scholarly journals TeV Gamma Rays from Ultrahigh Energy Cosmic Ray Interactions in the Cores of Active Galactic Nuclei: Lessons from Centaurus A

2010 ◽  
Vol 27 (4) ◽  
pp. 482-489 ◽  
Author(s):  
M. Kachelrieß ◽  
S. Ostapchenko ◽  
R. Tomàs
Keyword(s):  
Active Galactic Nuclei ◽  
Gamma Rays ◽  
Galactic Nuclei ◽  
Cosmic Ray ◽  
Far Infrared ◽  
High Energy ◽  
Ultrahigh Energy ◽  
Very High Energy ◽  
Tev Gamma Rays ◽  
Centaurus A

AbstractTeV gamma rays have been observed from blazars as well as from radio galaxies like M 87 and Centaurus A. In leptonic models, gamma rays above the pair production threshold can escape from the ultrarelativistic jet, because large Lorentz factors reduce the background photon densities compared to those required for isotropic emission. Here we discuss an alternative scenario, where very high energy photons are generated as secondaries from ultrahigh energy cosmic rays interactions in the cores of active galactic nuclei. We show that TeV gamma-rays can escape from the core despite large infrared and ultraviolet backgrounds. For the special case of Centaurus A, we study whether the various existing observations from the far infrared to the ultrahigh energy range can be reconciled within this picture.

scholarly journals Interpreting correlated observations of cosmic rays and gamma-rays from Centaurus A with a proton blazar inspired model

2020 ◽  
Vol 500 (1) ◽  
pp. 1087-1094
Author(s):  
Prabir Banik ◽  
Arunava Bhadra ◽  
Abhijit Bhattacharyya
Keyword(s):  
Cosmic Rays ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
High Energy ◽  
Energy Scale ◽  
Electromagnetic Spectrum ◽  
Ultrahigh Energy ◽  
Large Area ◽  
Centaurus A

ABSTRACT The nearest active radio galaxy Centaurus (Cen) A is a gamma-ray emitter in GeV–TeV energy scale. The high energy stereoscopic system (HESS) and non-simultaneous Fermi–Large Area Telescope observation indicate an unusual spectral hardening above few GeV energies in the gamma-ray spectrum of Cen A. Very recently the HESS observatory resolved the kilo parsec (kpc)-scale jets in Centaurus A at TeV energies. On the other hand, the Pierre Auger Observatory (PAO) detects a few ultrahigh energy cosmic ray (UHECR) events from Cen-A. The proton blazar inspired model, which considers acceleration of both electrons and hadronic cosmic rays in active galactic nuclei (AGN) jet, can explain the observed coincident high-energy neutrinos and gamma-rays from Ice-cube detected AGN jets. Here, we have employed the proton blazar inspired model to explain the observed GeV–TeV gamma-ray spectrum features including the spectrum hardening at GeV energies along with the PAO observation on cosmic rays from Cen-A. Our findings suggest that the model can explain consistently the observed electromagnetic spectrum in combination with the appropriate number of UHECRs from Cen A.

scholarly journals HIGH ENERGY COSMIC RAYS, GAMMA RAYS AND NEUTRINOS FROM AGN

2008 ◽  
Vol 23 (24) ◽  
pp. 1991-1997 ◽  
Author(s):  
YUKIO TOMOZAWA
Keyword(s):  
Energy Spectrum ◽  
Cosmic Rays ◽  
Active Galactic Nuclei ◽  
Gamma Rays ◽  
Heavy Particle ◽  
Galactic Nuclei ◽  
Cosmic Ray ◽  
High Energy ◽  
Neutrino Detectors ◽  
High Energy Cosmic Rays

The author reviews a model for the emission of high energy cosmic rays, gamma-rays and neutrinos from AGN (Active Galactic Nuclei) that he has proposed since 1985. Further discussion of the knee energy phenomenon of the cosmic ray energy spectrum requires the existence of a heavy particle with mass in the knee energy range. A possible method of detecting such a particle in the Pierre Auger Project is suggested. Also presented is a relation between the spectra of neutrinos and gamma-rays emitted from AGN. This relation can be tested by high energy neutrino detectors such as ICECUBE, the Mediterranean Sea Detector and possibly by the Pierre Auger Project.

scholarly journals Very high energy neutrino expectation from Fanaroff-Riley I sources

2014 ◽  
Vol 10 (S313) ◽  
pp. 169-174
Author(s):  
Antonio Marinelli ◽  
Nissim Fraija
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Event Rate ◽  
High Energy ◽  
Spectral Energy ◽  
Energy Distributions ◽  
Very High Energy ◽  
Tev Gamma Rays ◽  
Very High ◽  
Centaurus A

AbstractFanaroff-Riley I radiogalaxies have been observed in TeV gamma-rays during the last decades. The origin of the emission processes related with this energy band is still under debate. Here we consider the case of the two closest Fanaroff-Riley I objects: Centaurus A and M87. Their entire broadband spectral energy distributions and variability fluxes show evidences that leptonic models are not sufficient to explain their fluxes above 100 GeV. Indeed, both objects have been imaged by LAT instrument aboard of Fermi telescope with measured spectra well connected with one-zone leptonic models. However, to explain the TeV spectra obtained with campaigns by H.E.S.S., for Centaurus A, and by VERITAS, MAGIC and H.E.S.S. for M87, different emission processes must be introduced. In this work we introduce hadronic scenarios to describe the TeV gamma-ray fluxes observed and to obtain the expected neutrino counterparts for each considered TeV campaign. With the obtained neutrino spectra we calculate, through Monte Carlo simulations, the expected neutrino event rate in a hypothetical Km3 neutrino telescope and we compare the results with what has been observed by IceCube experiment up to now.

