Extremely rapid bursts of TeV photons from the active galaxy Markarian 421
Article Abstract:
Previous studies have concluded that the flux from TeV energy sources, together with the timescales on which they vary, limits the emission mechanisms of their sources. This means that the emission region of TeV energy may grow at a steady rate. However, two observations of TeV photons from the active galaxy Markarian 421 challenge such an assertion. During the first burst, which had a doubling time of about one hour, the flux increased above the relatively quiescent value by more than a factor of 50. During the second burst, which lasted about 30 minutes, the flux increased by a factor of 20-25.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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Catching photons from hell
Article Abstract:
Markarian 421 (Mk 421), a large elliptical galaxy with an active nucleus, is the most energetic source of gamma-rays yet detected outside the Milky Way Galaxy. M. Punch and colleagues used more than 100 fast photomultipliers at the Whipple Observatory in Arizona from Mar to Jun 1992 to determine Mk 421's output of teraelectronvolt gamma-rays. The results indicate that Mk 421's intrinsic luminosity may be more than 10 orders of magnitude greater than that of such Milky Way gamma-ray sources as the Crab supernova remnant.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1992
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Detection of TeV photons from the active galaxy Markarian 421
Article Abstract:
Active galaxy Markarian 421 (Mk 421) has been identified as the first known extragalactic source of TeV photons. Observations of Mk 421, a large and elliptical galaxy, were made from Mar to Jun 1992 using the gamma-ray telescope at the Whipple Observatory in Arizona. The failure to detect TeV photons from brighter but more distant objects probably results from the thinning out of the photons through interaction with extragalactic starlight.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1992
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