quasars! exoplanets! dark matter at small scales!

CampHogg group meeting was impressive today, with spontaneous appearances by Andreu Font-Ribera (LBL), Heather Knutson (Caltech), and Lucianne Walkowicz (Adler). All three told us something about their research. Font-Ribera showed a two-dimensional quasar—absorption cross-correlation, which in principle contains a huge amount of information about both large-scale structure and the illumination of the IGM. He seems to find that IGM illumination is simple or that the data are consistent with a direct relationship between IGM absorption and density.

Knutson showed us results from a study to see if stars hosting hot Jupiters on highly inclined (relative to the stellar rotation) orbits are different in their binary properties from those hosting hot Jupiters on co-planar orbits. The answer seems to be "no", although it does look like there is some difference between stars that host hot Jupiters and stars that don't. This all has implications for planet migration; it tends to push towards disk migration having a larger role.

We interviewed Walkowicz about the variability of the Sun (my loyal reader will recall that we loved her paper on the subject). She made a very interesting point for future study: The "plage" areas on the Sun (which are brighter than average) might be just as important as the sunspots (which are darker than average) in causing time variability. Also, the plage areas are very different from the sunspots in their emissivity properties, so they might really require a new kind of model. Time to call the applied mathematics team!

In the afternoon, Alyson Brooks (Rutgers) gave the astro seminar, on the various issues with CDM on small scales. Things sure have evolved since I was working in this area: She showed that the dynamical influence of baryonic physics (collapse, outflows, and so on) are either definitely or conceivably able to create the issues we see with galaxy density profiles at small scales, the numbers of visible satellites, the density distribution of satellites, and the sizes of disk-galaxy bulges. On the latter it still seems like there is a problem, but on the face of it, there is not really any strong reason to be unhappy with CDM. As my loyal reader knows, this makes me unhappy! How can CDM be the correct theory at all scales? All that said, Brooks herself is hopeful that precise tests of CDM at galaxy scales will reveal new physics and she is doing some of that work now. She also gave great shout-outs to Adi Zolotov.

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