CODEX 2006 - LP

Concept study for the

COsmic

Dynamics

EXperiment

CODEX 2006 - LP

ESO: G. Avila, B. Delabre, H. Dekker, S. D’Odorico,

J. Liske, L. Pasquini, P. Shaver

Observatoire Geneve : M. Dessauges-Zavadsky, M. Fleury, C. Lovis, M. Mayor, F. Pepe, D. Queloz, S. Udry

INAF-Trieste: P. Bonifacio, S. Cristiani, V. D’Odorico, P. Molaro, M. Nonino, E.

Vanzella

Institute of Astronomy Cambridge: M. Haehnelt, M. Murphy, M. Viel

Others:F. Bouchy (Marseille), S. Borgani (Daut-Ts), A. Grazian (Roma), S. Levshakov, (St-Petersburg), L. Moscardini (OABo-INAF), S. Zucker (Tel Aviv), T. Wilklind (ESA)

The Team

CODEX 2006 - LP

Directly measure the expansion of the Universe by observing the change of redshift with a time interval of a few

(10-20) years

”It should be possible to choose between various models of the expanding universe if the deceleration of a given galaxy could be measured. Precise predictions of the expected change in z=d/0 for reasonable observing times (say 100 years) is exceedingly small. Nevertheless, the predictions are interesting, since they form part of the available theory for the evolution of the universe” Sandage 1962 ApJ 136,319

The experiment

CODEX 2006 - LP

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Cosmic Signal

In a homogeneous, isotropicUniverse a FRW metric

CODEX 2006 - LP

Why measure dynamics?

All the results so far obtained in the ‘concordance model’ assumes All the results so far obtained in the ‘concordance model’ assumes that GR in the FRW formulation is the correct theory.that GR in the FRW formulation is the correct theory.~0.7 : but we do not know what ~0.7 : but we do not know what is and how it evolves. is and how it evolves.

If GR holds, geometry and dynamics are related, matter and If GR holds, geometry and dynamics are related, matter and energy content of the Universe determine both. energy content of the Universe determine both. Dynamics has, however, never been measured.Dynamics has, however, never been measured.

All other experiments, extremely successful such as All other experiments, extremely successful such as High Z SNae search and WMAPHigh Z SNae search and WMAP measure geometry: dimming of magnitudes and scattering at the measure geometry: dimming of magnitudes and scattering at the recombination surface. recombination surface.

CODEX 2006 - LP

The change in sign is the signature of the non zero cosmological constant

The SignalIs SMALL!

CODEX 2006 - LP

How to Measure this signal?

Masers : in principle very good candidates: lines are very narrow and measurements accurate: however they sit at the center of huge potential wells: large peculiar motions, larger than the Cosmic Signal are expected

Radio Galaxies with ALMA : The CODEX aim has been independently studied for ALMA: as for Masers, local motions of the emitters are real killers. Few radio galaxies so far observed show variability at alevel much higher than the signal we should detect

Ly forest: Absorption from the many intervening lines in front of high Z QSOs are the most promising candidates. Simulations, observations and analysis all concur in indicating that Ly forest and associated metal lines are produced by systems sitting in a warm IGM following beautifully the Hubble flow !

CODEX 2006 - LP

QSO absorption lines

To Earth

CIVSiIVCIISiIILyem

Ly forest

Lyman limit Ly

NVem

SiIVem

Lyem

Ly SiII

Quasar

CIVem

CODEX 2006 - LP

A LARGE signal ..

But this is for 107 years… Having much less time at our disposal the shift is much smaller.. Why can we conceive to detect It NOW?

CODEX 2006 - LP

What’s new

• VLT-UVES & Keck HIRES observed hundreds of QSOs at High Res (R>40000), z between 2 and 5, V=16-18. Ly clouds have been extensively simulated: their hot gas belongs to the IGM and they trace the Hubble flow

• Exoplanets (HARPS) long term accuracy 1m/s, short term (hours) 0.1m/s (and largely understood)

• ELT !! LOT OF PHOTONS (we need them!!)

