New Directions in Observational Cosmology: A New View of our Universe New Directions in...
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New Directions in Observational New Directions in Observational Cosmology: A New View of our Cosmology: A New View of our
UniverseUniverse
Tony TysonUC Davis
Berkeley May 4, 2007
Technology drives the New SkyTechnology drives the New Sky
Microelectronics Software Large Optics Fabrication
Wide+Deep+Fast: EtendueWide+Deep+Fast: Etendue
Primary mirror diameter
Field of view(full moon is 0.5 degrees)
KeckTelescope
0.2 degrees10 m
3.5 degrees
LSST
Relative Survey PowerRelative Survey Power
0
40
80
120
160
200
240
280
320
Ete
nd
ue
(m
2 de
g2 )
LSST PS4 PS1 Subaru CFHT SDSS MMT DESx0.3
4m VST VISTAIR
SNAPx2
15 sec exposures
2000 exposures per field
Large Synoptic Survey Large Synoptic Survey TelescopeTelescope
The LSST optical design: three large The LSST optical design: three large mirrorsmirrors
The telescope design is completeThe telescope design is complete
Altitude over azimuth configuration
Camera andSecondary assembly
Carrousel dome
Finite elementanalysis
The LSST siteThe LSST site
1.5m photometriccalibration telescope
3.2 gigapixel camera3.2 gigapixel camera
Five Filters in stored locationL1 Lens
L2 Lens
ShutterL1/L2 Housing
Camera Housing
L3 Lens
Raft Tower
Filter in light path
Shutter
Filter Changer
Filter Carousel
Manual Changer access port
Back Flange
Filter Changer rail
Camera body with five filters and shutterCamera body with five filters and shutter
Wavefront Sensor Layout
Guide Sensors (8 locations)
Wavefront Sensors (4 locations)
3.5 degree Field of View (634 mm diameter)
Curvature Sensor Side View Configuration
Focal plane2d
40 mm
Sci CCD
The LSST Focal PlaneThe LSST Focal Plane
1E+06
1E+07
1E+08
1E+09
1E+10
1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014
Year
Nu
mb
er
of
pix
els
Pan-STARRS
GAIA (space)SLAC VXD3CFHT & SAO Megacam
LSSTSNAP (space)
ESO omegacam
SDSS
UH4K
NOAO4K
lots of 8K mosaics!
Large CCD mosaicsLarge CCD mosaics
RAFT TOWER
Electronics
Raft Assembly
Flex Cable &
Electronics Cage
Thermal Straps
3 x 3 CCD Sensor Array
SENSOR
4Kx4K Si CCD Sensor
CCD Carrier
Thermal Strap(s)
basic building block: the raft basic building block: the raft towertower
The LSST thick CCD SensorThe LSST thick CCD Sensor
16 segments/CCD200 CCDs total3200 Total Outputs
LSST ProjectLSST Project
Cerro Pachón2006 Site Selection
Construction Proposals
(NSF and DOE)
2007-2009 Complete Engineering
2010-2015 Construction
2015 Commissioning
Milestones and Schedule
Partnership of government Partnership of government (NSF and DOE) and private (NSF and DOE) and private support.support.
The Data ChallengeThe Data Challenge
~2 Terabytes per ~2 Terabytes per hour that must hour that must be mined in real be mined in real time.time.
More than 10 More than 10 billion objects billion objects will be monitored will be monitored for important for important variations in real variations in real time.time.
Knowledge Knowledge extraction in real extraction in real time. time.
