Extragalactic ALFA Survey Plans Arecibo Legacy Fast ALFA

Extragalactic ALFA Survey Plans • Arecibo Legacy Fast ALFA (ALFALFA) Team leader: Giovanelli (Cornell) • Arecibo Galaxy Environments Survey (AGES) Team leader: Davies (Cardiff) • ALFA Ultra-Deep Survey (AUDS). Team leader: Freudling (ESO) • Zone of Avoidance Survey (ZOA). Team leader: Henning (New Mexico)

Arecibo Galaxy Environments Survey • HI mass function in various environments • Spatial distribution of HI-selected galaxies • Identify individual low MHI and low NHI objects, cp. to QSO absorption line studies and simulations

MHI vs. cz for 12 s and 300 s (AGES) integration, 1000 hrs each and HIPASS mass fcn, = -1. 3

AGES • Exact survey regions tbd, but include: • Virgo, to MHI 6 x 106 M to compare HI of cluster galaxies with “field”, effects of cluster environment on galaxy evolution, search for low MHI galaxy companions, HI clouds. 300 sec integration 6 x 106 M (5 sigma and 30 km/s width)

AGES • A Local Void: search for HI associated with very LSB galaxies, or clouds • Virgo Southern extension: if galaxies fall into clusters along filaments, these should be in intermediate state between galaxies in field and cluster, eg. more dwarfs per giant in cluster, cluster dwarfs gas poor – opposite of field. When does transformation begin?

AGES • Groups and individual galaxies: observe number of isolated galaxies, groups, investigate link between dwarf companions and HVCs, and HI at large distances from center of galaxies. First target is NGC 2903, precursor study (Irwin, Queen’s)

AGES Observational Technique • Drift scanning, versus “leapfrog”, individual step-and-stare pointings near meridian interleaved to cover sky (AGES precursor proposal)

Arecibo Ultra-Deep Survey (AUDS) Strategy: Very long integration time on small patches of sky

Main Scientific Motivation: Evolution of gas from z < 0. 15 s r e b r ion t a l o p ra m o r α Ly so b a f t x E STORRIE-LOMBARDI & WOLFE, 2000, Ap. J 543, 552 m r o f r lu o Ev n o i t of a t s n o i at e t ra PEI, FALL, & HAUSER 1999, Ap. J, 522, 604

More science goals • The cosmic web • Low column density gas in the local Universe • Extragalactic OH megamaser emission • Extragalactic HI absorption

Possible survey parameters • • • Need to be sensitive to MHI~109 -10 M 200 km/sec linewidth 0. 2 m. Jy at z~0. 16 rms~0. 05 m. Jy/beam (260 x deeper than HIPASS) 0. 36 deg 2 in 1000 hrs, or 70 hrs/beam Volume = 8000 Mpc 3 160 galaxies in range 109 -10 M

Precursor Proposal to test sensitivity limitations on small region: • • __ σ 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 200 MHz bandpass

Zone of Avoidance (ZOA) • Obscuration due to dust and high stellar density in our Galaxy blocks ~20% of optical extragalactic universe, less in the IR • Need all-sky map of surrounding mass inhomogeneity to understand LG’s motion, dynamical evolution • HI surveys can map galaxies, large-scale structure in regions of bad obscuration and stellar confusion

New Part of Norma SC PKS 1343 cluster New Puppis void Puppis Hydra wall and Monoceros extension

• ZOA in the AO sky cuts some important (known) LSS: Pisces-Perseus SC; Local, Orion, Taurus, edge of Monoceros voids

ZOA with ALFA • Due to likely pressure on popular, low-b portions of AO sky, best bet is commensal observing • Option 1: GALFA ØSingle, or double-drift mapping of |b| < 5° ØUniform sky sensitivity ØNyquist sampling with double drift • Would look much like an E-ALFA survey, trace large-scale structure further north than Parkes with better positions.

ZOA with ALFA, cont. • Option 2: PALFA ØGalactic plane survey, |b| < 5°, all AO longitudes Ø 300 s beam-1 oodles of time ØStep and stare mode, tiling to cover sky at ½ power point • Enormously deep, but observing mode introduces complications from varying feedsky geometry • A concern: Need 2 spectrometers for any commensal observing. Timing?

ZOA data processing • If Drift, then based on AIPS++/HIPASS software • If Leapfrog, then traditional ON/OFF, with rather complicated indexing