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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• 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

SDSS2 - commenced July 2005

• Legacy survey– complete SDSS1 goals

• SEGUE – Galactic structure

• Supernovae– Repeated imaging of southern equatorial stripe

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

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

Imaging

Spectroscopy

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 quasars

154,925 stars

Imaging

Spectroscopy

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

z=6.4 Quasar

Gunn-PetersonTrough

Fan et al 2003

Cmbgg OmOlCMB

+

LSS

WMAP only+ SDSS

Tegmarket al 2004

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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

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

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 dwarfz =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

http://apm14.ast.cam.ac.uk/status/wfcam/

UKIDSS Status

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

Currentestimates

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

Sky Coverage

“EDR+” inc. areas with incomplete filter coverage

Sky Coverage

Matched with SDSS DR5 main galaxy target

Sky Coverage

Has redshift and K-band detection

K-band Completeness

LAS galaxies 16.0SDSS matches 14.0

r-K colours

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

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

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

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

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

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 …

Websites

• http://www.sdss.org

• http://www.ukidss.org

• http://surveys.roe.ac.uk/wsa