scholarly journals The intrinsic gamma-ray spectrum of TXS 0506+056: intergalactic propagation effects

2020 ◽  
Vol 500 (2) ◽  
pp. 2188-2195
Author(s):  
Andrey Saveliev ◽  
Rafael Alves Batista
Keyword(s):  
Gamma Ray ◽  
Recent Observation ◽  
High Energy ◽  
Spectral Energy ◽  
Electromagnetic Spectrum ◽  
Extragalactic Background Light ◽  
Background Light ◽  
Propagation Effects ◽  
Very High Energy ◽  
Energy Gamma

ABSTRACT The recent observation of high-energy neutrinos from the 2017 flare of the blazar TXS 0506+056, together with counterparts across the whole electromagnetic spectrum, opens up new possibilities for investigating the properties of this class of objects as well as the traversed medium. Propagation effects such as the attenuation of the very-high-energy gamma-ray component by the extragalactic background light are well known, and usually taken into account when fitting spectral energy distributions of objects. Other effects such as those of intergalactic magnetic fields are, however, often neglected. In this work, we present a comprehensive study of the influence of these fields and the extragalactic background light on the determination of the intrinsic gamma-ray spectrum of this blazar.

scholarly journals TeV J2032+4130 - very high energy gamma-ray source of unresolved nature

2019 ◽  
Vol 208 ◽  
pp. 14009
Author(s):  
V.G. Sinitsyna ◽  
V.Y. Sinitsyna ◽  
K.A. Balygin ◽  
S.S. Borisov ◽  
A.M. Kirichenko ◽  
...  
Keyword(s):  
Supernova Remnants ◽  
Gamma Ray ◽  
High Energy ◽  
Electromagnetic Spectrum ◽  
Object Type ◽  
Very High Energy ◽  
Energy Gamma ◽  
Star Formation Regions ◽  
High Energy Emission ◽  
Very High

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.

scholarly journals Prospect on intergalactic magnetic field measurements with gamma-ray instruments

2012 ◽  
Vol 8 (S294) ◽  
pp. 459-470
Author(s):  
Hélène Sol ◽  
Andreas Zech ◽  
Catherine Boisson ◽  
Henric Krawczynski ◽  
Lisa Fallon ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Gamma Ray ◽  
Field Measurements ◽  
High Energy ◽  
Wide Field ◽  
Extragalactic Background Light ◽  
Spatially Extended ◽  
Very High Energy ◽  
Energy Gamma ◽  
Intergalactic Magnetic Field

AbstractObserving high-energy gamma-rays from Active Galactic Nuclei (AGN) offers a unique potential to probe extremely tiny values of the intergalactic magnetic field (IGMF), a long standing question of astrophysics, astroparticle physics and cosmology. Very high energy (VHE) photons from blazars propagating along the line of sight interact with the extragalactic background light (EBL) and produce e+e− pairs. Through inverse-Compton interaction, mainly on the cosmic microwave background (CMB), these pairs generate secondary GeV-TeV components accompanying the primary VHE signal. Such secondary components would be detected in the gamma-ray range as delayed “pair echos” for very weak IGMF (B < 10−16G), while they should result in a spatially extended gamma-ray emission around the source for higher IGMF values (B > 10−16G). Coordinated observations with space (i.e. Fermi) and ground-based gamma-ray instruments, such as the present Cherenkov experiments H.E.S.S., MAGIC and VERITAS, the future Cherenkov Telescope Array (CTA) Observatory, and the wide-field detectors such as HAWC and LHAASO, should allow to analyze and finally detect such echos, extended emission or pair halos, and to further characterize the IGMF.

scholarly journals Lorentz Violation by the Preferred Frame Effects and Cosmic and Gamma Ray Propagation

Galaxies ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 119
Author(s):  
Georgy I. Burde
Keyword(s):  
Gamma Ray ◽  
Background Radiation ◽  
Lorentz Invariance ◽  
High Energy ◽  
Particle Dynamics ◽  
Microwave Background ◽  
Extragalactic Background Light ◽  
Preferred Frame ◽  
Very High Energy ◽  
Energy Gamma

The ‘relativity with a preferred frame’, designed to reconcile the relativity principle with the existence of the cosmological preferred frame, incorporates the preferred frame at the level of special relativity (SR) while retaining the fundamental spacetime symmetry, which, in the standard SR, manifests itself as Lorentz invariance. In this paper, the processes, accompanying the propagation of cosmic rays and gamma rays through the background radiation from distant sources to Earth, are considered on the basis of particle dynamics and electromagnetic field dynamics developed within the framework of the ‘relativity with a preferred frame’. Applying the theory to the photopion-production and pair-production processes shows that the modified particle dynamics and electrodynamics lead to measurable signatures in the observed cosmic and gamma-ray spectra which can provide an interpretation of some puzzling features found in the observational data. Other processes responsible for gamma-ray attenuation are considered. It is found, in particular, that electromagnetic cascades, developing on cosmic microwave background and extragalactic background light, may be reduced or suppressed due to the preferred frame effects which should influence the shape of the very high-energy gamma-ray spectra. Other possible observational consequences of the theory, such as the birefringence of light propagating in vacuo and dispersion, are discussed.

