The TeV energy spectrum of Markarian 421 measured in a high flaring state
نویسندگان
چکیده
The BL Lac object (blazar) Mrk 421 was observed during its outburst in 2004 April with the Whipple 10 m telescope for a total of about 24.5 hr. The measured g-ray rate varied substantially over the range from 4 to 10 minute 1 and eventually exceeded the steady g-ray rate of the Crab Nebula (standard candle) by a factor of 3. The overall significance of the g-ray signal exceeded 70 j and the total number of excess events was more than 10,000. This unique Mrk 421 outburst enabled the measurement of a high-quality spectrum of very high energy g-rays in a high state of emission. This spectrum is a power law and it extends beyond 10 TeV. Subject headings: BL Lacertae objects: individual (Markarian 421) — galaxies: active Online material: color figure
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