ALFA Ultra-Deep Survey

1
ALFA Ultra-Deep Survey
Strategy Very long integration time on small
patches of sky
Team leader Wolfram Freudling
Team Elias Brinks, Noah Brosch, Barbara
Catinella, Christopher Conselice, Jonathan
Davies, Erwin de Blok, Virginia Kilborn, Suzanne
Linder, Karen Masters, Martin Meyer, Robert
Minchin, Emmanuel Momjian, Karen O'Neil, Daniel
Pisano, Jessica Rosenberg, Kristine Spekkens,
Lister Staveley-Smith, Wim van Driel, Martin
Zwaan
2
Main Scientific Motivation Evolution of gas
content at z lt 0.15
Evolution of star-formation rate
Extrapolation from Ly-a absorbers
STORRIE-LOMBARDI WOLFE, 2000, ApJ 543, 552
PEI, FALL, HAUSER 1999, ApJ, 522, 604
3
More Scientific Goals
?The Cosmic Web ? Low column-density gas in
the local Universe ? Extragalactic OH Megamaser
Emission ? Extragalactic HI Absorption
4
Possible survey parameters

• Need to be sensitive to MHI109-10 M?
• 200 km/sec linewidth ? 0.2mJy at z0.16
• rms0.05 mJy/beam (260x deeper than HIPASS)
• 0.36 deg2 in 1000 hrs, or 70 hrs/beam
• Volume 8000 Mpc3
• 160 galaxies in range 109-10 M?

5
Precursor Proposal to test sensitivity
limitations on small region

• ___
• s??Tint for long integrations?
• RFI
• Baselines, standing waves
• Efficiency (time on source)

proposal 70 hours of repeated drift scans over
an area with known gas rich galaxies within
200Mhz bandpass