high-z galaxy clusters as cosmological probes:

High-z galaxy clusters as cosmological probes:

High-z galaxy clusters as cosmological probes:

Mike Gladders Carnegie Observatories

hubble fellow symposium, stsci, april20th, 2006

Mike Gladders Carnegie Observatories

hubble fellow symposium, stsci, april20th, 2006

Recent Results and Future prospects

Recent Results and Future prospects

U. Toronto: Kris Blindert, Dave Gilbank, Howard Yee

U. Toronto: Kris Blindert, Dave Gilbank, Howard Yee

U. Colorado: Erica Ellingson, Amelia Hicks

U. Colorado: Erica Ellingson, Amelia Hicks

MIT: Mark Bautz

U. Victoria: Henk Hoekstra

MIT: Mark Bautz

U. Victoria: Henk Hoekstra

OCIW: Alan Dressler, Edo Berger,Gus Oemler, Francois

Schweizer, Luis Ho, Pat McCarthy, Nidia Morel,Kathleen Koviak

OCIW: Alan Dressler, Edo Berger,Gus Oemler, Francois

Schweizer, Luis Ho, Pat McCarthy, Nidia Morel,Kathleen Koviak

U. Catolica: Felipe Barrientos, Leopoldo Infante

U. Catolica: Felipe Barrientos, Leopoldo Infante

Cast of CharactersCast of Characters

York U.: Pat Hall

U. Chicago: John Carlstrom

York U.: Pat Hall

U. Chicago: John Carlstrom

The PlotThe Plot

The RCS Galaxy cluster Surveys

Cosmology from N(M,z) Analysis of RCS-1

Strong Lensing

Follow-up Challenges: New Instruments

(Pushing the Redshift Envelope: High-z Clusters in Association with Short/Hard GRBs)

The RCS Galaxy cluster Surveys

Cosmology from N(M,z) Analysis of RCS-1

Strong Lensing

Follow-up Challenges: New Instruments

(Pushing the Redshift Envelope: High-z Clusters in Association with Short/Hard GRBs)

The Basics: galaxy clusters and cosmology

The Basics: galaxy clusters and cosmology

• Galaxy cluster represent the large-scale bound endpoint of structure formation via gravitational collapse

• Clusters sit at the intersections of filaments in the “cosmic web”, and are composed mostly of dark matter with a frosting of baryons in the form of hot gas and stars

• Clusters evolve over time by accumulation of other galaxies, groups and clusters from their surrounding environment

• this evolution is cosmology dependent

• Galaxy cluster represent the large-scale bound endpoint of structure formation via gravitational collapse

• Clusters sit at the intersections of filaments in the “cosmic web”, and are composed mostly of dark matter with a frosting of baryons in the form of hot gas and stars

• Clusters evolve over time by accumulation of other galaxies, groups and clusters from their surrounding environment

• this evolution is cosmology dependent

the surveys: RCS-1(complete)

• 95 square degrees of R (6500Å) and z’ (9200Å) imaging to a depth sufficient to find clusters to z~1.4; best at 0.4<z<1.0

• Cluster finding using a refined version of the algorithm in Gladders & Yee (2000), first catalogs in Gladders & yee (2005). clusters found as concentrations in color, magnitude and position

• Contamination and completeness tested extensively via simulations

• 95 square degrees of R (6500Å) and z’ (9200Å) imaging to a depth sufficient to find clusters to z~1.4; best at 0.4<z<1.0

• Cluster finding using a refined version of the algorithm in Gladders & Yee (2000), first catalogs in Gladders & yee (2005). clusters found as concentrations in color, magnitude and position

• Contamination and completeness tested extensively via simulations

the surveys: RCS-2 (Ongoing)

• 830 square degrees of new grz imaging, shallower than RCS-1 but much deeper than SDSS. with CFHT Legacy deep/wide added is 1000 square degrees.

• completion planned 2007a: first of the next-gen large cluster surveys designed to measure dark energy.

• extensive follow-up, principally to calibrate mass-observables, is ongoing in parallel, using mostly rcs-1 clusters

• 830 square degrees of new grz imaging, shallower than RCS-1 but much deeper than SDSS. with CFHT Legacy deep/wide added is 1000 square degrees.

• completion planned 2007a: first of the next-gen large cluster surveys designed to measure dark energy.

• extensive follow-up, principally to calibrate mass-observables, is ongoing in parallel, using mostly rcs-1 clusters

RCS-1: Cosmological Analysis


•Recently we have completed a first analysis of the entire RCS-1 catalog (Gladders et al. 2006) using the so-called “self-calibration” method (Majumdar & Mohr 2004).

•The catalog is richness and significance limited, over the redshift interval 0.35<z<0.95; at the chosen limits incompleteness corrections are small (<20%, typically 10%) and well understood.

•Recently we have completed a first analysis of the entire RCS-1 catalog (Gladders et al. 2006) using the so-called “self-calibration” method (Majumdar & Mohr 2004).

