1 / 20

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

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

jadon
Télécharger la présentation

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

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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 deg2), with arc second resolution • Well studied optically - NOAO Deep Wide File Survey (NDWFS) • Accessible for spectroscopic follow up (MMT-Hectospec, Gemini, Keck, …) • Multiwavelength coverage (SST-IRAC, VLA-FIRST, GALEX, …) • Centered at =14h 32m =34 06’

  3. Science Objectives • Complete Flux Limited Contiguous Survey • Optical Ids • Redshifts • Spectroscopic complete to R < (21-22) • Photometric to R < (24-26) • Large Scale Structure • Angular and Spatial Correlations • Luminosity Function • Classes • 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

  5. 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

  6. X-Ray Survey Detection Results • 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: • 4578 pt sources (0.5-7 keV) • 3352 pt sources (0.5-2 keV) • 2008 pt sources (2-7 keV) • 42 extended sources (0.5-2 keV) • 2942 pt sources (0.5-7 keV) ≥4 counts • 1636 pt sources (0.5-7 keV) with 2 and 3 counts

  7. 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.

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

  9. 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

  10. 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 deg2

  11. 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)

  12. Source Identifications • NDWFS - 9 deg2 in Boötes(Jannuzi and Dey, 1999; Brown et al., 2003) • Bw (U and B), R, I => 26 mag • K 19 - 19.5 => mag • K partial coverage (6 deg2) • Sub arc second astrometry • Multicolor magnitudes to few hundredths • Can get estimated photometric redshifts for galaxies, need spectra for AGN • Match to X-ray sources with ≥ 4 counts (need good positions)

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

  14. 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

  15. 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

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

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

  18. 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

  19. Conclusions • 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. • 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. • When complete will provide a true 3D survey over 9.3 square degrees

More Related