The LSST Corporation has 21 members The LSST Corporation has 21 members
Brookhaven National Laboratory California Institute of TechnologyColumbia UniversityGoogle, 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 UniversityThe University of ArizonaUniversity of California at Davis University of California at Irvine University of Illinois at Urbana-Champaign University of Pennsylvania University of Washington
LSST imaging & operations simulationsLSST imaging & operations simulations
Sheared HDF raytraced + perturbation + atmosphere + wind + optics + pixel
LSST Operations, including real weather data: coverage + depth
Performance verification using Subaru 15 sec imagingPerformance verification using Subaru 15 sec imaging
Figure : Visits numbers per field for the 10 year simulated survey
Photometric RedshiftsPhotometric Redshifts
• 4 billion galaxies with redshifts4 billion galaxies with redshifts• Time domain: Time domain: 100,000 asteroids100,000 asteroids 1 million supernovae1 million supernovae 1 million lenses1 million lenses new phenomenanew phenomena
LSST survey of 20,000 sq LSST survey of 20,000 sq degdeg
LSST Science Charts New LSST Science Charts New TerritoryTerritory
Probing Dark MatterAnd Dark Energy Mapping the Milky Way
Finding Near Earth Asteroids
3-D Mass Tomography3-D Mass Tomography
2x2 degree mass map from Deep Lens Survey
Resolving galaxiesResolving 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 = 0.5 – 3.0 for 23-25 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
Comparing HST with SubaruComparing HST with Subaru
ACS: 34 min (1 orbit)PSF: 0.1 arcsec (FWHM)
2 arcmin
Comparing HST with SubaruComparing HST with Subaru
Suprime-Cam: 20 minPSF: 0.52 arcsec (FWHM)
DSS: digitized photographic DSS: digitized photographic platesplates
On
e q
ua
rte
r th
e d
iam
eter
of
the
mo
on
Sloan Digital Sky SurveySloan Digital Sky Survey
Deep Lens SurveyDeep Lens Survey
Massively Parallel Massively Parallel AstrophysicsAstrophysics
• Dark matter/dark energy via weak lensingDark matter/dark energy via weak lensing• Dark energy via baryon acoustic oscillations Dark energy via baryon acoustic oscillations • Dark energy via supernovaeDark energy via supernovae• Galactic Structure encompassing local groupGalactic Structure encompassing local group• Dense astrometry over 20000 sq.deg: rare moving objectsDense astrometry over 20000 sq.deg: rare moving objects• Gamma Ray Bursts and transients to high redshiftGamma Ray Bursts and transients to high redshift• Gravitational micro-lensingGravitational micro-lensing• Strong galaxy & cluster lensing: physics of dark matterStrong galaxy & cluster lensing: physics of dark matter• Multi-image lensed SN time delays: separate test of Multi-image lensed SN time delays: separate test of
cosmologycosmology• Variable stars/galaxies: black hole accretionVariable stars/galaxies: black hole accretion• QSO time delays vs z: independent test of dark energyQSO time delays vs z: independent test of dark energy• Optical bursters to 25 mag: the unknownOptical bursters to 25 mag: the unknown• 5-band 27 mag photometric survey: unprecedented 5-band 27 mag photometric survey: unprecedented
volumevolume• Solar System Probes: Earth-crossing asteroids, Comets, Solar System Probes: Earth-crossing asteroids, Comets,
TNOsTNOs
Key LSST Mission: Dark Key LSST Mission: Dark EnergyEnergy
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)
Critical IssuesCritical Issues
WL shear reconstruction errors Show control to better than required precision Show control to better than required precision
using existing new facilitiesusing existing new facilities Photometric redshift errors
Develop robust photo-z calibration planDevelop robust photo-z calibration plan Undertake world campaign for spectroscopyUndertake world campaign for spectroscopy ()
Photometry errors Develop and test precision flux calibration Develop and test precision flux calibration
techniquetechnique
Distinguishing DE theoriesDistinguishing DE theories
Zhan/0605696
Dark Energy Precision vs timeDark Energy Precision vs time
CombinedCombinedSeparate DE ProbesSeparate DE Probes
Mass in CL0024LSST will constrain the nature of dark matterLSST will constrain the nature of dark matter
Mass in CL0024LSST will measure total neutrino massLSST will measure total neutrino mass
LSST WL+BAO+P(k) + Planck
LSST Science CollaborationsLSST 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)
http://www.lsst.org
LSST Ranked High PriorityLSST 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
DLS
DS
= 4GM/bc2
b
DLS
DS4GM/bc2
sheared image
shear
Gravity & Cosmology change the growth rate of mass structureCosmology changes
geometric distance factors
Cosmic shear vs redshiftCosmic shear vs redshift
Shear TomographyShear Tomography
Shear spatial power spectra at redshifts to z Shear spatial power spectra at redshifts to z 2. 2.
z
z
0.01
0.001
Ne
ede
d sh
ear sen
sitivity
Linear regime Non-linear regime
ΛCDM
Cosmology Fit Region
Residual shear correlationResidual shear correlation
Cosmic shear signalTest 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.
Compare with expected cosmic shear signal.
Conclusion: 200 exposures per sky patch will yield negligible PSF induced shear systematics. Wittman (2005)
Stars
• Characteristic Characteristic oscillations in oscillations in the CMB the CMB powerpower
WMAP reveals a picture of the fireball at the moment of decoupling: redshift z = 1080
Tem
pera
ture
Pow
er
Angular scale
Cosmic Microwave Cosmic Microwave BackgoundBackgound
RS~140 Mpc
Standard Ruler
Two Dimensions on the Sky Angular Diameter Distances
Three Dimensions in Space-Time Hubble Parameter
Baryon Acoustic OscillationsBaryon Acoustic Oscillations
CMB (z = 1080) BAO (z < 3)