Observation of Markarian 421 in TeV gamma rays over a 14-year time span
Abstract
The variability of the blazar Markarian 421 in TeV gamma rays over a 14-year time period has been explored with the Whipple 10 m 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 878.4 h of observation with the Whipple telescope, spread over 783 nights. The peak energy response of the telescope was 400 GeV 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 0.446 ± 0.008 Crab flux units. The flux exceeded 10 Crab flux units on three separate occasions. For the 2000-2001 season the average flux reached 1.86 Crab units, while in the 1996-1997 season the average flux was only 0.23 Crab units.
- Publication:
-
Astroparticle Physics
- Pub Date:
- February 2014
- DOI:
- 10.1016/j.astropartphys.2013.10.004
- arXiv:
- arXiv:1310.8150
- Bibcode:
- 2014APh....54....1A
- Keywords:
-
- AGN;
- TeV gamma rays;
- Markarian 421;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 29 pages, 15 figures. Accepted for publication in Astroparticle Physics