Date of Award

5-2017

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Astrophysics

Committee Member

Dr. Marco Ajello, Committee Chair

Committee Member

Dr. Dieter Hartmann

Committee Member

Dr. Bradley Meyer

Abstract

MeV blazars are the most powerful sources among the blazar class. With bolometric luminosities exceeding 1048 erg s−1 and powerful relativistic jets, they are usually detected at high-redshifts (z > 2) and they generally harbor extremely massive black holes (MBH ∼ 109 M⊙ ). Being able to derive their physical properties such as jet power, accretion disk luminosity, bulk Lorentz factor of the jet (Γ) 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 γ-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, Γ and viewing angle (θv ). 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.

Share

COinS