der Paul van der Werf Sterrewacht Leiden Legacy surveys with SCUBA2 - to coldly go where no man has gone before… Obergurgl March 2007

SCUBA-2 Legacy Surveys2 SCUBA surveys  Many teams, many surveys  Blank field surveys (confusion- limited)  Gravitationally lensed surveys  Few 100 SMGs detected  Small field  slow buildup of samples

SCUBA-2 Legacy Surveys3 A survey of SCUBA surveys HDF SHADES 8 mJy

SCUBA-2 Legacy Surveys4 From SCUBA to SCUBA-2  Field of view 8’  8’: 10  SCUBA  SCUBA-2 brings rectangular array imaging to submm astronomy  8 arrays of 40  32 TES detectors – 4 arrays at 850  m, 4 at 450  m  Fully sampled imaging at 850  m  Per pixel NEP 50 (220) mJy/√Hz at 850 (450)  m

SCUBA-2 Legacy Surveys5 SCUBA-2 type surveys SCUBA-2 field-of-view 1 deg 2 field, will be mapped to confusion limit in 23 hours by SCUBA-2 at 850  m (from Gastañaga et al.)

SCUBA-2 Legacy Surveys6 Outline  JCMT Legacy Survey process  SCUBA-2 Legacy Surveys  SCUBA-2 Cosmology Legacy Survey  850  m survey science  450  m survey science

SCUBA-2 Legacy Surveys7 Legacy survey process  Concept of legacy surveys proposed to JCMT board  Legacy surveys can use both SCUBA-2 and HARP (16-pixel 350 GHz receiver) (16-pixel 350 GHz receiver)  Call for proposals by the board – resulted in oversubscription of all assumed (usable) JCMT time in time by factor 5.5 (usable) JCMT time in time by factor 5.5  International workshop in Leiden led to coordinated proposals  Each proposal evaluated by a number of referees from outside the JCMT community community  Process overseen by the JCMT Survey Steering Group, which made a recommendation to the JCMT board, which was adopted recommendation to the JCMT board, which was adopted

SCUBA-2 Legacy Surveys8 Outcome of the process  Two sets of surveys: 2-year surveys and 5-year surveys  Two-year plan approved; 5-year plan approved in principle, but new call for surveys after 2 years call for surveys after 2 years  During this period, 55% of the available time on JCMT will go to the Legacy Surveys Legacy Surveys  Surveys are overseen by the JCMT Survey Oversight Committee, which advises the JCMT board; teams will report every six months and which advises the JCMT board; teams will report every six months and must demonstrate progress, keeping up with the data stream, ability to must demonstrate progress, keeping up with the data stream, ability to produce a uniform dataset, etc. produce a uniform dataset, etc.  Data initially proprietary, but obligation to release reduced data

SCUBA-2 Legacy Surveys9 JCMT Legacy Surveys  Cosmology Legacy Survey (most highly rated): 490 hours band 1 (this is 90% of the expected available band 1 time!) 490 hours band 1 (this is 90% of the expected available band 1 time!) and 630 hours band 2/3 and 630 hours band 2/3  SCUBA-2 All-Sky Survey (SASSy): 500 hours band 4 to 150 mJy depth (all-sky in 5 years) – see Stephen Serjeant for details (all-sky in 5 years) – see Stephen Serjeant for details  Debris disks – complete set of nearby stars  Nearby galaxies survey – SCUBA-2 and HARP  Gould’s Belt survey (2 nd highly rated) – SCUBA-2 and HARP  Galactic Plane survey – SCUBA-2 and HARP  Spectral line survey – HARP only

SCUBA-2 Legacy Surveys10 Debris disk survey  Few hundred nearby stars, mapped to the confusion limit mapped to the confusion limit at 850  m at 850  m  Will likely produce very nice target set for adaptive optics target set for adaptive optics observations of SMGs observations of SMGs Fomalhaut at 450  m ? 850  m Size of Pluto’s orbit Beam size Holland et al. (2001)

SCUBA-2 Legacy Surveys11 Star formation Our lack of detailed understanding of star formation is a major stumbling block:  while we know a lot about low-mass star formation, very little is known about the formation of high-mass stars (rare and short-lived); yet these about the formation of high-mass stars (rare and short-lived); yet these power the SMGs. power the SMGs.  there is no good theory for the origin of the IMF and whether or not there should be a “universal” IMF; yet this central to estimated of SFR, there should be a “universal” IMF; yet this central to estimated of SFR, stellar mass etc. stellar mass etc.

