scholarly journals Ground-Based Gamma-Ray Detection of High Energy Galactic Sources: An Update

2004 ◽  
Vol 218 ◽  
pp. 407-414
Author(s):  
G. P. Rowell
Keyword(s):  
Present Status ◽  
Supernova Remnants ◽  
Gamma Ray ◽  
High Energy ◽  
X Ray ◽  
Shell Type ◽  
Γ Ray ◽  
Galactic Sources

I review the present status of ground-based γ-ray astronomy, concentrating on the population of Galactic TeV sources. A number of new telescope systems are now being completed, and promise to yield exciting new discoveries, expanding rapidly the number of sources. The TeV Galactic sources today include a number of plerions, shell-type supernova remnants, an X-ray binary, and also one unidentified candidate. Their present status, and our understanding of their TeV γ-ray emission processes are summarized and some motivation driving development of the field is outlined.

scholarly journals Fermi-LAT and WMAP observations of the supernova remnant Puppis A

2013 ◽  
Vol 9 (S296) ◽  
pp. 295-299
Author(s):  
Marie-Hélène Grondin ◽  
John W. Hewitt ◽  
Marianne Lemoine-Goumard ◽  
Thierry Reposeur ◽  
Keyword(s):  
Supernova Remnants ◽  
Supernova Remnant ◽  
Gamma Ray ◽  
High Energy ◽  
Radio Spectrum ◽  
Wilkinson Microwave Anisotropy Probe ◽  
Large Area ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Γ Ray

AbstractThe supernova remnant (SNR) Puppis A (aka G260.4-3.4) is a middle-aged supernova remnant, which displays increasing X-ray surface brightness from West to East corresponding to an increasing density of the ambient interstellar medium at the Eastern and Northern shell. The dense IR photon field and the high ambient density around the remnant make it an ideal case to study in γ-rays. Gamma-ray studies based on three years of observations with the Large Area Telescope (LAT) aboard Fermi have revealed the high energy gamma-ray emission from SNR Puppis A. The γ-ray emission from the remnant is spatially extended, and nicely matches the radio and X-ray morphologies. Its γ-ray spectrum is well described by a simple power law with an index of ~2.1, and it is among the faintest supernova remnants yet detected at GeV energies. To constrain the relativistic electron population, seven years of Wilkinson Microwave Anisotropy Probe (WMAP) data were also analyzed, and enabled to extend the radio spectrum up to 93 GHz. The results obtained in the radio and γ-ray domains are described in detail, as well as the possible origins of the high energy γ-ray emission (Bremsstrahlung, Inverse Compton scattering by electrons or decay of neutral pions produced by proton interactions).

scholarly journals OBSERVATION OF GALACTIC SOURCES OF VERY HIGH ENERGY γ-RAYS WITH THE MAGIC TELESCOPE

2007 ◽  
Vol 22 (29) ◽  
pp. 2167-2174
Author(s):  
H. BARTKO
Keyword(s):  
Supernova Remnants ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
High Energy ◽  
Γ Radiation ◽  
La Palma ◽  
Very High Energy ◽  
Γ Rays ◽  
Galactic Sources ◽  
Very High

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.

scholarly journals High Energy Astrophysics and Cosmology

1980 ◽  
Vol 5 ◽  
pp. 753-761
Author(s):  
L. Woltjer
Keyword(s):  
High Energy ◽  
Selection Effects ◽  
High Energy Astrophysics ◽  
X Ray ◽  
Cosmological Tests ◽  
Γ Ray ◽  
X Ray Background ◽  
Galactic Sources

AbstractA brief review is given of cosmological tests based on quasars, of source evolution and of the X-ray background. The cosmological tests are still inconclusive because of the limited material available and the possibility of serious selection effects. Quasars and other extra-galactic sources account for most or all of the background in the 1-10 kev range and very possibly also at higher X- and γ-ray energies.

scholarly journals Theories of discrete X-ray and γ-ray sources: (Invited discourse)

1970 ◽  
Vol 37 ◽  
pp. 216-237
Author(s):  
James E. Felten
Keyword(s):  
Synchrotron Radiation ◽  
Supernova Remnants ◽  
Galactic Plane ◽  
Theoretical Work ◽  
X Rays ◽  
X Ray ◽  
Γ Ray ◽  
Low Efficiency ◽  
Optical Flux ◽  
Galactic Sources