scholarly journals Effect of axion-like particles on the spectrum of the extragalactic gamma-ray background

2021 ◽  
Vol 2021 (11) ◽  
pp. 030
Author(s):  
Yun-Feng Liang ◽  
Xing-Fu Zhang ◽  
Ji-Gui Cheng ◽  
Hou-Dun Zeng ◽  
Yi-Zhong Fan ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Small Region ◽  
High Energy ◽  
Extragalactic Background Light ◽  
Background Light ◽  
Very High Energy ◽  
The Universe ◽  
Very High

Abstract Axion-like particles (ALPs) provide a feasible explanation for the observed lower TeV opacity of the Universe. If the anomaly TeV transparency is caused by ALPs, then the fluxes of distant extragalactic sources will be enhanced at photon energies beyond TeV, resulting in an enhancement of the observed extragalactic gamma-ray background (EGB) spectrum. In this work, we have investigated the ALP modulation on the EGB spectrum at TeV energies. Our results show that in the most optimistic case, the existence of ALPs can cause the EGB spectrum to greatly deviate from the prediction of a pure extragalactic-background-light (EBL) absorption scenario. The deviation occurs at approximately ≳1 TeV, and the current EGB measurements by Fermi-LAT cannot identify such an effect. We also find that most of the sensitive ALP parameters have been ruled out by existing constraints, leaving only a small region of unrestricted parameters that can be probed using the EGB effect investigated in this work. Observations from forthcoming very-high-energy instruments like LHAASO and CTA may be beneficial for the study of this effect.

scholarly journals Study of Galaxy Evolution Using VHE γ-ray Observations with Ground-based Čerenkov Telescopes

2001 ◽  
Vol 204 ◽  
pp. 151-151
Author(s):  
A. Konopelko
Keyword(s):  
Galaxy Evolution ◽  
Gamma Ray ◽  
Spectral Energy Distribution ◽  
High Energy ◽  
Spectral Energy ◽  
Extragalactic Background Light ◽  
The Galaxy ◽  
Energy Gamma ◽  
Γ Rays ◽  
Luminosity Evolution

The spectral distribution of the extragalactic background light (EBL) in the infrared yields important information about the evolution of galaxies. The spectrum of a galaxy in the 0.1–200 μm region is a footprint of the intrinsic starlight at ~ 1μm and its extinction by dust with re-emission at ~ 100 μm. The overall spectral energy distribution of the EBL is then determined by the galaxy luminosity evolution. High-energy γ-rays are absorbed by the EBL photons through γγ → e+e- reactions. Such an effect has been seen recently in the Mkn 501 TeV spectrum measured by the HEGRA (High Energy Gamma Ray Astronomy) collaboration using an advanced system of imaging atmospheric Čerenkov telescopes (IACTs). The intrinsic spectra of AGNs in the 50 GeV-1 TeV energy range may be constrained by the X-ray fluxes measured with satellite instruments aboard missions such as RXTE, XMM, and ASCA. By reducing the energy threshold down to 50 GeV, forthcoming ground-based IACTs systems (CANGAROO IV, H.E.S.S., VERITAS) may be able to study the absorption cutoff in energy spectra of distant AGNs (z< 0.4), to unfold the true galaxy luminosity evolution function.

scholarly journals Te-REX: a sample of extragalactic TeV-emitting candidates

2019 ◽  
Vol 492 (3) ◽  
pp. 3728-3741
Author(s):  
Barbara Balmaverde ◽  
A Caccianiga ◽  
R Della Ceca ◽  
A Wolter ◽  
A Belfiore ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Host Galaxy ◽  
Spectral Energy ◽  
X Rays ◽  
X Ray ◽  
Cherenkov Telescopes ◽  
Sky Survey ◽  
Very High Energy ◽  
Energy Gamma

ABSTRACT The REX (Radio-Emitting X-ray sources) is a catalogue produced by cross-matching X-ray data from the ROSAT-PSPC archive of pointed observations and radio data from the NRAO VLA Sky Survey, aimed at the selection of blazars. From the REX catalogue, we select a well-defined and statistically complete sample of high-energy peaked BL Lac (HBL). HBL are expected to be the most numerous class of extragalactic TeV-emitting sources. Specifically, we have considered only the REX sources in the currently planned CTA extragalactic survey area satisfying specific criteria and with an optical spectroscopic confirmation. We obtain 46 HBL candidates that we called Te-REX (TeV-emitting REX). We estimate the very high-energy gamma-ray emission, in the TeV domain, using an empirical approach i.e. using specific statistical relations between gamma-rays (at GeV energies) and radio/X-rays properties observed in bright HBL from the literature. We compare the spectral energy distributions (SEDs) with the sensitivities of current and upcoming Cherenkov telescopes and we predict that 14 Te-REX could be detectable with 50 h of observations of CTA and 7 of them also with current Cherenkov facilities in 50 h. By extrapolating these numbers on the total extragalactic sky, we predict that about 800 HBL could be visible in pointed CTA observations and ∼400 with current Cherenkov telescopes in 50 h. Interestingly, our predictions show that a non-negligible fraction (∼30 per cent) of the HBL that will be detectable by CTA is composed of relatively weak objects whose optical nuclear emission is swamped by the host-galaxy light and not (yet) detected by Fermi-LAT.

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