(More) Cosmological Tests from COSMOS Lensing - 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) 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 Relative Lensing Strength Z(z) Your cluster goes here Bartelmann & Schneider 1999
To get a well-defined lens redshift, try looking behind clusters Use 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% 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 Lens at z = 0.2 0.5% relative change
To get a well-defined lens redshift, try looking behind clusters Use 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% 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 Lens at z = 0.5 0.5% 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
Try this behind COSMOS Groups and Clusters (X-ray derived Mass) Log(volume) (plot from Leauthaud et al. 2009)
Try this behind COSMOS Groups and Clusters ~67 in top 14 objects? (X-ray derived Mass) Log(volume) (plot from Leauthaud et al. 2009)
Try this behind COSMOS Groups and Clusters could get another ~60 from less massive groups? (X-ray derived Mass) Log(volume) (plot from Leauthaud et al. 2009)
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 Cosmos A surprising number of nearby galaxies show up in the COSMOS field
Local Dwarfs in Cosmos A surprising number of nearby galaxies show up in the COSMOS field
Local Dwarfs in Cosmos A surprising number of nearby galaxies show up in the COSMOS field
Local Dwarfs in Cosmos plus lots of other weird LSB stuff…
Local Dwarfs in Cosmos All booming away in the FUV, NUV…
Local Dwarfs in Cosmos Where could these be?
Local Dwarfs in Cosmos Where could these be?
Local Dwarfs in Cosmos Where could these be? Leo I: 10 Mpc dist., mu ~25 3.3 Mpc away in projection Leo II: 20 Mpc dist., mu =30.5 1.74 Mpc away in projection NB: if in LEO II, Implies ~120 galaxies in group