Download - Hudson IAP July 4 Galaxy- Galaxy Lensing in CFHTLS Hudson (Waterloo) 2/3 Canadian 2/3 French
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)