Slide 1 11 Oct 2008 Dark Energy - Leopoldina Munich Euclid A Space Mission to Map the Dark Universe R. Laureijs (ESA), A. Refregier (CEA), A. Cimatti (Univ. Bologna), on behalf of the (growing) Euclid Community

Slide 2 11 Oct 2008 Dark Energy - Leopoldina Munich Opportunity ESAs Cosmic visions programme has selected a dark energy mission as a possible candidate for a launch slot in Euclid will address the outstanding questions in cosmology –Nature of the Dark Energy –Nature of the Dark Matter –Initial conditions –Theory of Gravity

Slide 3 11 Oct 2008 Dark Energy - Leopoldina Munich Outline Euclid selection and concept Science Objectives Mission Payload Status and programmatics

Slide 4 11 Oct 2008 Dark Energy - Leopoldina Munich Selection of ESAs Dark Energy Mission Dark energy is recognized by the ESA Advisory Structure as the most timely and important science topic among the M mission proposals and is therefore recommended as the top priority. Dark energy was addressed by two Cosmic Visions M proposals: –DUNE (PI: A. Refregier-CEA Saclay) – All sky visible and NIR imaging to observe weak gravitational lensing –SPACE (PI: A. Cimatti – Bologna Univ.) – All sky NIR imaging and spectroscopy to detect baryonic acoustic oscillations patterns An Advisory Team recommended a concept for a single M-Class Dark Energy Mission

Slide 5 11 Oct 2008 Dark Energy - Leopoldina Munich Named in honour of the pioneer of geometry Euclid will survey the entire extra-galactic sky ( deg 2 ) to simultaneously measure its two principal dark energy probes: –Weak lensing: Diffraction limited galaxy shape measurements in one broad visible R/I/Z band.AB=24.5 mag Redshift determination by Photo-z measurements in 3 NIR bands (Y,J,H) to H(AB)=24 mag, 5σ point source –Baryonic Acoustic Oscillations: Spectroscopic redshift survey for 33% of all galaxies brighter than H(AB)=22 mag, σ z <0.001 With constraints: –Aperture: max 1.2 m diameter –Limited number of NIR detectors –Mission duration: max ~5 years Euclid’s Concept

Slide 6 11 Oct 2008 Dark Energy - Leopoldina Munich WL: shear measurement In Space: availability of small and stable PSF:  larger number of resolved galaxies  reduced systematics weak lensing shear space ground Typical cosmic shear is ~ 1%, and must be measured with high accuracy

Slide 7 11 Oct 2008 Dark Energy - Leopoldina Munich WL: Obtaining NIR photometric redshifts z spec Will need redshifts for 10 9 galaxies − photo-z error possible to ~5% in combination with ground-based Pan-Starrs survey etc. But need 1-2 micron IR for z >1 − impossible from ground (sky brightness) Need >10 5 spectroscopic redshifts for calibration z photo OPT OPT+IR Abdalla et al.

Slide 8 11 Oct 2008 Dark Energy - Leopoldina Munich NIR Spectroscopy: DMD based multi-object slit spectroscopy DMD= Digital Micro-mirror Device

Slide 9 11 Oct 2008 Dark Energy - Leopoldina Munich Euclid’s Primary Science Objectives IssueTarget Dark EnergyMeasure the DE parameters w n and w a to a precision of 2% and 10%, respectively, using both expansion history and structure growth. Dark MatterTest the Cold Dark Matter paradigm for structure formation, and measure the sum of the neutrino masses to a precision better than 0.04eV when combined with Planck The seeds of cosmic structures Improve by a factor of 20 the determination of the initial condition parameters compared to Planck alone Test of General Relativity Distinguish General Relativity from the simplest modified-gravity theories, by measuring the growth factor exponent γ with a precision of 2%

Slide Oct 2008 Dark Energy - Leopoldina Munich Other Probes Besides its two principal dark energy probes, Euclid will obtain information of: –Galaxy clustering: the full power spectrum P(k) Determination of the expansion history and the growth factor using all available information in the amplitude and shape of P(k) –Redshift-space distortions: Measures the growth rate (derivative of growth factor) from the redshift distortions produced by peculiar motions. –Number density of clusters Measures a combination of of growth factor (from number of clusters) and expansion history (from volume evolution). –Integrated Sachs-Wolfe Effect Measures the expansion history and the growth.

