Jim Geach on behalf of the S2CLS consortium

The SCUBA-2 Cosmology Legacy Survey

What is the SCUBA-2 Cosmology Legacy Survey?Largest of the JCMT Legacy Surveys: 65% of all SCUBA-2 time to be spent on JLS, over half this is spent on CLS

CLS (high redshift) 1778 hours 50.9%

GBS (local star formation) 412 hours 11.8%

SASSy (‘all/ambitious’ sky survey) 480 hours 13.8%

NGLS (nearby galaxies) 100 hours 2.9%

JPS (Galactic plane) 450 hours 12.9%

SONS (stars) 270 hours 7.7%

3490 hours 291 nights

What is the SCUBA-2 Cosmology Legacy Survey?

Simple two tier strategy covering well-known fields:

• Wide survey at 850um in grade 2-3 conditions • Target area 10 deg2 (probably get 50% of this)• Uniform coverage to 1sigma=1.2mJy. • PONG mapping. ~80% complete

• Deep survey at 450um + 850um in grade 1 conditions• Target area 0.25 deg2 • Uniform coverage 1sigma=1.2mJy @ 450um,

confusion limited at 850um. • DAISY mapping. ~50% complete

Science drivers• Comprehensive survey of SMGs detected at 850um

(N~104) over several ~degree scale fields

‣ measure clustering / halo properties‣ constrain bright-end counts‣ reliably probe properties of fainter SMGs (3-5mJy)‣ AGN/starburst connection, transition objects‣ ‘very’ high-z science (IR luminosity density at z>5, rare

objects)‣ cross-correlation studies

• ‘Keyhole’ confusion limited survey at 450+850um

‣ properties of 450um-selected SMGs below HSO confusion limit‣ resolving CIB at 450um (closer to peak)‣ probing very faint end of counts (P(D) analyses)‣ joint stellar/dust/gas morphologies (CANDELS overlap, ALMA)

Targets

‣ COSMOS (2 deg)‣ UKIDSS-UDS/SXDF (1 deg)‣ GOODS-N‣ Extended Groth Strip / AEGIS

‣ Akari-NEP‣ Lockman Hole Owen‣ SSA22

Including deep CANDELS

Other wide fields

EGSUDS

Lockman Hole

SSA22

Akari-NEP

COSMOS

1 degree

Average cost of an SMG: £400*

Legacy value: priceless

*don’t quote me on this

S2CLS is a ‘factory’ for detecting dusty starbursts at z>1

Excellent ancillary data (e.g. CANDELS) probing stellar emission, redshifts, morphologies

ALMA offers HST-matched resolution: directly compare dust and gas to stellar emission on sub-galactic scales

Pinpoint counterparts with ~few asec accuracy

Cumulative area

~3 deg2 at rms<2mJy… improvement over SHADES by order of magnitude

Why are we doing this?

Dole+06

Dole+06

Why are we doing this?

ULIRG

LIRG

JEG+Papadopoulos 12

Negative k-correction at 850um provides uniform luminosity selection at fixed flux limit out to z~10! Huge volume column.

At z>2, bulk of IR luminosity density is emitted by ULIRGs: epoch of formation of most massive galaxies today

Why are we doing this?Observed 850um flux density

Bethermin+11

Early science highlights and prospects

Cycle 1 ALMA follow-up of CLS sources at sub-arcsec resolution

First measurement of 450um number counts

JEG+ 2013

Directly resolve ~15% of CIB @ 450um

Recover ~50% with MIPS stack

Herschel

SCUBA-2

JEG+ 2013

Average sub-mm flux of Lyman Break GalaxiesCoppin, JEG+ 2014 arXiv:1407.6712

Stacked LBGs in SXDF at z=3, 4, 5 (850um)

Typical S850 ~ 0.2 - 1 mJy

Cross-correlating galaxies with CLS

Smith, JEG+ 2014 in prep

SCUBA-2 SAURON/FORS

Rare objects: Lyman-alpha BlobsJEG+ 2014

Next steps…

Clear need to complete COSMOS field – tremendous legacy value in this field (including HSC UD). Would require at least another winter (probably two) to reach full CLS depth.

Complete the deep 450+850 mapping of CANDELS fields – progress has been severely hampered by poor weather. Complement to HSC UD.

Obvious continuation of CLS would be wider area –mapping of all HSC deep fields to ~30 deg2? Time investment would be ~1000s hours for useful depths.