CODEX 2006 - LP

Simulating the dependence on resolution ( Ly forest only)

Results of simulations (1)

Above a R~50000 there is no more gain for the Ly Forest. Higher Resolution is requiredby metal lines andCalibration accuracy.

CODEX 2006 - LP

Results of simulation (1): real spectrum

Dependence on cumulative S/N/pixel (0.015 A)

CODEX 2006 - LP

Simulating the dependence on Z

Results of Simulation (1)

Information “saturates”: a) Too many lines

b) High Redshift makes them broader.

CODEX 2006 - LP

Many simulations have been carried out independently by 3 groups; using observed and

fully simulated spectra. A very good agreement is found, and we can produce a simple scaling law:

v = 1.4*(2350/(S/N))(30/NQSO)0.5 (5/(1+Z))1.8

cm/sec

Where v is the total uncertainty (difference between 2 epochs) while the other parameters

refers to the characteristics of one epoch observation; Pixel size considered: 0.0125. About half of the signal is coming from the metal lines

associated to the Ly

Results of simulations (2)

CODEX 2006 - LP

The full experiment

DT=10 yrs

1500 HoursMetals

V=16.5

Eff. 15%

Results of simulations (3)

CODEX 2006 - LP

Result of simulations (4)

NQSO = 30 randomly distributed in the range 2 < zQSO <4.5S/N = 3000 per 0.0125 Å pixel/epoch (no metal lines used)t = 20 years

Green points: 0.1 z bins Blue: 0.5 z binsRed line: Model with H0=70 Km/s/MpcΩm=0.3 Ω=0.7

The cosmic signal is Detected at >99% significance(!)

The full experiment

CODEX 2006 - LP

Can we do it ?

Telescope + Instrument Efficiency required to complete the experiment under the following assumptions:•V=16.5 QSO• 36 QSO each S/N 2000 (0.015 pixel), for a total of • 2000 obs. hs/epoch ( 1cm/sec/yr)

Red line: VLT+UVESpeak efficiency

In 1st approx. precision scales as D for a given efficiency.

CODEX 2006 - LP

QSO have been selected from existing catalogues and

compilations (Veron, SDSS ) Selection

criteria: magnitude and z

Magnitudes: redwards of Ly, selected band

depends on z

Verification of targets and reference mission

In this Figure only the 5 brightest QSOs of each 0.25 z bin are shown. Hypothesis: e.g. 2000 h observations with an 80 m telescope and 14% efficiency; all QSO brighter or around the iso-accuracy lines are suitable.

CODEX 2006 - LP

With a telescope in the range of the 30-40m, will the experiment

still be possible ?

Scaling to a smaller telescope diameter

1) Increase the timeline; with 20 yrs (double), accuracy also scales to 2 cm/sec, inverse to Dtel

2) Use the full spectral range, including, e.g. the Ly region (contaminated by Ly)

20 yrs baseline

CODEX 2006 - LP

Ly = vacc~100 Km/sec Tacc~109 yr.. negligible

Metal systems associated to damped Ly:vacc~3-400 Km/sec Tacc~108 BUT hundreds systems-

statistically level outDifferent from the maser and radio-galaxy case…

Calls for many line of sight

PECULIAR MOTIONS

CODEX 2006 - LP

CODEX 2006 - LP

Detailed, state of the art

hydrodynamical simulations

confirm that the effects are negligible

PECULIAR MOTIONS: Simulations

CODEX 2006 - LP

Peculiar motions at the Earth

The solar acceleration in the Galaxy will be measured with an accuracy of ~ 0.5 mm/sec/yr by GAIA

Parameter Induced error on the correction [cm s-1]

Comment

Earth orbital velocity- Solar system ephemerides < 0.1 JPL DE405

Earth rotation- Geoid shape- Observatory coordinates- Observatory altitude- Precession/nutation corrections

~ 0.5< 0.1< 0.1< 0.1

Any location in atm. along photon path may be chosen

Target coordinates- RA and DEC- Proper motion- Parallax

?~ 0~ 0

70 mas 1 cm s-1

negligiblenegligible

Relativistic corrections- Local gravitational potential

< 0.1

Timing- Flux-weighted date of observation

? 0.6 s 1 cm s-1

CODEX 2006 - LP

3 outstanding projects were 3 outstanding projects were selected:selected:- - Cosmological variation of the Fine-Cosmological variation of the Fine-Structure ConstantStructure Constant: CODEX will exceed the accuracy of the OKLO reactor (D/ ~5x 10-9)

Beyond expansion….