SCUBA-2 Legacy Surveys12 The IMF problem(s) in SMGs Integral under green curve would exceed local stellar mass estimates for normal IMF. SFR implied by SMG’s

SCUBA-2 Legacy Surveys13 SCUBA Galactic Centre Survey ≈15 shifts (or 120 hrs) of telescope time M8 M16 SCUBA-2 Galactic PLANE Survey SCUBA-2 Galactic plane survey

SCUBA-2 Legacy Surveys14 (Pierce-Price et al.) SCUBA-2 FOV SCUBA Galactic centre survey SCUBA FOV 450  m 850  m

SCUBA-2 Legacy Surveys15 IRAS 100  m: Gould’s Belt

SCUBA-2 Legacy Surveys16 Star formation surveys  Galactic plane survey will reveal systematically reveal the progenitors of massive star formation (IR dark clouds and similar very dense structures) massive star formation (IR dark clouds and similar very dense structures)  anatomy of the Milky Way at 850  m – important reference point for extragalactic studies extragalactic studies  Gould’s Belt survey – comprehensive survey of low-mass star formation These surveys could only be implemented as a result of the Legacy Survey process.

SCUBA-2 Legacy Surveys17 SCUBA-2 Cosmology Legacy Survey  4 PIs: Jim Dunlop, Mark Halpern, Ian Smail, Paul van der Werf; Ian Smail, Paul van der Werf; + ≈ 100 co-I’s + ≈ 100 co-I’s SCUBA-2 field-of-view  Time allocation for the 2-year program: 41 nights band 1 weather, program: 41 nights band 1 weather, 61 nights band 2/3 61 nights band 2/3  2-year program: large survey (20 deg 2 ) at 850  m, large survey (20 deg 2 ) at 850  m, deep survey at 450  m (0.5 deg 2 ) deep survey at 450  m (0.5 deg 2 )  5-year program: large survey (50 deg 2 ) at 850  m, large survey (50 deg 2 ) at 850  m, deep survey at 450  m (1.3 deg 2 ) deep survey at 450  m (1.3 deg 2 )

SCUBA-2 Legacy Surveys18 Survey properties  Survey volumes are always very long in the radial direction. long in the radial direction.  A deeper submm survey does not probe a larger volume, but probe a larger volume, but fainter galaxies at all redshifts. fainter galaxies at all redshifts.  JCMT/SCUBA-2 confusion limit at 850  m is 0.8 mJy; to 3  we at 850  m is 0.8 mJy; to 3  we resolve only ≈20% of background. resolve only ≈20% of background.  Bright sources are typically 20 mJy  limited dynamic range in flux  limited dynamic range in flux  Wide 850  m survey of only 1 layer (from Andrew Blain)

SCUBA-2 Legacy Surveys19 Survey depths and widths (2-yr plan)  Wide 850  m survey: 20 deg 2 to 1  = 0.7 mJy. Comparable to a Schmidt plate to the depth of the SCUBA-HDF-N map. Comparable to a Schmidt plate to the depth of the SCUBA-HDF-N map. Expected to yield several 10 3 sources at >10 , several 10 4 at >3 . Expected to yield several 10 3 sources at >10 , several 10 4 at >3 .  Deep 450  m survey: 0.5 deg 2 to 1  = 0.5 mJy (expected confusion limit). Intended area of SHADES, to average over sufficient cosmic volume. Intended area of SHADES, to average over sufficient cosmic volume. Expected to yield several 10 2 sources at >10 , several 10 3 at >3 . Expected to yield several 10 2 sources at >10 , several 10 3 at >3 .  Deep 850  m survey: 0.5 deg 2 to 1  = 0.15 mJy (ignoring confusion). In parallel with 450  m map, which will be used for deconvolution. In parallel with 450  m map, which will be used for deconvolution.

