SNIAPROG · A Close Look at Type Ia Supernova Progenitors

A close look at type Ia supernova progenitors

The project was terminated after only five months due to the researcher (Dr Carlos Badenes) being offered a permanent position as professor at the University of Pittsburgh in the USA. Despite the premature termination of the project, a large fraction of the initial project goals were achieved with the support of the IRG grant. The main objective of the grant was to advance our knowledge of Type Ia Supernova progenitors through investigations of two very different kinds of objects - binary white dwarfs (WDs) and supernova remnants (SNRs) - that can be studied in great detail due to their proximity. In the five months that the IRG project was active, the following advancements were accomplished: An observing trip to Kitt Peak National Observatory (KPNO) in Tucson, Arizona was funded from the IRG grant (April 2011). In this trip, valuable data were collected for the SWARMS project (a survey to identify short-period WD binaries, see the grant proposal for details) using the 4m telescope at KPNO. Despite bad weather, two interesting binary WD systems were confirmed, and their periods determined. These binary WDs are of special interest for Type Ia SN progenitors in the double degenerate scenario, because their primary components are relatively massive, which is not the case for most of the systems discovered in the recent past. The KPNO data are currently being reduced and prepared for publication. The project to measure the WD merger rate in the Milky Way using the time-resolved spectra from the Sloan Digital Sky Survey has been completed, and the results are ready for submission. We have found that this rate is very close to the measured rate of Type Ia SNe in Sbc spiral galaxies, of which the Milky Way is a prototype. This is a key measurement in stellar astrophysics, and the main deliverable from the IRG grant. The merger rate has already been presented at three international conferences (Sydney, June 2011; Newport Rhode Island, September 2011; and Oxford, September 2011), and has been very well received by the community. The paper that describes our results is in the last stages of completion, and will be submitted to the Astrophysical Journal in the following weeks. A visit from Antonela Monachesi from the University of Michigan was funded from the grant. Dr Monachesi's unique expertise in resolved stellar populations helped us to jump start the project to measure the SN rate and delayed time distribution in the nearby galaxy M33, which was one of the key objectives of the IRG proposal. During Dr Monachesi's visit to Tel-Aviv in August of 2011, we were able to define suitable regions within M33 to assemble the necessary star formation history map, using public data from the Hubble Space Telescope and Phil Massey's Nearby Galaxy Survey, as well as the published catalogue of M33 SNRs by Long et al. The high quality SN delay time distributions obtained from resolved stellar populations in this project will shed light on the nature of SN Ia progenitors, especially at short delay times, where current measurements are more uncertain. An active collaboration has been established with Dr Daniel Patnaude from the Harvard-Smithsonian Center for Astrophysics, with the goal of building hydrodynamic and spectral models for the Kepler SNR. As described in the grant proposal, the unique properties of Kepler, which shows clear signs of a strong interaction with some kind of circumstellar material, make it is especially interesting for Type Ia SN progenitor studies. We have found that the morphology and X-ray spectra of the Kepler SNR cannot be explained by the standard scenario that involves a slow wind from the single degenerate binary progenitor.

Data: CORDIS, © European Union