نتایج جستجو برای: γ ray
تعداد نتایج: 371341 فیلتر نتایج به سال:
The diffuse Galactic γ-ray emission is produced by cosmic rays (CRs) interacting with the interstellar gas and radiation field. Measurements by the Energetic Gamma-Ray Experiment Telescope (EGRET) instrument on the Compton Gamma-Ray Observatory (CGRO) indicated excess γ-ray emission ≥ 1 GeV relative to diffuse Galactic γ-ray emission models consistent with directly measured CR spectra (the so-c...
With frequent flaring activity of its relativistic jets, Cygnus X-3 (Cyg X-3) is one of the most active microquasars and is the only Galactic black hole candidate with confirmed high-energy γ -ray emission, thanks to detections by Fermi Large Area Telescope (Fermi/LAT) and AGILE. In 2011, Cyg X-3 was observed to transit to a soft X-ray state, which is known to be associated with high-energy γ -...
Prompt optical emission from the γ-ray burst of GRB 041219A has been reported by Vestrand et al. (2005). The facts that the fast rise of optical emission simultaneous with the dominant γ-ray pulse, and a tight correlation with the prompt γ-ray emission have been displayed. These indicate that the prompt optical emission and γ-ray emission would naturally have a common origin. We then propose th...
We investigate the γ-ray and X-ray properties of the flat spectrum radio quasar (FSRQ) 4C 50.11 at redshift z = 1.517. The Fermi Large Area Telescope (LAT) data indicate that this source was in an active state since 2013 July. During the active period, the γ-ray flux increased by more than a factor of three and two distinct flares were detected with the variability timescale as short as several...
Prompt optical emission from the γ-ray burst of GRB 041219A has been reported by Vestrand et al. There was a fast rise of optical emission simultaneous with the dominant γ-ray pulse, and a tight correlation with the prompt γ-ray emission has been displayed. These indicate that the prompt optical emission and γ-ray emission would naturally have a common origin. We propose that this optical compo...
The radio source 3C 84 associated with the radio/giant elliptical galaxy NGC 1275 is one of the best targets to probe the radio counterpart of the γ-ray emitting region. Although this source shows clear time variability in γ-ray bands, no clear correlation in radio light curve was found on the timescale of γ-ray variability. The location of the γ-ray flaring region has been an open question. In...
There is clear evidence that the γ-ray emission from active galactic nuclei (AGNs) is attributed to the inverse Compton scatterings in the relativistic blobs near the massive black holes. If the soft seed photons are from the regions outside the blobs, a linear relation between (νFν,γ/νFν,synu ) and Doppler factor δ is expected, where νFν,γ and νFν,syn are monochromatic γ-ray and synchrotron fl...
One way to understand the nonthermal history of the universe is by establishing the origins of the unresolved and truly diffuse extragalactic γ rays. Dim blazars and radio/γ galaxies certainly make an important contribution to the galactic γ-ray background given the EGRET discoveries, and previous treatments are reviewed and compared with a new analysis. Studies of the γ-ray intensity from cosm...
One way to understand the nonthermal history of the universe is by establishing the origins of the unresolved and truly diffuse extragalactic γ rays. Dim blazars and radio/γ galaxies certainly make an important contribution to the galactic γ-ray background given the EGRET discoveries, and previous treatments are reviewed and compared with a new analysis. Studies of the γ-ray intensity from cosm...
Abstract. In a survey of the inner part of the Galaxy, performed with the H.E.S.S. Instrument (High energy stereoscopic system) in 2004 and 2005, a large number of new unidentified very high energy (VHE) γ-ray sources above an energy of 100 GeV was discovered. Often the γ-ray spectra in these sources reach energies of up to ∼ 10 TeV. These are the highest energy particles ever attributed to sin...
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