New Directions in Observational Cosmology: A New View of our Universe Tony Tyson UC Davis

Transcription

1 New Directions in Observational Cosmology: A New View of our Universe Tony Tyson UC Davis Berkeley May 4, 2007

2 Technology drives the New Sky! Microelectronics! Software! Large Optics Fabrication

3 Wide+Deep+Fast: Etendue Primary mirror diameter Field of view (full moon is 0.5 degrees) 10 m 0.2 degrees Keck Telescope 3.5 degrees LSST

4 Relative Survey Power 320 Etendue (m 2 deg 2 ) sec exposures 2000 exposures per field 40 0 LSST PS4 PS1 Subaru CFHT SDSS MMT DES x0.3 4m VST VISTA IR SNAP x2

5 Large Synoptic Survey Telescope

6 The LSST optical design: three large mirrors

7 The telescope design is complete Camera and Secondary assembly Carrousel dome Finite element analysis Altitude over azimuth configuration

8 The LSST site 1.5m photometric calibration telescope

9 3.2 gigapixel camera Raft Tower L3 Lens Shutter L1/L2 Housing L1 Lens Five Filters in stored location Camera Housing L2 Lens Filter in light path

10 Camera body with five filters and shutter Back Flange Filter Changer rail Filter Carousel Shutter Manual Changer access port Filter Changer

11 The LSST Focal Plane Wavefront Sensors (4 locations) Guide Sensors (8 locations) Wavefront Sensor Layout 2d Focal plane Sci CCD 40 mm Curvature Sensor Side View Configuration 3.5 degree Field of View (634 mm diameter)

12 Large CCD mosaics 1E+10 SNAP (space) Pan-STARRS LSST Number of pixels 1E+09 1E+08 SLAC VXD3 UH4K CFHT & SAO Megacam SDSS ESO omegacam lots of 8K mosaics! GAIA (space) 1E+07 NOAO4K 1E Year

13 basic building block: the raft tower 3 x 3 CCD Sensor Array Raft Assembly 4Kx4K Si CCD Sensor CCD Carrier Thermal Strap(s) SENSOR Flex Cable & Thermal Straps Electronics Cage Electronics RAFT TOWER

14 The LSST thick CCD Sensor 16 segments/ccd 200 CCDs total 3200 Total Outputs

15 LSST Project Partnership of government (NSF and DOE) and private support. Milestones and Schedule Cerro Pachón 2006 Site Selection Construction Proposals (NSF and DOE) Complete Engineering Construction 2015 Commissioning

16 The Data Challenge! ~2 Terabytes per hour that must be mined in real time.! More than 10 billion objects will be monitored for important variations in real time.! Knowledge extraction in real time.

17 The LSST Corporation has 21 members Brookhaven National Laboratory California Institute of Technology Columbia University Google, Inc. Harvard-Smithsonian Center for Astrophysics Johns Hopkins University Kavli Institute for Particle Astrophysics and Cosmology - Stanford University Las Cumbres Observatory Global Telescope Network, Inc. Lawrence Livermore National Laboratory National Optical Astronomy Observatory Princeton University Research Corporation Stanford Linear Accelerator Center The Pennsylvania State University Purdue University The University of Arizona University of California at Davis University of California at Irvine University of Illinois at Urbana-Champaign University of Pennsylvania University of Washington

18 LSST imaging & operations simulations Sheared HDF raytraced + perturbation + atmosphere + wind + optics + pixel Figure : Visits numbers per field for the 10 year simulated survey LSST Operations, including real weather data: coverage + depth Performance verification using Subaru 15 sec imaging

19 Photometric Redshifts

20 LSST survey of 20,000 sq deg 4 billion galaxies with redshifts Time domain: 100,000 asteroids 1 million supernovae 1 million lenses new phenomena

21 LSST Science Charts New Territory Probing Dark Matter And Dark Energy Mapping the Milky Way Finding Near Earth Asteroids

22 3-D Mass Tomography 2x2 degree mass map from Deep Lens Survey

23 Resolving galaxies A given galaxy at high redshift should appear smaller. But two effects oppose this: cosmological angle-redshift relation, and greater star formation in the past (higher surface brightness). Here are plots of galaxy surface brightness vs radius (arcsec) in redshift bins from z = for apparent mag. At a surface brightness of 28 i mag/sq.arcsec (horizontal dashed line) most galaxies at z<3 are resolved in 0.6 arcsec FWHM seeing (vertical dashed line). HST/ACS GOODS, Ferguson 2007

