Observation of Markarian 421 in TeV gamma rays over a 14-year time span.

Authors :: Acciari, V.A.
Arlen, T.
Aune, T.
Benbow, W.
Bird, R.
Bouvier, A.
Bradbury, S.M.
Buckley, J.H.
Bugaev, V.
de la Calle Perez, I.
Carter-Lewis, D.A.
Cesarini, A.
Ciupik, L.
Collins-Hughes, E.
Connolly, M.P.
Cui, W.
Duke, C.
Dumm, J.
Falcone, A.
Federici, S.
Source :: Astroparticle Physics. Feb2014, Vol. 54, p1-10. 10p.
Publication Year :: 2014
Abstract: Abstract: The variability of the blazar Markarian 421 in TeV gamma rays over a 14-year time period has been explored with the Whipple 10m telescope. It is shown that the dynamic range of its flux variations is large and similar to that in X-rays. A correlation between the X-ray and TeV energy bands is observed during some bright flares and when the complete data sets are binned on long timescales. The main database consists of 878.4h of observation with the Whipple telescope, spread over 783 nights. The peak energy response of the telescope was 400GeV with 20% uncertainty. This is the largest database of any TeV-emitting active galactic nucleus (AGN) and hence was used to explore the variability profile of Markarian 421. The time-averaged flux from Markarian 421 over this period was Crab flux units. The flux exceeded 10Crab flux units on three separate occasions. For the 2000–2001 season the average flux reached 1.86Crab units, while in the 1996–1997 season the average flux was only 0.23Crab units. [Copyright &y& Elsevier]