1. Initial Results from the Chandra Shallow X-ray Survey in the NDWFS in Boötes S. Murray, C. Jones, W. Forman, A. Kenter, A. Vikhlinin, P. Green, D. Fabricant, G. Fazio - CfA B. Jannuzi, A. Dey, J. Najita, M. Brown, K. Brand - NOAO J. Shields, B. McNamara - OhioU M. Rieke - AzU C. Kochanek - OSU

2. Survey Characteristics Large contiguous area (9.3 deg 2 ), with arc second resolution Large contiguous area (9.3 deg 2 ), with arc second resolution Well studied optically - NOAO Deep Wide File Survey (NDWFS) Well studied optically - NOAO Deep Wide File Survey (NDWFS) Accessible for spectroscopic follow up (MMT-Hectospec, Gemini, Keck, …) Accessible for spectroscopic follow up (MMT-Hectospec, Gemini, Keck, …) Multiwavelength coverage (SST-IRAC, VLA-FIRST, GALEX, …) Multiwavelength coverage (SST-IRAC, VLA-FIRST, GALEX, …) Centered at  =14 h 32 m  =34  06’ Centered at  =14 h 32 m  =34  06’

3. Science Objectives Complete Flux Limited Contiguous Survey Complete Flux Limited Contiguous Survey Optical Ids Optical 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 Structure Large Scale Structure Angular and Spatial Correlations Angular and Spatial Correlations Luminosity Function Luminosity Function Classes Classes Cluster Survey Cluster Survey

4. Mosaic of X-ray Fields 126 ACIS-I pointings (ACIS-S2 chip also) 5 ksec exposure (4287 - 5120 sec) Fields overlap by about 1 arc minute Total of 630 ksec of Chandra time (about 2 orbits) March/April 2003

6. Representative Single Field Seq 3602 (N-F57) Total counts ~3000 Smoothed with 2 arc second Gaussian Raw image analyzed with wavelet detect 31 sources (  2 cts) 1 extended source

7. Source Existence Typically fields have ~3000 events (in 5000 sec) Typically fields have ~3000 events (in 5000 sec)  B = 7.2x10 -4 ct/pixel (~0.5 arc second) On axis detect cell is 2x2 arcsec = 16 pixels => B=1.2x10 -2 On axis detect cell is 2x2 arcsec = 16 pixels => B=1.2x10 -2 Poisson Statistics give: P(≥2)=7.143x10 -5 (3.8  ) Poisson Statistics give: P(≥2)=7.143x10 -5 (3.8  ) P(≥3)=2.9x10 -7 (>5  ) P(≥3)=2.9x10 -7 (>5  ) Off axis detect cell is 8x8 arcsec = 256 pixels =>B=1.84x10 -1 Off axis detect cell is 8x8 arcsec = 256 pixels =>B=1.84x10 -1 P(≥2) => 2.2 , P(≥3) => 3.1 , P(≥4) =>3.9 , P(≥5)=>4.7  P(≥2) => 2.2 , P(≥3) => 3.1 , P(≥4) =>3.9 , P(≥5)=>4.7  At a 4 count threshold, >99% of sources should be real no matter where they are in each field. Closer to the center even sources with 2 counts are likely to be real At a 4 count threshold, >99% of sources should be real no matter where they are in each field. Closer to the center even sources with 2 counts are likely to be real Use simulations to quantify these conclusions Use simulations to quantify these conclusions

8. X-Ray Survey Detection Results Analysis in 0.5-2 keV, 2-7 keV and 0.5-7 kev bands independently Analysis in 0.5-2 keV, 2-7 keV and 0.5-7 kev bands independently CIAO Wavedetect using 1,2,4,8 x 2  scales, 2 count (5 x 10 -5 ) threshold yields: CIAO Wavedetect using 1,2,4,8 x 2  scales, 2 count (5 x 10 -5 ) 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 counts 2942 pt sources (0.5-7 keV) ≥4 counts 1636 pt sources (0.5-7 keV) with 2 and 3 counts 1636 pt sources (0.5-7 keV) with 2 and 3 counts

9. Spurious Sources Fully simulate 400 source free fields using archival ACIS-I background data Scale to 126 fields: Expect ~22 spurious for ≥ 4 counts. Expect ~625 spurious for ≥ 2 counts.

