Dark Energy Survey

Dark Energy SurveyDark Energy SurveyDark Energy SurveyDark Energy Survey

The DES CollaborationJosh Frieman, Ofer Lahav, JW

The DES CollaborationJosh Frieman, Ofer Lahav, JW

Jochen Weller

EDEN in ParisDecember, 7th-9th

The DES CollaborationThe DES CollaborationThe DES CollaborationThe DES CollaborationFermilab: J. Annis, H. T. Diehl, S. Dodelson, J. Estrada, B. Flaugher, J. Frieman, S. Kent, H. Lin, P. Limon, K. W. Merritt, J. Peoples, V. Scarpine, A. Stebbins, C. Stoughton, D. Tucker, W. WesterUniversity of Illinois at Urbana-Champaign: C. Beldica, R. Brunner, I. Karliner, J. Mohr, R. Plante, P. Ricker, M. Selen, J. ThalerUniversity of Chicago: J. Carlstrom, S. Dodelson, J. Frieman, M. Gladders, W. Hu, S. Kent, A. Kravtsov, E. Sheldon, R. Wechsler Lawrence Berkeley National Lab: G. Aldering, N. Roe, C. Bebek, M. Levi, S. Perlmutter NOAO/CTIO: T. Abbott, C. Miller, C. Smith, N. Suntzeff, A. WalkerInstitut d'Estudis Espacials de Catalunya: F. Castander, P. Fosalba, E. Gaztañaga, J. Miralda-EscudeInstitut de Fisica d'Altes Energies: E. Fernández, M. MartínezUniversity College London: O. Lahav, P. Doel, M. Barlow, S. Bridle, S. Viti, S. Warwick, J. Weller University of Cambridge: G. Efstathiou, R. McMahon, W. Sutherland University of Edinburgh: J. Peacock University of Portsmouth: R. NicholUniversity of Michigan: R. Bernstein, B. Bigelow, M. Campbell, A. Evrard, D. Gerdes, T. McKay, M. Schubnell, G. Tarle, M. Tecchio

Jochen Weller


Dark Energy: Dark Energy: Stress Energy vs. Modified GravityStress Energy vs. Modified Gravity

Stress-Energy: G = 8G [T(matter) + T(dark energy)]

Gravity: G + f(g) = 8G T(matter)

Key Experimental Questions:• Is DE observationally distinguishable from a cosmological constant, for which T (vacuum) = g/8G? To decide, measure w: what precision is needed? • Can we distinguish between gravity and stress-energy?• If w 1, it likely evolves: how well can/must we measure dw/da to make progress in fundamental physics?

Jochen Weller


Probing Dark Energy withProbing Dark Energy with

the Expansion History of the Universethe Expansion History of the Universe

• comoving distance

• standard candles

• standard rulers

• volume factor

• growth of structure depends on H(z) probed with power spectrum

Jochen Weller


The Dark Energy SurveyThe Dark Energy Survey Study Dark Energy using 4 complementary* techniques: Cluster counts & clustering Weak lensing Galaxy angular clustering SNe Ia distances

• Two multiband surveys: 5000 deg2 g, r, i, z 40 deg2 repeat (SNe)

• Build new 3 deg2 camera Construction 2005-2009 Survey 2009-2014 (525 nights)

Study Dark Energy using 4 complementary* techniques: Cluster counts & clustering Weak lensing Galaxy angular clustering SNe Ia distances

• Two multiband surveys: 5000 deg2 g, r, i, z 40 deg2 repeat (SNe)

• Build new 3 deg2 camera Construction 2005-2009 Survey 2009-2014 (525 nights)

Blanco 4-meter at CTIO

*in systematics & in cosmological parameter degeneracies*geometric+growth: test Dark Energy vs. Gravity

Jochen Weller


The DES TelescopeThe DES TelescopeThe DES TelescopeThe DES Telescope NOAO/CTIO 4m Blanco telescope

• 1970 era, equatorial mount• An existing, working telescope• On-going studies: finite element analysis, laser metrology, PSF pattern modeling