•The catalog is richness and significance limited, over the redshift interval 0.35<z<0.95; at the chosen limits incompleteness corrections are small (<20%, typically 10%) and well understood.



We fit for Ωm and σ8 (presuming a flat w=-1 universe) and four parameters describing the mass-richness relation, namely the slope, α, and zeropoint, A, evolution in A in redshift as (1+z)γ, so that the relation between cluster mass, M200, and richness, R, is

M200=10A Rα(1+z)γ

We also account for scatter in this relation with a fixed fractional scatter in mass parameterised by fsc.

We fit for Ωm and σ8 (presuming a flat w=-1 universe) and four parameters describing the mass-richness relation, namely the slope, α, and zeropoint, A, evolution in A in redshift as (1+z)γ, so that the relation between cluster mass, M200, and richness, R, is

M200=10A Rα(1+z)γ

We also account for scatter in this relation with a fixed fractional scatter in mass parameterised by fsc.

The following results are obtained:

Ωm 0.31 +0.11 -0.10σ8 0.67 +0.18 -0.13

A 10.55 +2.27 -1.71α 1.64 +0.91 -0.90γ 0.4 +2.11 -3.80fsc 0.73 +0.18 -0.16

The following results are obtained:

Ωm 0.31 +0.11 -0.10σ8 0.67 +0.18 -0.13

A 10.55 +2.27 -1.71α 1.64 +0.91 -0.90γ 0.4 +2.11 -3.80fsc 0.73 +0.18 -0.16

0.238-0.266 WMAP 3-year

0.722-0.772 WMAP 3-year

9.89 +-0.89 Yee & Ellingson 2003, CNOC-1


consistent with marginal evolution0.6-0.7 Blindert et al. 2006 (RCS-1)

0.238-0.266 WMAP 3-year

0.722-0.772 WMAP 3-year



consistent with marginal evolution0.6-0.7 Blindert et al. 2006 (RCS-1)

Ωm 0.30 +0.12 -0.11 σ8 0.70 +0.27 -0.15

Ωm 0.30 +0.12 -0.11 σ8 0.70 +0.27 -0.15



Blindert et al. 2006

Strong LensingStrong Lensing

3 Samples:

RCS-1 Primary: arcs detected in R in survey imaging (Gladders et al. 2001,2003)

RCS-1 Secondary: arcs detected in I in follow-up imaging of high-z candidate clusters (Gladders et al. 2003)

RCS-2 Primary (initial): arcs detected in g and/or r in survey imaging

3 Samples:

RCS-1 Primary: arcs detected in R in survey imaging (Gladders et al. 2001,2003)

RCS-1 Secondary: arcs detected in I in follow-up imaging of high-z candidate clusters (Gladders et al. 2003)

RCS-2 Primary (initial): arcs detected in g and/or r in survey imaging

1 a

rcm

in1

arc

min

30 a

rcse

c3

0 a

rcse

c

RCS-1: Strong Lensing SamplesRCS-1: Strong Lensing Samples

Z=0.9Z=0.9

Z=3.86


9 hrs GMOS N&S Gilbank et al. 2006

RCS-1: Background GalaxiesRCS-1: Background Galaxies

LDSS-3 imaging

Z=0.698

49” radius!(one of the most massive objects

known)

RCS-2: Strong Lensing ExampleRCS-2: Strong Lensing Example

z=3.01

SZ Effect from the SZA, courtesy J. Carlstrom

RCS-2: Strong Lensing ExampleRCS-2: Strong Lensing Example

27 new clusters with giant arcs, ¼ of

the survey

27 new clusters with giant arcs, ¼ of

the survey



Three surprises:Three surprises:

• Large proportion of multiple arc clusters

distribution of lensing cross sections includes a small population with large cross section which dominate the lensing statistics. Latest modeling papers give similar results - its due to triaxiality and orientation effects (e.g. Ho & White ‘04).

• Large proportion of multiple arc clusters

distribution of lensing cross sections includes a small population with large cross section which dominate the lensing statistics. Latest modeling papers give similar results - its due to triaxiality and orientation effects (e.g. Ho & White ‘04).


Three surprises:Three surprises:• Redshift distribution of lenses skewed to

high-z implies evolution in cluster properties? implies that mass alone is not responsible for promoting

clusters as good lenses: something associated with cluster assembly enhances cross sections and/or an effect at low-z reduces cross sections….

• Redshift distribution of lenses skewed to high-z

implies evolution in cluster properties? implies that mass alone is not responsible for promoting

clusters as good lenses: something associated with cluster assembly enhances cross sections and/or an effect at low-z reduces cross sections….

• Clusters with arcs not obviously most massive

expectation from modeling is for a strong preference for the most massive systems to form bulk of all arcs.

• Clusters with arcs not obviously most massive

expectation from modeling is for a strong preference for the most massive systems to form bulk of all arcs.

