RT Journal Article
T1 Gamma-Ray excess from a stacked sample of high- and intermediate-frequency peaked blazars observed with the MAGIC telescope
A1 Antoranz Canales, Pedro
A1 Barrio Uña, Juan Abel
A1 Contreras González, José Luis
A1 Fonseca González, María Victoria
A1 Miranda Pantoja, José Miguel
A1 Nieto Castaño, Daniel
AB Between 2004 and 2009, a sample of 28 X-ray selected high-and intermediate-frequency peaked blazars with an X-ray flux larger than 2 mu Jy at 1 keV in the redshift range from 0.018 to 0.361 was observed with the MAGIC telescope at energies above 100 GeV. Seven among them were detected and the results of these observations are discussed elsewhere. Here we concentrate on the remaining 21 blazars which were not detected during this observation campaign and present the 3 sigma (99.7%) confidence upper limits on their flux. The individual flux upper limits lie between 1.6% and 13.6% of the integral flux from the Crab Nebula. Applying a stacking method to the sample of non-detections with a total of 394.1 hr exposure time, we find evidence for an excess with a cumulative significance of 4.9 standard deviations. It is not dominated by individual objects or flares, but increases linearly with the observation time as for a constant source with an integral flux level of similar to 1.5% of that observed from the Crab Nebula above 150 GeV.
PB IOP Publishing
SN 0004-637X
YR 2011
FD 2011-03-10
LK https://hdl.handle.net/20.500.14352/43896
UL https://hdl.handle.net/20.500.14352/43896
LA eng
NO © The American Astronomical Society. Supported by INFN Padova.We would like to thank the Instituto de Astrofisica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The support of the German BMBF and MPG, the Italian INFN, the Swiss National Fund SNF, and the Spanish MICINN is gratefully acknowledged. This work was also supported by the Polish MNiSzW Grant N N203 390834, by the YIP of the Helmholtz Gemeinschaft, and by grant DO02-353 of the Bulgarian National Science Fund.
NO INFN Padova
NO German BMBF
NO German MPG
NO Italian INFN
NO Swiss National Fund SNF
NO Spanish MICINN
NO Polish MNiSzW
NO YIP of the Helmholtz Gemeinschaft
NO Bulgarian National Science Fund
DS Docta Complutense
RD 7 abr 2025