In 2005 and 2006, the MAGIC telescope observed very high energy gamma-ray emission from the distant BL Lac object PG 1553 + 113. The overall significance of the signal was 8.8 sigma for 18.8 hr of observation time. The light curve shows no significant flux variations on a daily timescale; the flux level during 2005 was, however, significantly higher compared to 2006. The differential energy spectrum between similar to 90 and 500 GeV is well described by a power law with photon index. Gamma = 4.2 +/- 0.3. The combined 2005 and 2006 energy spectrum provides an upper limit of z = 0.74 on the redshift of the object.
Detection of very high energy radiation from the BL lacertae object PG 1553+113 with the MAGIC telescope
DE ANGELIS, Alessandro;DE LOTTO, Barbara;
2007-01-01
Abstract
In 2005 and 2006, the MAGIC telescope observed very high energy gamma-ray emission from the distant BL Lac object PG 1553 + 113. The overall significance of the signal was 8.8 sigma for 18.8 hr of observation time. The light curve shows no significant flux variations on a daily timescale; the flux level during 2005 was, however, significantly higher compared to 2006. The differential energy spectrum between similar to 90 and 500 GeV is well described by a power law with photon index. Gamma = 4.2 +/- 0.3. The combined 2005 and 2006 energy spectrum provides an upper limit of z = 0.74 on the redshift of the object.File in questo prodotto:
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