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Next generation redshift Next generation redshift surveys with the ESO-VLTsurveys with the ESO-VLT

Today Instrumentation for surveys on the VLT Several surveys covering up to z~6

Tomorrow ? Need for massive surveys Need for new instrumentation ?

Short term Long term

Olivier Le Fèvre, Laboratoire d’Astrophysique de Marseille

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Instrumentation for surveys at the VLTInstrumentation for surveys at the VLT

Optical instruments VIMOS-UT3: multi-slit 14x16 arcmin², 150 to 1000 slits (if 10arcsec

long, R~220 to 2500) FORS-UT2: multi-slit 7x7 arcmin², 100 slits max, red optimized FLAMES:-UT4 multi-fiber, 130 fibers, 15 small IFUs In dev.: MUSE (2011), 1 arcmin² IFU + adaptive optics

NIR instruments Not really for surveys but for follow-ups

Missing a NIR-MOS SINFONI: single object IFU cryogenic, JHK bands ISAAC: long-slit cryogenic, JHK bands In dev.: KMOS (2011), 24 IFUs, JHK bands

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VIMOS -VLT-UT3VIMOS -VLT-UT3

A highly efficient high redshift machine in operations since 2002 on the VLT

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Multi-slit mode

Low res.

High res.

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FLAMES=GIRAFFE+OzPoz130 fibers, 0.4-1 microns

FORS2, 0.4-1 microns7x7 arcmin², 100 slits

Instruments for surveys at the VLTInstruments for surveys at the VLT

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SINFONI3D-IFU1-2.5 microns

Instruments for follow-up from surveysInstruments for follow-up from surveys

On-going: 150 VVDS galaxies 1<z<1.8

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On-going redshift surveys at the VLTOn-going redshift surveys at the VLT Several surveys covering up to z~6 Wide and Deep [VIMOS]: VVDS aiming for up to 30deg²

and 1.5x105 redshifts Wide [VIMOS]: zCOSMOS (2 deg²) Medium-deep [VIMOS, FORS2]: UDF (1 deg²) Deep [VIMOS]:

GOODS, 7000 redshifts zCOSMOS, 1.5<z<3, 15000 redshifts

Ultra-Deep: VVDS [VIMOS], GMASS [FORS2] a few hundred sq.arcmin, a few thousand objects

Others 3D integral field: VVDS-SINFONI, FLAMES Other programs…

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VIMOS VLT Deep SurveyVIMOS VLT Deep Survey

Field IAB<22.5 WIDE 16+ deg_

IAB<24 DEEP 1deg_

IAB<24.75 Ultra-Deep 600 arcmin_

0226-04 ~14000 9000 Public

1000 (on-going)

1000+03 ~5000 1400+05 ~11000

2217+00 ~15000 (~10000 on -going)

CDFS ~1600 Public

Total ~35000 ~15500 ~1000 GOAL 100000 20000 1000

R~230, 5500-9300Å ~50000 spectra today~50000 spectra today Goal >20000 Deep and

100000 Wide

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N(z): IN(z): IABAB22.522.5 , IIABAB24, 24, IIABAB24.7524.75

VVDSredshift desert

Magnitude selection only: complete census of the population, minimize apriori selection bias

IAB≤22.5,

<z>=0.55

IAB≤24<z>=0.75High redshift tail to z~4-522.5≤IAB≤24.75<z>=1.4High redshift tail to z~540% of galaxies with z>1.5

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VVDS-Wide, 35000 redshiftsVVDS-Wide, 35000 redshifts

4 deg²

Measuring at z=0.8, using (rp,)=0.7±0.24From 8 deg² (Guzzo et al., submitted)

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VVDS-UltraDeepVVDS-UltraDeep Magnitude selected IAB≤24.75 Toward a complete census

No apriori ~50% of galaxies at z~3 are not

LBGs■ VVDS UDeep

LBG Box

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Measuring galaxy evolution fromthe VVDS

Distribution in LSS

N(z)

Galaxy density field

High redshift populations

Reddest Galaxies to z~2

130 faint QSOs to z=5

1000 galaxies 1.4 < z < 5

Luminosity / SFR / Mass evolution

Luminosity Function

Track evolution versus Environment, Luminosity, galaxy Type,…

Correlation function

Luminosity DensitySFR

Mass function

1000 galaxies IAB≤24.75

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VVDS resultsVVDS results

40+ papers published so far

MB=-17 MB=-21

Clustering

Stellar mass

Type density relation evol

Luminosity function to z~3By typeVs. environment

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zCOSMOSzCOSMOS With VLT-VIMOS