--Terrestrial planets in extra-solar Terrestrial planets in extra-solar systems: systems: Radial velocity of earth mass planets, spectroscopy of

transits - - Primordial nucleosynthesis: Primordial nucleosynthesis: probing SBB nucleosynthesis: primordial Li7, Li6/Li7

Many additional applications (as from 8m science..): Asteroseismology, Cosmochronometers, First Stars, Temperature evolution of CMB, Chemical evolution of IGM..

CODEX 2006 - LP

Variability of Physical Variability of Physical ConstantsConstants• Fundamental Constants play an important role in our

understanding of nature. Test of fundamental physics.

• Higher dimensional theories constants are defined in full dim space: string theories predict extra dimensions of space and dynamical dimensionless constants

• The existence of extra dimensions of space is related to the properties of dark energy, dark matter and cosmic inflation.

• One of the 9 hottest main questions

CODEX 2006 - LP

‘Local’ Constraints

α was larger in the past

Oklo (t=1.8 Gyr, Z=0.14) Δα/α 4.510-8

Lamoreaux & Torgerson 2004

Δα/α =(+8 ± 8) 10-7 Olive et al. 2004 from meteorites (z~0.4)

For 10 Gyr =>

Δα/α < 3.8×10-5

Laboratory measurements

CODEX 2006 - LP

Astrophysical Constraints

VLT/UVES 23 systems

Δα/α=(+0.6±0.6)×10-6 Chand et al 2004

Keck/Hires 143 systems Δα/α=(-0.57±0.11)×10-5

Murphy et al 2004

CODEX 2006 - LP

• Fujii & Iwamoto 2005 : apparent oscillatory time-dependence

• The behavior is produced by the scalar field responsible for the acceleration of the universe

SIDAM Method

Δα/α=(+0.4±1.5)×10-6

Levshakov et al. 2004, Quast et al. 2004

CODEX 2006 - LP

Expected ImprovementThe astronomical measurement of is based on the difference of measured wavelengths.

The uncertainty is caused by errors in wavelengths

scales with (S/N)-1 ad with ()3/2 (see e.g Bohlin et al. 83,

is the pixel size and the lines are resolved)For UVES =0.02, S/N~70, 23 systems (Chand et al. 2004)

~ 6x10-7

For CODEX: =0.5 uves , S/N~30 S/Nuves , 40 systems: a gain of : 2.8 x 30 x 1.3 ~ 1.1x102 with respect to UVES

or

~ 5x10-9

CODEX 2006 - LP

PlanetsPlanets

Earth (and other) planets discovered with other techniques needaccurate radial velocity measurements for confirmation and mass determination; ESO-ESA WG report explicitly recommends ESO for new accurate RV facility (Earth mass signal in habitable zone: 3-10 cm/sec)

Three main applications:

1) Discover and confirmation of rocky planets

2) Search for long period planets

3) Jupiter mass planets around faint stars

CODEX 2006 - LP

Example of an instrument tank: HARPS

CODEX 2006 - LP

The HARPS Experience

O-C < 80 cm/secTh-Th < 10 cm/sec

CODEX 2006 - LP

The HARPS Experience (cont’d)

Harps is finding planets with small O-C, small masses

CODEX 2006 - LP

Planets: HARPSPlanets: HARPS

New candidateO-C: 1.1 m/sec

Red: Gaseous giant planets Blue: Icy planets Green : Rocky planets

CODEX 2006 - LP

Planets: low Planets: low mass mass

Main problem: sources of ‘Noise’ : Photon noise, Oscillations, Activity-induced jitter