Model estimated from Dalal, Holder and Hennawi (2004)Model estimated from Dalal, Holder and Hennawi (2004)

Predictions, Realities(a little out of date…Dec05)

Strong Lensing: comparing to predictionsStrong Lensing: comparing to predictions

Background point are the VIRGO Hubble volume cluster catalog for

LCDM model

Strong Lensing: comparing to predictionsStrong Lensing: comparing to predictions

Hen

naw

i, e

t al.

2005

Strong Lensing: comparing to predictionsStrong Lensing: comparing to predictionsHennawi, et al. 2005

???

• If dark matter has a (very!) small non-gravitational self-interaction (a la Spergel and Steinhardt 1999) then…

• If the timescale for a particle in a cluster-like environment to have an interaction is of order a Hubble time, clusters at low-redshift will preferentially have isothermal (puffed up) cores – and hence be less efficient lenses…

• And This effect should work faster for more massive systems which would tend to move the lensing cross sections toward lower mass systems as well…

• If dark matter has a (very!) small non-gravitational self-interaction (a la Spergel and Steinhardt 1999) then…

• If the timescale for a particle in a cluster-like environment to have an interaction is of order a Hubble time, clusters at low-redshift will preferentially have isothermal (puffed up) cores – and hence be less efficient lenses…

• And This effect should work faster for more massive systems which would tend to move the lensing cross sections toward lower mass systems as well…

Strong Lensing:Dark Matter Properties?

Strong Lensing:Dark Matter Properties?

The Follow-Up ChallengeThe Follow-Up Challenge

•Ultimately the grand cosmological tests envisioned with massive clusters samples, and the study of unique subsets such as cluster lenses requires detailed and extensive follow-up observations at many wavelengths.

•Large amounts of large optical telescope time are required to get the necessary spectroscopy.

•Redshifting and field crowding are significant problems : new instruments would be useful…

•Ultimately the grand cosmological tests envisioned with massive clusters samples, and the study of unique subsets such as cluster lenses requires detailed and extensive follow-up observations at many wavelengths.

•Large amounts of large optical telescope time are required to get the necessary spectroscopy.

•Redshifting and field crowding are significant problems : new instruments would be useful…

•“My first instrument” is the LDSS-3 spectrograph. It is a complete overhaul of the old LDSS-2 spectrograph from the WHT 4m.

•New optics, dispersers, detector, electronics and filters all installed : Image quality now better than site delivers (<0”.2) and the throughput is the highest of any multi-object spectrograph…

•“My first instrument” is the LDSS-3 spectrograph. It is a complete overhaul of the old LDSS-2 spectrograph from the WHT 4m.

•New optics, dispersers, detector, electronics and filters all installed : Image quality now better than site delivers (<0”.2) and the throughput is the highest of any multi-object spectrograph…

LDSS-3: Clusters at high redshift

LDSS-3: Clusters at high redshift

Peak Throughput: 41%Peak Throughput: 41% Peak Throughput: 42%Peak Throughput: 42%

10% Edges: 3800Å-9200Å10% Edges: 3800Å-9200Å10% Edges: 3900Å-10200Å10% Edges: 3900Å-10200Å25% Edges: 4400Å-7800Å25% Edges: 4400Å-7800Å25% Edges: 4400Å-9900Å25% Edges: 4400Å-9900Å

LDSS-3: First Light – Feb 2005LDSS-3: First Light – Feb 2005

•GISMO (the Gladders Image-Slicing Multi-Slit Option for IMACS) is an addition to the IMACS ½ degree field MOS spectrograph at Magellan.

GISMO is a field-reformatter that allows the power of the large spectrograph to be brought to bear on a small (3.2’x3.5’: ACS!) field of view: 8x the normal spatial density of slits, with no spectral compromises!

•GISMO (the Gladders Image-Slicing Multi-Slit Option for IMACS) is an addition to the IMACS ½ degree field MOS spectrograph at Magellan.

GISMO is a field-reformatter that allows the power of the large spectrograph to be brought to bear on a small (3.2’x3.5’: ACS!) field of view: 8x the normal spatial density of slits, with no spectral compromises!

GISMO: Strong Lensing and Cluster Cores

GISMO: Strong Lensing and Cluster Cores

GISMOGISMO

GISMOGISMO

collimator

field lens

GISMO Optics

(96 elements)

GISMOGISMO

•Since high-z clusters are very rare, using easily visible signposts (this used to mean AGN!) is helpful. Short-hard gamma-ray bursts may be our new best window onto the highest redshift clusters…

•We have recently discovered a short-hard grb which appears to be hosted in a galaxy in a z~1.8 cluster!

Clusters at z~2: GRBs as SignpostsClusters at z~2:

GRBs as Signposts

Clusters at z~2: Short-Hard GRBsClusters at z~2: Short-Hard GRBs

GRB050813

background data from Miyazaki et al. 2003

Excess over field is ~50x


z~1.8


z=0.72 known foreground

high-z galaxy clusters as cosmological probes:

Documents

z analysis of rcs

entire rcs

highz clusters

highz galaxy clusters

z candidate clusters

stars clusters

strong lensing samplesrcs

cluster mass