Bibcode
DOI
Albert, J.; Aliu, E.; Anderhub, H.; Antoranz, P.; Baixeras, C.; Barrio, J. A.; Bartko, H.; Bastieri, D.; Becker, J. K.; Bednarek, W.; Berger, K.; Bigongiari, C.; Biland, A.; Bock, R. K.; Bordas, P.; Bosch-Ramon, V.; Bretz, T.; Britvitch, I.; Camara, M.; Carmona, E.; Chilingarian, A.; Coarasa, J. A.; Commichau, S.; Contreras, J. L.; Cortina, J.; Costado, M. T.; Curtef, V.; Danielyan, V.; Dazzi, F.; De Angelis, A.; Delgado, C.; de los Reyes, R.; De Lotto, B.; Dorner, D.; Doro, M.; Errando, M.; Fagiolini, M.; Ferenc, D.; Fernández, E.; Firpo, R.; Fonseca, M. V.; Font, L.; Fuchs, M.; Galante, N.; García-López, R. J.; Garczarczyk, M.; Gaug, M.; Giller, M.; Goebel, F.; Hakobyan, D.; Hayashida, M.; Hengstebeck, T.; Herrero, A.; Höhne, D.; Hose, J.; Huber, S.; Hsu, C. C.; Jacon, P.; Jogler, T.; Kosyra, R.; Kranich, D.; Kritzer, R.; Laille, A.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; Lorenz, E.; Majumdar, P.; Maneva, G.; Mannheim, K.; Mariotti, M.; Martínez, M.; Mazin, D.; Merck, C.; Meucci, M.; Meyer, M.; Miranda, J. M.; Mirzoyan, R.; Mizobuchi, S.; Moralejo, A.; Nieto, D.; Nilsson, K.; Ninkovic, J.; Oña-Wilhelmi, E.; Otte, N.; Oya, I.; Panniello, M.; Paoletti, R.; Paredes, J. M.; Pasanen, M.; Pascoli, D.; Pauss, F.; Pegna, R.; Persic, M.; Peruzzo, L.; Piccioli, A.; Prandini, E.; Puchades, N.; Raymers, A. et al.
Bibliographical reference
The Astrophysical Journal, Volume 681, Issue 2, pp. 944-953.
Advertised on:
7
2008
Journal
Citations
31
Refereed citations
20
Description
All but three (M87, BL Lac, and 3C 279) extragalactic sources detected
so far at very high energy γ-rays belong to the class of
high-frequency-peaked BL Lac objects. This suggested to us a systematic
scan of candidate sources with the MAGIC telescope, based on the Donato
et al. compilation of X-ray blazars. The observations took place from
2004 December to 2006 March and cover northern sky sources visible under
small zenith distances zd<30deg at culmination,
constraining the declination to -2° to +58°. The sensitivity of
the search was planned for detecting X-ray-bright [F(1 keV)>2 μJy]
sources emitting at least the same energy flux at 200 GeV as at 1 keV.
To avoid strong γ-ray attenuation close to the energy threshold,
source redshift was constrained to z<0.3. Of the 14 sources observed,
1ES 1218+304 (for the first time at VHE) and 1ES 2344+514 (strong
detection in a low flux state) were detected in addition to the known
bright TeV blazars Mrk 421 and Mrk 501. A marginal excess of 3.5 σ
from the position of 1ES 1011+496 was observed and then confirmed as a
VHE γ-ray source by a second MAGIC observation triggered by a high
optical state. For the remaining sources, we present 99% c.l. upper
limits on the integral flux >~200 GeV. We characterize the HBL sample
(including all HBLs detected at VHE so far) by looking for correlations
between their multifrequency spectral indices determined from
simultaneous optical, archival X-ray, and radio luminosities, finding
that VHE-emitting HBLs do not seem to constitute a unique subclass. The
HBLs' absorption-corrected γ-ray luminosities at 200 GeV are
generally not higher than their X-ray luminosities at 1 keV.
Related projects
Particle Astrophysics
The MAGIC Collaboration is integrated by 20 research institutes and university departments from Armenia, Bulgaria, Finland, Germany, Italy, Poland, Spain, Switzerland and USA. The collaboration comprises two 17m diameter telescopes, located at the Roque de los Muchachos Observatory, designed to measure the Cherenkov radiation associated with
Ramón
García López