Detection of a flare by Markarian 421 an Active Galactic Nuclei (AGN)
In January 2002, Solar Two detected a flaring event from the Blazar Markarian 421. Blazars are members of a class of astrophysical objects called Active Galactic Nuclei (AGN). The standard model of AGN suggests that gamma rays are produced when matter is accreted onto a super-massive black hole in the center of a galaxy. Charged particles are funneled along magnetic field lines to produce axial jets. Shock fronts in the jets can produce gamma ray flares if an over-density of matter is injected.
Data was taken by tracking Mkn421 for 28 minutes followed by 28 minutes tracking the same part of the sky 7 degrees displaced for background subtraction. In January, 2002 we noticed that a few "on/off" pairs taken on Mk421 showed significant excess in "real time". Mk421 has a quiescent flux ~1/4 of the Crab flux. Compared to our average Crab significance (~1 s) per 28 min run , it implies flaring event at ~ 3x Crab. This was detected with 4 sigma significance in 40 minutes observation time (flaring event circled in figure above). Coordinated measurements on the next night indicated that Whipple and HEGRA were also seeing fluxes ~1.5 - 2x Crab.