Public surveys with VISTA

Will Sutherland (QMUL)

VISTA Project Scientist

ESO Paranal Observatory, Chile

VISTA main parameters:

Telescope is “front-end to VIRCAM”.

Primary mirror 4.1 m , f/1.0

1.24 m secondary, f/3.25 Cassegrain focus.

Single instrument : VIRCAM (2.9 tonnes, 700 kg cold). Field corrector, active optics and guiding sensors included in VIRCAM.

16 Raytheon 2k x 2k near-IR detectors. Only current instrument with > 4 such detectors.

FoV 1.65 deg diameter, sparse-filled, 0.6 deg2 on-pixels. Mean pixel scale = 0.339 arcsec.

7 filters, broadband Z, Y, J, H, Ks, two narrowbands. ESO facility since Dec 09 (part of UK entry contribution)

> 75% of time for large-scale public surveys.

IR camera field sizes:

VISTA + IR Camera schematic

Primary mirror – first coating, Apr 2008.

IR Camera cross-section

IR focal plane:• 16 arrays, 67 Mpix = 0.60 deg2 = 2150 arcmin2 on-pixels , 0.34 arcsec/pixel.

- 6 offset `pawprints’ gives 1.5 x 1.0 deg2 `tile' , every star covered by 2 pawprints.

Six VISTA Public Surveys: sky coverage (schematic)

Sky coverage (to Jul 2011)

VHS: VISTA Hemisphere Survey(PI: McMahon)

Whole Southern hemisphere.

~ 3.5 mag deeper than 2MASS. 3 sub-areas with slightly different strategies:

DES area: 120 sec, J, H, Ks. (Y will come from DES). VST-ATLAS area: 60 sec Y, J, H, Ks. Rest of hemisphere : 60 sec J, Ks only.

Depth complementary to Skymapper, WISE. High-z quasars, cool brown dwarfs, ULIRGs; The near-IR complement to GAIA … sort out

reddening/metallicity degeneracy etc.

Wide surveys: point source sensitivity

VHS

VVV: VISTA Variables in Via Lactea520 deg2, multi-epoch.

(PIs: Minitti, Lucas)

• 5 bands to near confusion limit; ~ 100 epochs shallower Ks.

Science goals:

• Multi-epoch: RR Lyrae

• New globulars

• Sgr dwarf

• Microlensing

• Complement Spitzer, WISE.

Total ~ 1 billion sources, ~ 1 million variables. RR Lyrae (>50% of total), type II Cepheids Find variables in known star clusters (obtain distances, reddenings,

metallicities) Eclipsing binaries Rare variable sources Microlensing in inner bulge Look for variable stars in Sag. dwarf

Search for new globulars and open clusters Search for high proper motion objects and background QSOs

VVV [VISTA Variables in the Via Lactea]

92 new open cluster candidates, (Borissova et al 2011)

VMC: VISTA Magellanic Clouds survey(PI: Cioni)

Entire LMC, SMC, stream. Y, J, Ks; 10σ at Ks ~ 20.4Goals: structure, star formation history, stellar populations.Some multi-epoch (mean mags for RRLs, periods for AGBs).

VMC (Vista Magellanic Survey)

Resolved stellar populationsOld populations + active star formation + ongoing

merging + nearby= ideal laboratory. Globally resolved history of star formation with

unprecedented accuracyTrace past interactionsComplements optical (VST) and kinematic studies of

Magellanic system

VMC colour-mag diagrams(Cioni et al, A+A 2011)

VIKING : VISTA Kilo-degree Infrared Galaxy survey

(PI: Sutherland)

1500 deg2 , high |b|, in two stripes, NGP + SGP.

Area matches 2dFGRS and VST-KIDS. Optimal areas for Chilean followup: VLT, ALMA, etc.

NGP stripe on equator, overlaps UKIDSS, Sloan, GAMA.

9-band combined survey: ugri (VST), ZYJHKs (VISTA) Depth: ~ UKIDSS + 1.5 mag, Sloan + 2 mag.

Science goals: photo-z’s , weak lensing, LSS, high-z quasars, galactic structure, etc.

400 deg2 common with Herschel ATLAS survey.

VIKING: Exposure times + depths.

~ 400 sec per near-IR filter. J split into 2 x 200 sec.

