Der Paul van der Werf Sterrewacht Leiden Legacy surveys with SCUBA2 - to coldly go where no man has gone before… Obergurgl March 2007.
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Paul van derder Werf
Sterrewacht Leiden
Legacy surveys with SCUBA2 -Legacy surveys with SCUBA2 -to coldly go where no man has gone to coldly go where no man has gone
before…before…
ObergurglObergurgl
March 2007March 2007
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 2
SCUBA surveysSCUBA surveys Many teams, many surveysMany teams, many surveys Blank field surveys Blank field surveys
(confusion-limited)(confusion-limited) Gravitationally lensed Gravitationally lensed
surveyssurveys Few 100 SMGs detectedFew 100 SMGs detected Small field Small field slow buildup slow buildup
of samplesof samples
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 3
A survey of SCUBA surveysA survey of SCUBA surveys
HDF SHADES
8 mJy
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 4
From SCUBA to SCUBA-2From SCUBA to SCUBA-2
Field of view 8’Field of view 8’8’: 108’: 10 SCUBA SCUBA SCUBA-2 brings rectangular array imaging to submm SCUBA-2 brings rectangular array imaging to submm
astronomyastronomy 8 arrays of 408 arrays of 4032 TES detectors – 4 arrays at 850 32 TES detectors – 4 arrays at 850 m, 4 m, 4
at 450 at 450 mm Fully sampled imaging at 850 Fully sampled imaging at 850 mm Per pixel NEP 50 (220) mJy/√Hz at 850 (450) Per pixel NEP 50 (220) mJy/√Hz at 850 (450) mm
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 5
SCUBA-2 type surveysSCUBA-2 type surveys
SCUBA-2 field-of-view
1 deg1 deg22 field, will be mapped to confusion field, will be mapped to confusion limit in 23 hours by SCUBA-2 at 850 limit in 23 hours by SCUBA-2 at 850 mm
(from Gastañaga et al.)
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 6
OutlineOutline
JCMT Legacy Survey processJCMT Legacy Survey process
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys
SCUBA-2 Cosmology Legacy SurveySCUBA-2 Cosmology Legacy Survey
850 850 m survey sciencem survey science
450 450 m survey sciencem survey science
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 7
Legacy survey processLegacy survey process
Concept of legacy surveys proposed to JCMT boardConcept of legacy surveys proposed to JCMT board Legacy surveys can use both SCUBA-2 and HARP 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 Call for proposals by the board – resulted in
oversubscription of oversubscription of all all assumed assumed (usable) JCMT time in 2007-2009 time by factor 5.5(usable) JCMT time in 2007-2009 time by factor 5.5 International workshop in Leiden led to coordinated International workshop in Leiden led to coordinated proposalsproposals Each proposal evaluated by a number of referees from Each proposal evaluated by a number of referees from
outside the JCMT outside the JCMT communitycommunity Process overseen by the JCMT Survey Steering Group, Process overseen by the JCMT Survey Steering Group,
which made a which made a recommendation to the JCMT board, which was adoptedrecommendation to the JCMT board, which was adopted
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 8
Outcome of the processOutcome of the process Two sets of surveys: 2-year surveys and 5-year surveysTwo sets of surveys: 2-year surveys and 5-year surveys
Two-year plan approved; 5-year plan approved in principle, but newTwo-year plan approved; 5-year plan approved in principle, but new call for surveys after 2 yearscall for surveys after 2 years
During this period, 55% of the available time on JCMT will go to theDuring this period, 55% of the available time on JCMT will go to the Legacy SurveysLegacy Surveys
Surveys are overseen by the JCMT Survey Oversight Committee,Surveys are overseen by the JCMT Survey Oversight Committee, which advises the JCMT board;which advises the JCMT board; teams will report every six months andteams will report every six months and must demonstrate progress, keeping up with the data stream, ability tomust 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 Data initially proprietary, but obligation to release reduced data
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 9
JCMT Legacy SurveysJCMT Legacy Surveys
Cosmology Legacy SurveyCosmology Legacy Survey (most highly rated): (most highly rated): 490 hours band 1490 hours band 1 (this is 90% of the expected available band 1 time!) (this is 90% of the expected available band 1 time!) and and 630 hours band 2/3630 hours band 2/3 SCUBA-2 All-Sky Survey (SASSy): 500 hours band 4 to 150 mJy depthSCUBA-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 starsDebris disks – complete set of nearby stars Nearby galaxies survey – SCUBA-2 and HARPNearby galaxies survey – SCUBA-2 and HARP
Gould’s Belt survey (2Gould’s Belt survey (2ndnd highly rated) – SCUBA-2 and HARP highly rated) – SCUBA-2 and HARP Galactic Plane survey – SCUBA-2 and HARPGalactic Plane survey – SCUBA-2 and HARP
Spectral line survey – HARP only Spectral line survey – HARP only
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 10
Debris disk surveyDebris disk survey
Few hundred nearby stars,Few hundred nearby stars, mapped to the confusion limitmapped to the confusion limit at 850 at 850 mm
Will likely Will likely produce very niceproduce very nice target set for adaptive opticstarget set for adaptive optics observations of SMGsobservations of SMGs
Fomalhaut at 450m
?
