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The Chandra Multi-wavelength Project (ChaMP)

A serendipitous X-ray survey using Chandra archival data to study AGN populations, high-z clusters, and cosmic variance.

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The Chandra Multi-wavelength Project (ChaMP)

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  1. The Chandra Multi-wavelength Project (ChaMP) PIs: Paul Green & Belinda Wilkes X-ray: Dong-Woo Kim Imaging: Rob Cameron, Wayne Barkhouse Spectroscopy: John Silverman and the ChaMP Collaboration SerendipitousX-raySurveyusingChandraArchival Data

  2. Principal Motivations • Sample X-ray selected AGN across L,z plane • Study populations contributing to the CXRB • Find high-z clusters to constrain Cosmology • Study cosmic variance and clustering • Sample DLyα absorbers to XSQSOs • Detect mass limits of stellar coronal emission

  3. Quasar and AGN Evolution: What do we know? Optical surveys: Unobscured population (view the BLR and/or NLR) Technically feasible for wide and deep sky coverage to sample to z~6 2dF (Boyle et al. 2000) SDSS (Fan et al. 2001) 0<z<2 depletion of fuel? (Cavaliere & Vittorini 2000) z>3 SMBH growth and highly efficient accretion? (Wyithe & Loeb 2002 etc.)

  4. Quasar and AGN EvolutionPast X-ray surveys Cosmic X-Ray Background (CXRB): Significant obscured population (Gilli et al. 2001, Comastri et al. 1995) Einstein Medium Sensitivity Survey (Maccacaro et al. 1991; EMSS) 420 AGNs, z<2 and fx>10-13 erg s-1 cm-2 resolved ~40% CXRB at 2 keV ROSAT(Miyaji et al. 2000) Compilation of various depth surveys 690 AGNs with 8 at z>3 resolved ~90% 0.5-2.0 keV CXRB Luminosity evolution similar to optical surveys ROSAT Luminosity function

  5. Space Density of Luminous Quasars • Optical and radio LFs peak at z~2 • X-ray space density MAY flatten at z>3 • Need more high-z, X-ray selected AGN (Miyaji et al 2000)

  6. Chandra Advances ~1” positions, small PSF & low background 10-100× fainter flux limits unambiguous source IDs Source extent and morphology XMM is Complementary 4× Effective Area + larger Field-of-View Harder energy band: 0.5-20 keV

  7. Redshift distribution of deep Chandra sources Obscured AGN population resides at z<1.5 Barger et al., Cowie et al. 2003 ●1043 < Lx(2-8 keV)< 1044 erg/s ○ 1044 < Lx < 1045 erg/s Do High and Low L AGN Evolve Differently?

  8. Resolved ~80-90% of the 2-8 keV CXRB CDF-N (Brandt et al. 02) , CDF-S (Giacconi et al 01), Lockman Hole (Hasinger et al. 01) Chandra bandpass CXRB is not a fully solved issue Quasar and AGN EvolutionCurrent Chandra and XMM deep surveys Comastri et al. 1995

  9. Hard CXRB Dominated by “Bright” Sources Cowie et al. (2002)

  10. Outline of the ChaMP • 135 selected ACIS fields from Cycles 1&2 • X-ray source detection & photometry • Source IDs via optical imaging: g’r’i’ • Classification in X-ray/optical multicolor plane • Optical spectroscopy of bright subsample • Radio: NVSS+FIRST; VLA • 2MASS; near-IR Imaging (TBD)

  11. ChaMP Field Distribution • 137 Cycle 1&2 ACIS Fields: ~14 sq. deg • Exposure times 2-190 ksec • ~6000 X-ray sources

  12. Predicted Number Counts Grimes, Green, Kim • 4000 AGN (800 abs’bd) 2000 galaxies, 200-300 M stars, 40 clusters • Chandra Deep Surveys: 1&2 Msec (ACIS-I) • ROSAT compilation (Miyaji et al. 2000)

  13. Kim et al. 2003 ChaMP logN-logS Bridges flux gaps between ROSAT, ASCA &Chandra Deep Fields Soft Band Hard Band

  14. Kim et al. 2003 ChaMP logN-logS: Results • Soft band differential logN-logS requires a broken powerlaw • βbright=2.3±0.2,βfaint=1.7±0.1, Sbreak=6×10-15 • Hard band: β=1.3±0.1 single PL acceptable • Both consistent with XMM(Baldi et al. 2001),CDF-N (Brandt et al. 2001)

  15. Cosmic Variance? • 62 fields • counts>20; θ<400” • typical errors shown • No significant Cosmic Variance! • 3C295 cluster field exposures marked • 100ksec exposure belies earlier claim of overdensity Kim et al. 2003

  16. ChaMP logN-logS: Clusters 29 cluster target fields 33 non-cluster fields Kim et al. 2003

  17. X-ray Simulations SAOSAC raytrace simulations Grid of off-axis angles 10 – 1000 count sources Std XPIPE detection & Photometry Compare input/output - detection rates - positions - fluxes

  18. Wavdetect Positional Uncertainties • Typically <1‘’ • Strong increase with θ due to PSF • Greatly improved after detection by a 2d wavdet pass using small kernel • Centroid uncertainty decreases for strong sources.