2 visits per tile: Z,Y, J1 (non-bright); J2,H,Ks (any Moon)

VIKING Science drivers – I z> 6.5 quasars, ultracool brown dwarfs: colour selection in Z, Y, J :

45 VIKING Quasar candidates – NTT i, z followup. (Bram Venemans + Joe Findlay) .

z = 6.9 →

z = 6.8 →8500 Å 10300 Å

Latest results: 3 z > 6.5 quasars !

~35 min VLT/FORS2, poor conditions (seeing ~1.4”)

▪ Above, two z>6.5 quasars:YAB ~ 21.2 and 21.3 → M1450 = -25.7

Third quasar z ~ 6.6 confirmed last week. 2 more candidates awaiting spectra, total search area ~ 300 deg2

Herschel-ATLAS sky coverage.

Colourmap = 100um cirrus White = ATLASPurple = DESLight blue = VIKINGGreen = RA/Dec lines.

VIKING science – II Herschel-ATLAS identifications (S. Fleuren).

21,000 submm sources in GAMA-09 field; 72% statistically detected, 50% have reliable single-object

VIKING ID’s.

Galaxy evolution: Intermediate between “local” SDSS and “deep” few deg2 VVDS,

DEEP2, COSMOS , VIDEO ; Probe evolution at z ~ 0.2 – 0.8 , in restframe 0.4 – 1.2 μm.

Galaxy Morphologies: ~ 100,000 galaxies at z < 0.1 ; 2x better resolution and 4x deeper

surface brightness limit cf SDSS. Fundamental local benchmark sample probing all environments.

VIDEO: VISTA Deep Extragalactic Observations(PI: Matt Jarvis)

12 deg2 in 3 SWIRE / SERVS fields,

Ks(AB) ~ 23.5 Science goals:

Photometric redshifts for sources from Spitzer, Herschel, SCUBA2.

Galaxy evolution, redshift ~ 1 - 3 .

High-z galaxy clusters. Active galactic nuclei.

XMM-LSS

CDF-S

ELAIS-S1White = SWIRERed = VIDEO

VIDEO + Spitzer SERVS depths

VIDEO SERVS

Ultra-VISTA (PIs Dunlop, Franx, Fynbo, Le Fevre)

• 0.75 deg2 ultra-deep + 0.75 deg2 deep.

• Y, J, H, Ks + narrow 1.18 μm.

• Depth near FIRES, Ks(AB) ~ 25.5; 200x area, more bands.

• On Hubble-COSMOS field: • Equatorial for all-facility access, excellent data at many other wavelengths.

• One HST-CANDELS field inside a deep stripe.

• Science goals:• Comprehensive galaxy population, sub-L* at z ~ 2 – 4 • Ly-break galaxies, z ~ 6 – 8+ • Ly-α emitters at z ~ 8.8 .

Data processing

VISTA data rate is challenging, mean ~ 200 GB/night

Dedicated Data-flow system (VDFS) Pipeline based at CASU, Cambridge Science Archive at WFAU, Edinburgh. Post-processing quality control by survey teams.

Complementary visible surveys

VHS: strong complementarity with VST-Atlas, DES, Skymapper, GAIA.

VIKING: matched to VST-KIDS ; also DECam/DES at CTIO, starting 2012.

VIDEO: deep visible imaging valuable, but not so critical. DES Supernova fields likely to target VIDEO fields.

UltraVISTA: excellent visible data exists, mostly public.

Conclusion: has been bottleneck up to now in Southern visible surveys, but VST is now working, plus DES in ~ 2012. Visible data should catch up soon.

Summary VISTA has been surveying the Southern sky since late

2009.

Six major public surveys running in parallel, until ~ 2015; early data releases coming soon.

Should be world’s leading near-IR survey facility for many years (probably until Euclid / WFIRST ~ 2020 ?).

More details available at www.eso.org

Possible future instrument “4MOST”:

ESO-funded design study ongoing for “4MOST” : very large multiplex , visible wide-field spectrograph.

(PI: Roelof de Jong).

Fibre-fed, ~ 1500 – 2500 fibres, R > 7500, maybe 20000. Science drivers : GAIA and E-Rosita followup, + others. Two options under study:

3 deg diameter FoV on VISTA , or 2 deg diameter on NTT.

In competition with VLT-MOONS for selection late 2012. Natural future use of VISTA if Euclid goes ahead.

Supplementary pretty pictures etc: