High Precision Spectroscopy LP CODEX …Opening a new parameter Space…

High Precision Spectroscopy LP High wavelength calibration accuracy… Very accurate Doppler shift measurements… Measurement of isotopic ratios… High Precision Spectroscopy requires very high S/N ratios  photon starved  Very and Extremely Large Telescopes Why a new window now

High Precision Spectroscopy LP Four 8 Meter telescopes 11 Instruments at Cass or Nasmyth Foci + Combined coherent focus+VLTI + Combined Incoherent Focus (16m equivalent) ESO is operating the VLT…

High Precision Spectroscopy LP 42 Meter ‘adaptive’ Telescope First light 2015 And ESO is planning the E-ELT!

High Precision Spectroscopy LP ELT 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 Instituto de Astrofisica Canarias: R. Garcia-Lopez, R. Rebolo, M. Zapatero 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)

High Precision Spectroscopy LP - Direct measurement of the dynamics of the Universe - Cosmological variation of the Fine-Structure Constant - Direct measurement of the dynamics of the Universe - Cosmological variation of the Fine-Structure Constant: CODEX will aim at an accuracy of ∆  /  ~5x Four Outstanding Cases - Terrestrial planets in extra-solar systems: - Terrestrial planets in extra-solar systems: RV of earth mass planets, spectroscopy of transits - Primordial nucleosynthesis: - Primordial nucleosynthesis: probing SBB nucleosynthesis: primordial Li 7, Li 6 /Li 7 Many additional applications (as from this conference....): Asteroseismology,Abundances in Stars, Variability of µ, Temperature evolution of CMB, Chemical evolution of IGM..

High Precision Spectroscopy 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 Dynamics of the Universe

High Precision Spectroscopy LP t 0 =actual epoch t e =emission epoch Cosmic Signal In a homogeneous, isotropic Universe a FRW metric

High Precision Spectroscopy LP Direct measurement ! Bias-free determination of cosmological parameters Different redshift (CMB, SNIa); measure dynamics and not geometry Not dependent from evolutionary effects of sources Legacy Mission to future astronomers (First epoch measurements)

High Precision Spectroscopy LP High Redshift Supernovae.. SNae: observe magnitudes at different Redshifts Assume SNae are standard candles at all z Assume SNae are standard candles at all z Require non-trivial K corrections Require non-trivial K corrections Require determination of Reddening… Require determination of Reddening…

High Precision Spectroscopy LP The measurement concept ….. But this is for 10 7 years… Having much less time at our disposal the shift is much smaller….

High Precision Spectroscopy LP The change in sign is the signature of the non zero cosmological constant The expected acceleration Is SMALL! Note: the standard model was not always standard..

High Precision Spectroscopy LP Simulating the dependence on Z Results of Simulation (..) Information “saturates”: a) Too many lines b) High Redshift makes them broader.

High Precision Spectroscopy 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/N QSO ) 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: About half of the signal is coming from the metal lines associated to the Ly  Results of simulations (…)

High Precision Spectroscopy LP Result of simulations (……) N QSO = 30 randomly distributed in the range 2 < z QSO <4.5 S/N = 3000 per Å pixel/epoch (no metal lines used)  t = 20 years Green points: 0.1 z bins Blue: 0.5 z bins Red line: Model with H 0 =70 Km/s/Mpc Ω m =0.3 Ω  =0.7 The cosmic signal is Detected at >99% significance(!) The full experiment

High Precision Spectroscopy LP With a telescope in the range of the 30-40m the experiment will be possible: Scaling with telescope diameter 1)With a timeline of 20 yrs the accuracy scales to 2 cm/sec 2)Use the full spectral range, including the Ly  region 20 yrs baseline VLT and Keck have devoted already > 1000 h each to QSOs..

High Precision Spectroscopy LP CODEX design parameters Location Underground in nested stabilized environment Telescope diameter 42 m FeedCoude’ + Fibre or Fibre only Overall DQE 20% Coude’ + Fibre, 13% Fibre only Entrance aperture 1 arcsec Wavelength range 380 – 680 nm Spectral Resolution Number of Spectrographs 3 (for 1 arcsec aperture at 42 m) Main disperser 3 x R4 echelle 42 l/mm 160 x 20 cm Crossdisperser6 x VPHG 1500 l/mm 20 x 10 cm Camera6 x F/ CCD6 x 8K x 8K (15 um pixels)

High Precision Spectroscopy LP How to improve accuracy and stability Scramblers to reduce effect of guiding errors Image dissector, multiple instruments Simultaneous wavelength calibration Use of wavelength calibration based on “laser comb” Fully passive instrument, ultra-high temperature stability Instrument in vacuum tank High precision control of detector temperature Underground facility, zero human access Blaze Correction and Flat Fielding System VLT

High Precision Spectroscopy LP Underground hall 20 x 30 m; height 8 m 1 K Instrument room 10 x 20 m; height 5 m Instrument room 10 x 20 m; height 5 m 0.1 K Control room and aux. equipment (laser) 1 K Instrument tanks, dia. ~ 2.5 x 4 m, Instrument tanks, dia. ~ 2.5 x 4 m, 0.01 K Optical bench and detector K CODEX laboratory floor plan