Solid primary mirror• 50cm thick Cervit, 15 tons

Mechanical mirror support system• radial: purely mechanical• axial: 3 load cell hard points + controllable

support cells Primary cage

• DES will replace entire cage• will have radial (alignment) movement

Cerro Tololo• site delivers median 0.65” Sept-Feb• current Mosaic II+telescope delivers median 0.9”

Sept-Feb

NOAO/CTIO 4m Blanco telescope• 1970 era, equatorial mount• An existing, working telescope• On-going studies: finite element analysis, laser metrology, PSF pattern modeling

Solid primary mirror• 50cm thick Cervit, 15 tons

Mechanical mirror support system• radial: purely mechanical• axial: 3 load cell hard points + controllable

support cells Primary cage

• DES will replace entire cage• will have radial (alignment) movement

Cerro Tololo• site delivers median 0.65” Sept-Feb• current Mosaic II+telescope delivers median 0.9”

Sept-Feb

24 Radial Supports

3 Hard Points

33 Pressure Pads

Abbott, Walker, Peoples, Bernstein...

Jochen Weller


Dark Energy Survey InstrumentDark Energy Survey InstrumentDark Energy Survey InstrumentDark Energy Survey Instrument

3.5 meters

Camera

Filters

Optical Lenses

ScrollShutter

1.5 meters

New Prime Focus Cage, Camera, and Corrector for the Blanco 4m Telescope 500 Megapixels, 0.27”/pixel Project cost: ~20M$ (incl. labor)

Jochen Weller


Photometric RedshiftsPhotometric RedshiftsPhotometric RedshiftsPhotometric Redshifts

• Measure relative flux in four filters griz: track the 4000 A break

• Estimate individual galaxy redshifts with accuracy (z) ~ 0.1 (~0.02 for clusters)

• This is sufficient for Dark Energy probes (biases ?)

• Note: good detector response in z band filter needed to reach z~1.3

0

10

20

30

40

50

60

70

80

90

100

300 400 500 600 700 800 900 1000 1100

Wavelength (nm)

Quantum Efficiency (%)

Thinned CCD Deep Depleted LBNL high resistivity

Seeing IssuesSeeing IssuesSeeing IssuesSeeing Issues

‘Seeing’ is due to intrinsic PSF, telescope flexure, atmospheric turbulence the dome,…

Recent records for medians @ CTIO site 0.67 arcsec during Sep-Feb;

@ Blanco Mosaic II 0.9 arcsec

Efforts to reduce it!

‘Seeing’ is due to intrinsic PSF, telescope flexure, atmospheric turbulence the dome,…

Recent records for medians @ CTIO site 0.67 arcsec during Sep-Feb;

@ Blanco Mosaic II 0.9 arcsec

Efforts to reduce it!

* Seeing affects the number of galaxy images ‘usable’ for lensing

Jochen Weller


Improved Optical Image Quality of DECAM vs. Mosaic IIImproved Optical Image Quality of DECAM vs. Mosaic II

•Focus and wavefront sensor chips: actively correct focus and collimation

•New optical corrector designed to deliver good image quality

over FOV and won’t be cracked

•Reduce power dissipation in vicinity of camera

•Precision focal plane alignment

•Model and track PSF vs. focal plane position, zenith angle (refraction),

defocus, decollimation

•Typical object will be imaged ~24 times in riz and enough

survey time to use best conditions for WL

Gladders, Kent

Jochen Weller


DES Area and Depth: Synergy with DES Area and Depth: Synergy with South Pole TelescopeSouth Pole Telescope

South Pole Telescope: • 4000 sq. deg. survey • Detect ~20,000 clusters through Sunyaev-Zel’dovich effect

• Dark Energy Survey: measure photometric redshifts for these clusters to z ~ 1-1.3: griz ~ 24

