MIT ASTROPHYSICS COLLOQUIUM — Microarcsecond Astronomy: Reaching Toward The Schwarzschild Limit, And Other Matters Arising

Tuesday October 2, 2012 4:00 pm

Two fundamental questions have to be addressed if astronomical objects are to be studied with microarcsecond resolution. First, will there be anything to see; second, how are you going to do it. An aperture of 10^11-10^12 wavelengths is not easy to come by — 100 kilometers at optical wavelengths, or the earth-moon distance at centimeter wavelengths. The first question has an easy answer — studies of radio source scintillations caused by the interstellar medium give direct evidence that there are microarcsecond structures. The second question has an easy answer: the VLBI studies by the group led by Haystack's Shep Doeleman using millimeter wavelengths at an earth diameter have already demonstrated structures at the galactic center, close to the Schwarzschild limit. Most of my talk will focus on a new instrument that has lately come on line, the RADIOASTRON VLBI satellite. It was launched last summer, and underwent checkout during the past winter. The satellite is performing well, and a review in May 2012 by the Radioastron International Science Committee (RISC) led to the conclusion that an AO should be issued as soon as possible. Interesting resuls have already been obtained by observing pulsar scintillations at the maximum baseline of 200,000 km, and the various possible scientific programs that can be undertaken will be examined.

Event Contact

Debbie Meinbresse