CLASH:
Cluster Lensing And Supernova survey with Hubble
An HST Multi-Cycle Treasury Program designed to place new constraints on the
fundamental components of the cosmos: dark matter, dark energy, and baryons.
Use galaxy clusters as cosmic lenses to reveal dark matter and magnify distant galaxies.
WFC3 (UVIS + IR) and ACS will be used to image 25 relaxed clusters in 14 passbands
from 0.22 - 1.6 microns. Total exposure time per cluster: 20 orbits.
Clusters chosen based on their smooth and symmetric x-ray surface brightness profiles;
simpler lenses to model and minimizes lensing bias. All clusters have T > 5 keV with
masses ranging from ~5 to ~30 x 1014 M . . Redshift range covered: 0.18 < z < 0.90.
Multiple epochs enable a z > 1 SN search in the surrounding field (where lensing
magnification is low).
Marc Postman (P.I.)
Megan Donahue
Dani Maoz
Stella Seitz
Matthias Bartelmann
Rosa Gonzales-Delgado
Elinor Medezinski
Keiichi Umetsu
Narciso Benitez
Holland Ford
Leonidas Moustakas
Arjen van der Wel
Larry Bradley
Leopoldo Infante
Eniko Regoes
Wei Zheng
Tom Broadhurst
Daniel Kelson
Adam Riess
Adi Zitrin
Dan Coe
Ofer Lahav
Piero Rosati
CLASH: An HST Multi-Cycle Treasury Program
Deep HST image of
massive cluster
R
Einstein
NArcs
R
WHERE
IS THE RESULTING
SPATIAL RESOLUTION OF THE
DARK MATTER MAP
Simulation of dark matter around a forming cluster (Springel et al. 2005)
CLASH: An HST Multi-Cycle Treasury Program
Both strong AND weak lensing measurements are needed to make
accurate constraints on the DM profile.
CLASH data will allow us to definitively derive the representative
equilibrium mass profile shape and robustly measure the cluster
DM mass concentrations and their dispersion as a function of
cluster mass and their evolution with redshift.
CLASH: An HST Multi-Cycle Treasury Program
Abell 209
MACS 0329-0211
RXJ 0647+7015
Abell 383 core
MACS 0717+3745
RXJ 1347-1145
Abell 611
Abell 963
Abell 2261
CLJ1226+3332
MACS 0744+3927
MACS 1115+0129
MACS 1149+2223
MACS 1206-0847
RXJ 1423+2404
MS-2137 core
RXJ 1702+3536
RXJ 2129+0005
Cutouts of Chandra images of 18 of the 25 CLASH clusters from ACCESS database
CLASH: An HST Multi-Cycle Treasury Program
28.5'
3.4'
RXJ1347-1145 (z = 0.45)
SUPRIME CAM Image
ACS/WFC Image
CLASH: An HST Multi-Cycle Treasury Program
Why 14 filters?
Mag distn of multiply lensed arcs in A1689 and CL0024
Will yield
photometric
redshifts with
rms error of
~2% x (1 + z) for
sources down to
~26 AB mag.
With 14 filters, 80% photo-z completeness is reached at AB ~26 mag and
useful redshift information is available for ~5 times as many lensed objects
than would be possible solely from spectroscopically acquired redshifts.
CLASH: An HST Multi-Cycle Treasury Program
The blue and red solid curves show the expected
number of z=8 and z=10 galaxies, respectively, to be
discovered behind our 25 clusters as a function of
magnitude in the detection band (F110W at z=8 and
F140W at z=10).
A significant advantage of searching for high-z
objects behind strongly lensing clusters is that the
lens model can also be used to discriminate between
highly-reddened objects and truly distant, high-z
objects as the projected position of the lensed image
is a strong function of the source redshift.
The parallel fields of the cluster survey
provide the means to find ~10 SNe Ia at
z >1 and would double the number of
known SNe Ia at z > 1.2 (and
potentially more, the precise number
depending on the assumed time delay).
CLASH is done
CLASH: An HST Multi-Cycle Treasury Program
WFC3
Parallels
Cluster
Pointings
ACS
Parallels
Footprint of our 2 ORIENT survey. ACS
FOV in green, WFC3/IR FOV in red,
WFC3/UVIS in magenta. The area of the
complete 14-band coverage in the cluster
center is 4.07 square arcminutes (88% of
the WFC3/IR FOV).
~20o
3.5
26.3
26.8 26.7
26.1
26.1
F140W
F850LP
F775W
F606W
27.6 27.9 27.1
F475W
F390W
F275W
0.5
F336W
26.6 26.9
1
F125W
26.4 26.8
26.9
F105W
27.8
2
1.5
WFC3-IR
F160W
ACS-WFC
G800L … as needed
WFC3-UVIS
F814W
2.5
F110W
3
F225W
Orbits per filter per Cluster
6 arcmin. = 2.2 Mpc @ z=0.5
0
Limiting SNR=5 AB magnitudes (for flat spectrum point source) for each passband shown above
CLASH: Top STScI Data/CAL Issues
• Need accurate calibration frames (i.e., flats) for
each of our 14 bands that span the 3 detector
systems: WFC3/UVIS, ACS/WFC, WFC3/IR
• Need accurate geometric distortion maps in all 14
bands, to allow distortion correction to ~0.1 pixel
over the full field of view of each camera.
Determining the skew terms will, thus, be essential.
• Need an efficient way to correct for ACS CTE. I
understand that Jay Anderson has a promising
algorithm that is currently being evaluated.
• Rapid access to data via dedicated disk with fast
FTP (for SN search).