| Summary: | This thesis presents long-tenn X-ray and TeV y-ray observations from 2000 to 2006 of three TeV blazar type Active Galactic Nuclei (AGN): Mrk 421, Mrk 501, and H1426i428. Standard emission models for TeV blazars predict correlated and highly variable X-ray and TeV y-ray radiation from accelerated electrons in a jet orientated along our line of sight By using a large sample . of near simultaneous observations, this thesis examines potential flux and spectral correlations between the X-ray and TeV y-ray energy bands. Joint nightly observations ofMrk 421 with the X-ray instrument RXTEPCA, and at 0.5-10 TeV y-ray energies with the Whipple 10 m telescope during periods ranging from a week to 6 months revealed complicated, high amplitude flaring. Spectral variability was investigated for the rising and decay phases of large isolated day timescale flares. Generally, the X-ray and TeV y-ray spectra hardened with increasing integral flux, but a consistent spectral evolution was not shown between individual flares. Absorption of the TeV y-ray energy spectrum by the extragalactic background light (EBL) was corrected for. During a large flare in \. March 2001; tentative evidence was found for a highly curved intrinsic TeV y-ray energy spectrum peaking at 0.85 ± 0.22 TeV simultaneous to a curved X-ray spectruI)1 peaking at 2.14 ± 0.19 keY. RXTEPCA and Whipple io m campaigns on Mrk 501 and H1426i428 showed significant X-ray spectral variability, however the TeV y-ray integral flux remained near the detection limit of the Whipple 10 m. The broadband 0.6-20 keY X-ray spectrum of the 3 TeV blazars was investigated with XMM-Newton and RXTE peA observations. In addition to simultaneous day timescale variability, the large sample of Whipple 10 m observations from 2000 to 2006 allowed for a detailed study of long-tenn y-ray variability. For Mrk 421, a weak correlation, with large spread is shown for the Whipple 10 m integral flux above 0.6 TeV and RXTEASM X-ray rate on month timescales. From 2001 to 2006, Mrk 501 was recorded by the Whipple 10 m in a low flux state of 27% of the integral flux from the Crab nebula supernova remnant. In July 2005, the MAGIC telescope recorded large TeV y-ray flaring in Mrk 501 by a factor> 3 of the Crab nebula flux. This high flux state occured after the Whipple 10 m observing period on Mrk 501 in June 2005, and so could not be verified in this work. The detection of H1426-t428 at TeV y-ray energies by the Whipple 10 m in 2001 is confirmed in this work, however the source was not detected again by the Whipple 10 m over a 5 year period. The detailed study ofTeV blazar X-ray and y-ray variability in this work highlights the need for high sensitivity observations to better resolve complicated and unpredictable flaring states.
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