Steffen and I just got back from our trip to New Haven, where we’ve been for the last three days. Going to Yale is always a bit like coming home. So many people to meet and greet, so much to catch up on. One reason why it feels so much like home is because you randomly meet people in the street. That clearly doesn’t happen in New York very often.
During our stay, Steffen not only met some of my closest friends in the US, but also gave the Yale Center for Astronomy & Astrophysics seminar on Tuesday, which was well received. Moreover, I was happy to sit down with Ana and discuss the final stage of our stream project. It’s soon done, I’m very excited! On Wednesday, Stream-Team member Adrian Price-Whelan came over from Columbia and gave a talk about his Sagittarius stream modeling at galaxy lunch. Adrian’s Rewinder method to infer the Galactic gravitational potential from the positions and velocities of just 8 (!) stars is getting more and more impressive. In his famously direct way, Frank van den Bosch asked the slightly condescending question of what would be so interesting about measuring the mass and shape of the Milky Way’s dark matter halo!? Since the halo-to-halo variations were huge, a sample of one wouldn’t tell us much, he argued. That was obviously the point-of-view of a cosmologist. He may have forgotten that there’s a whole field in astronomy which entirely focuses on our Milky Way, and that for this field of Galactic astronomy the mass of the Galaxy is in many cases very much relevant. But I see his point, just because the dark halo of the Milky Way may be spherical or triaxial doesn’t prove or disprove anything. Still, the Milky Way halo is the only one which we can see in “3D” since we’re sitting in the middle of it. Ignoring it would be ignorant.