(More) Cosmological Tests

from COSMOS Lensing

(More) Cosmological Tests

from COSMOS Lensing

in 2009-2010:- photo-zs have improved

dramatically- images/psf now corrected

for CTE- new shear calibration

underway+ updated group catalog(s)

so expect stronger signal around peaks in lensing map, and cleaner dependence on source and lens redshift

time for some 2nd generation tests of the lensing signal

Measuring Geometry: Shear Ratio Test (Jain & Taylor 2003, Bernstein & Jain 2004, Taylor et al. 2007)

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Bartelmann & Schneider 1999

Relative Lensing Strength Z(z)

Your cluster goes here

Take ratio of shear of objects behind a particular cluster, as a function of redshift

Details of mass distribution & overall calibration cancel clean geometric test

Can extend this to continuous result by fitting to all redshifts Z(z) DLS/DS

To get a well-defined lens redshift, try looking behind clustersUse strength of signal behind cluster as a function of redshift to measure DA(z):

weak but distinctive signal; relative change (change in distance ratio) is only 0.5%

Lens at z = 0.2

0.5% relative change

Base: h = 0.73, m = 0.27( or X = 1 - m)

Variants (different curves):m = 0.25,0.30,0.32

w0 = -1,-0.95,-0.9,-0.85,-0.8

w(z) = w0 + wa(1-a)with w0 = -1, wa = 0.05, 0.1

h = 0.7, 0.75

To get a well-defined lens redshift, try looking behind clustersUse strength of signal behind cluster as a function of redshift to measure DA(z):

weak but distinctive signal; relative change (change in distance ratio) is only 0.5%

Lens at z = 0.5 Base: h = 0.73, m = 0.27( or X = 1 - m)

Variants (different curves):m = 0.25,0.30,0.32

w0 = -1,-0.95,-0.9,-0.85,-0.8

w(z) = w0 + wa(1-a)with w0 = -1, wa = 0.05, 0.1

h = 0.7, 0.750.5% relative change

How to stack clusters?Tangential shear goes as:

so redshift dependence enters via critical surface density:

Thus if we define (assumes flat models)

and

then

independent of cosmology

Log(volume)

Try this behind COSMOS Groups and Clusters

(plot from Leauthaud et al. 2009)

(X-ray derived Mass)

Log(volume)

Try this behind COSMOS Groups and Clusters

(plot from Leauthaud et al. 2009)

(X-ray derived Mass)

~67 in top 14 objects?

Log(volume)

Try this behind COSMOS Groups and Clusters

(plot from Leauthaud et al. 2009)

(X-ray derived Mass)

could get another~60 from less massive groups?

We see the signal!

Stack of regions within 6’ of

~200+ x-ray groups

good fit in front of/behind

cluster

significance still unclear;

seems less than expected

effect of other structures along the line of sight decreases chi2, but hard to quantify

Local Dwarfs in CosmosA surprising number of nearby galaxies show up in the COSMOS field

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Local Dwarfs in CosmosA surprising number of nearby galaxies show up in the COSMOS field

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Local Dwarfs in CosmosA surprising number of nearby galaxies show up in the COSMOS field

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Local Dwarfs in Cosmosplus lots of other weird LSB stuff…

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Local Dwarfs in CosmosAll booming away in the FUV, NUV…

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Local Dwarfs in CosmosWhere could these be?

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Local Dwarfs in CosmosWhere could these be?

Local Dwarfs in CosmosWhere could these be?

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Leo I: 10 Mpc dist., mu ~253.3 Mpc away in projection

Leo II: 20 Mpc dist., mu =30.51.74 Mpc away in projection

NB: if in LEO II, Implies ~120 galaxies in group