TCP SWG Notes 2014/12/11
(notes taken by PD)
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
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,
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
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