  19. Optical Identification P. Green, W. Barkhouse. R. Cameron, J. Silverman, A. Mossman With reduced, stacked NOAO MOSAIC images • Detect sources with SExtractor • Astrometric solution: GSC II, <0.3” rms • Cross-correlate X-ray and optical • Fine tune X-ray astrometry • Prioritize counterparts by X-O distance • Visual check of all optical IDs

  20. X-ray/Optical Matching Cameron, Silverman, Green • NOAO 4m/MOSAIC • Sloan g’ r’ i’ • Automated OAA dependent matching • Visual inspection

  21. Optical Counterparts Green et al. 2003: 6 fields>30ksec 483 sources > 3e-16 328optical IDs (68%) 125 spectra (25%) 194 sources > 3e-15 156 optical IDs (78%) 78 spectra (40%) spectra for 64% of r<22 IDs 55 sources > 1e-14 52 optical IDs (95%) 34 spectra (62%) spectra for 72% of r<22 IDs

  22. Optical Spectroscopic ProgramJ. Silverman, P. Green, P. Smith (Steward), S. Ellison (PUC), C. Foltz (NSF), C. Smith, M. Smith (CTIO), E. Colmenero-Romero (SAAO) • Spectroscopic identification r’<23 Telescope/Instrument # of nights Magellan/6.5m 9 -LDSS-2 multi-slit spectrograph (FOV ~5’) MMT/6.5m 9 -long slit KPNO/WIYN, CTIO/4m 19 -HYDRA multi-fiber (FOV 1 deg) KPNO/4m 3 -MARS(Multi-aperture red spectrograph) FLWO/1.5m FAST, SAAO -longslit (Queue observing) Additional spectra from J. Huchra, G. Torres, W. Brown, K. Adelberger, K. Krisciunas(CTIO), B. Kirshner 30/40 clear nights (~400 spectra)

  23. r’=21.5 r’=20.6 2’ x 2’ FOV r’=21.5 r’=22.0 Quasars at z > 3 Chandra Image 30 ksec exposure ACIS-I 8.5’ ACIS-S

  24. Covering the Lx-z Plane ChaMP complements the CDFs by finding numerous: • high-z, high-L QSOs • low-z, moderate-L AGN

  25. Covering the Lo-z Plane ChaMP garners high-L galaxies and QSOs. But ~no galaxies beyond z~0.8 ! Galaxy z limit set by r’<22

  26. Optical vs. X-ray Fluxes • BLAGN and stars well-separated • Different sample than optical surveys • Some ALGs have QSO-like fx/fopt • Many bright X-ray sources unmatched to r =25

  27. Hidden AGN • Hard sources appear at fX <10-14 • May compose CXRB • Many have no broad lines: Optical Type2 AGN? • Yes! LX >1043 • X-ray, optical absorption not 1:1

  28. Normal galaxy (optical) z=0.228 r’=19.6 Soft=2 counts Hard=89 counts X-ray absorption properties Soft: 0.3-2.5 keV Hard : 2.5-8.0 keV • As expected, BLAGN are predominately unobscured • Hard X-ray Sources are • obscured AGN • (Lx >10^42 erg/s) • NELG and ALG have a • wide range of X-ray • spectral properties • No type II QSOs detected • -selection effect • -5 detected in the CDF-S • -1 “ “ “ CDF-N

  29. Absorbed Objects X-ray faint objects tend to be redder X-ray hard objects tend to be redder

  30. ChaMP X-ray Spectral Fits CHaMP’s XFit pipeline uses Slang scripting running Sherpa fitting in CIAO Fits span 28 models (35 for known z)

  31. Serendipitous Clusters z=0.3? cluster with extended X-ray emission

  32. Serendipitous Clusters z=0.72 QSO with extended X-ray emission offset from QSO by rcore

  33. Spin-Off Projects • Clusters from optical and X-ray images • Lenses, pairs, jets • Variability pipeline (Bayesian block analysis) • Damped Lyα survey • AGN-AGN and AGN-galaxy clustering

  34. X-ray Properties of Optically Selected Clusters • Select clusters from both optical and X-ray images. • Use VTP on photometric catalog for optical cluster detection (Ramella et al. 2001). • Use color slices to raise sensitivity to red sequence.

  35. Damped Lyα Survey • ΩDLA increases with optical magnitude(Ellison et al. 2001) • Radio-selected quasar results show higher n(z) at 1σ • Are optical QSO DLA surveys are dust-biased? • ChaMP z>2 QSOs with r>20 will provide a stringent test

  36. Clustering & QSO Lifetimes • Current Limits • Proximity Effect  TQSO >105 yr • Overall Population  TQSO<109 yr (Martini & Weinberg 2001; Haiman & Lam 2001)

  37. ChaMP & the Community • ChaMP fields: ~20% of archived Cycle 1&2 targets • Public database: X-ray sources, optical IDs, matched optical images, photometry and colors • Will enhance Chandra science return! • Graduate student thesis projects available. Thanks to NASA for CXC Archival Research funding, to NOAO for telescope time awarded, and thanks to the whole ChaMP Collaboration!

  38. ‘Cosmic Variance’ consistent with Poisson No significant source overabundance associated with clusters αox or fx/fr dependence on L or z consistent with expectations from LF simulations + limits Half the objects with Lx>1043 are hard; presumably obscured AGN Wide area suitable for samples of rare objects. ChaMP Results to Date

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