Slide Oct 2008 Dark Energy - Leopoldina Munich Why is the combined mission so powerful The weak lensing will reconstruct directly the distribution of the dark matter and the evolution of the growth rate of dark matter perturbations with redshift. The baryon acoustic oscillations act as standard rods,determine P(k) and provide a measure of H(z) and hence w(z). They also map out the evolution of the baryonic component of the Universe. Together, these enable many systematic effects to be controlled – for example, intrinsic alignments in weak lensing, bias factors in baryon acoustic oscillations. Both act as independent dark energy probes. If they differ, we learn about modifications to GR. High precision and accurate DE measurements require a combination of two or more probes. Euclid aims at the most promising dark energy probes: an all sky survey of weak lensing and galaxy redshifts.

Slide Oct 2008 Dark Energy - Leopoldina Munich Planck prior is used. The errors are calculated using Fisher matrices using a w(a)=w 0 +(1-a)w a model, hence the caveat that the errors shown here are correlated (from J. Weller). Predicted redshift dependence of w(z) errors

Slide Oct 2008 Dark Energy - Leopoldina Munich Euclid’s Legacy  Visible/NIR imaging survey: morphologies and vis/NIR colors for billions of galaxies out to z~2, 3D dark matter map  Spectroscopic survey: 3D map of the luminous matter distribution, spectra of ~200 million galaxies to z~2  Deep survey: infrared imaging to H(AB)=26 and spectroscopy to H(AB)=24, galaxies with 2 7 and up to z~10 can be colour-selected from the Y,J,H colours  Impossible to reach from the ground

Slide Oct 2008 Dark Energy - Leopoldina Munich Mission profile (1) CDF study case Launcher SOYUZ ST 2-1b from Kourou Launch mass margin: 28% Sky coverage sq. degrees extragalactic sky Two galactic polar caps, latitude  b  > 30° Solar aspect angle adjusted for scan optimisation

Slide Oct 2008 Dark Energy - Leopoldina Munich Mission profile (2) Spacecraft Body-mounted solar array, 3-axis stabilised platform Relative pointing error: 25 marcsec with FGS Attitude control with proportional cold gas system Hydrazine propulsion for orbit manoeuvres Satellite mass (wet): 1540 kg Orbit Large amplitude Lissajous around SEL2 Free insertion, 30-day transfer time DeltaV budget: 50 m/s Orbit maintenance: 1 manoeuvre/month Communications Housekeeping in X-band, Science telemetry in K-band 700 Gbits/day after compression 4 hours/day link with Cebreros 35-m antenna Mission duration: 5 years including commissioning First Assessment: All mission elements are standard and feasible

Slide Oct 2008 Dark Energy - Leopoldina Munich Payload (1) Data-handling Spectroscopy target selection Full frame images lossless compression NIR detectors noise reduction Power One power conditioning unit per instrument Total payload: ~200 W peak Telescope 1.2 meter Korsch TMA Thermal Passive cooling CCDs at T=170 K NIR detectors at T=140 K

Slide Oct 2008 Dark Energy - Leopoldina Munich Payload (2) Observation mode -Step and stare case fully investigated -Continuous scanning requires a de-scan mechanism for infrared channels Payload mass ~660 kg, including 300 kg for the 3 instruments NIS VIS NIP 3 instruments Visible Imaging VIS: 0.21” PSF at 800 nm, 0.1”/pixel NIR Photometry NIP: 0.33”/pixel, 3 bands (Y, J, H) NIR Spectroscopy NIS:  m, set of 3 cameras, multi-objects (micro-mirror array), R~400 Each of them with a field of view ~0.48 deg 2 First Assessment: High technological readiness with some level of complexity

Slide Oct 2008 Dark Energy - Leopoldina Munich Status and programmatics Two independent industrial studies have started on the system (including mission and payload): 1 year study until Sep 2009 Two payload consortia: –Euclid Imaging Channels (EIC), headed by A. Refregier (CEA, France) –Euclid Near-Infrared Spectrometer (ENIS), headed by A. Cimatti (Univ Bologna, Italy) 10 month study until Aug 2009 DMD flight qualification study started Overall coordination by ESA and the Science Study Team Down selection in 2009 –Definition phase –Implementation phase