Refiloe edited subsection_Black_holes_and_Active__.tex  over 8 years ago

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\cite{Burke_1997} states that the lobes derive energy from the jets, as the jets dissipate into the lobes and the total energy in the lobes can reach up to $10^{53} J$.  Released gravitational energy of stellar material falling into a supermassive black hole is believed to be the main source of the galaxy’s energy. \cite{Mo_2009} theorizes that almost all spheroidal galaxy components (i.e., ellipticals and bulges) have a SMBH with a mass which correlated with that of the host galaxy, suggesting that the formation of SMBHs is related to the formation of their host galaxies.  In AGN Bremsstrahlung, Synchrotron and Compton emission processes are most common. Synchrotron radiation accounts for much of the radio emissions in AGN. In AGN the jets produce synchrotron radiation due to near-relativistic electrons spiraling around magnetic field lines.  This process produces polarized radiation in the direction of propagation of the emitting electron. The torus emits unpolarized thermal radiation. It has been theorized that the ionized disk associated with the torus produces a varying magnetic field across its surface. The varying magnetic field then induces a large electric field which accelerates particles to relativistic speeds. These particles spiral along the magnetic field lines and produce synchrotron radiation. (http://www.jeffstanger.net/Astronomy/emissionprocesses.html - Jeff Stanger ).  Within AGN the radiation is emitted by a variety of sources, where some of the sources are thermal and others non-thermal. \cite{Burke_1997} states that the relative strength of these sources depends on the orientation of the AGN. The overall spectrum however, can be represented by a simple power law.  Fanaroff and Riley classification of radio galaxies groups them into two major categories FR-I and FR-II. The two catagories are based on whether radio-galaxies have edgedarkened (FR-I) morphologies or edge-brightened (FR-II) morphologies. (http://arxiv.org/pdf/1206.6893v1.pdf) believes that these morphologies arose from the interaction of jets and the material in their surrounding environment. Spectroscopy obeservations further reveal that FR-I radio galaxy hosts s exhibit optical spectra with only absorption lines, while FR-II hosts display mixed characteristicts. Some FR-II hosts are similar to FR-Is in that they only exhibit absorption lines ,but some others have spectra with strong high ionization emission lines.