Autori: J. Albert et al.

Editorial: Astrophysical Journal, 654, p.119-122, 2007.

Rezumat:

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 σ 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 ~90 and 500 GeV is well described by a power law with photon index Γ = 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.

Cuvinte cheie: astrofizica, radiatie gamma, agn // astrophysics, gamma-radiation, agn

URL: http://iopscience.iop.org/1538-4357/654/2/L119?ejredirect=migration