, and the discovery of 16 new sources of VHE γ-rays. The High Energy Spectroscopic System (H.E.S.S.) Galactic plane survey (HGPS) was a decade-long observation program carried out by the H.E.S.S. I array of Cherenkov telescopes in Namibia from 2004 to 2013. The observations amount to nearly 2700 h of quality-selected data, covering the Galactic plane at longitudes from ℓ = 250° to 65° and latitudes |b|≤ 3°. In addition to the unprecedented spatial coverage, the HGPS also features a relatively high angular resolution (0.08° ≈ 5 arcmin mean point spread function 68% containment radius), sensitivity (≲1.5% Crab flux for point-like sources), and energy range (0.2–100 TeV). We constructed a catalog of VHE γ-ray sources from the HGPS data set with a systematic procedure for both source detection and characterization of morphology and spectrum. We present this likelihood-based method in detail, including the introduction of a model component to account for unresolved, large-scale emission along the Galactic plane. In total, the resulting HGPS catalog contains 78 VHE sources, of which 14 are not reanalyzed here, for example, due to their complex morphology, namely shell-like sources and the Galactic center region. Where possible, we provide a firm identification of the VHE source or plausible associations with sources in other astronomical catalogs. We also studied the characteristics of the VHE sources with source parameter distributions. 16 new sources were previously unknown or unpublished, and we individually discuss their identifications or possible associations. We firmly identified 31 sources as pulsar wind nebulae (PWNe), supernova remnants (SNRs), composite SNRs, or gamma-ray binaries. Among the 47 sources not yet identified, most of them (36) have possible associations with cataloged objects, notably PWNe and energetic pulsars that could power VHE PWNe.


2011 ◽  
Vol 7 (S285) ◽  
pp. 294-295 ◽  
Author(s):  
Stefano Ciprini ◽  
Dario Gasparrini ◽  
Denis Bastieri

AbstractThe Fermi Flare Advocate (also known as Gamma-ray Sky Watcher, FA-GSW) service provides a daily quick-look analysis and review of the high-energy gamma-ray sky seen by the Fermi Gamma-ray Space Telescope. The duty offers alerts for potentially new gamma-ray sources, interesting transients and flares. A weekly digest containing the highlights about the GeV gamma-ray sky is published in the web-based Fermi Sky Blog. During the first 3 years of all-sky survey, more than 150 Astronomical Telegrams, several alerts to the TeV Cherenkov telescopes, and targets of opportunity to Swift and other observatories, were realized. That increased the rate of simultaneous multi-frequency observing campaigns and the level of international cooperation. Many gamma-ray flares from blazars (such as extraordinary outbursts of 3C 454.3, intense flares of PKS 1510-089, 4C 21.35, PKS 1830-211, AO 0235+164, PKS 1502+106, 3C 279, 3C 273, PKS 1622-253), short/long flux duty cycles, unidentified transients near the Galactic plane (like J0910-5041, J0109+6134, the Galactic center region), flares associated with Galactic sources (like the Crab nebula, the nova V407 Cyg, the microquasar Cyg X-3), emission of the quiet and active sun, were observed by Fermi and communicated by FA-GSWs.


2018 ◽  
Vol 27 (13) ◽  
pp. 1842003 ◽  
Author(s):  
Lara Nava

The number of gamma-ray bursts (GRBs) detected at high energies ([Formula: see text][Formula: see text]GeV) has seen a rapid increase over the last decade, thanks to observations from the Fermi-Large Area Telescope. The improved statistics and quality of data resulted in a better characterization of the high-energy emission properties and in stronger constraints on theoretical models. In spite of the many achievements and progresses, several observational properties still represent a challenge for theoretical models, revealing how our understanding is far from being complete. This paper reviews the main spectral and temporal properties of [Formula: see text][Formula: see text]GeV emission from GRBs and summarizes the most promising theoretical models proposed to interpret the observations. Since a boost for the understanding of GeV radiation might come from observations at even higher energies, the present status and future prospects for observations at very-high energies (above [Formula: see text][Formula: see text]100[Formula: see text]GeV) are also discussed. The improved sensitivity of upcoming facilities, coupled to theoretical predictions, supports the concrete possibility for future ground GRB detections in the high/very-high energy domain.


2019 ◽  
Vol 208 ◽  
pp. 14009
Author(s):  
V.G. Sinitsyna ◽  
V.Y. Sinitsyna ◽  
K.A. Balygin ◽  
S.S. Borisov ◽  
A.M. Kirichenko ◽  
...  

The Cygnus Region is one of the brightest regions in all ranges of the electromagnetic spectrum and contains a number of potential GeV and TeV emission sources. It includes active star formation regions, pulsars and supernova remnants. Some of the sources have been detected at high and very high energies. One of them discovered due to its proximity to the well-known microquasar Cyg X-3 is the object TeV J2032+4130. This object is still of unresolved nature and is being intensively studied in different energy ranges. The results of twenty-year observations of TeV J2032+4130 by the SHALON experiment are presented in this paper. The collected experimental data on fluxes, spectrum shape and morphology of TeV J2032+413 can help in the future to determine an object type and reveal mechanisms of generation of very high energy emission.


2008 ◽  
Vol 30 (2) ◽  
pp. 47-53 ◽  
Author(s):  
M. Ohishi ◽  
M. Mori ◽  
Y. Adachi ◽  
A. Asahara ◽  
G.V. Bicknell ◽  
...  

Author(s):  
Jovana Petrovic ◽  
Tijana Prodanovic ◽  
Milos Kovacevic

Diffuse gamma ray emission from the Galactic center at 2-3 GeV, as well as the 12 TeV gamma ray excess in the Galactic disk, remain open for debate and represent the missing puzzles in the complete picture of the high-energy Milky Way sky. Our papers emphasize the importance of understanding all of the populations that contribute to the diffuse gamma background in order to discriminate between the astrophysical sources such as supernova remnants and pulsars, and something that is expected to be seen in gamma rays and is much more exotic - dark matter. We analyze two separate data sets that have been measured in different energy ranges from the ?Fermi-LAT? and ?Milagro? telescopes, using these as a powerful tool to limit and test our analytical source population models. We model supernova remnants and pulsars, estimating the number of still undetected ones that contribute to the diffuse background, trying to explain both the Galactic center and the 12 TeV excess. Furthermore, we aim to predict the number of soon to be detected sources with new telescopes, such as the ?HAWC?.


2017 ◽  
Author(s):  
Dario Grasso ◽  
Daniele Gaggero ◽  
Antonio Marinelli ◽  
Marco Taoso ◽  
Alfredo Urbano ◽  
...  

2014 ◽  
Vol 1 (1) ◽  
pp. 227-230
Author(s):  
Matthias Beilicke

The galactic center has long been a region of interest for high-energy and very-high-energy observations. Many potential sources of GeV/TeV gamma-ray emission are located in this region, e.g. the accretion of matter onto the central black hole, cosmic rays from a nearby shell-type supernova remnant, or the annihilation of dark matter. The galactic center has been detected at MeV/GeV energies by EGRET and recently by <em>Fermi</em>/LAT. At TeV energies, the galactic center was detected at the level of 4 standard deviations with the Whipple 10m telescope and with one order of magnitude better sensitivity by H.E.S.S. and MAGIC. We present the results from 3 years of VERITAS galactic center observations conducted at large zenith angles. The results are compared to astrophysical models.


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