Wide: 2 deg², 25000 spectra, IAB≤22.5, 0<z<1.2

Deep: 1 deg², 15000 spectra, BzK+UGR selected 1.5<z<3

1.5<z<3Combined spectra with Lya in emission vs; in absorption

On HST-COSMOS 2 deg² field

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On-going redshift surveys at the VLT: On-going redshift surveys at the VLT: summarysummary

At z~1 : ~10 deg², ~100Mpc scales, several 104 redshifts, coming up: ~105 redshifts

At z~2-3: ~1-2 deg², ~50Mpc scales, a few hundred redshifts now, several 103 redshifts coming up

At z=4-6: A few tens of redshifts

20-100 smaller at z~1 in dz=0.2 than 2dFGRS-SDSS

Keep in mind the huge human effort needed Currently VVDS, zCOSMOS require 1week, 2 people for 500 spectra automated z measurement when 0<z<5 is not yet achieved

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Probing the Universewith spectroscopic surveys

Understand galaxy formation and evolutionTowards reionisation z~15Very deep, M* at z~10Small fieldsSeveral thousand objets

Understand LSS formation and evolution

Large scales, >100 Mpc

Wide fields >10deg²Deep, M* at z~3>10^5 objects

High redshifts z>~1-6

Multi-object spectroscopyNIR-MIR Multi-object

spectroscopy

3D spectroscopyNIR-MIR

Measure Cosmology parameters

SNIaBaryons oscillations,8

…

Lensing, CMB, SnIa…

Multi- photometry, visible + near-IR

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Next surveys at the VLT: Test casesNext surveys at the VLT: Test cases

1. “SDSS at z~1”: 106 galaxies, 50-100 deg² >200Mpc scales AB~23

2. All-sky survey to z~1 A few 108 galaxies, 10000 deg²

3. “VVDS at z~3-6” 105 galaxies, 25deg²

4. Extremely deep probe z~10 A few hundred objects, AB~26

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1. VIMOS VLT Large Survey 1. VIMOS VLT Large Survey SDSS at z~1SDSS at z~1

“SDSS at z~1”: BAO++… (galaxies, clusters, QSOs) 7x106 galaxies, 100 deg² >200Mpc scales AB~22.5

100 deg²: 4800h with VIMOS 48 VIMOS pointings to cover 1deg² 45 min integrations for IAB≤22.5 (85% completeness) + overhead

Need 480 nights = 5 years project @ 100n/y

CAN BE DONE TODAY !

Dedicate VLT-UT3+VIMOS

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Requirements: 10000 deg² (high galactic latitude) z~0.5-1, IAB≤22.5 1 in 4 sampling 5-10 years survey

Need 1000y with VIMOS: need to think of new instrument ! Boost the multiplex gain

2. ‘All-sky’ survey at z~12. ‘All-sky’ survey at z~1

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Ground-based facility Need ~104 simultanous redshifts in 1h to complete in 5-10y

2x108 redshifts Concepts:

WFMOS: on 8m, 1.75deg² field, 4000 fibers, need ~800 nights MEGAMOS: on the VLT, >1.5deg², 10000 spectra with micro-mirrors / shutters. Not easy: feasibility study

Space-based facility Submitted to ESA ‘Cosmic-Vision’: SPACE mission telescope 1.5m, 0.5deg field, 10000 spectra with micro-mirrors

Can do 0.5x109 redshifts in 3y mission, down to H=23 (15 min)

2. ‘All-sky’ survey at z~12. ‘All-sky’ survey at z~1

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3. VVDS-like at z=3-63. VVDS-like at z=3-6

Requirements: U, B, V and R-band Lyman-break and Ly- selection at IAB≤25

25 deg² to probe >100Mpc and beat cosmic variance 105 spectra for stats

With existing facilities VIMOS:

need 20h integrations 4000h=500 nights program

Space-based facility SPACE-like instrument: deep probe of several 105 zCA

N BE DONE TODAY !

Dedicate VLT-UT3+VIMOS

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4. Ultra-deep probe z=104. Ultra-deep probe z=10

Requirements: H~26 A few hundred objects Field: guess, depends on the number density

With existing facilities Not possible with 8m (?) Need space (beat sky and thermal background)

Future facilities ELT multi-slit and multi-IFU SPACE-like instrument: telescope 1.5m, 0.5deg field, 10000 spectra with micro-mirrors

JWST

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Summary Next generation surveys with the VLT

Dedicate VLT for very large redshift surveys Motivate the community

Short term: dedicate VLT-VIMOS to a few large surveys z~1, 106 redshifts z~3-6, 105 redshifts

Long term: New instrument on 8m very wide field MOS with 10000 slits/fibers

Note: further develop automation of z measurement at high z. Not trivial