Initial Results from the Chandra Initial Results from the Chandra Shallow X-ray Survey in the Shallow X-ray Survey in the

NDWFS in BoötesNDWFS in Boötes

S. Murray, C. Jones, W. Forman, A. Kenter, A. S. Murray, C. Jones, W. Forman, A. Kenter, A. Vikhlinin, Vikhlinin,

P. Green, D. Fabricant, G. Fazio - CfAP. Green, D. Fabricant, G. Fazio - CfA

B. Jannuzi, A. Dey, J. Najita, M. Brown, K. Brand - B. Jannuzi, A. Dey, J. Najita, M. Brown, K. Brand - NOAONOAO

J. Shields, B. McNamara - OhioUJ. Shields, B. McNamara - OhioU

M. Rieke - AzUM. Rieke - AzU

C. Kochanek - OSUC. Kochanek - OSU

Survey CharacteristicsSurvey Characteristics

Large contiguous area (9.3 degLarge contiguous area (9.3 deg22), ), with arc second resolutionwith arc second resolution

Well studied optically - NOAO Deep Well studied optically - NOAO Deep Wide File Survey (NDWFS)Wide File Survey (NDWFS)

Accessible for spectroscopic follow up Accessible for spectroscopic follow up (MMT-Hectospec, Gemini, Keck, …)(MMT-Hectospec, Gemini, Keck, …)

Multiwavelength coverage (SST-Multiwavelength coverage (SST-IRAC, VLA-FIRST, GALEX, …)IRAC, VLA-FIRST, GALEX, …)

Centered at Centered at =14=14hh 32 32mm =34=34 06’ 06’

Science ObjectivesScience Objectives Complete Flux Limited Contiguous SurveyComplete Flux Limited Contiguous Survey

Optical IdsOptical Ids Redshifts Redshifts

Spectroscopic complete to R < (21-22)Spectroscopic complete to R < (21-22) Photometric to R < (24-26)Photometric to R < (24-26)

Large Scale StructureLarge Scale Structure Angular and Spatial CorrelationsAngular and Spatial Correlations

Luminosity FunctionLuminosity Function Classes Classes

Cluster SurveyCluster Survey

Mosaic of X-ray FieldsMosaic of X-ray Fields

126 ACIS-I 126 ACIS-I pointings (ACIS-S2 pointings (ACIS-S2 chip also) chip also)

5 ksec exposure 5 ksec exposure (4287 - 5120 sec)(4287 - 5120 sec)

Fields overlap by Fields overlap by about 1 arc minuteabout 1 arc minute

Total of 630 ksec Total of 630 ksec of Chandra time of Chandra time (about 2 orbits)(about 2 orbits)

March/April 2003March/April 2003

Representative Single Representative Single FieldField

Seq 3602 (N-F57)Seq 3602 (N-F57) Total counts ~3000Total counts ~3000 Smoothed with 2 arc Smoothed with 2 arc

second Gaussiansecond Gaussian Raw image analyzed Raw image analyzed

with wavelet detectwith wavelet detect 31 sources (31 sources (2 cts)2 cts) 1 extended source1 extended source

X-Ray Survey Detection X-Ray Survey Detection ResultsResults

Analysis in 0.5-2 keV, 2-7 keV and 0.5-7 Analysis in 0.5-2 keV, 2-7 keV and 0.5-7 kev bands independentlykev bands independently

CIAO Wavedetect using 1,2,4,8 x 2CIAO Wavedetect using 1,2,4,8 x 2 scales, 2 count (5 x 10scales, 2 count (5 x 10-5-5) threshold yields:) threshold yields: 4578 pt sources (0.5-7 keV)4578 pt sources (0.5-7 keV) 3352 pt sources (0.5-2 keV)3352 pt sources (0.5-2 keV) 2008 pt sources (2-7 keV)2008 pt sources (2-7 keV) 42 extended sources (0.5-2 keV)42 extended sources (0.5-2 keV)

2942 pt sources (0.5-7 keV) ≥4 counts2942 pt sources (0.5-7 keV) ≥4 counts 1636 pt sources (0.5-7 keV) with 2 and 3 1636 pt sources (0.5-7 keV) with 2 and 3

countscounts

Spurious SourcesSpurious Sources

Fully simulate 400 Fully simulate 400 source free fields source free fields using archival ACIS-using archival ACIS-I background dataI background data

Scale to 126 fields:Scale to 126 fields: Expect ~22 spurious Expect ~22 spurious

for ≥ 4 counts. for ≥ 4 counts. Expect ~625 Expect ~625

spurious for ≥ 2 spurious for ≥ 2 counts.counts.