850m
Size of Pluto’s orbit
Beam size
Holland et al. (2001)
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 11
Star formationStar formation
Our lack of detailed understanding of star formation is a major Our lack of detailed understanding of star formation is a major stumbling block:stumbling block:
while we know a lot about low-mass star formation, very little is knownwhile 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 theseabout 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 notthere 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 SurveysSCUBA-2 Legacy Surveys 12
The IMF problem(s) in SMGsThe IMF problem(s) in SMGs
Integral under green curve Integral under green curve would exceed local would exceed local stellar mass estimates stellar mass estimates for normal IMF.for normal IMF.
SFR implied by SMG’s
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 13
SCUBA Galactic Centre Survey
≈15 shifts (or 120 hrs) of telescope time
M8
M16
SCUBA-2 Galactic PLANE Survey
SCUBA-2 Galactic plane surveySCUBA-2 Galactic plane survey
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 14(Pierce-Price et al.)
SCUBA-2 FOV
SCUBA Galactic centre surveySCUBA Galactic centre survey
SCUBA FOV
450m
850m
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 15
IRAS 100 IRAS 100 m: m: Gould’s BeltGould’s Belt
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 16
Star formation surveysStar formation surveys
Galactic plane survey will reveal systematically reveal the progenitors ofGalactic 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 anatomy of the Milky Way at 850 m – important reference point form – important reference point for extragalactic studiesextragalactic studies
Gould’s Belt survey – comprehensive survey of low-mass star formationGould’s Belt survey – comprehensive survey of low-mass star formation
These surveys could only be implemented as a result of the Legacy SurveyThese surveys could only be implemented as a result of the Legacy Surveyprocess. process.
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 17
SCUBA-2 Cosmology Legacy SurveySCUBA-2 Cosmology Legacy Survey 4 PIs: Jim Dunlop, Mark 4 PIs: Jim Dunlop, Mark Halpern, Halpern, Ian Smail, Paul van der Ian Smail, Paul van der Werf; Werf; + ≈ 100 co-I’s + ≈ 100 co-I’s
SCUBA-2 field-of-view
Time allocation for the 2-Time allocation for the 2-year year program: program: 41 nights band 1 41 nights band 1 weather,weather, 61 nights band 61 nights band 2/32/3
2-year program:2-year program: large survey (20 deglarge survey (20 deg22) at ) at 850 850 m, m, deep survey at 450 deep survey at 450 m m (0.5 deg(0.5 deg22)) 5-year program:5-year program: large survey (50 deglarge survey (50 deg22) at ) at 850 850 m, m, deep survey at 450 deep survey at 450 m m (1.3 deg(1.3 deg22))
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 18
Survey propertiesSurvey properties
Survey volumes are always Survey volumes are always very very longlong in the radial direction. in the radial direction. A A deeperdeeper submm survey submm survey
does not does not probe probe a larger volume, buta larger volume, but fainter galaxies at all fainter galaxies at all redshiftsredshifts..
