KIPAC@10, day 2

Today was the second day (I missed the first) of the KIPAC@10 meeting at KIPAC at SLAC. There was a whirlwind of talks on compact objects and galaxy evolution, too many to summarize, but some highlights for me were the following:

Steiner (UW) showed neutron-star mass and radius measurements and discussed their implications for the properties of matter at extreme density. He showed some very noisy likelihood functions (ish) in mass–radius space, one per measured neutron star (and there are 8-ish with measurements) and tried to draw a curve through them. I have opinions about how to do that and he seems to be doing it right; each time we tried to discuss this over coffee something interrupted us.

Perna (Colorado) talked about magnetars; I hadn't appreciated how extremely short-lived these stars must be; their lifetimes are measured in kyr, which is not a unit you see every day. Romani (Stanford) made a pitch that Fermi-discovered gamma-ray pulsars are the bees knees. He didn't show folded light-curves but apparently there are now hundreds where you can see the periodicity in the (sparse) Fermi data. Tomsick (Berkeley) showed some outrageously awesome NuSTAR data, making me want to hear much more about that mission. It's PI is my old friend from graduate school, Fiona Harrison (Caltech), to drop a name.

Cordes (Cornell) talked about pulsar timing and gravitational radiation, a subject on which I have opinions (from a precision measurement perspective). He, like is common in that business, concentrated on the stochastic gravitational wave background; I would like to hear or think more about coherent source detection. It is usually easier! Along those lines, at one point Blandford (KIPAC) asked Aarons (Berkeley) if physical models of pulsar emission were likely to help in measurements of pulsar timing. Aarons didn't commit either way, but I think the answer has to be yes. Indeed, I have suggested previously that modeling the emission almost has to improve the measurements.

Stark (Arizona) showed very nice new data on galaxies at extremely high redshifts. He noted that almost every result at redshifts beyond six depends entirely on photometric redshifts. That's true, but is it a concern? I guess it is because there could be interloping lower-redshift objects (or stars) having a big effect on the conclusions. Kriek (Berkeley) and Lu (KIPAC), in separate talks, showed that it is difficult to explain the evolution of galaxies in sizes and stellar populations with simple models of star formation and merging. Also, Kriek called into question the star-formation-rate estimates people have been using, which is interesting; she finds a factor-of-two-ish range in the mistakes that could be being made, and this is the same order of magnitude as the amplitude of the variation in specific star-formation rate with galaxy mass. She didn't claim that there is an error there.

In the discussions at lunch, Stuart Lynn (Adler) pitched an idea from David Harris (NAS) that we start a journal of short contributions. Marshall was all over that; it might get launched tomorrow in the unconference session.