Related papers: The Molecular Environment of the Gamma-ray Source …
Microquasars are radio-emitting X-ray binaries accompanied by relativistic jets. They are established sources of 100~TeV gamma rays and are considered promising candidates for cosmic-ray acceleration. Motivated by recent detections of $\sim…
Gamma-ray binaries are orbital modulated gamma-ray sources in the Galaxy detected both at GeV and TeV energies. The high-energy radiation may come from the interaction of energetic electrons injected by a young pulsar and photons from the…
We report the discovery of variable $\gamma$-rays up to petaelectronvolt from Cygnus X-3, an iconic X-ray binary. The $\gamma$-ray signal was detected with a statistical significance of approximately 10 $\sigma$ by the Large High Altitude…
The spectra of very high energy gamma-radiation from distant extragalactic objects suffer significant deformations during the passage of primary gamma-rays through the intergalactic medium. The recently reported fluxes of diffuse infrared…
The TeV gamma-ray source MGRO J1908+06 is one of the highest-energy sources known, with observed emission by the High Altitude Water Cherenkov (HAWC) Observatory extending well past 100 TeV. The source exhibits both energy-dependent…
We report the observation of TeV gamma-rays from the Cygnus region using the ARGO-YBJ data collected from 2007 November to 2011 August. Several TeV sources are located in this region including the two bright extended MGRO J2019+37 and MGRO…
We have compared the TeV gamma-rays with the new 12CO J=2-1 data toward HESS J1745-303 in the Galactic center and confirmed that the molecular gas MG358.9-0.5 toward (l, b)=(358.9, -0.5 at VLSR=-100-0 km s-1 shows a reasonable positional…
We present results from deep observations towards the Cygnus region using 300 hours of very-high-energy (VHE) $\gamma$-ray data taken with the VERITAS Cherenkov telescope array and over seven years of high-energy $\gamma$-ray data taken…
The Cygnus Cocoon is the first gamma-ray superbubble powered by a massive stellar association, the OB2 association. It was postulated that the combined effects of the stellar winds of all the massive O-type stars of the OB2 association can…
A surprisingly large flux of extraterrestrial high-energy neutrinos was discovered by the IceCube experiment. While the flux of muon neutrinos with energies $E>100$ TeV is consistent with the extragalactic gamma-ray background (EBL)…
The first source catalog of Large High Altitude Air Shower Observatory reported the detection of a very-high-energy gamma ray source, 1LHAASO J1219+2915. In this paper a further detailed study of the spectral and temporal behavior of this…
Identifying Galactic PeVatrons (PeV particle accelerators) from the ultra-high-energy (UHE, >100 TeV) $\gamma$-ray sources plays a crucial role in revealing the origin of Galactic cosmic rays. The UHE source 1LHAASO J1857+0203u is suggested…
Molecular clouds are expected to emit non-thermal radiation due to cosmic ray interactions in the dense magnetized gas. Such emission is amplified if a cloud is located close to an accelerator of cosmic rays and if energetic particles can…
$\gamma$-ray observations of the Cygnus Cocoon, an extended source surrounding the Cygnus X star-forming region, suggest the presence of a cosmic ray accelerator reaching energies up to a few PeV. The very-high-energy (VHE; 0.1-100~TeV)…
We observed the unidentified TeV gamma-ray source HESS J1804-216 with the CANGAROO-III atmospheric Cerenkov telescopes from May to July in 2006. We detected very high energy gamma rays above 600 GeV at the 10 sigma level in an effective…
It is commonly assumed that high-energy gamma-rays are made via either purely electromagnetic processes or the hadronic process of pion production, followed by decay. We investigate astrophysical contexts where a third process (A*) may…
We report the detection of a $\gamma$-ray bubble spanning at least 100$\rm deg^2$ in ultra high energy (UHE) up to a few PeV in the direction of the star-forming region Cygnus X, implying the presence Super PeVatron(s) accelerating protons…
We develop a model for a possible origin of hard very high energy spectra from a distant blazar. In the model, both the primary photons produced in the source and secondary photons produced outside the source contribute to the observed high…
Very recently, diffuse gamma rays with $0.1\,{\rm PeV}<E_\gamma <1\,\rm PeV$ have been discovered from the Galactic disk by the Tibet air shower array and muon detector array (Tibet AS+MD array). While the measured sub-PeV flux may be…
The extended TeV gamma-ray source HESS J1023-575 is coincident with the massive, young stellar cluster Westerlund 2 (Wd2) and its surrounding HII region RCW 49. On the basis of an analysis of the CO emission and 21 cm absorption along the…