Galactic Dust Map

Jochen Weller


10m South Pole Telescope (SPT)and 1000 Element Bolometer Array

Low noise, precision telescope•1.0 arcminute • 3 levels of shielding

- ~1 m radius on primary- inner moving shields- outer fixed shields

SZE and CMB Anisotropy - 4000 sq deg SZE survey - deep CMB anisotropy fields - deep CMB Polarization fields

1000 Element Bolometer Array - 3 to 4 interchangeable bands (90) 150, 250 & 270 GHz

PeopleCarlstrom (UC)Holzapfel (UCB)Lee (UCB,LBNL)Leitch (UC)Meyer (UC)Mohr (U Illinois)Padin (UC)Pryke (UC)Ruhl (CWRU)Spieler (LBNL)Stark (CfA)

Jochen Weller


Cluster Redshift Distribution and Cluster Redshift Distribution and Dark EnergyDark Energy

Cluster Redshift Distribution and Cluster Redshift Distribution and Dark EnergyDark Energy

Raising w at fixed DE:

decreases volume surveyed

Volume effect Growth effect

decreases growth rate of density perturbations

Constraints:

€

dN(z)

dzdΩ=

dV

dz dΩn z( )

€

dA ∝dz'E (z')0

z∫

Mohr

Jochen Weller


Cosmology with ClustersCosmology with ClustersCosmology with ClustersCosmology with Clusters

Requirements1. Quantitative understanding of the

formation of dark matter halos in an expanding universe

2. Clean way of selecting a large number of massive dark matter halos (galaxy clusters) over a range of redshifts

3. Redshift estimates for each cluster (photo-z’s adequate)

4. Observables that can be used as mass estimates at all redshifts

Requirements1. Quantitative understanding of the

formation of dark matter halos in an expanding universe

2. Clean way of selecting a large number of massive dark matter halos (galaxy clusters) over a range of redshifts

3. Redshift estimates for each cluster (photo-z’s adequate)

4. Observables that can be used as mass estimates at all redshifts

Sensitivity to Mass

€

dN(z)dzdΩ

= cH z( )

dA2 1+z( )2 dM

dnM,z( )

dMf M( )

0

∞∫Jenkins, et al

SZE vs. Cluster Mass: SimulationsSZE vs. Cluster Mass: SimulationsSZE vs. Cluster Mass: SimulationsSZE vs. Cluster Mass: Simulations

Motl, et al

Integrated SZE flux decrement insensitive to gas dynamics in the cluster core

Jochen Weller


Flux decrement vs. mass andFlux decrement vs. mass andredshiftredshift

Nagai - astro-ph/051220811 clusters; ART (Kravtsov)

blue: star formation, metal enrichmentand thermal feedback due to the supernovae type II and type Ia, self-consistent advection of metals, metallicity dependent radiative cooling and UV heating due to cosmological ionizing background

shifted for clarity

Jochen Weller


DES Cluster Photometric Redshift SimulationsDES Cluster Photometric Redshift Simulations

(z)~0.02to z=1.3

Jochen Weller


Lima and HuHu

wa

-1

1

Self-calibration with Clustering

See also Battye and Weller,Majumdar & Mohr

Jochen Weller


Mapping the Massin a Cluster of Galaxiesvia WeakGravitationalLensing(no arcs)

Abell 3667

CTIO 4-m imageJoffre, etal

Jochen Weller


Calibration of the Mass - TemperatureCalibration of the Mass - TemperatureRelation with Weak LensingRelation with Weak Lensing

(Dodelson & Weller, in preparation)

Jochen Weller


Observer

Overdensities

Background sources

Statistical measure of shear pattern, ~1% distortion. Radial distances, r(z), depends on geometry of Universe. Dark Matter pattern & growth depends on cosmological parameters.