Oscillations and Jitter are ubiquitus(cf. Figure K2V-G2IV stars with HARPS)Solution: many epoch measurements to average the effects but EXPENSIVE: ~10’s - ~100 hours/star

Bonus: Very high S/N spectra to study the spectrum at different planet phases

1) Observe stars that have high probability of hosting earths2) Follow-up and confirmation of planet candidates discovered by other facilities

CODEX 2006 - LP

Jupiters around faint Jupiters around faint stars stars

With HARPS it is shown that v=1m/sec with a S/N~80/pixel

With CODEX @ ELT S/N~80 in 10 min for V~16.5 and v=10m/sec in 1 hour V~21.5 (!)

Hot Jupiters in Solar Stars of Clusters, Bulge, Sagittarius, LMC …

Studying planet formation in very different environments seems one of the natural next steps

CODEX 2006 - LP

Primordial Nucleosynthesis and Primordial Nucleosynthesis and the early universethe early universe

WMAP and BBN : Real Disagreement ?

CODEX 2006 - LP

Primordial 6Li ?

Li6/Li7 Plateau??Asplund et al. 2005

Conventional way: 7Li depleted, 6Li produced in the early Galaxy by +

Decaying particles at the BBN epoch change the final abundances. Jedamzik (2004) has shown that decaying neutralinos could deplete 7Li and synthesize 6Li.

CODEX 2006 - LP

Codex Li Observations

• Measure 7Li and 6Li/7Li in a variety of metal - poor populations in the Galaxy and in other galaxies (GC, Bulge, Sagittarius, LMC..)

• Measure 6Li/7Li in metal poor ISM, with D primordial values by using QSOs as lighthouses.

CODEX 2006 - LP

Interstellar Li (and 7Li/6Li)

Knauth Federman Lambert 2003Mc Donald R=360000 SNR=500 texp 10h

EW 7Li=0.4 mA, 6Li= 0.04 mA

Interstellar Li today only available for solar material

IS 7Li/6Li in metal poor material (HVCs Complex C, MCs …)

CODEX 2006 - LP

CODEX design parameters

Location Underground in nested stabilized environmentTelescope diameter 100 m Feed Coude’ + Fibre or Fibre onlyOerall DQE 14% Coude’ + Fibre , 9% Fibre onlyEntrance aperture 0.65 arcsec (1 arcsec for a 60 m. Tel.)Wavelength range 400 – 680 nmSpectral Resolution 150 000 Number of Spectrographs 5 (11 for 1 arcsec aperture at 100 m)Main disperser 5 x R4 echelle 42 l/mm 160 x 20 cmCrossdisperser 5 x VPHG 1500 l/mm 20 x 10 cmCamera 5 x F/1.4-2.8CCD 5 x 8K x 8K (15 um pixels)

No Optimization or trade-off done yet

CODEX 2006 - LP

How to improve RV accuracy and stability

• Scramblers to reduce effect of guiding errors

• Image dissector, multiple instruments

• Simultaneous wavelength calibration

• Use of wavelength calibration “laser comb”

• Fully passive instrument, ultra-high temperature stability

• Instrument in vacuum tank

• High precision control of detector temperature

• Underground facility, zero human access

CODEX 2006 - LP

Entrance aperture 1” on 60 m or 0.65” on 100 m

37 Fibres array, 8 fibres/spectrograph

OWL

Fiber feed + Pre-slit

Lightpipe: forming anhomogeneously illuminated Slit & scrambling

CODEX 2006 - LP

Light from fibres enters here

CODEX Unit SpectrographB. Delabre ESO

CODEX 2006 - LP

Underground hall 20 x 30 m; height 8 mUnderground hall 20 x 30 m; height 8 m

1 K

Instrument room 10 x 20 m; Instrument room 10 x 20 m; height 5 mheight 5 m

0.1 K

Control room and aux. equipment Control room and aux. equipment (laser) (laser)