This is a critical review of theories of known discrete X-ray sources. The Crab is omitted, having been dealt with in Woltjer's review. Two of the identified sources, Sco X-1 and Cyg X-2, seem to be of the same sort. A binary or gas-stream model like that of Prendergast and Burbidge, with dimension R ∼ 109 cm and density n ∼ 1016 cm−3, appears reconcilable with the observed features of these sources, though much detailed work remains to be done. Neither object is yet known to be binary. Theoretical work becomes more difficult if, as appears to be the case at least for Sco X-1, the objects are optically thick due to electron scattering; this may affect the optical and X-ray spectra.The recent searches for iron lines in the X-ray spectrum of Sco X-1 are reviewed briefly. The calculations and the energy resolution are not yet good enough to make this a dependable test of models.Several possibilities are offered for explaining the excess radio flux from Sco X-1.Other theories of Sco X-1-type sources are discussed briefly. The theory of Manley and Olbert seems a little superfluous when the gas-stream theory is still in a strong position.There are serious discrepancies between X-ray and optical estimates of the distance to Sco X-1. 21-cm measurements must also be considered. The situation is reviewed, and ways out of the difficulty are discussed.Cen X-2 seems to be like Sco X-1, but several other unidentified sources have hard spectra like the Crab. It is tempting to speculate that most of the galactic sources are supernova remnants.The extended γ-ray source in the galactic plane may be the extrapolated unresolved sum of galactic X-ray sources, as suggested by Ogelman. There are several other possibilities.M87 is the only established extragalactic source. Radio, optical and X-ray observations are summarized and graphed. A power-law extrapolation to the X-ray band is far from mandatory; nevertheless the optical flux from the jet is known to be synchrotron radiation. The time-scale difficulties in the jet are described, and several theories of the survival of the optical electrons are reviewed.Processes for producing X-rays other than thermal bremsstrahlung and synchrotron radiation are listed. These other processes are characterized by low efficiency, and are likely to be unimportant in discrete sources, though several have attracted attention with reference to the diffuse background.

scholarly journals Study on the escape timescale of high-energy particles from supernova remnants through thermal X-ray properties

2020 ◽  
Vol 72 (5) ◽  
Author(s):  
Hiromasa Suzuki ◽  
Aya Bamba ◽  
Ryo Yamazaki ◽  
Yutaka Ohira
Keyword(s):  
Power Law ◽  
Supernova Remnants ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
High Energy ◽  
Spectral Shape ◽  
X Ray ◽  
Galactic Cosmic Ray ◽  
High Energy Particles ◽  
Accelerated Particles

Abstract In the current decade, GeV/TeV gamma-ray observations of several supernova remnants (SNRs) have implied that accelerated particles are escaping from their acceleration sites. However, when and how they escape from the SNR vicinities are yet to be understood. Recent studies have suggested that the particle escape might develop with thermal plasma ages of the SNRs. We present a systematic study on the time evolution of particle escape using thermal X-ray properties and gamma-ray spectra using 38 SNRs associated with GeV/TeV gamma-ray emissions. We conducted spectral fittings on the gamma-ray spectra using exponential cutoff power-law and broken power-law models to estimate the exponential cutoff or the break energies, both of which are indicators of particle escape. Plots of the gamma-ray cutoff/break energies over the plasma ages show similar tendencies to those predicted by analytical/numerical calculations of particle escape under conditions in which a shock is interacting with thin interstellar medium or clouds. The particle escape timescale is estimated as ∼100 kyr from the decreasing trends of the total energy of the confined protons with the plasma age. The large dispersions of the cutoff/break energies in the data may suggest an intrinsic variety of particle escape environments. This might be the cause of the complicated Galactic cosmic ray spectral shape measured on Earth.

MULTIWAVELENGTH PROPERTIES OF γ-RAY LOUD BINARY SYSTEMS

2008 ◽  
Vol 17 (10) ◽  
pp. 1917-1924
Author(s):  
M. CHERNYAKOVA ◽  
A. NERONOV
Keyword(s):  
Binary Systems ◽  
Gamma Ray ◽  
High Energy ◽  
X Ray ◽  
Γ Ray ◽  
X Ray Binaries

Gamma-ray-loud binary systems are a newly identified class of X-ray binaries detected up to TeV energies. Three such systems — PSR B1259–63, LS 5039 and LSI +61 303 — have been firmly detected as persistent or regularly variable TeV γ-ray emitters. The origin of the high-energy activity of these sources is not clear. In this paper we review the multiwavelength properties of these systems and discuss their similarities and peculiarities.

