Kinematics/Dynamics

Chemistry/dustStellar populations

Searches for z ~ 6-7

« Hot » scientific researches at VLT in cosmology

Mass

Galaxy formation/gas accretion

Star formation/enrichmentAges, history

Beyond the reionisation epochs

At increasing redshifts

To be improved by:

higher spectral resolution (3000 < R < 15000)

3D spectroscopy in the near IR (high z)

R>1000 spectroscopy for:

- extinction ( Balmer lines corrected for stellar absorption)- SFRs

-gas chemistry

-proper analysis of stellar populations

Galaxy spectroscopy pre-requisites(Liang et al, 2003a, A&A submitted)

Spectral resolution

Assuming low read-out noise CCDs and that OH sky lines dominateat > 0.7 m

Low resolution: should be > 1000 (extinction, SFRs, gas abundances)Medium resolution : ~ 10000-20000 (dynamics, stellar populations)

Much better detection of emission/absorption lines at R ~ few 1000

Recently illustrated by:Steidel (2004): several 100 spectra 1.4 < z < 2.6 (DEIMOS R=5000)

~ 10/arcmin2, 5 times more than LBGsVIMOS survey, I=24 (R=250): very few objects at z > 1.4

3000

500

Based on ISAAC ETC

Estimating extinctions and SFRs at z ~1 (Flores et al, 2003, A&A in press)

FORS2/ISAAC: 16 ISO galaxies, 0.4< z <1 , R=1250 to 2000

- extinction corrected H SFRs are close to mid-IR estimates (Elbaz et al, 2002) for SFR < 150 MO/yr (i.e. below ULIRGs)

Double check on SFR estimates

3D to test the merging hypothesis

Galaxy populations: what do we know ?Redshift/

# objects

z < 1.3

Several 10000s

1.3 < z < 2.6

z desert ?

but Steidel..

z=3-5

1000 LBGs

SCUBA’s

z > 6

2 QSOs,

3 galaxies ??

Epoch of Formation of disks ?

??? Ellipticals forming?

Reionisation

First stars ?

Extinction/

SFR

Still uncertain but SIRTF/VLT

Unknown

??

Largely model dependent

unknown

Stellar mass/

Metal

Uncertain

Few measures

Very uncert.

??

Very uncert.

5 measures ?

???

??

Mass/

Dynamics

TF uncertain

FP for E’s ?

none Small ’s ? ??

Image quality requirements

Distant galaxies are small and

low surface brightness sources!

3D spectroscopy at R> 3000

0.2 « FWHM » arcsec (8 m) or

0.06 « FWHM » arcsec ( 30m) 

0.02 « FWHM » arcsec ( 100m)

need to concentrate the light!

IJK

ISAAC, Ks=28, van Dokkum et al. 2003

FWHM

Microlenses

AO sharpens the PSF

FWHM decreases.

Gain in angular

resolution.

Spatial resolution

Increase of the fraction of light

into a sub-aperture.

More object, less sky.

Increase of the spectral S/N

Integration of DM and pupil relay optics in an « adaptive button » µ-DM required. Problem : no optical feedback from DM to WFS. Critical point : servo loop, to be studied.

sky coverage is essential

Several independent AO systems in a wide field.

IFUs WFS

FALCON AO system

10 Cosmological fields (b 45°), 100 objects/fieldTomographic reconstruction of on-axis phase (F Assemat et al, 2003)

Fraction of light in a 0.25 square aperture increased by at least a factor 2 in J band (1.25 µm) and H band (1.65 µm).FWHM < 0.2 arcsec sky coverage of 50% (GS with V<16, S/N=10) allow to reach ~ 0.06 arcsec (FWHM) on a 30m, 0.02 arcsec on a 100mRequirements : µ-DMs with 50-70 actuators for 8m, 15 times more for 30 m (but density conserved), very sensitive WFS with a high number of apertures.

Performances based on simulations

multi-object 3D spectroscopy at R>> 1000 (AO does not need to correct all the field, just the scientific targets!)

- Small fields severely affected by cosmic variance (e.g. HDF-N & S, ~ 6 arcmin2)

- Galaxy correlation scales 4-9 Mpc (z=0 to z=4, LBGs)

=9 to 20 arcmin a minimum

also # density of LBGs, LIRGs, sub-mm, Ellipticals :

0.01 to few / arcmin2

Which field of view for galaxy spectroscopy ?

z= 1000 (WMAP):

accurate physics & cosmological parameters

z= 0:

first detailed star formation histories (Local Group)

detailed dynamics (FP) and galaxy properties

z= 1 to > 6:

ELTs + (3D spectroscopy, R>>1000 and fov=10 arcmin):

the only way to understand the physics of the galaxy formation

Discussion