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Comparing Galaxies and QSO Absorption Lines
Martin Zwaan (ESO)


At z=0, galaxies are DLAs seen in emission
· Local galaxies can account for low z DLA incidence rate · ... and explain DLA metallicities · ... and other properties: impact parameters, luminosities

zero evolution

Zwaan et al 2005


The shape of f(N) does not evolve
· What is this telling us? · Laws of star formation similar at all redshifts?

local galaxies DLAs at z=2.2 5


Number of HI atoms does not evolve much
· DLAs are a "phase" not a "reservoir"

· Where is the missing gas?


Kinematics of DLAs different from local galaxies
· Interactions, winds and outflows increasingly important at higher z

DLAs at z~3

galaxies at z=0 (THINGS)

Zwaan et al 2008

velocity width


The future...
Measure
HI

in emission at z>0 AUDS, and... SKA pathfinders
HI

· HIPASS/ALFALFA at z=0.2-0.5 · Why do we still want to know Find the `missing gas' · ALMA surveys Understand DLAs · Map individual DLAs · SF in DLAs molecules

?

need SKA

CII emission with ALMA

Map sub-DLAs/Lyman Limit Systems in 21-cm emission · Deep surveys AUDS, SKA...


Arecibo Ultra-Deep Survey (AUDS)

(Freudling et al)

· Deepest blind HI survey: 50 Jy rms, 1000 hours are allocated · 0.36 degree2 out to z=0.16 · Two fields in SDSS regions, no bright 20-cm sources · Precursor observations: · 53 hours of `drift-and chase' resulted in 14 detections between z=0.07 and z=0.15 · Detections confirmed with WSRT