Cosmic ShearCosmic Shear

Lensing TomographyLensing TomographyLensing TomographyLensing Tomography

Shear at z1 and z2 given by integral of growth function &

distances over lensing mass distribution. Shear at z1 and z2 given by integral of growth function &

distances over lensing mass distribution.

z1

z2

zl1

lensing mass

zl2

Jochen Weller


DES Weak Lensing Tomography DES Weak Lensing Tomography

• Measure shapes for ~300 million

source galaxies with z = 0.7

• Shear-shear & galaxy-shear

correlations probe distances &

growth rate of perturbations

• Requirements: Sky area, depth, photo-z’s, image quality & stability

• Measure shapes for ~300 million

source galaxies with z = 0.7

• Shear-shear & galaxy-shear

correlations probe distances &

growth rate of perturbations

• Requirements: Sky area, depth, photo-z’s, image quality & stability

Huterer

Jochen Weller


DESgriz filters

10 Limiting Magnitudes g 24.6 r 24.1 i 24.0 z 23.9

+2% photometric calibrationerror added in quadrature

(z)~0.1 to z~1.3

Galaxy Photo-z SimulationsGalaxy Photo-z Simulations

Cunha, Lima, Oyaizu, Lin, Frieman, Collister, Lahav

Jochen Weller


DES + VISTAgriz+YJHKs filters10 Limiting Magnitudes Y 22.45 J 22.15 H 21.65 Ks 21.15

(~15 min exposures)

(z) ~ 0.07

Galaxy Photo-z SimulationsGalaxy Photo-z Simulations

Jochen Weller


Ma, Hu, & Huterer (2005)

Impact of Uncertainty in Photo-z Error Distribution on Impact of Uncertainty in Photo-z Error Distribution on ww

Spectroscopic

`Training Set’

needed to measure

photo-z error

distribution to

required accuracy:

N ~ 50,000 - 100,000

Jochen Weller


DES Supernovae DES Supernovae Repeat observations of 40 deg2 , 10% of survey

time

• ~1900 well-measured riz SN Ia lightcurves, 0.25 < z < 0.75

Repeat observations of 40 deg2 , 10% of survey time

• ~1900 well-measured riz SN Ia lightcurves, 0.25 < z < 0.75

SN constraints `orthogonal’to the other methods

z=0.1 bins assumed

Huterer

Jochen Weller


Forecast DES Constraints on Forecast DES Constraints on ww Forecast DES Constraints on Forecast DES Constraints on wwKey Priors: Constant w, spatially flat, power-law, adiabatic, Gaussian initial fluctuations,w/ CDM, massless neutrinos Marginalize over 3-parameter SZ(M) with no scatter 5 halo model bias parameters per photo-z bin WL: l<1000 SN: sys. error floor, (m)=0.25, 300 low-z SNe to anchor Hubble diagram

Key Priors: Constant w, spatially flat, power-law, adiabatic, Gaussian initial fluctuations,w/ CDM, massless neutrinos Marginalize over 3-parameter SZ(M) with no scatter 5 halo model bias parameters per photo-z bin WL: l<1000 SN: sys. error floor, (m)=0.25, 300 low-z SNe to anchor Hubble diagram

Method/priors Uniform WMAP Planck

Cluster abundance:5 SZ clusters w/ WL mass

calibration(no clustering information)

0.09 0.08 0.03

shear-shear (SS)galaxy-shear (GS) + galaxy-

galaxy(GG)SS+GS+GGSS+bispectrum

0.150.080.030.07

0.050.050.030.03

0.050.050.020.03

Galaxy angular clustering 0.36 0.20 0.11

Supernovae Ia 0.34 0.15 0.04

Flaugher, Walker, Abbott...

Jochen Weller


DES+SPT next step in dark energy measurements:• Will measure constant w to ~ 0.02–0.1 statistical accuracy* using

multiple complementary probes, and begin to constrain dw/dz

• Survey strategy delivers substantial DE science after 2 years

• Scientific and technical precursor to the more ambitious and costly Dark Energy projects to follow: LST and JDEM

• DES in unique position to synergize with SPT on this timescale

*accuracy on each probe separately, with Planck priors

Dark Energy: 2009-2014Dark Energy: 2009-2014

Date post:	14-Jan-2016
Category:	Documents
Upload:	boris
View:	33 times
Download:	2 times

Dark Energy Survey

Documents