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SDSS and UKIDSS

SDSS and UKIDSS. Jon Loveday University of Sussex. Outline. Sloan Digital Sky Survey status UK Infrared Deep Sky Survey overview and status K -band luminosity function from matched SDSS-UKIDSS sample Future prospects. SDSS1 Survey Goals. Make definitive map of local universe

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SDSS and UKIDSS

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  1. SDSS and UKIDSS Jon Loveday University of Sussex

  2. Outline • Sloan Digital Sky Survey status • UK Infrared Deep Sky Survey overview and status • K-band luminosity function from matched SDSS-UKIDSS sample • Future prospects

  3. SDSS1 Survey Goals • Make definitive map of local universe • Image quarter-sky in five colours ugriz • Measure 50 million galaxy images to r~22 • Obtain spectra for 1 million galaxies and 100,000 quasars • SDSS1 ended June 2005, immediately followed by SDSS2 http://www.sdss.org

  4. SDSS2 - commenced July 2005 • Legacy survey • complete SDSS1 goals • SEGUE • Galactic structure • Supernovae • Repeated imaging of southern equatorial stripe

  5. SDSS Status (March 2006) • Unique area imaged (sq deg) • North: 7561 essentially completed 30 Jan 2006 • South: 739 • 210 million objects detected • Spectroscopy: 1819 plates inc spectra of • 697,757 galaxies • 93,083 QSOs • 253,261 stars

  6. Data Release 4 • Published July 2005 • Imaging area 6670 deg2 • Photometry of 180 million unique objects • Spectra of 849,920 objects over 4783 deg2: 565,715 galaxies 76,483 quasars 102,714 stars

  7. Imaging Spectroscopy

  8. Data Release 5 • Due summer 2006 • Imaging area 8000 deg2 • Photometry of 215 million unique objects • Spectra of 1,048,960 objects over 5740 deg2: 674,749 galaxies 90,611 quasars154,925 stars

  9. Imaging Spectroscopy

  10. SDSS Cosmological Highlights • Highest known redshift quasar (z = 6.4) • Large scale structure cosmological constraints • Galaxy properties and environment • Detection of baryon acoustic peak • More than 1000 publications using SDSS data, with 29,000 citations

  11. z=6.4 Quasar Gunn-PetersonTrough Fan et al 2003

  12. Cmbgg OmOl CMB + LSS WMAP only + SDSS Tegmark et al 2004

  13. UKIDSS • UK Infrared Deep Sky Survey • Consortium of most UK astronomy departments • UKIRT 3.8m telescope plus WFCAM (4x20482 Hawaii-II arrays, 0.21 deg2) • Etendue of 2.38 m2 deg2 largest of any IR camera until VISTA • zYJHK (1 ~ 2.5 ) near-IR filters • 5 surveys, 3 extragalactic • Significantly deeper than 2MASS

  14. UKIDSS (contd) • Observing started May 2005 • 7 year observing plan (~50% of UKIRT time) • Pipeline processing in Cambridge, archive in Edinburgh • No proprietary data period • Data immediately available to ESO members once verified • Rest of world 18 months later

  15. UKIDSS filters

  16. Why Near-IR? • 2 light traces mass in evolved stars - provides good estimate of stellar mass • Helps identify cool dwarf stars and high-z quasars (optical dropouts) • Less sensitive than optical light to dust reddening and type-dependent K-corrections

  17. Quasars vs dwarf stars T6 brown dwarfz =7 quasar

  18. UKIDSS Surveys

  19. Comparison with 2MASS Lawrence et al 2006 in prep

  20. UKIDSS Status http://apm14.ast.cam.ac.uk/status/wfcam/

  21. UKIDSS Early Data Release • Available to ESO community 2006 Feb 10 • ~1% of final sample, comparable to 2MASS

  22. Data Access • Via WFCAM Science Archive (Edinburgh) http://surveys.roe.ac.uk/wsa • Need to register with your community contact • SQL interface will be familiar to SDSS CAS users • NB: EDR data not all of final survey quality

  23. Early application of SDSS + UKIDSS • K-band luminosity function • UKIDSS K-band photometry • SDSS redshifts

  24. Current estimates Bell et al 2003Grey: Cole et al 2001

  25. K-band luminosity function • Use UKIDSS “EDR+” sample: includes areas of sky with incomplete filter coverage • Match UKIDSS EDR+ LAS with SDSS DR5 main sample galaxies (r < 17.7) • Tolerance 2 arcsec (nearly all matches within 1 arcsec) • Use Petrosian magnitudes

  26. Sky Coverage “EDR+” inc. areas with incomplete filter coverage

  27. Sky Coverage Matched with SDSS DR5 main galaxy target

  28. Sky Coverage Has redshift and K-band detection

  29. K-band Completeness LAS galaxies 16.0 SDSS matches 14.0

  30. r-K colours Completeness of matched sample (K=14) limited by SDSS r limit (17.77) and reddest r-K colour (~3.8)

  31. LF Estimate • Use complete sample (K < 14)  1287 galaxies (fewer than 50%) • K-corrections to z = 0.1 from template fit to SDSS ugriz using kcorrect v4 • STY, SWML estimators of (MK) - independent of density inhomogeneities

  32. Bivariate LF • Use entire matched sample by estimating SWML bivariate (Mr, MK) allowing for SDSS r flux limit (r < 17.7) • Sample size 3249 galaxies, but faintest galaxies will now be bluer than average • Integrate over Mr to obtain (MK) • Fit Schechter function by least squares

  33. Conclusions/Future Prospects • UKIDSS-SDSS K-band LF consistent with earlier estimates using 2MASS • Measurements will improve considerably with more data • UKIDSS Data Release 1 (DR1) due mid-2006 will have ~10 times as much data • Two year goals: • LAS half complete • DXS full depth in JK over 3.1 deg2 • UDS K = 22.8, J = 23.8

  34. Future Plans • Investigate type-dependence of K-band LF and its evolution • Comparison with optical distinguishes stellar mass accumulation with star formation history • Evolution to z ~ 0.3 with SDSS redshifts • Higher-redshift evolution using photometric redshifts

  35. Future Plans (2) • SDSS Southern stripe co-added data plus UKIDSS DXS excellent for photo-z • Possible volume-limited redshift survey using AAOmega • Clustering evolution of K-limited (stellar mass selected) samples • VISTA …

  36. Websites • http://www.sdss.org • http://www.ukidss.org • http://surveys.roe.ac.uk/wsa

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