10. Extended Sources Matched Filter Analysis - (Vikhlinin 1995) 42 Sources (0.5-2 keV) Optical follow ups indicate most are clusters Spectroscopic redshifts are next

11. Cosmic Variance on ACIS-I 16’x16’ FOV 126 Fields, 4767 sources ≥ 2 counts, 0.5-7 keV Consistent with Poisson distribution with mean 36.33 sources per field

12. 2-Point Angular Correlation  (  ) is the excess probability of finding a source with  ±  of another source (Peebles, 1980) We estimate  (  ) according to Landy and Szalay, 1993 Kenter et al. Poster (43.15 yesterday) for more details Solid line is from Vikhlinin 1995 for ROSAT 140 deg 2

13. Log N - Log S Use convolution method (Kenter and Murray 2003) to fit survey data with 2 ct threshold. Note this is differential N(S), not integral N(>S) Results agree with previous surveys, including Chandra Deep Fields (e.g., Giaconni 2001)

14. Source Identifications NDWFS - 9 deg 2 in Boötes (Jannuzi and Dey, 1999; Brown et al., 2003) NDWFS - 9 deg 2 in Boötes (Jannuzi and Dey, 1999; Brown et al., 2003) B w (U and B), R, I => 26 mag B w (U and B), R, I => 26 mag K 19 - 19.5 => mag K 19 - 19.5 => mag K partial coverage (6 deg 2 ) K partial coverage (6 deg 2 ) Sub arc second astrometry Sub arc second astrometry Multicolor magnitudes to few hundredths Multicolor magnitudes to few hundredths Can get estimated photometric redshifts for galaxies, need spectra for AGN Can get estimated photometric redshifts for galaxies, need spectra for AGN Match to X-ray sources with ≥ 4 counts (need good positions) Match to X-ray sources with ≥ 4 counts (need good positions)

15. Fraction ≥ 4 Counts Matched Solid Curve - R Dashed Curve - B w Dotted Curve - I Dot-dashed Curve - K 95% have at least some match within the X-ray position uncertainty

16. X-ray Optical Matches Typical match Use greater of 1.5” or 3  X-ray position error R=23.78 m, X=5.24 ct ~50% of X ≥ 4 ct have R > 22 m match

17. Accurate X-ray Positions Group of possible IDs One uniquely within 1.5 arc seconds R=19 m, X=11.26 Might be a group

18. Empty Field X = 12.76 R lim =25.8 Only 5% of ≥ 4 count X-ray sources have no match => ~150, but only ~20 spurious expected May be extremely absorbed sources

19. Near Bright Galaxy X = 4.18 Bright elliptical galaxy is 10 arc seconds offset Can mask possible faint candidate

20. Spectroscopy MMT Hectospect Run 4 Nights for NDWFS 676 X-ray selected 208 R<19.2 175 19.2<R<20.0 293 20.0<R<22.0 Redshifts for 509; 353 AGN, 152 Galaxy (all z<1) 98 0.0<z<1.0 183 1.0<z<2.0 72 z>2.0

21. Conclusions Survey detects expected numbers of point and extended sources. Survey detects expected numbers of point and extended sources. The NDWFS is a good match to the X-ray depth and identifies most of the sources. The NDWFS is a good match to the X-ray depth and identifies most of the sources. Optical positions can be used for multi-object spectroscopy to obtain redshifts (4 nights with MMT-Hectospec in April, a good start > 676 spectra of X-ray selected objects), more in June Optical positions can be used for multi-object spectroscopy to obtain redshifts (4 nights with MMT-Hectospec in April, a good start > 676 spectra of X-ray selected objects), more in June X-ray follow up, especially for extended sources. X-ray follow up, especially for extended sources. When complete will provide a true 3D survey over 9.3 square degrees When complete will provide a true 3D survey over 9.3 square degrees