Download DoE LPPC 2006

Cluster Cosmology at LPPC
Illuminating Dark Energy with BCS and PISCO
F. William High
Year Grad Student
Harvard Univ Dept of Physics
2nd
Monday, 21 August 2006
Cluster Cosmology
Redshift z:
1+z=
λ(observed) / λ(emitted)
t ~ 14 Gyr
z=0
t ~ 9 Gyr t ~ 7 Gyr
z~½
z~1
t ~ 3 Gyr
z~2
t=0
z=∞
t ~ 1 Gyr
z~6
21 August 2006
Clusters@LPPC
F. William High
Cluster Cosmology: Illuminating Dark
Energy
 Accelerating expansion
 Cluster abundance
versus redshift
 Depends heavily on Λ and
w
Number of
clusters
1/10 of the sky
 Λ: Einstein’s cosmological constant
 w: eqn of state (w = -1)
 Overall normalization
depends on σ8
21 August 2006
Clusters@LPPC
redshift
F. William High
Discovering Clusters
mm-wave
 SZ effect
 APEX, ACT, SPT, …
 Redshift independent
signal in mm
X-ray
21 August 2006
Clusters@LPPC
F. William High
BCS (500 clusters), then PISCO (3000 clusters), then DES (the rest)
21 August 2006
Clusters@LPPC
F. William High
Two Challenges
 Mass of clusters?
 Distance to clusters?
Probability:
Matter evolution:
Observable:
 Solution: BCS
21 August 2006
 Solution: PISCO
Clusters@LPPC
F. William High
BCS
Blanco Cosmology Survey
Pre-SPT
To z ~ 1
Training set for SPT and PISCO
Weak gravitational lensing to calibrate SZ
cluster mass estimator
PI: Joe Mohr (U Illinois)
21 August 2006
Clusters@LPPC
F. William High
PISCO
Parallel Imager for Southern Cosmological
Observations
Dedicated camera to measure redshift of
high-z clusters
Field of view matched to size of high redshift
clusters: 5’ = 1 Mpc at z = ½, clusters are 1-10
Mpc across
Highest possible efficiency broadband
photometer: 4 simultaneous bands
To be mounted on 6.5m Magellan, Chile
21 August 2006
Clusters@LPPC
F. William High
PISCO: Photo-z
LRG
spectrum
 Principle: measure differential
broadband flux (color) of
objects with broad features in
spectrum
 Photo-z gives redshifts (to
10%) from the colors of
luminous red galaxies (LRG)
 Cluster member galaxies have
scatter in redshift at 3% level
 PISCO measures photo-z’s
of all galaxies in a cluster at
once, in a single exposure
21 August 2006
Clusters@LPPC
F. William High
PISCO: Design
Ideal broadband photometer!
Dichroic beamsplitters
define bandpasses
21 August 2006
Clusters@LPPC
F. William High
PISCO: Design
21 August 2006
Clusters@LPPC
F. William High
CC@LPPC Summary
BCS
PISCO
 Use weak gravitational
lensing to calibrate other
cluster mass-observables
 Improve cluster mass
estimation for all future
surveys
 Status: first year data
reduced, ready to do start
WL study in September
21 August 2006
 Characterize DE with
clusters quickly, cheaply,
efficiently
 Can get z’s of all SPT
clusters in 10 nights at
Magellan!
 Status: CCD’s in hand,
CCD control online,
design soon finalized,
Carnegie enthusiastic, …
Clusters@LPPC
F. William High