SCUBA-2 Legacy Surveys20 Survey fields  850  m survey:  450  m survey: fieldRAarea [deg 2 ] XMM-LSS25 ECDFS33 Cosmos102 Lockman104 Bootes142 EGS141 ELAIS-N1162 Akari-NEP181fieldRAarea UDS2<0.25 ECDFS3<0.25 Cosmos10<0.25 GOODS-N Akari-NEP SA Field selection (partly) driven by complementary data of the required depth; e.g., K AB =25

SCUBA-2 Legacy Surveys21 Science case 850  m survey  Clustering of SMGs  Relation with other populations through massive source stacking  Extreme objects (>30 mJy) – how many? what are they?  10  detections: easier identification, better photo- z  Properties of host galaxies – stellar masses, K — z diagram, growing AGN?  New tests for semi-analytical models  Rich source of follow-up by e.g., ALMA

SCUBA-2 Legacy Surveys22 Clustering and evolution  Clustering signal even without any redshift information any redshift information  Photo- z ’s  clustering as function of z function of z  Assign halo masses to SMGs  Same at all redshifts?

SCUBA-2 Legacy Surveys23 Relations between source populations  Availability of very deep data from e.g., UDS and IRAC allows recovery of submm signal from a selected population. of submm signal from a selected population.  E.g.: Lyman Break Galaxies have no detectable submm emission even after massive source stacking, but Distant Red Galaxies (DRGs) do! massive source stacking, but Distant Red Galaxies (DRGs) do!  Defined by J s — K s > 2.3, which brings the Balmer break between J s and K s for z > 2 for z > 2  DRGs: massive galaxies with high SFRs; source density 3 arcmin –2 for K 0.8 mJy at 850  m (as estimated for K 0.8 mJy at 850  m (as estimated from lensing surveys). from lensing surveys).  1 unlensed DRG detected directly with SCUBA (5 mJy).

SCUBA-2 Legacy Surveys24 Stacking DRGs DRGs, EROs random positions DRGs: S 850 = 1.11  0.28 mJy ≈20% of background (Knudsen et al., 2005)

SCUBA-2 Legacy Surveys25 Microwave Background IR/Optical Background X-Ray Background Big Bang Stars+BlackHoles AGN 1mm 1  m 1nm (Puget et al. 1996, Hauser et al Fixsen et al. 1998) Cosmic backgrounds IRBG peaks at ≈200  m. At 850  m, 30  lower At 450  m, only 3  lower

SCUBA-2 Legacy Surveys26 Science case 450  m survey  Probe the IR/submm background close to its spectral peak  Resolve ≈ 75% of the 450  m background: new territory!  Out to z =3: full census of ULIRGs in survey volume Out to z =2: full census of >3  L  galaxies Out to z =2: full census of >3  L  galaxies Out to z =1: full census of >2  L  galaxies Out to z =1: full census of >2  L  galaxies  Connection to other populations without stacking  Deconvolve confusion-limited 850  m map  Evolution of IR/submm luminosity function, obscured star formation history obscured star formation history

SCUBA-2 Legacy Surveys27 Elbaz diagram SCUBA (450  m)

SCUBA-2 Legacy Surveys28 Deep 850  m source counts  Currently from gravitationally lensing cluster fields  small survey lensing cluster fields  small survey volumes, affected by cosmic variance volumes, affected by cosmic variance  Deconvolved deep 850  m map large enough to average out cosmic enough to average out cosmic variance variance  Several 10 3 sources expected at >10  down to 1.5 mJy (resolves ≈ 40% of down to 1.5 mJy (resolves ≈ 40% of 850  m background) 850  m background) (Knudsen, Van der Werf & Kneib, 2007) 10 

SCUBA-2 Legacy Surveys29 Practical challenges at 450  m  Even in excellent weather observing at 450  m is challenging.  Special care needed in calibration – monitor conditions and take beammaps several times per night beammaps several times per night  Need to establish a rigorous observing protocol, since the data are going to be taken by many different persons (often not even member of the to be taken by many different persons (often not even member of the cosmology survey team). cosmology survey team).  Surface accuracy of JCMT dish <22  m is needed; this needs to be monitored and maintained. this needs to be monitored and maintained.  Crucial requirement for 450  m survey depth and uniformity

SCUBA-2 Legacy Surveys30 Conclusions and outlook  850  m survey will produce statistically accurate results, and robust samples for easier follow-up. samples for easier follow-up.  Clustering is a key application  The 450  m survey is unique in probing lower SFRs  Deep complementary data is essential  Follow-up is crucial: deep radio, near-IR deployable IFUs, redshift machines using CO redshift machines using CO  Numbers are still “low”  a next-generation instrument?