Mapping the U.S. Scientific Future in VLBI. VLBI Future Committee:
VLBI Future Committee:
Shep Doeleman (Haystack Obs.) Dave Hough (Trinity College) Shri Kulkarni (Caltech) Colin Lonsdale (Haystack Obs.) co-chair Alan Marscher (Boston Univ.) Chris O'Dea (STScI) Greg Taylor (NRAO) co-chair David Wilner (Harvard-Smithsonian CfA) Joan Wrobel (NRAO)
Dedicated in 1993
Peck & Taylor (2001)
Spectral index map from 1.3/5 GHz VLBI observations
free-free optical depth:
tff ~ T-3/2 ne2n-2 d
Ne ~ 3 x 1022 cm-2
ionization ~ 10%
resolution at 5 GHz: 10” 1” 0.1” 0.01” 0.001”
1 10 20 days
VLA Light Curves (Berger et al 2003, submitted)
4th Epoch – May 19
Beam is 0.67 x 0.24 mas
Jet component at 0.28 +/- 0.05 mas
Not consistent with standard model
prediction of 0.12 mas expansion
average expansion velocity of 19c
HI absorption in 1946+708Peck & Taylor (2001)“Global” VLBIobservationscore:t ~ 0.2FWHM = 350 km/sNH = 3 x 1023 cm-2for Tspin = 8000 KM ~ 108 Msun
100 --- 10000 AU
100s of AU
A few stellar radii
Masers around an evolved
6. Is lack of funding (e.g. graduate student support) a significant impediment to including VLBI observations in your own research program?
7. In general, if you wanted to get VLBI data and results, would you make VLBI observations yourself, or would you pursue a collaboration? Why?
8. What is your perception of the accessibility of the VLBI technique?
9. Based on your view of the future of your field, and the new instruments and capabilities expected in coming years, do you see potential synergies developing with VLBI where none exist today?
10. Please share any additional insights you may have on the state and future of VLBI in the U.S.