Refiloe edited subsection_Black_holes_and_Active__.tex  over 8 years ago

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Radio galaxies are galaxies dominated by radio emissions from jets stemming from SMBHs. AGN are the small, dense and luminous components of the centers of galaxies as represented in Figure 3 and Figure 4. The majority of their energy is thought to be derived from gravitational potential energy and SMBH spin as opposed to nuclear sources within stars.  It was in the late 1940s when the connection between cosmic radio waves and synchrotron emission was established. Synchrotron emission in AGN is due to the presence of magnetic fields. This Electrons moving at near relativistic speeds spiral around magnetic field lines. Synchrotron  emission is observable as polarized emission. Astrophysical objects emit intense radio waves through the synchrotron emission. It is widely held that radio sources in the Universe emit by the synchrotron process, especially process  at lower radio frequencies in the meter and centimeter wavelength range. (http://www.ugr.es/~battaner/escritos/granada_paper.pdf). range.\cite{Wielebinski_2006}  The radio  core of an AGN emits synchrotron radiation emitted through particle acceleration and collimation into a double lobed structure. These are typical traits of radio galaxies. AGN also have a pair of jets of material ejected from their core. The structure of a radio source is also determined by the interaction of its energetic jets with ionized gas which surround the host galaxy. (Krawczynski et al, 2013) \cite{Krawczynski_2013}  also observes observe  that the black holes in AGN accrete matter and convert the gravitational energy of the accreted matter (and possibly also the rotational energy of the black hole) into mechanical and electromagnetic energy. We also have that inside the accretion disk, a portion fraction  of the gravitational energy of the accreted material is converted to heat and electromagnetic radiation which is then radiated away by the accretion disk. The jets are formed from a portion of the material processed through the accretion disk which escapes the accretion system as collimated and uncollimated outflows. Jet plasma velocity can be denoted by v where v $v  = β_jet c ≈ \beta_{jet}*c \approx  c $  ,and c represents the speed of light. Γ_j The $\Gamma_{jet}$ , the  bulk Lorentz factor of the plasma is given by Γ_(jet ) = (1-〖β_jet〗^2 )^(-1/2) $ \Gamma_{jet} \eq (1 - (\Gamma_{jet})^2 )^{-1/2}  . Emissions from the jets can be red or blue-shifted as a result of the relativistic Doppler factor δ_jet= 1/(Γ_j $\delta_{jet} = \Frac{1}{\Gamma_{jet} \times  (1- β_jet⁡(cos⁡θ ))) \beta_{jet}\times\cos{\theta})}  Where θ being the angle between the jet axis and the line of sight as measured in the observer frame. (Krawczynski et al, 2013). The lobes as seen in figure 5 develop when the jets are stopped by pressure from the gas surrounding the host galaxy. The lobe structure is fairly symmetrical when viewed closer to the nucleus of the galaxy.