TCP SWG Notes 2014/12/11

(notes taken by PD)


Paul Demorest, Geoff Bower, Steve Myers, Frazer Owen, Sophie Mason, Michael Rupen, Laura Chomiuk, Sarah Burke-Spoloar, Jim Braatz, Brian Metzger


Geoff: Main task is prepare for Jan 4th workshop, see schedule from SOC. We have 1h20m total time as of now. We should come up with one more speaker.

Laura: do we still need 3 "killer" topics? Geoff: probably does not need to be a tight constraint. Some broad topics: GC pulsars; plasma physics (including solar, galaxy clusters, exoplanets, pulsar emission, etc); cosmology.

Laura: suggests Adam Riess speak to put megamaser work into overall context of distance ladder, etc. Big uncertainty in calibrating cepheids, more geometrical distances would help reduce systematics.

Jim: In favor of Riess as speaker. some problems: more measurements than NGC 4258 exist now; however next closest source is 50 Mpc, too far for cepheids. Geoff: what about with next-gen optical telescopes? Jim: megamaser goal is to bypass cepheids completely, directly measure H0, this is complementary to distance ladder approach. 4258 measurement is systematic-limited, not clear NGVLA would help. (..some discussion about details of cosmology params..)

Additional maser discussion: Steve: Is the main NGVLA capability VLB/astrometry? or surveying? Jim: Both. Michael: what about kilo-masers? Jim: some uncertainty about luminosity function, very bright close sources would have been found already. 10s of new sources could be measured between ~50-150 Mpc with NGVLA. Frazer: NGVLA is not a VLB array, much different telescope concept.

Frazer: Suggests variability or plasma physics as a 2nd focus topic rather than megamasers (maybe Hu Li or Kulkarni as speaker). Or for an astrometry focus, maybe Mark Reid. Geoff: WGs are structured by science/astrophys not observing technique. Steve/Frazer: that doesn't matter too much at this point.

Geoff: Hesitant to ask Adam Riess now because it's so late.

(?? several people talking): maybe Jeremy Darling, some desire for an "outside the group" speaker.

Geoff: will check with Mark Reid first, then Jeremy Darling.

Frazer/Michael: don't forget time-domain stuff. Geoff: Transients, variability can be included in WG report.

(more back and forth on possible speakers, extra suggestions: Tom Maccarone, Zeljko I., ?)

Geoff: For WG report, will make an outline then solicit slides from people in the group. will distribute before holidays for comments.

Geoff: Time for discussion of plasma, solar/stellar?

Sophie: for solar, high-freq imaging, more resolution needed? higher freqs probe closer to sun. Geoff: are long baselines interesting? Sophie: not clear. higher time resolution is better, instantaneous freq coverage useful as well. Getting coverage for long periods of time may be a problem. Michael: triggered observations could happen. Frazer: Solar observations help connect theory to other plasma observations.

Michael: nearby solar stars (painfully) detected with VLA; could be better with NGVLA. worth checking numbers for imaging, including increase in BW.

Geoff: SOC has asked whether 100 GHz is necessary. Can we detect nearby thermal emission from stars?

Avery: Discussion of Faraday rotation, general consensus is that this is too high freq for most sources, except maybe "exotic" stuff (galactic nuclei).

Frazer: unknown what source spectra up to 100 GHz is. High surface brightness sensitivity is needed (dense core of array). Some local discussion of whether antennas can/should be movable.

Attending AAS: Laura, Paul, Steve, Michael, Geoff (+ maybe others not on call)
Topic revision: r1 - 2015-01-02, PaulDemorest
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