Beyond the IGPS

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Beyond the IGPS - Future Radio Surveys of the
Galactic Plane
John M. Dickey University of Minnesota
URSI General Assembly Maastricht, August 20,
2002 session J3 1844
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Outline Mosaic Surveys of the Galactic Plane

• astrophysics motivation
• survey sensitivity
• flux limited vs.
• brightness limited
• R the mapping speed
• R vs. wavelength
• one quick example

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The Cycle of Galactic Evolution
SN explosions
winds
nucleosynthesis
Star formation
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Cm-wave continuum traces both ends.
non-thermal continuum and X-rays
SN explosions
winds
nucleosynthesis
thermal continuum and infrared
Star formation
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Milky Way centimeter-wave continuum
non-thermal (synchrotron)
thermal (bremstrahlung)
log( flux )
log( brightness Temp )
log ( n )
log ( n )
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l21-cm Galactic Plane Surveys trace...
SN explosions
winds
Turbulence
HI emission mapping
nucleosynthesis
HI absorption
Star formation
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SIRTF Legacy Project
GLIMPSE
Galactic Legacy Infrared Mid-Plane Survey Extraord
inaire
P.I. Ed Churchwell, University of Wisconsin
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qs (arc sec)
Time to survey 500 s.d. (days)
qs (arc min)
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qs (arc sec)
Time to survey 500 s.d. (days)
qs (arc min)
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VLA resolution vs. wavelength
l (cm)
Constant velocity resolution
qs (arc sec)
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VLA resolution vs. wavelength
l (cm)
qs (arc sec)
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VLA resolution vs. wavelength
l (cm)
NH3
qs (arc sec)
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ATCA resolution vs. wavelength
l (cm)
qs (arc sec)
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ATCA resolution vs. wavelength
l (cm)
qs (arc sec)
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• Conclusions Spectral Line Surveys
• 21-cm surveys are relatively easy. Existing
• telescopes (ATCAVLA) are able to do
• surveys to q 45.
• The VLA E array would make it possible
• to do surveys of NH3 and other molecular
• lines over wide areas of the Milky Way.
• The SKA will make it possible to survey
• HI to 5 to 10, NH3 to tenths of arc
  seconds,
• given a 10 km core with f 0.25.

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• Conclusions Continuum Surveys
• Surveys of Stokes I continuum are
• relatively easy at 21-cm, possible
• down to 3.5 cm or maybe 2 cm.
• Surveys of linear polarization
• and Faraday rotation need similar
• sensitivity to spectral line surveys.
• Galactic plane surveys at cm-waves
• are useful for comparison with both
• X-ray and infra-red surveys.

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• We need a better way to do this.
• VLA mapping speed is limited by overhead,
• mostly due to telescope control software.
• Data calibration and mapping is complicated
• by the huge numbers of pointing centers.
• Isnt there a better way to do a
• mosaic of 105 primary beam areas ?

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high contrast
low contrast
SGPS mosaic of the 21-cm continuum emission in
the fourth Galactic quadrant.
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Download a copy of this talk from ftp//ftp.astro
.umn.edu/pub/users/john/ursi.ppt
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Visit the SGPS at http//www.astro.umn.edu/naomi
/sgps.html