scholarly journals A Search for Very High Energy Gamma Rays from Active Galactic Nuclei Visible from the Southern Hemisphere

1999 ◽  
Vol 521 (2) ◽  
pp. 547-551 ◽  
Author(s):  
P. M. Chadwick ◽  
K. Lyons ◽  
T. J. L. McComb ◽  
K. J. Orford ◽  
J. L. Osborne ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Southern Hemisphere ◽  
Gamma Rays ◽  
Galactic Nuclei ◽  
High Energy ◽  
High Energy Gamma ◽  
Very High Energy ◽  
Energy Gamma ◽  
Very High

scholarly journals Search for 10 TeV Gamma-Rays from the Nearby AGNs with the Tibet Air Shower Array

1998 ◽  
Vol 188 ◽  
pp. 440-441
Author(s):  
L.K. Ding ◽  
T. Kobayashi ◽  
K. Mizutani ◽  
A. Shiomi ◽  
Y.H. Tan ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
High Energy ◽  
Bl Lac Objects ◽  
Air Shower ◽  
Very High Energy ◽  
Tev Gamma Rays ◽  
Shower Array ◽  
Air Shower Array

The detection by EGRET of gamma-rays from more than 50 active galactic nuclei (AGNs) allowed us to expect these objects to be the sources of extragalactic cosmic rays at very high energy. The TeV gamma-rays from nearby BL Lac objects of the AGNs examined were detected by the Whipple Observatory collaboration. In this paper, we present the results given by the Tibet air shower array on the search for 10 TeV gamma-ray emission from 18 relatively nearby AGNs with redshifts of z < 0.07.

scholarly journals Recent Results from the CANGAROO Project

1996 ◽  
Vol 160 ◽  
pp. 363-364
Author(s):  
S.A. Dazeley ◽  
P.G. Edwards ◽  
J.R. Patterson ◽  
G.P. Rowell ◽  
M. Sinnott ◽  
...  
Keyword(s):  
Gamma Rays ◽  
South Australia ◽  
Cosmic Ray ◽  
High Energy ◽  
Relativistic Electrons ◽  
Large Numbers ◽  
Inverse Compton ◽  
Very High Energy ◽  
Large Telescopes ◽  
Very High

TheCollaboration ofAustralia andNippon for aGAmmaRayObservatory in theOutback operates two large telescopes at Woomera (South Australia), which detect the Čerenkov light images produced in the atmosphere by electronpositron cascades initiated by very high energy (~1 TeV or 1012eV) gamma rays. These gamma rays arise from a different mechanism than at EGRET energies: inverse Compton (IC) emission from relativistic electrons.The spoke-like images are recorded by a multi-pixel camera which facilitates the rejection of the large numbers of oblique and ragged cosmic ray images. A field of view ~3.5° is required. The Australian team operates a triple 4 m diameter mirror telescope, BIGRAT, with a 37 photomultiplier tube camera and energy threshold 600 GeV. The Japanese operate a single, highly accurate 3.8 m diameter f/1 telescope and high resolution 256 photomultipler tube camera. In 1998 a new 7 m telescope is planned for Woomera with a design threshold ~;200GeV.

scholarly journals Secondary-electron radiation accompanying hadronic GeV–TeV gamma-rays from supernova remnants

2020 ◽  
Vol 492 (3) ◽  
pp. 4246-4253 ◽  
Author(s):  
Yan Huang ◽  
Zhuo Li ◽  
Wei Wang ◽  
Xiaohong Zhao
Keyword(s):  
Synchrotron Radiation ◽  
Gamma Rays ◽  
Supernova Remnants ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
Far Infrared ◽  
Hadronic Interactions ◽  
Electrons And Positrons ◽  
Tev Gamma Rays ◽  
The Magnetic Field

ABSTRACT The synchrotron radiation from secondary electrons and positrons (SEPs) generated by hadronic interactions in the shock of supernova remnant (SNR) could be a distinct evidence of cosmic ray (CR) production in SNR shocks. Here, we provide a method where the observed gamma-ray flux from SNRs, created by pion decays, is directly used to derive the SEP distribution and hence the synchrotron spectrum. We apply the method to three gamma-ray bright SNRs. In the young SNR RX J1713.7−3946, if the observed GeV−TeV gamma-rays are of hadronic origin and the magnetic field in the SNR shock is B ≳ 0.5 mG, the SEPs may produce a spectral bump at 10−5–10−2 eV, exceeding the predicted synchrotron component of the leptonic model, and a soft spectral tail at ≳100 keV, distinct from the hard spectral slope in the leptonic model. In the middle-aged SNRs IC443 and W44, if the observed gamma-rays are of hadronic origin, the SEP synchrotron radiation with B ∼ 400–500 μG can well account for the observed radio flux and spectral slopes, supporting the hadronic origin of gamma-rays. Future microwave to far-infrared and hard X-ray (&gt;100keV) observations are encouraged to constraining the SEP radiation and the gamma-ray origin in SNRs.

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