24 Comparing HST with Subaru ACS: 34 min (1 orbit) PSF: 0.1 arcsec (FWHM) 2 arcmin

25 Comparing HST with Subaru Suprime-Cam: 20 min PSF: 0.52 arcsec (FWHM)

26 One quarter the diameter of the moon DSS: digitized photographic plates

27 Sloan Digital Sky Survey

28 Deep Lens Survey

29 Massively Parallel Astrophysics Dark matter/dark energy via weak lensing Dark energy via baryon acoustic oscillations Dark energy via supernovae Galactic Structure encompassing local group Dense astrometry over sq.deg: rare moving objects Gamma Ray Bursts and transients to high redshift Gravitational micro-lensing Strong galaxy & cluster lensing: physics of dark matter Multi-image lensed SN time delays: separate test of cosmology Variable stars/galaxies: black hole accretion QSO time delays vs z: independent test of dark energy Optical bursters to 25 mag: the unknown 5-band 27 mag photometric survey: unprecedented volume Solar System Probes: Earth-crossing asteroids, Comets, TNOs

30 Key LSST Mission: Dark Energy Precision measurements of all four dark energy signatures in a single data set. Separately measure geometry and growth of dark matter structure vs cosmic time. " Weak gravitational lensing correlations + CMB (multiple lensing probes!) " Baryon acoustic oscillations (BAO) + CMB " Counts of dark matter clusters + CMB " Supernovae to redshift 1 (complementary to JDEM)

31 Critical Issues " WL shear reconstruction errors! Show control to better than required precision using existing new facilities # " Photometric redshift errors! Develop robust photo-z calibration plan #! Undertake world campaign for spectroscopy (#) " Photometry errors! Develop and test precision flux calibration technique #

32 Distinguishing DE theories Zhan /

33 Dark Energy Precision vs time Separate DE Probes Combined

34 LSST will constrain Mass CL0024 the nature of dark matter

35 LSST Mass will measure in CL0024total neutrino mass LSST WL+BAO+P(k) + Planck

36 LSST Science Collaborations 1. Supernovae: M. Wood-Vasey (CfA) 2. Weak lensing: D. Wittman (UCD) and B. Jain (Penn) 3. Stellar Populations: Abi Saha (NOAO) 4. Active Galactic Nuclei: Niel Brandt (Penn State) 5. Solar System: Steve Chesley (JPL) 6. Galaxies: Harry Ferguson (STScI) 7. Transients/variable stars: Shri Kulkarni (Caltech) 8. Large-scale Structure/BAO: Andrew Hamilton (Colorado) 9. Milky Way Structure: Connie Rockosi (UCSC) 10. Strong gravitational lensing: Phil Marshall (UCSB)

37

38 LSST Ranked High Priority NRC Astronomy Decadal Survey NRC New Frontiers in the Solar System NRC Quarks-to-Cosmos SAGENAP Quantum Universe Physics of the Universe Dark Energy Task Force + P5

39 sheared image! = 4GM/bc 2 D S b shear D LS # $ " = D LS D S 4GM/bc 2 Cosmology changes geometric distance factors " Gravity & Cosmology change the growth rate of mass structure

40 Cosmic shear vs redshift

41 Shear Tomography Shear spatial power spectra at redshifts to z % 2. &CDM z=3.2 z= Needed shear sensitivity Cosmology Fit Region Linear regime Non-linear regime

42 Residual shear correlation Test of shear systematics: Use faint stars as proxies for galaxies, and calculate the shear-shear correlation after correcting for PSF ellipticity via a different set of stars. Cosmic shear signal Stars Compare with expected cosmic shear signal. Conclusion: 200 exposures per sky patch will yield negligible PSF induced shear systematics. Wittman (2005)

43 Cosmic Microwave Backgound Characteristic oscillations in the CMB power WMAP reveals a picture of the fireball at the moment of decoupling: redshift z = 1080 Temperature Power $ % Angular scale

44 Baryon Acoustic Oscillations R S ~140 Mpc CMB (z = 1080) BAO (z < 3) Standard Ruler Two Dimensions on the Sky Angular Diameter Distances Three Dimensions in Space-Time Hubble Parameter