Chapter 2 Galactic Gamma-ray Sources

2021 ◽  
Author(s):  
Yang Chen ◽  
Xiao Zhang
Keyword(s):  
Supernova Remnants ◽  
Gamma Ray ◽  
Galactic Center ◽  
Galactic Plane ◽  
Theoretical Models ◽  
High Energy ◽  
Maximum Energy ◽  
Radiation Mechanisms ◽  
Galactic Sources ◽  
Very High

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.

HIGH ENERGY SIGNATURES OF POST ADIABATIC SUPERNOVA REMNANTS

2007 ◽  
Vol 22 (35) ◽  
pp. 2617-2629 ◽  
Author(s):  
IGOR TELEZHINSKY ◽  
BOHDAN HNATYK
Keyword(s):  
Supernova Remnants ◽  
Gamma Ray ◽  
High Energy ◽  
Proton Density ◽  
Transition Stage ◽  
X Ray ◽  
Hot Gas ◽  
Gas Cooling ◽  
Dense Shell ◽  
Hydrodynamical Description

Between the well-known adiabatic and radiative stages of the Supernova remnant (SNR) evolution there is, in fact, a transition stage with a duration comparable to the duration of adiabatic one. Physical existence of the transition stage is motivated by cooling of some part of the downstream hot gas with formation of a thin cold shell that is joined to a shell of swept up interstellar medium (ISM). We give an approximate analytical method for full hydrodynamical description of the transition stage. On its base we investigate the evolution of X-ray and γ-ray radiation during this stage. It is shown that formation of a dense shell during the transition stage is accompanied by the decrease of X-ray luminosity because of hot gas cooling and increase of gamma-ray flux according to the increase of target proton density and CR energy in the newly born shell. The role of nonuniformity of ISM and its influence on the high energy fluxes from the SNRs is also discussed.

THE OPTICAL-X-RAY–GAMMA-RAY SPECTRAL ENERGY DISTRIBUTIONS OF GEV GAMMA-RAY LOUD BLAZARS AND CONNECTION AMONG LBLs, HBLs AND FSRQs

2003 ◽  
Vol 12 (05) ◽  
pp. 781-789 ◽  
Author(s):  
G. Z. XIE ◽  
S. X. DING ◽  
H. DAI ◽  
E. W. LIANG ◽  
H. T. LIU
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Spectral Energy ◽  
Spectral Indices ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
X Ray ◽  
Γ Ray ◽  
High Energy Emission ◽  
Bl Lacs

In this paper, we introduce a new composite spectral indices αγxγ = αxγ - αγ, and prove [Formula: see text], that means αγxγ is intrinsic. We plot a αxox - αγxγ diagram for 25 Gev γ-ray blazars for which αx and αγ have been provided in the literature, where αxox = αox - αx which was introduced by Sambruna et al. (1996) and proved that it is intrinsic by our previous paper (Xie et al. 2001). Using this new composite color–color (αxox - αγxγ) diagram, we investigated the nature of the HBLs–LBLs relationship, and the BL Lacs–FSRQs relationship, in high-energy emission. The results show that the spectral energy distributions of three subclasses of Gev γ-ray loud blazars are different, but essentially continuous: HBLs and FSRQs occupy separated regions while LBLs bridge the gap between HBLs and FSRQs. The results are consistent with that derived from a low energy color–color(αxox - αoro) diagram by Sambruna et al. (1996) and Xie et al. (2001). However, on the αox - αxγ diagram, FSRQs, LBLs and HBLs occupy same region. Because both αγxγ and αxox are intrinsic, thus, the new connection among HBLs, LBLs and FSRQs obtained by us is intrinsic.

scholarly journals Comptonization as Blazar High Energy Emission

1996 ◽  
Vol 175 ◽  
pp. 421-422 ◽  
Author(s):  
Oliver Dreissigacker
Keyword(s):  
Particle Acceleration ◽  
Gamma Ray ◽  
High Energy ◽  
Energy Output ◽  
Relativistic Electrons ◽  
X Ray ◽  
Γ Ray ◽  
Exotic Particle ◽  
Jet Plasma ◽  
High Energy Emission

We explain the overall continuous Grazar (Gamma Ray Blazar) spectrum from the synchrotron turnover to the EGRET GeV detections by means of Comptonization in the parsec scale jet's substructures.While making use of the constraints on the synchrotron spectrum and other measurable quantities, no exotic particle acceleration is needed to achieve the high energy output.We show, that the “Lighthouse Model” of blobs of relativistic electrons, travelling with the jet plasma at relativistic speeds, produce both, correct timescales and shapes for the lightcurve, and correct ratios and slopes of the synchrotron, X-ray and γ-ray branches.

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