Extended SourcesExtended Sources

•Matched Filter Analysis - (Vikhlinin 1995)

• 42 Sources (0.5-2 keV)

• Optical follow ups indicate most are clusters

• Spectroscopic redshifts are next

Cosmic Variance on Cosmic Variance on ACIS-I 16’x16’ FOVACIS-I 16’x16’ FOV

126 Fields, 4767 126 Fields, 4767 sources ≥ 2 sources ≥ 2 counts, 0.5-7 keVcounts, 0.5-7 keV

Consistent with Consistent with Poisson Poisson distribution with distribution with mean 36.33 mean 36.33 sources per fieldsources per field

2-Point Angular 2-Point Angular CorrelationCorrelation

• (() is the excess probability of finding a source with ) is the excess probability of finding a source with ±± of another source (Peebles, 1980) of another source (Peebles, 1980)

• We estimate We estimate (() according to Landy and Szalay, 1993) according to Landy and Szalay, 1993• Kenter et al. Poster (43.15 yesterday) for more detailsKenter et al. Poster (43.15 yesterday) for more details• Solid line is from Vikhlinin 1995 for ROSAT 140 degSolid line is from Vikhlinin 1995 for ROSAT 140 deg22

Log N - Log SLog N - Log S

Use convolution method (Kenter and Murray Use convolution method (Kenter and Murray 2003) to fit survey data with 2 ct threshold. Note 2003) to fit survey data with 2 ct threshold. Note this is differential N(S), not integral N(>S)this is differential N(S), not integral N(>S)

Results agree with previous surveys, including Results agree with previous surveys, including Chandra Deep Fields (e.g., Giaconni 2001)Chandra Deep Fields (e.g., Giaconni 2001)

Source IdentificationsSource Identifications NDWFS - 9 degNDWFS - 9 deg22 in Boötes in Boötes

(Jannuzi and Dey, 1999; Brown et al., 2003)(Jannuzi and Dey, 1999; Brown et al., 2003) BBww (U and B), R, I => 26 mag (U and B), R, I => 26 mag K 19 - 19.5 => magK 19 - 19.5 => mag K partial coverage (6 degK partial coverage (6 deg22))

Sub arc second astrometrySub arc second astrometry Multicolor magnitudes to few hundredthsMulticolor magnitudes to few hundredths Can get estimated photometric redshifts Can get estimated photometric redshifts

for galaxies, need spectra for AGNfor galaxies, need spectra for AGN Match to X-ray sources with ≥ 4 counts Match to X-ray sources with ≥ 4 counts

(need good positions)(need good positions)

Fraction ≥ 4 Counts Fraction ≥ 4 Counts MatchedMatched

Solid Curve - RSolid Curve - R Dashed Curve - BDashed Curve - Bww

Dotted Curve - IDotted Curve - I Dot-dashed Curve - Dot-dashed Curve -

KK 95% have at least 95% have at least

some match within some match within the X-ray position the X-ray position uncertaintyuncertainty

X-ray Optical MatchesX-ray Optical Matches

Typical matchTypical match Use greater of 1.5” Use greater of 1.5”

or 3or 3 X-ray position X-ray position errorerror

R=23.78 m, R=23.78 m, X=5.24 ctX=5.24 ct

~50% of X ≥ 4 ct ~50% of X ≥ 4 ct have R > 22 m have R > 22 m matchmatch

Accurate X-ray PositionsAccurate X-ray Positions

Group of possible Group of possible IDsIDs

One uniquely One uniquely within 1.5 arc within 1.5 arc secondsseconds

R=19 m, X=11.26R=19 m, X=11.26 Might be a groupMight be a group

Empty FieldEmpty Field X = 12.76X = 12.76 RRlimlim=25.8=25.8 Only 5% of ≥ 4 Only 5% of ≥ 4

count X-ray count X-ray sources have no sources have no match => ~150, match => ~150, but only ~20 but only ~20 spurious expectedspurious expected

May be extremely May be extremely absorbed sourcesabsorbed sources

Near Bright GalaxyNear Bright Galaxy

X = 4.18X = 4.18 Bright elliptical Bright elliptical

galaxy is 10 arc galaxy is 10 arc seconds offsetseconds offset

Can mask possible Can mask possible faint candidate faint candidate

SpectroscopySpectroscopy MMT Hectospect RunMMT Hectospect Run 4 Nights for NDWFS4 Nights for NDWFS 676 X-ray selected676 X-ray selected

208 R<19.2208 R<19.2 175 19.2<R<20.0175 19.2<R<20.0 293 20.0<R<22.0293 20.0<R<22.0

Redshifts for 509; 353 Redshifts for 509; 353 AGN, 152 Galaxy (all AGN, 152 Galaxy (all z<1)z<1) 98 0.0<z<1.098 0.0<z<1.0 183 1.0<z<2.0183 1.0<z<2.0 72 z>2.072 z>2.0

ConclusionsConclusions Survey detects expected numbers of point Survey detects expected numbers of point

and extended sources.and extended sources. The NDWFS is a good match to the X-ray The NDWFS is a good match to the X-ray

depth and identifies most of the sources.depth and identifies most of the sources. Optical positions can be used for multi-object Optical positions can be used for multi-object

spectroscopy to obtain redshifts (4 nights spectroscopy to obtain redshifts (4 nights with MMT-Hectospec in April, a good start > with MMT-Hectospec in April, a good start > 676 spectra of X-ray selected objects), more 676 spectra of X-ray selected objects), more in June in June

X-ray follow up, especially for extended X-ray follow up, especially for extended sources.sources.

When complete will provide a true 3D survey When complete will provide a true 3D survey over 9.3 square degreesover 9.3 square degrees