Radiative Cooling of Non-equilibrium Ionization Plasmas Based on AtomDB

The detail ionization state is difficult to know from observations, collisional ionization equillibrium (CIE) or simple parameterized ionizing assumption are usually applied in modeling. But such assumption doesn’t work in some respects, e.g. for studying the overionized plasma which is recently confirmed in supernova remnants. We performed this work to study the different radiative cooling rates in CIE and non-equillibrium ionization (NEI) cases in detail, which is crucial in modeling the evolution of plasma in realistic cases. This work is based on the most developed atomic database, AtomDB v2.0.2 (see Foster et al. 2012, ApJ, 756, 128), and applied the companied APEC program for calculations. We focus on the hot optically thin gas, such as the diffuse interstellar medium. We present our primary results of CIE plasma in a density range of 1e-5 cm^-3 to 1e10 cm^-3 and a temperature range of 1e4 K to 1e8 K, and for NEI plasma, both ionizing and recombining cases, in the same density and temperature ranges, with the initial ionization temperatures from 1e4 K to 1e8 and the ionization timescales from 1e0 to 1e13 cm^-3*s. There are 30 elements included in the calculation, from hydrogen to zinc. Detailed comparison between CIE and NEI plasma are shown. Further implication from such comparison are discussed.