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Concept study for the CO smic D ynamics EX periment

Concept study for the CO smic D ynamics EX periment. The Team. 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:

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Concept study for the CO smic D ynamics EX periment

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  1. Concept study for the COsmic Dynamics EXperiment CODEX 2006 - LP

  2. The Team 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) CODEX 2006 - LP

  3. The experiment 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=dl/l0 for reasonable observing times (say 100 years) is exceedingly small. Nevertheless, the predictions are interesting, since they form part ofthe available theory for the evolution of the universe” Sandage 1962 ApJ 136,319 CODEX 2006 - LP

  4. Cosmic Signal t0=actual epoch In a homogeneous, isotropic Universe a FRW metric te=emission epoch CODEX 2006 - LP

  5. 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. CODEX 2006 - LP

  6. The Signal Is SMALL! The change in sign is the signature of the non zero cosmological constant CODEX 2006 - LP

  7. 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 ! CODEX 2006 - LP

  8. QSO absorption lines Quasar To Earth Lyaem SiII CIV Lyman limit Lya SiII CII SiIV Lyb Lybem NVem Lya forest CIVem SiIVem CODEX 2006 - LP

  9. 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

  10. 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

  11. Results of simulations (1) Simulating the dependence on resolution ( Ly forest only) Above a R~50000 there is no more gain for the Ly Forest. Higher Resolution is required by metal lines and Calibration accuracy. CODEX 2006 - LP

  12. Results of simulation (1): real spectrum Dependence on cumulative S/N/pixel (0.015 A) CODEX 2006 - LP

  13. Results of Simulation (1) Simulating the dependence on Z Information “saturates”: a) Too many lines b) High Redshift makes them broader. CODEX 2006 - LP

  14. Results of simulations (2) 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 CODEX 2006 - LP

  15. Results of simulations (3) The full experiment DT=10 yrs 1500 Hours Metals V=16.5 Eff. 15% CODEX 2006 - LP

  16. Result of simulations (4) The full experiment NQSO = 30 randomly distributed in the range 2 < zQSO <4.5 S/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 bins Red line: Model with H0=70 Km/s/Mpc Ωm=0.3 Ω=0.7 The cosmic signal is Detected at >99% significance(!) CODEX 2006 - LP

  17. 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 1st approx. precision scales as D for a given efficiency. CODEX 2006 - LP

  18. Verification of targets and reference mission 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 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

  19. Scaling to a smaller telescope diameter With a telescope in the range of the 30-40m, will the experiment still be possible ? 20 yrs baseline Increase the timeline; with 20 yrs (double), accuracy also scales to 2 cm/sec, inverse to Dtel Use the full spectral range, including, e.g. the Ly region (contaminated by Ly) CODEX 2006 - LP

  20. PECULIAR MOTIONS Ly = vacc~100 Km/sec Tacc~109 yr.. negligible Metal systems associated to damped Ly:vacc~3-400 Km/sec Tacc~108BUT hundreds systems-statistically level out Different from the maser and radio-galaxy case… Calls for many line of sight CODEX 2006 - LP

  21. CODEX 2006 - LP

  22. PECULIAR MOTIONS: Simulations Detailed, state of the art hydrodynamical simulations confirm that the effects are negligible CODEX 2006 - LP

  23. 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 CODEX 2006 - LP

  24. 3 outstanding projects were selected:- Cosmological variation of the Fine-Structure Constant: CODEX will exceed the accuracy of the OKLO reactor (D/ ~5x 10-9) -Terrestrial planets in extra-solar systems: Radial velocity of earth mass planets, spectroscopy of transits - Primordial nucleosynthesis: probing SBB nucleosynthesis: primordial Li7, Li6/Li7 Beyond expansion…. Many additional applications (as from 8m science..): Asteroseismology, Cosmochronometers, First Stars, Temperature evolution of CMB, Chemical evolution of IGM.. CODEX 2006 - LP

