SPECTRAL SIGNATURES OF FAST SHOCKS .1. LOW-DENSITY MODEL GRID

A high-velocity radiative shock provides an efficient means to generat e a strong local UV photon held. The optical emission from the shock a nd precursor region is then dominated by the photoionized gas, rather than by the cooling region, and the total optical and UV emission scal es as the mechanical energy flux through the shock. In addition, for r easonable values of the magnetic held, such shocks become supported by magnetic pressure in the photoionization/recombination zone of the sh ock. The effect of the limited compression factor has a profound influ ence on the output spectrum. Models without precursors apply to unreso lved shocks in gas-poor environments or to fast shocks in individually resolved filaments of supernova remnants. Models with precursors shou ld be applicable to unresolved structures in gas-rich environments. In this paper, we present extensive tabular results designed to be of ma ximum utility to observationalists for a grid of low-density steady-fl ow models covering the shock velocity range 150 less than or equal to V-s less than or equal to 500 km s(-1), and magnetic parameter O less than or equal to B/n(1/2) less than or equal to 4 mu G cm(-3/2). In th e next paper of this series, we will apply these models to diagnostic plots for narrow-line regions of active galactic nuclei.