Large-scale microturbulence and BLR emission lines

Large-scale microturbulence within broad line region (BLR) clouds of active galactic nuclei (AGN) has a significant effect on the smoothness and intensity of BLR emission lines, Line widths of individual clouds become much wider than their thermal widths and thus collectively produce broad, smooth emission line profiles. Turbulence also affects line transfer. In general the line spectrum grows stronger as turbulence increases, This occurs because lines more easily escape due to diminished optical depth. Permitted lines are selectively strengthened from pumping by the continuum. Large-scale microturbulence produces shock heating unless turbulent motions are non-dissipative, Non-dissipative turbulence is possible if they are manifest as MHD waves in energy equipartition with the magnetic field. A fractal BLR structure may result as a natural consequence, producing a distribution of BLR clouds in density and position, thereby having indirect impact upon the emission from AGN, Dissipation of turbulence within a BLR cloud into heat may also affect the emission line spectra of AGN.