JCMT/SCUBA-2 confusion JCMT/SCUBA-2 confusion
limit limit at 850 at 850 m is 0.8 mJy; to 3m is 0.8 mJy; to 3 we we resolve only resolve only ≈20%≈20% of of background.background. Bright sources are typically Bright sources are typically
20 mJy20 mJy limited dynamic range in limited dynamic range in fluxflux
Wide Wide 850 850 m survey of only m survey of only
1 layer1 layer
(from Andrew Blain)
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 19
Survey depths and widths (2-yr plan)Survey depths and widths (2-yr plan)
Wide 850Wide 850 m survey: 20 degm survey: 20 deg22 to 1 to 1 = 0.7 mJy = 0.7 mJy.. Comparable to a Schmidt plate to the depth of the Comparable to a Schmidt plate to the depth of the SCUBA-HDF-N map.SCUBA-HDF-N map. Expected to yield several 10Expected to yield several 1033 sources at >10 sources at >10, several , several 101044 at >3 at >3..
Deep 450Deep 450 m survey: 0.5 degm survey: 0.5 deg22 to 1 to 1 = 0.5 mJy = 0.5 mJy (expected (expected confusion limit).confusion limit). Intended area of SHADES, to average over sufficient Intended area of SHADES, to average over sufficient cosmic volume.cosmic volume. Expected to yield several 10Expected to yield several 1022 sources at >10 sources at >10, several , several 101033 at >3 at >3..
Deep 850Deep 850 m survey: 0.5 degm survey: 0.5 deg22 to 1 to 1 = 0.15 mJy = 0.15 mJy (ignoring (ignoring confusion).confusion). In parallel with 450 In parallel with 450 m map, which will be used for m map, which will be used for deconvolution.deconvolution.
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 20
Survey fieldsSurvey fields 850 850 m survey:m survey: 450 450 m survey:m survey:
fieldfield RARA areaarea
[deg[deg22]]
XMM-LSSXMM-LSS 22 55
ECDFSECDFS 33 33
CosmosCosmos 1010 22
LockmanLockman 1010 44
BootesBootes 1414 22
EGSEGS 1414 11
ELAIS-N1ELAIS-N1 1616 22
Akari-NEPAkari-NEP 1818 11
fieldfield RARA areaarea
[deg[deg22]]
UDSUDS 22 <0.25<0.25
ECDFSECDFS 33 <0.25<0.25
CosmosCosmos 1010 <0.25<0.25
GOODS-NGOODS-N 1212 0.050.05
Akari-NEPAkari-NEP 1818 0.020.02
SA22SA22 2222 0.020.02
Field selection (partly) driven by Field selection (partly) driven by complementary data complementary data of theof therequired depthrequired depth; e.g., ; e.g., KKABAB=25=25
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 21
Science case 850 Science case 850 m surveym survey
Clustering of SMGsClustering of SMGs
Relation with other populations through massive source stackingRelation with other populations through massive source stacking
Extreme objects (>30 mJy) – how many? what are they?Extreme objects (>30 mJy) – how many? what are they?
1010 detections: easier identification, better photo- detections: easier identification, better photo-zz
Properties of host galaxies – stellar masses, Properties of host galaxies – stellar masses, KK——zz diagram, growing AGN? diagram, growing AGN?
New tests for semi-analytical modelsNew tests for semi-analytical models
Rich source of follow-up by e.g., ALMARich source of follow-up by e.g., ALMA
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 22
Clustering and evolutionClustering and evolution
Clustering signal even Clustering signal even without without any redshift informationany redshift information
Photo-Photo-zz’s ’s clustering as clustering as function of function of zz
Assign halo masses to Assign halo masses to SMGsSMGs
Same at all redshifts?Same at all redshifts?
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 23
Relations between source populationsRelations between source populations Availability of very deep data from e.g., UDS and IRAC allows recoveryAvailability 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 afterE.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 Defined by JJss——KKss > 2.3, which brings the Balmer break between > 2.3, which brings the Balmer break between JJss and and KKss
for for zz > 2 > 2
DRGs: massive galaxies with high SFRs; source density 3 arcminDRGs: massive galaxies with high SFRs; source density 3 arcmin–2–2
for for KK<22.5 is comparable to SMGs with >0.8 mJy at 850 <22.5 is comparable to SMGs with >0.8 mJy at 850 m (as estimatedm (as estimated from lensing from lensing surveys).surveys).