High Precision Spectroscopy LP The case was studied for the combined focus of the 4 VLT telescopes: Coude’ train is the most efficient solution and the only one which preserves the BLUE Telescope Link: Transmission

High Precision Spectroscopy LP Light from fibres enters here CODEX Unit Spectrograph B. Delabre ESO

High Precision Spectroscopy 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 I(1)I(1) n2n2n

High Precision Spectroscopy LP Comb: spectra simulations R=100k,  =15GHz, =5000Å Total velocity precision better than 1cms -1 in a single shot for SNR ~ 1000 ( Å) Running study with MPQ (Nobel Prize 2005)

High Precision Spectroscopy LP Precision ELT Extremely Large Telescopes will provide for the first time enough photons to guarantee a quantum jump in high resolution spectroscopy To open these new windows, High Resolution must be coupled to extremely high accuracy and stability We have developed a design for such an instrument, and we will propose ESPRESSO, the CODEX the VLT

High Precision Spectroscopy LP Laser Comb: Advantages and Challenges Advantages:  Absolute calibration  Long term frequency stability  Evenly spaced and highly precise frequencies allow mapping of distortions, drifts and intra-pixel sensitivity variations of CCD  Naturally fibre feed system. HARPS prototype possible. Challenges:  Line-spacing currently limited to ~1GHz. We need ~10–15 GHz...  Large spectral range required ( nm): Existing technology can possibly be extended.

High Precision Spectroscopy 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 ParameterInduced error on the correction [cm s -1 ] Comment Earth orbital velocity - Solar system ephemerides< 0.1JPL DE405 Earth rotation - Geoid shape - Observatory coordinates - Observatory altitude - Precession/nutation corrections ~ 0.5 < 0.1 Any location in atm. along photon path may be chosen Target coordinates - RA and DEC - Proper motion - Parallax ? ~ 0 70 mas  1 cm s -1 negligible Relativistic corrections - Local gravitational potential< 0.1 Timing - Flux-weighted date of observation? 0.6 s  1 cm s -1

High Precision Spectroscopy LP Why measure dynamics? All the results so far obtained in the ‘concordance model’ assumes that GR in the FRW formulation is the correct theory.  ~0.7 : but we do not know what  is and how it evolves. If GR holds, geometry and dynamics are related, matter and energy content of the Universe determine both. Dynamics has, however, never been measured. All other experiments, extremely successful such as High Z SNae search and WMAP measure geometry: dimming of magnitudes and scattering at the recombination surface.

High Precision Spectroscopy 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  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

High Precision Spectroscopy LP Once QSOs are established targets, through basic knowledge and simulations we determine the spectrograph parameters. Spectral range: QSO in the range Z~ At higher Z too many absorbers wipe out information, Ly  is visible from earth at Z>1.8 For 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 nm. UV: trade-off (less sensitivity, few Ly  absorbers..) Resolving Power : Ly  line have a typical width of 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~ Such 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

High Precision Spectroscopy LP CODEX Image and Pupil Evolution Several new features : Anamorphic collimator Pupil Slicer Anamorphic Crossidsperser (Slanted VPH)

High Precision Spectroscopy LP With the assumptions of homogeneity and isotropy, the concordance model finds a FRW metric with a non zero cosmological constant Standard Cosmological Model

High Precision Spectroscopy 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 a level 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 !

High Precision Spectroscopy 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 required by metal lines and Calibration accuracy.

High Precision Spectroscopy LP Results of simulation (2): real spectrum Dependence on cumulative S/N/pixel (0.015 A)

High Precision Spectroscopy 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+UVES peak efficiency In 1 st approx. precision scales as D for a given efficiency.

High Precision Spectroscopy LP Ly  =  v acc ~100 Km/sec T acc ~10 9 yr.. negligible Metal systems associated to damped Ly  :  v acc ~3-400 Km/sec T acc ~10 8 BUT hundreds systems-statistically level out Different from the maser and radio-galaxy case… Calls for many line of sight PECULIAR MOTIONS

High Precision Spectroscopy LP Detailed, state of the art hydrodynamical simulations confirm that the effects are negligible PECULIAR MOTIONS: Simulations

High Precision Spectroscopy LP What’s new VLT-UVES & Keck HIRES observed hundreds of QSOs at High Res (R>40000), z between 2 and 5, V= 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!!)

High Precision Spectroscopy 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 h observations with an 80 m telescope and 14% efficiency; all QSO brighter or around the iso-accuracy lines are suitable.

High Precision Spectroscopy 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 an homogeneously illuminated Slit & scrambling

High Precision Spectroscopy LP ELT More info & discussion at the Aveiro Conference on Precision Spectroscopy in Astrophysics September 2006, Aveiro, Portugal

High Precision Spectroscopy LP The full experiment DT=10 yrs 1500 Hours Metals V=16.5 Eff. 15% Results of simulations (….)

High Precision Spectroscopy LP QSO absorption lines To Earth CIV SiIVCIISiII Ly  em Ly  forest Lyman limit Ly  NV em SiIV em Ly  em Ly  SiII Quasar CIV em