LASER ACTION IN FAR-INFRARED ASTROPHYSICAL SOURCES

Employing new atomic data and a 15 level collisional-radiative model, it is shown that population inversion, and consequent laser action, ca n be achieved in far-infrared (FIR) lines [C II] 157 mum, [N III] 58 m um, [O IV] 26 mum, [Ne VI] 7.6 mum, and [Mg VIII] 3 mum. Coupling of t he lasing transition 2s(2)2p(2P3/2o-2P1/2o) to higher energy levels of the 2s2p2 configuration in boron-like ions provides the dominant pump ing flux. Lasing column lengths are found to be l almost-equal-to 10(- 4)-1.0 pcs, at T(e) almost-equal-to 10(4)-10(6) K, N(e) almost-equal-t o 10(4)-10(10) cm-3, conditions and sizes prevalent in broad-line regi ons of active-galactic nuclei and novae. Detectable emission fluxes ar e estimated. Lasing activity in the source could significantly affect abundance determinations. The FIR line emission should be readily obse rvable with the upcoming Infrared Space Observatory.