Hudson IAP July 4

Galaxy-Galaxy Lensing

in CFHTLS

Hudson (Waterloo)

2/3 Canadian2/3 French

Hudson IAP July 4

My Last Meeting at IAP…My Last Meeting at IAP…

m/0.3)0.68

Pike & Hudson 2005

(Pre-WMAP 3)

Hudson IAP July 4

CFHTLS-DEEP photo-redshiftsCFHTLS-DEEP photo-redshifts

Knowledge of the source redshifts is currently the dominant limiting factor for cosmic shear surveys.

Also critical for galaxy-galaxy lensing

NB: Not tested with spectroscopy in last bin (24 < i’ < 25).

Hudson IAP July 4

Photo-z Accuracy by MagnitudePhoto-z Accuracy by MagnitudeMH’s “in

progress”photo-z

vs. DEEP2spectro(z< 1.4)

Note that fraction of

catastrophic errors

doubles

each mag

Hudson IAP July 4

Photo-z Accuracy by MagnitudePhoto-z Accuracy by Magnitude

works well at bright magnitudes …good for lenses in g-g lensing

fraction outside 0.15*(1+z)

Hudson IAP July 4

Photo-z Accuracy by MagnitudePhoto-z Accuracy by Magnitude

… not as well at faint magnitudes …S/N or increase in blue gals with featureless spectra

fraction outside 0.15*(1+z)

Hudson IAP July 4

Photo-z Accuracy by MagnitudePhoto-z Accuracy by Magnitude

… but at least the code’s error estimates are OK.

95% err

Hudson IAP July 4

Photo-z for SourcesPhoto-z for Sources

• Drop objects with large errors and/or secondary peaks.• Probably OK for cosmic shear which is

cosmic variance limited.

• Characterize true z distribution as a function of slices in colour / magnitude space.• via photo-z based on deeper IR or

Spizter/IRAC …

Hudson IAP July 4

G-G lensing G-G lensing with photo-zwith photo-z

• HDF (Hudson, Gwyn, Dahle, Kaiser 98)

Hudson IAP July 4

CFHTLS-WIDE with photo-zCFHTLS-WIDE with photo-z

• Cast of dozens in Canada and France• especially

• Parker (Waterloo -> ESO -> McMaster) • Hoekstra (Victoria)• van Waerbeke / Heymanns (UBC)• Mellier / Fu / Terapix (IAP)

• Very, very preliminary• both shear cats, photometry and photo-z• Using only 14 sq deg with u*griz in WIDE• Am using photo-z for lenses only• No correction for dilution due to physical pairs or intrinsic

alignment

but at least this is not an “astro-ph” talk …

Hudson IAP July 4

CFHTLS-WIDE with photo-zCFHTLS-WIDE with photo-z

~200000 lenses0.2 < zlens < 0.8

~700000 sources

22.5 < i’ < 24.5

Hudson IAP July 4

CFHTLS-WIDE with photo-zCFHTLS-WIDE with photo-z

Note horizontal axis in physical units

0.2 < zlens < 0.8

S/N of isothermal fit at R<300 kpc~15

Hudson IAP July 4

CFHTLS-WIDE with photo-zCFHTLS-WIDE with photo-z0.2 < zlens <

0.8

~10 ~5 ~10 ~7

Hudson IAP July 4

CFHTLS-DEEP with photo-zCFHTLS-DEEP with photo-z

c/o Laura Parker (also very preliminary!) low < zlens> ~0.35

high < zlens> ~0.61

Hudson IAP July 4

The FutureThe Future• Short term: end of summer

• ~25 sq deg WIDE + 4 sq deg DEEP with u*g’r’i’z’• WIDE allows us to parameterize as a function of colour,

magnitude• DEEP will give baseline for evolution of Tully-Fisher/Faber-

Jackson/Mass-to-light• Signal/Noise ~ at least x sqrt(2) shown here• Refinements of photo-z, analysis (maximum-likelihood)

• Longer term: ~170 sq deg of survey enables subsamples by morphology, luminosity, stellar mass & redshift • Halo masses, shapes as a function of above• Large-scale bias as a function of above• etc. etc.

Hudson IAP July 4

Photo-z accuracy by magnitudePhoto-z accuracy by magnitude

• Ilbert et al(tuned with

VVDS redshifts)