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SDSS and UKIDSS Jon Loveday University of Sussex
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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
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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
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SDSS2 - commenced July 2005 Legacy survey –complete SDSS1 goals SEGUE –Galactic structure Supernovae –Repeated imaging of southern equatorial stripe
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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
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Data Release 4 Published July 2005 Imaging area 6670 deg 2 Photometry of 180 million unique objects Spectra of 849,920 objects over 4783 deg 2 : 565,715 galaxies 76,483 quasars 102,714 stars
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Imaging Spectroscopy
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Data Release 5 Due summer 2006 Imaging area 8000 deg 2 Photometry of 215 million unique objects Spectra of 1,048,960 objects over 5740 deg 2 : 674,749 galaxies 90,611 quasars 154,925 stars
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Imaging Spectroscopy
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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
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z=6.4 Quasar Gunn - Peterson Trough Fan et al 2003
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Cmbgg OmOl CMB + LSS WMAP only + SDSS Tegmark et al 2004
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UKIDSS UK Infrared Deep Sky Survey Consortium of most UK astronomy departments UKIRT 3.8m telescope plus WFCAM (4x2048 2 Hawaii-II arrays, 0.21 deg 2 ) Etendue of 2.38 m 2 deg 2 largest of any IR camera until VISTA zYJHK (1 ~ 2.5 ) near-IR filters 5 surveys, 3 extragalactic Significantly deeper than 2MASS
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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
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UKIDSS filters
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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
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T6 brown dwarf z =7 quasar Quasars vs dwarf stars
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UKIDSS Surveys
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Lawrence et al 2006 in prep Comparison with 2MASS
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http://apm14.ast.cam.ac.uk/status/wfcam/ UKIDSS Status
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UKIDSS Early Data Release Available to ESO community 2006 Feb 10 ~1% of final sample, comparable to 2MASS
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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
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Early application of SDSS + UKIDSS K-band luminosity function UKIDSS K-band photometry SDSS redshifts
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Bell et al 2003 Grey: Cole et al 2001 Current estimates
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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
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Sky Coverage “EDR+” inc. areas with incomplete filter coverage
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Sky Coverage Matched with SDSS DR5 main galaxy target
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Sky Coverage Has redshift and K-band detection
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K-band Completeness LAS galaxies 16.0 SDSS matches 14.0
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r-K colours Completeness of matched sample (K=14) limited by SDSS r limit (17.77) and reddest r-K colour (~3.8)
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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 (M K ) - independent of density inhomogeneities
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Bivariate LF Use entire matched sample by estimating SWML bivariate (M r, M K ) allowing for SDSS r flux limit (r < 17.7) Sample size 3249 galaxies, but faintest galaxies will now be bluer than average Integrate over M r to obtain (M K ) Fit Schechter function by least squares
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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 deg 2 UDS K = 22.8, J = 23.8
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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
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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 …
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Websites http://www.sdss.org http://www.ukidss.org http://surveys.roe.ac.uk/wsa
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