A Study of the Evolutionary State of the Supernova Remnant G299.2-2.9

Using archival data from the Einstein Slew Survey (ESS) and the Infrared Astronomical Satellite (IRA S), as well as results from the ROSAT All-Sky Survey (Busser et al.), we present an investigation of the newly discovered supernova remnant (SNR) G299.2 -2.9. The object appears morphologically similar in the IR and X-ray bands, with a partially complete shell that is brightest in the northeast. The radio morphology is also similar, although a bright region in the western portion of the remnant is also evident. Results reported from the ROSAT Position Sensitive Proportional Counter (PSPC) observation include a low value for the line-of-sight interstellar column density, suggestive of a nearby remnant (distance ∼0.5 kpc), leading Busser et al. to conclude G299.2 -2.9 is a young remnant that has not yet entered the adiabatic stage of evolution. We investigate the properties expected from such a scenario and find that the results imply an extremely underluminous SNR. As an alternative, we consider an interpretation whereby the SNR is at a larger distance and in the Sedov phase of evolution. Using a model for a nonradiative shock propagating through a dusty interstellar medium, we show that a self-consistent model can reproduce the X-ray and IR fluxes. We discuss the plausibility of each of these models and propose observational tests to differentiate between the two scenarios.