Date of Award
Master of Science (MS)
Dr. Marco Ajello, Committee Chair
Dr. Dieter Hartmann
Dr. Bradley Meyer
MeV blazars are the most powerful sources among the blazar class. With bolometric luminosities exceeding 1048 erg sâˆ’1 and powerful relativistic jets, they are usually detected at high-redshifts (z > 2) and they generally harbor extremely massive black holes (MBH âˆ¼ 109 MâŠ™ ). Being able to derive their physical properties such as jet power, accretion disk luminosity, bulk Lorentz factor of the jet (Î“) and black hole mass, enables us to put constraints in the understanding of this not well sampled class of objects and use them for example to probe the formation of massive black holes in the early universe. In this thesis we have analyzed the broadband emission of three high redshift blazars, focusing on the high energy part of their spectral energy distribution. In fact, being able to obtain hard X-ray data from the recently launched NuSTAR and having Î³-ray detections from the Fermi-LAT, we were able to constrain more accurately the high energy peak of their distribution and therefore more precisely infer their jet power, underlying electron distribution, Î“ and viewing angle (Î¸v ). Gathering optical and UV data allowed us to determine the black hole mass of such powerful objects as well as their accretion disk luminosity. This work has recently been published in ApJ (Marcotulli et al., 2017). In Section 1, the broad family of active galactic nuclei (ANGs) and their main physical characteristics are introduced, with a focus on the subclass of blazars and specifically MeV blazars. In Section 2, the main instruments used in our research to gather and analyze data are described, with a particular interest on imaging in the hard X-ray regime. Section 3 contains the data analysis description, the results obtained combining the observations with a one-zone leptonic emission model and the discussion on our findings. In Section 4 we report our conclusions and present an outlook on future MeV blazars studies possibilities. Appendix A, B and C contain an overlook of relativistic beaming, radiative processes and model used for these sources.
Marcotulli, Lea, "High-redshift Blazars through NuSTAR Eyes" (2017). All Theses. 2653.