2021ApJ...914...64T

Transients powered by interaction with the circumstellar medium (CSM) are often observed in wavelengths other than the optical, and multiwavelength modeling can be important when inferring the properties of the explosion and CSM, or for distinguishing from other powering mechanisms. We develop a model calculating the time-dependent emission spectrum of interaction-powered transients. We solve the energy equations of electron-proton plasma in the shocked supernova ejecta and CSM and the radiation transfer equation out to the outer edge of the CSM, incorporating collisional relaxation and the Comptonization of bremsstrahlung radiation. We compare our model to observations of Type IIn supernovae covering a frequency range from the optical to X-rays. For SN 2010jl the observed optical and X-ray light curves can be consistently explained if a clumpy or asymmetric structure in the CSM is assumed, in agreement with previous studies. For SN 2014C our model successfully reproduces the X-ray bremsstrahlung component and the emergence of Hα emission at 400 days after explosion. Finally we find a parameter space where the supernova is extremely X-ray bright, reaching 10⁴³-10⁴⁴ erg s^–1, for up to 100 days. Such X-ray transients are likely to be detectable with all-sky surveys by, e.g., eROSITA.