  25. Variability of Physical Constants • 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

  26. ‘Local’ Constraints For 10 Gyr=> Δα/α < 3.8×10-5 Laboratory measurements Δα/α =(+8 ± 8) 10-7 Olive et al. 2004 from meteorites (z~0.4) Oklo (t=1.8 Gyr, Z=0.14)Δα/α 4.510-8Lamoreaux& Torgerson 2004 α was larger in the past CODEX 2006 - LP

  27. Astrophysical Constraints VLT/UVES 23 systems Δα/α=(+0.6±0.6)×10-6Chand et al 2004 Keck/Hires 143 systems Δα/α=(-0.57±0.11)×10-5 Murphy et al 2004 CODEX 2006 - LP

  28. SIDAM Method Δα/α=(+0.4±1.5)×10-6 Levshakov et al. 2004, Quast et al. 2004 • Fujii & Iwamoto 2005 : apparent oscillatory time-dependence • The behavior is produced by the scalar field responsible for the acceleration of the universe CODEX 2006 - LP

  29. Expected Improvement The 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.gBohlin 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

  30. Planets Earth (and other) planets discovered with other techniques need accurate 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: Discover and confirmation of rocky planets 2) Search for long period planets 3) Jupiter mass planets around faint stars CODEX 2006 - LP

  31. Example of an instrument tank: HARPS CODEX 2006 - LP

  32. The HARPS Experience Th-Th < 10 cm/sec O-C < 80 cm/sec CODEX 2006 - LP

  33. The HARPS Experience (cont’d) Harps is finding planets with small O-C, small masses CODEX 2006 - LP

  34. Planets: HARPS Red: Gaseous giant planets Blue: Icy planets Green : Rocky planets New candidate O-C: 1.1 m/sec CODEX 2006 - LP

  35. Planets: low 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 Observe stars that have high probability of hosting earths Follow-up and confirmation of planet candidates discovered by other facilities CODEX 2006 - LP

  36. Jupiters around faint 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

  37. Primordial Nucleosynthesis and the early universe WMAP and BBN : Real Disagreement ? CODEX 2006 - LP

  38. Primordial6Li ? 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. Li6/Li7 Plateau?? Asplund et al. 2005 CODEX 2006 - LP

  39. 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

  40. Interstellar Li (and 7Li/6Li) Knauth Federman Lambert 2003 Mc 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

  41. CODEX design parameters Location Underground in nested stabilized environment Telescope diameter 100 m Feed Coude’ + Fibre or Fibre only Oerall DQE 14% Coude’ + Fibre , 9% Fibre only Entrance aperture 0.65 arcsec (1 arcsec for a 60 m. Tel.) Wavelength range 400 – 680 nm Spectral 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 cm Crossdisperser 5 x VPHG 1500 l/mm 20 x 10 cm Camera 5 x F/1.4-2.8 CCD 5 x 8K x 8K (15 um pixels) No Optimization or trade-off done yet CODEX 2006 - LP

  42. 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

  43. Fiber feed + Pre-slit Entrance aperture 1” on 60 m or 0.65” on 100 m 37 Fibres array, 8 fibres/spectrograph OWL Lightpipe: forming an homogeneously illuminated Slit & scrambling CODEX 2006 - LP

  44. CODEX Unit Spectrograph B. Delabre ESO Light from fibres enters here CODEX 2006 - LP

  45. CODEX laboratory floor plan Underground hall 20 x 30 m; height 8 m 1 K Instrument room 10 x 20 m; height 5 m 0.1 K Instrument tanks, dia. ~ 2.5 x 4 m, 0.01 K Optical bench and detector 0.001 K Control room and aux. equipment (laser) 1 K CODEX 2006 - LP

  46. 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

  47. CODEX @ ELT A visible H-R spectrograph designed to test GR and able to address fundamental questions 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 atVLT CODEX Lab CODEX 2006 - LP

  48. 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

  49. 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

  50. BASIC SPECTROGRAPH REQUIREMENTS 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>1.8 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 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~150000 Such a resolution is challenging for any seeing limited ELT: the final number will be a trade off between size, sky aperture, detector noise… CODEX 2006 - LP

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