Multi-wavelength studies of VHE gamma-ray blazars
Abstract
Blazars, particularly those detected in TeV γ-rays, are some of the most violent astrophysical objects yet observered. They display extreme variability on multiple timescales over a broad range of energies. These sources make excellent laboratories for studying the environment within the jets of active galactic nuclei, as the bulk of the detected emission is from the jets. These sources have been well studied at multiple wavelengths, and much insight has been gained into the nature of these extreme objects. This work described in this dissertation attempts to expand the understanding of two particular blazars, Markarian 421 and Markarian 501, by improving on previous observational techniques and utilizing state of the art detectors for obtaining data. The first project described focused on obtaining strictly simultaneous multi-wavelength data, covering a broad energy range, to search for any multi-wavelength correlations and to provide an accurate spectral energy distribution. This simultaneous data is essential for these sources due to their rapid variability. The most widely accepted models for emission within blazars, known as synchrotron self Compton, depend on a strong connection between the X-ray and γ-ray photons. The simplest of these models predicts a strong correlation between the observed flux in these two bands, but this study did not observe such a correlation, though the synchrotron self Compton models could match the data. The second project focused on obtaining a state of the art measurement of the quiescent state of the blazar Markarian 501. This object is generally quite weak, and previous very high energy (E > 100 GeV) γ-ray experiments were not able to detect the source in the quiescent state. Neither was the source detected by previous γ-ray space telescopes operating in a lower energy range. This project used data from the current generation of experiments to obtain a carefully sampled spectral energy distribution of the source in the quiet state and investigated some of the characteristic timescales involved in this state.
Degree
Ph.D.
Advisors
Cui, Purdue University.
Subject Area
Astrophysics|Astronomy
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