Systematic search for VHE gamma-ray emission from X-ray bright high-frequency BL Lac objects
Jun, 200715 pages
Published in:
- Astrophys.J. 681 (2008) 944-953
e-Print:
- 0706.4453 [astro-ph]
DOI:
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Abstract: (arXiv)
Motivated by the fact that all but two (M87, BL Lac) extragalactic sources detected so far at VHE energies belong to the so-called HBL class of high-frequency peaked BL Lac objects, a systematic scan of the compilation of X-ray blazars by Donato et al. (2001) has been performed using the MAGIC telescope. The observations took place from December 2004 to March 2006 and cover sources on the northern sky visible under small zenith distances zd < 30degr at culmination, constraining the declination to values between -2degr and +58degr. The sensitivity of the search was planned for detecting X-ray bright (F(1keV) > 2uJy) sources emitting at least the same energy flux at 200GeV as at 1keV. In order to avoid strong gamma-ray attenuation close to the energy threshold, the redshift of the sources was constrained to values z < 0.3. Of the 14 sources observed, 1ES 1218+30.4 (for the first time at very high energies) and 1ES 2344+51.4 (strong detection in a low flux state) have been detected in addition to the known bright TeV blazars Mrk 421 and Mrk 501. For the remaining sources, we present here the 99% confidence level upper limits on the integral flux above ~200GeV. A marginal excess of 3.5 sigma from the position of 1ES 1011+49.6 (with the largest redshift z = 0.212 so far reported for any extragalactic VHE source) may indicate another new source. We compare the absorption corrected gamma-ray luminosities at 200GeV with simultaneous optical, archival X-ray, and radio luminosities, to constrain the statistical properties of the sample.- gamma ray: cosmic radiation
- cosmic radiation: particle source
- X-ray: cosmic radiation
- blazar
- cosmic radiation: energy
- cosmic radiation: flux
- upper limit
- Cherenkov counter: imaging
- experimental results
- GAMMA-RAY OBSERVATIONS
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