Large-scale structure at high z: the SHADES survey

Large-scale structure at high z:the SHADES survey Eelco van Kampen, University of Edinburgh with Jim Dunlop, John Peacock, Will Percival, Chris Rimes, Susie Scott

Semi-numerical models of galaxy formation and evolution Ingredients: • Cosmological model • Halo formation and merger history • Gas dynamics and radiative cooling • Star formation and feedback • Stellar population synthesis Robust ? Unique ? CDM model of van Kampen, Rimes & Peacock (2002)

The Edinburgh model Differences with previously published models: • halo merger history from a special N-body technique • inclusion of two bursting star formation modes • realistic disk model with heuristic star formation law Semi-numerical model: retains substructure using a special N-body techique Semi-analytical models: erasure of all substructure van Kampen (2000)

Galaxy and halo merger trees An example of a simple halo/galaxy merger sequence

What are we trying to do ? • Understanding all ingredients for a model of galaxy formation and evolution • Assessing the robustness and uniqueness of such a model • Applying the model to solve specific problems: • galaxy occupation number • the abundance of dwarf satellites • structures of galaxies • interpreting high-redshift galaxy data

Model uniqueness Mostly quiescent star formation, z=3 Mostly bursting star formation, z=3 Bursting and quiescent star formation, z=3 z=0 z=0 z=0

SHADES A very large sub-mm survey (half a square degree) at 0.85 mm, complete to a flux limit of 8 mJy SCUBA time was granted a few months ago: 240 useable shifts, which means 1/3 of the JCMT for 3 years – consortium commited to staffing 420 nights on the JCMT from Oct 2002 P.I. Jim Dunlop (Edinburgh)

SCUBA sources: where, what, when ? • high surface density of submm sources: 700 deg-2 for  5mJy • co-moving number density ~10-5 Mpc-3 • significant (luminosity) evolution • 25-30% of the sub-mm background has been resolved into sources  2mJy • epoch of dust-enshrouded star formation and/or AGN-activity ‘at high redshifts’ • bright sub-mm sources progenitors of ERO’s (z~1) and local massive ellipticals (z~0) ? Scott et al. (2002)

SHADES: 0.5 sq. degrees, ~300 sources needs 1/3 of JCMT over next 3 years

Redshift information Combining SCUBA 850-micron data with the BLAST balloon experiment data at 250, 350 and 450 microns

SCUBA galaxies 8 mJy Star formation rate as a function of redshift for a single galaxy

>8 mJy sources for 1.5 < z < 2.5

>8 mJy sources for all z

>2 mJy sources for all z

Simulated SCUBA/BLAST survey Simulation of the SCUBA map and BLAST redshift distribution

Model predictions compared clustering strength: w(θ)=(θ/A)-δ redshift distribution

Question time !

A range of models • simple merger model (Will Percival, Edinburgh) • Sussex model (Oliver et al.) • Padova model (Granato et al.) • INAOE model (Gaztañaga et al.) • semi-analytical model (Durham) • semi-numerical model (Edinburgh)

Understanding all ingredients for a galaxy formation model • halo merger histories from N-body simulations: • overmerging due to small particle numbers • undermerging due to poor numerical resolution in haloes • environmental effects on galaxy properties: • ram-pressure stripping of gas disks in galaxy clusters • star bursts driven by interactions and mergers

Large-scale structure at high z: the SHADES survey