September 24: After a late-ish breakfast with my gracious host, Jason, I risked life and limb by cycling on a borrowed bike along Cambridge Street to Harvard. It always makes me more than a bit nervous to cycle along a busy road when there’s no bike lane and people keep wanting to pass me… Anyway, I made it in around 10:30 am or thereabouts.
Rosanne Di Stefano was in her office when I arrived. I did a summer research project on gravitational microlensing with Rosanne when I was an undergrad, now about 15 years ago (16, really, when we started it); the research resulted in these two papers. Amusingly enough, the other project she offered me at the time, of which I didn’t see the appeal at the time, was on super-soft X-ray sources (SSSs) — generally believed to be accreting white dwarfs, one of the more popular models for (single-degenerate) SN Ia progenitors. This is what we spent much of today talking about.
Rosanne introduced me to her new Ph.D. student, Max, who will be working on SN Ia progenitors from a binary population synthesis (BPS) point of view. The goal is to bring the BPS models into better alignment with observations by basing as many of the inputs to the evolution code as possible on observed quantities. We talked for some time about weird SNe Ia found way outside any plausible host galaxy (see here and here for two recent examples). Rosanne was really curious about what the fact of finding these supernovae way out there might tell us about the progenitor or the delay time to explosion; I don’t think anyone else in the community has really processed that yet, but they’re definitely unusual.