1 K

Instrument tanks, dia. ~ Instrument tanks, dia. ~ 2.5 x 4 m, 2.5 x 4 m, 0.01 K Optical bench and Optical bench and

detectordetector

0.001 K

CODEX laboratory floor CODEX laboratory floor planplan

CODEX 2006 - LP

Challenges & Feedback

Calibration source, stable, reproducible, equally spaced.. LASER COMB CCD control (thermal… )

High throughput of the spectrograph and injection system: EFFICIENT COUDE’ FOCUS

Light scrambling capabilities (1 cm/sec 0.0000003 arcsec centering accuracy on a slit…) TELESCOPE POINTING AND CENTERING ~0.02 arcsec

System aspects (from pointing to calibration to data reduction)

ALL aspects strongly suggest extensive prototyping

CODEX 2006 - LP

CODEX Lab

CODEX @ ELT

A visible H-R spectrograph designed to test GR and able to address fundamentalquestions

Spectrograph feasible even for a seeing - limited case up to 100m telescope diameter

H-R must be coupled to extremely high accuracy and stability

Prototype at VLT

CODEX 2006 - LP

CODEX @ ELT

More info & discussion at the Aveiro Conference on Precision Spectroscopy in Astrophysics 11-15 September 2006, Aveiro, Portugal

http://www.oal.ul.pt/psa2006

CODEX 2006 - LP

CODEX Planning and Costs

The preliminary project plan shows that the full development time for

1 full prototype operating for 3 years at the VLT + 5 CODEX unit spectrographs

is 12 years, with a HW cost of 24 ME and ~100 FTEs

Starting with Phase A in 2006, CODEX could be operated at OWL in 2019.

• The project is larger, but comparable to big VLT instrumens• Each CODEX unit comparable to e.g. UVES

• Estimates are based on the experience with UVES and HARPS

(Optics, Vacuum Vessel…) and MUSE (same CCD) preliminary tenders

CODEX 2006 - LP

Once QSOs are established targets, through basic knowledge and simulations we determine the

spectrograph parameters.

Spectral range: QSO in the range Z~1.5 - 5. At higher Z too many absorbers wipe out information, Ly is visible

from earth at Z>1.8For lower Z, metal lines only can be used. But to span a

large Z range is important also to link it to lower Z experiments: ideal range 300-680 nm. UV: trade-off (less

sensitivity, few Ly absorbers..)

Resolving Power: Ly line have a typical width of 20-30 Km/sec and R=50000 would suffice. Higher spectral resolution is required by metallic lines (b<~3 Km/sec) and

by calibration accuracy requirement; R~150000Such a resolution is challenging for any seeing limited ELT:

the final number will be a trade off between size, sky

aperture, detector noise…

BASIC SPECTROGRAPH REQUIREMENTS

CODEX 2006 - LP

Calibration System: Laser Frequency Comb

Metrology labs recently revolutionized by introduction of femtosecond-pulsed, self-referenced lasers driven by atomic clock standards

Cesium atomic clock n 2n(or even GPS signal!)Result is a reproducible, stable “comb” of evenly spaced lines who’s frequencies are known a priori to better than 1 in 1015

I(1)

n 2n

CODEX 2006 - LP

Laser Comb: Advantages and Challenges

Advantages:Absolute calibration: long term frequency stabilityEvenly spaced and highly precise frequencies allow mapping of distortions, drifts and intra-pixel sensitivity variations of CCDNaturally fibre feed system. HARPS prototype possible.

Challenges:Line-spacing currently limited to 1GHz by laser size and energy considerations. We need ~10–15GHz. New technology needed. Development project underway with Max Plank of Quantum Optics.Transmission of non-linear optical fibre questionable as low as <400nm. Existing technology can probably be extended.