1 unlensed DRG detected directly with SCUBA (5 mJy). 1 unlensed DRG detected directly with SCUBA (5 mJy).
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 24
Stacking DRGsStacking DRGs
DRGs, EROsDRGs, EROs
random positionsrandom positions
DRGs:DRGs:SS850850 = 1.11 = 1.11 0.28 mJy 0.28 mJy
≈≈20% of background20% of background
(Knudsen (Knudsen et al.et al., 2005), 2005)
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 25
MicrowaveBackground IR/Optical
Background
X-RayBackground
Big BangBig Bang
Stars+BlackHolesStars+BlackHoles
AGNAGN
1mm 1m 1nm
(Puget et al. 1996, Hauser et al. 1998Fixsen et al. 1998)
Cosmic backgroundsCosmic backgrounds
IRBG peaks at ≈200m.At 850m, 30 lowerAt 450m, only 3 lower
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 26
Science case 450Science case 450m surveym survey Probe the IR/submm background close to its spectral peakProbe the IR/submm background close to its spectral peak
Resolve ≈ 75% of the 450Resolve ≈ 75% of the 450m background: new territory!m background: new territory!
Out to Out to zz=3: full census of ULIRGs in survey volume=3: full census of ULIRGs in survey volume Out to Out to zz=2: full census of >3=2: full census of >310101111 LL galaxies galaxies Out to Out to zz=1: full census of >2=1: full census of >210101111 LL galaxies galaxies
Connection to other populations without stackingConnection to other populations without stacking
Deconvolve confusion-limited 850Deconvolve confusion-limited 850m mapm map
Evolution of IR/submm luminosity function,Evolution of IR/submm luminosity function, obscured star formation historyobscured star formation history
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 27
Elbaz diagramElbaz diagram
SCUBA (450m)
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 28
Deep 850Deep 850m source counts m source counts
Currently from Currently from gravitationally gravitationally lensing cluster lensing cluster fieldsfields small survey small survey volumes, affected by cosmic volumes, affected by cosmic variancevariance
Deconvolved deep 850Deconvolved deep 850m m map largemap large enough to average out enough to average out cosmic cosmic variancevariance
Several 10Several 1033 sources sources expected at >10expected at >10 down to 1.5 mJy (resolves ≈ down to 1.5 mJy (resolves ≈ 40% of 40% of 850 850 m background)m background)
((Knudsen, Van der WerfKnudsen, Van der Werf & Kneib, & Kneib, 20072007))
1010
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 29
Practical challenges at 450Practical challenges at 450mm
Even in excellent weather observing at 450Even in excellent weather observing at 450m is challenging.m is challenging.
Special care needed in calibration – monitor conditions and takeSpecial care needed in calibration – monitor conditions and take beammaps several times per nightbeammaps several times per night
Need to establish a Need to establish a rigorous observing protocolrigorous observing protocol, since the data are going, since the data are going to be taken by many different persons (often not even member of theto be taken by many different persons (often not even member of the cosmology survey team).cosmology survey team).
Surface accuracy of JCMT dish <22Surface accuracy of JCMT dish <22m is needed; m is needed; this needs to be monitored and maintainedthis needs to be monitored and maintained..
Crucial requirement for 450Crucial requirement for 450m survey depth and uniformitym survey depth and uniformity
SCUBA-2 Legacy SurveysSCUBA-2 Legacy Surveys 30
Conclusions and outlookConclusions and outlook
850 850 m survey will produce statistically accurate results, and robustm survey will produce statistically accurate results, and robust samples for easier follow-up.samples for easier follow-up.
Clustering is a key applicationClustering is a key application
The 450The 450m survey is unique in probing lower SFRsm survey is unique in probing lower SFRs
Deep complementary data is essentialDeep complementary data is essential
Follow-up is crucial: deep radio, near-IR deployable IFUs,Follow-up is crucial: deep radio, near-IR deployable IFUs, redshift machines using COredshift machines using CO
Numbers are still “low” Numbers are still “low” a next-generation instrument? a next-generation instrument?
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