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10 January 2006 AAS EVLA Town Hall Meeting 1
The EVLA: A North American Partnership
The EVLA Project on the Webhttp://www.aoc.nrao.edu/evla/
N ational R esearch C ounci lC anada
C onsei l national de recherchesC anada
New Science Impactof the EVLA Supercomputing Correlator
P. Dewdney Herzberg Institute of AstrophysicsNational Research Council Canada
M. P. Rupen National Radio Astronomy Observatory
N ational R esearch C ounci lC anada
C onsei l national de recherchesC anada
Key EVLA Processing Capabilities
Deep ImagingPolarization
8 GHz Bandwidth (dual polarization). Full polarization processing. Wide-field imaging.
Narrow spectral linesWideband searches
16,000 channels at max. bandwidth (BW). >105 channels at narrow BWs. Spectral resolution to match any linewidth. Spectral polarization (Zeeman Splitting).
8 tunable 2 GHz wide bands. Each band - 16 tunable sub-bands. Sub-band – independent spectral resolution. Simultaneous line and continuum.
Flexibility Many resources
High time resolution 1000 pulsar “phase bins”. “Single-dish” data output to user
instruments. Very fast time sampling (20 s).
Star-Forming Galaxies at High Redshift
• Enabled by enhanced sensitivity of EVLA.
• Complementary to ALMA & Spitzer.
• K-correction compensates for z-losses in the 45 GHz band.
• Resolution 50 mas. (200 pc @ z=10).
• Imaging: 1 arcsec over 30 arcmin @ 1.5 GHz.
• EVLA/ALMA gives complete galaxy SED’s:– 3 orders of magnitude
of frequency,– Large range of redshift.
Arp220 SED scaled to high redshifts.
NGC 3690 (optical)
Spitzer
non-thermal/AGN
ionized gas
dust
CO Surveys of High-z Star-Forming Galaxies
ARP 220 (optical)
• EVLA sensitivity (red line) in 8 hrs (1 ).
• Detects (J=1-0, 2-1, 3-2, 4-3).
• More transitions at high z.• Precise redshift not
necessary in advance.• Spectral resolution will
match channel to line-width.
• Other lines: HCN, HCO+…
COJ=3-2
Z = 6.42
Peak ~ 0.6 mJy
This is a struggle!
N ational R esearch C ounci lC anada
C onsei l national de recherchesC anada
Setup for CO Z-Search
• 40-50 GHz band provides lowest redshift.
• z = 1.4 to 1.9 for J=1-0.
• z = 3.8 to 4.8 for J=2-1.
• v ~ 5.0 km s-1 (1 MHz).
• 200 km-s-1 galaxy would occupy ~40 channels.
• Interferometry• High resolution imaging.• Good spectral baselines. 2 , 1 , 0 .5 , ... G H z O bs e rv ing B andw id ths
16 S ub -B ands (s how n w ith de fau lt pos itions and w id ths )
1 2 3 4 ... 15 16
R ight P o la r iza tion L e f t P o la r iza tion
48-50 G Hz48-50 G Hz
46-48 G Hz 46-48 G Hz
44-46 G Hz44-46 G Hz
42-44 G Hz 42-44 G Hz
2-41-2 4-8 8-12 12-18 18-27 27-40 40-50L S C X U K Ka Q
G Hz
S k y F re q u e n c y B a n d s
8 tu n ab le IF B an d s
Note: S ub-bands can beseam lessly jo ined acrosseach observing bandwidth.
• ~30 H+ radio recomb. lines in one observation. • “Stack” lines to improve sensitivity.• H+, He+, C+ recomb. lines.
• EVLA resolution provides images of:
gas density, temperature, metallicity, B-fields (Zeeman).
• Sensitivity (12 hr, 5): Sline ~ 0.1 mJy (stacked, integral) B ~ 150 Gauss.
• Orion, W3, Gal. Center …
Magnetic Fields in Star-Forming Regions
2-41-2 4-8 8-12 12-18 18-27 27-40 40-50L S C X U K K a Q
GH z
S k y F re q u e n c y B a n d s
R ig h t P o l'n Lef t P o l'n
8 M H z
25 km/s
H II
H eIIC II
(8 0 0 k m /s )
1 0 2 4 chan 's.R ec irc . fac to r = 1 6 v = 0 .8 k m /s
C o ntinuum S e tup C o ntinuum S e tup
N ational R esearch C ounci lC anada
C onsei l national de recherchesC anada
Hundreds of Spectral Lines• Kaifu, et al., TMC-1, 2004.• Nobeyama spectral scan.• 414 lines (8 to 50 GHz)• 38 species.• Some likely to show
Zeeman splitting.• “D-array” EVLA
– Resolution,– Spectral baseline stability,– Imaging.
• EVLA can observe 8 GHz at one time – an average of 80 lines --- at 10 km/s velocity res’n (30 GHz)
• EVLA Correlator can “target” many (~60) lines at once.
2-41-2 4-8 8-12 12-18 18-27 27-40 40-50L S C X U K Ka Q
G Hz
S k y F re q u e n c y B a n d s
TA*
8 GHz