CODEX 2006 - LP

CODEX Image and Pupil Evolution

F i b e r 1 2 0 x 1 2 0 _ m

F / 2 . 4

S T A R T

A n a m o r p h i c

c o l l i m a t o r

E q u i v a l e n t f i b e r 4 8 0 x 1 2 0 _ m

P u p i l 4 0 x 1 6 0 m m

P u p i l s l i c e r

f i b e r 1 6 8 0 x 2 1 0 _ m

P u p i l 2 0 0 x 4 0 0 m m

( o n e c h e l l e g r a t i n g )

A n a m o r p h i c

V P H

R a t i o 2 . 2 5

P u p i l 1 5 4 x 1 3 1 m m

E q u i v a l e n t f i b e r 7 4 0 x 2 1 0 _ m

C a m e r a

F i b e r i m a g e

2 1 2 x 6 0 _ m

D E T E C T O R

F / 2 . 2 x 2 . 5

C O D E X

Several new features :

Anamorphic collimator

Pupil Slicer

Anamorphic Crossidsperser(Slanted VPH)

CODEX 2006 - LP

CODEX Lab

CODEX @ OWL

CODEX 2006 - LP

Variability of fine Variability of fine structure structure α

• α = e2/hc

• Characterize the strength of the electromagnetic interaction

Fine and hyperfine structure of n=1 level H

CODEX 2006 - LP

With the assumptions of homogeneity and isotropy, the concordance model finds a

FRW metric with a non zero cosmological

constant

Standard Cosmological Model

CODEX 2006 - LP

Since the discovery of Hubble in the late 20’ of the expansion of the universe, this became one of the pillars of “Big Bang” cosmology . Later additions are

the CMB and the Primordial Nucleosynthesis

Although not all believe this ‘big bang’ a large consensus exists among

cosmologists,who have produced a ‘standard model’

Historical background in short

CODEX 2006 - LP

Comb: spectra simulations R=100k, =15GHz, =5000Å

Total velocity precision better than 1cms-1 in a single shot for SNR ~ 1000 (4500-6500Å)

CODEX 2006 - LP

Geometry tells us that the Universe is Expanding, so why bother to measure

dynamics?

Measurement of the dynamics of the Universe can be compared to basic

experiments such as the measurement of the principle of equivalence between

Inertial and Gravitational mass…

Without it, it is like measuring the geometrical orbits of planets w/o

measuring their accelerations… (e.g. No 2nd Kepler law..)

If we do not measure, we do not know

CODEX 2006 - LP

COMPONENT COST (KE)

Calibration Unit 450

Acquisition-guiding system 350

Fibre Fed (includes scrambler) 350

Transport & Insurance 450

Integration & Test cost 500

Project management, miscellanea 700

CODEX Lab and facilities 500

TOTAL COMMON 3300

CODEX HARDWARE COSTS: COMMON MODULE Special Laboratory cost not included

CODEX 2006 - LP

CODEX HARDWARE COSTS: SINGLE SPECTROGRAPH

COMPONENT COST (KE)

Comments

Spectrograph Optics

1300 includes X-disperser

Echelle Grating

600 20x160 cm mosaic of 2 UVES echelles

Spectrograph Mechanics

400 Includes optical bench

Spectrograph Electronics

100

Vacuum System 500

Criogeny and CCDs

600 4 4Kx4K CCDs + Cryostat + Controller

TOTAL/Spectro 3500

CODEX 2006 - LP

Direct measurement !

• Bias-free determination of cosmological parameters

• Different redshift (CMB, SNIa)

• Not dependent from evolutionary effects of sources

• Legacy Mission to future astronomers

(First epoch measurements)

CODEX 2006 - LP

The Concept Study Work Structure

Organized according to the Statement of Work agreed by all partners in 5 work packages:

WP1000 Management (L.Pasquini, ESO, PI)

WP2100 Main Science Case (S. Cristiani, INAF-Trieste)

WP2200 Science Methodology (F. Pepe, Obs. Geneve)

WP 2300 Immediate Science Cases (P. Molaro, INAF-Trieste)

WP 3000 Technical Design (H. Dekker, ESO)