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SDSS and UKIDSS Jon Loveday University of Sussex.

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Presentation on theme: "SDSS and UKIDSS Jon Loveday University of Sussex."— Presentation transcript:


2 SDSS and UKIDSS Jon Loveday University of Sussex

3 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

4 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

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

6 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


8 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

9 Imaging Spectroscopy

10 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

11 Imaging Spectroscopy

12 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

13 z=6.4 Quasar Gunn - Peterson Trough Fan et al 2003

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


16 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

17 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

18 UKIDSS filters

19 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

20 T6 brown dwarf z =7 quasar Quasars vs dwarf stars

21 UKIDSS Surveys

22 Lawrence et al 2006 in prep Comparison with 2MASS

23 UKIDSS Status

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

25 Data Access Via WFCAM Science Archive (Edinburgh) 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


27 Early application of SDSS + UKIDSS K-band luminosity function UKIDSS K-band photometry SDSS redshifts

28 Bell et al 2003 Grey: Cole et al 2001 Current estimates

29 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

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

31 Sky Coverage Matched with SDSS DR5 main galaxy target

32 Sky Coverage Has redshift and K-band detection

33 K-band Completeness LAS galaxies 16.0 SDSS matches 14.0

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

35 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


37 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



40 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

41 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

42 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 …

43 Websites

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