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VERITAS Observations of Day-scale Flaring of M 87 in 2010 April
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2012 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 746, no 2, 141Article in journal (Refereed) Published
Abstract [en]

VERITAS has been monitoring the very-high-energy (VHE; > 100 GeV) gamma-ray activity of the radio galaxy M 87 since 2007. During 2008, flaring activity on a timescale of a few days was observed with a peak flux of (0.70 ± 0.16) × 10–11 cm–2 s–1 at energies above 350 GeV. In 2010 April, VERITAS detected a flare from M 87 with peak flux of (2.71 ± 0.68) × 10–11 cm–2 s–1 forE > 350 GeV. The source was observed for six consecutive nights during the flare, resulting in a total of 21 hr of good-quality data. The most rapid flux variation occurred on the trailing edge of the flare with an exponential flux decay time of 0.90+0.22 –0.15 days. The shortest detected exponential rise time is three times as long, at 2.87+1.65 –0.99 days. The quality of the data sample is such that spectral analysis can be performed for three periods: rising flux, peak flux, and falling flux. The spectra obtained are consistent with power-law forms. The spectral index at the peak of the flare is equal to 2.19 ± 0.07. There is some indication that the spectrum is softer in the falling phase of the flare than the peak phase, with a confidence level corresponding to 3.6 standard deviations. We discuss the implications of these results for the acceleration and cooling rates of VHE electrons in M 87 and the constraints they provide on the physical size of the emitting region.

Place, publisher, year, edition, pages
2012. Vol. 746, no 2, 141
Keyword [en]
galaxies: individual: M 87 VER J1230+123, gamma rays: galaxies
National Category
Astronomy, Astrophysics and Cosmology
Research subject
Physics, Astroparticle Physics
Identifiers
URN: urn:nbn:se:lnu:diva-42804DOI: 10.1088/0004-637X/746/2/141OAI: oai:DiVA.org:lnu-42804DiVA: diva2:807512
Available from: 2015-04-23 Created: 2015-04-23 Last updated: 2015-05-05Bibliographically approved

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Prokoph, Heike
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CiteExportLink to record
Permanent link

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Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
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  • en-US
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  • Other locale
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