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AGN in X-Ray Surveys

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  1. AGN in X-Ray Surveys For Astro597 Jian Wu November 10, 2004

  2. OUTLINE • Part IAGN Surveys in Different Bands • Part IIAGN X-ray Surveys

  3. Part IAGN Surveys in Different Bands • AGN Surveys in different bands • Retrospect • Optical selection and implications • Radio selection • Infrared selection • High-Energy selection • Selection Effects

  4. Part IIAGN X-ray Surveys • Soft X-rays Surveys • Hard X-ray Surveys • Pre-Chandra and XMM-Newton • Deep Chandra and XMM-Newton Surveys • Deep Extragalactic X-ray Surveys • 2Ms Chandra Point-Source CATA

  5. Part I AGN Surveys in Different Bands

  6. Retrospect • Lamppost Effect • find something in where we can find it • Three types of surveys • Find object • Find object consistently • Find with well-defined selection criteria

  7. Retrospect • First indication (optical) • NGC1068-broad emission lines (Fath, 1913) • M87-jet (Curtis 1917) • Extragalactic radio sources • The origin of name for quasar (Schmidt et.al., 1964)

  8. Retrospect • Early AGN Surveys • Cambridge xC Surveys • Markarian Survey • Zwichky Survey • Recent Large Surveys • 2dF • SDSS • How to find AGN-SED • Power law (1013Hz-1020Hz) • Highly ionized Emission lines-C N O • Low-ionization emission lines-Fe

  9. Optical Selection • Principle (Sandage 1971) • Systematic optical color deviation from starlight • Bonus • Photometric red-shift estimation • Declaration of “complete samples” • Fatal bug • Lb does not correlated well with Lgalaxy→ cannot see low luminosity AGN in massive galaxies (contamination) • Aftermath • Omission (radio, IR, X-ray)

  10. Optical Selection • Optical selection effect • Luminosities • Hard to evaluate • Alternatives • Variability • Absence of proper motion

  11. Radio Selection • Principles • Flat-spectrum, compact radio source • Object with low IR/radio • morphology • Advantages • Efficient • Sensitive • Accurate • Find objects omitted by optical techniques • Disadvantages • Incomplete (selection effect) • Star-forming region

  12. Infrared Selection • Disadvantages • Color difference is subtle • Equivalent width insufficient • An Island • Potential advantages • mid-IR to be a “pivot point” in SED • PAH and high ionization IR lines • Prospect • SIRTF

  13. High-Energy Selection • X-ray and γ-ray • Disadvantages • Soft X-ray suffer from larger extinction • Red-shift distribution • γ-ray position • Soft X-ray bias

  14. Selection Effect • Dilution of the optical/IR brightness and color by the starlight. • Obscuration • Another selection effect

  15. Part II AGN X-ray Surveys

  16. Advantages • High contrast between AGN and stellar light

  17. Advantages • Penetrating power of X-rays.

  18. Advantages • Great sensitivity of Chandra and XMM-Newton

  19. Advantages • Accurate positions from Chandra • ~ 0.5 arcsec

  20. Advantages • A relatively large fraction of the bolometric energy (3-20%) is radiated in the classical X-ray bands. • High area density (400 deg-2) • Large amplitude and frequency of variability in the X-ray band. • Little Contamination from other objects • High red-shift quasars are easy to detect • Close to the black hole

  21. Early X-ray Surveys • Uhuru (1970 10-1973 3) [2-20 keV] • Ariel-V (1973 10-1980 3) [0.3-40 keV] • HEAO-1 (1977 8-1979 1) [0.2keV-10MeV]

  22. Soft X-ray Surveys • Einstein (1978 11-1981 4) [0.2-20 keV] • ROSAT (1990 1-1999 2) [0.1-2.5 keV]

  23. Soft X-ray Surveys • Fruit • Moderate correlation of optical and X-ray

  24. Hard X-ray surveys • ASCA (1993 2-2001 3) [0.4-10 keV] • BeppoSAX (1996 4-2002 4) [0.1-300 keV] • Fruit • ~ 500 serendipitous sources over ~ 100 deg2

  25. Deep Chandra and XMM-NewtonSurveys • Chandra (1999 7-present) • XMM-Newton (1999 10-present)

  26. Deep Chandra and XMM-NewtonSurveys • Fruit • Numerous “optically dull” objects • Greatly enlarge the AGN population

  27. Deep Extragalactic X-ray Surveys

  28. Deep Extragalactic X-ray Surveys

  29. Deep Extragalactic X-ray Surveys

  30. Deep Extragalactic X-ray Surveys • Source classification difficulties • Too faint to be identified by optical spectrum • Many of the X-ray sources have modest optical luminosities, often due to obscuration • “schism” between optical (type1 and type2) and X-ray (unobscured and obscured )

  31. Deep Extragalactic X-ray Surveys

  32. Deep Extragalactic X-ray Surveys • Basic AGN Types • Unobscured AGN • Obscured AGN with clear optical/UV AGN signatures. • Optically faint X-ray sources • XBONGs (X-ray Bright Optically Normal Galaxies)

  33. [Bargar et al. 2002] [Bargar et al. 2003] AGN Red-shift Distribution • Most AGN in deep X-ray surveys have z =0~2 • Redshift distribution show “spikes” in z=0.5~2.5

  34. Luminosity-redshift Plot

  35. AGN Selection Completeness • Reasons of incompleteness • Compton thick AGN • Luminous at non-X-ray, but X-ray weak • How many we haven’t seen 2000-3000 deg-2

  36. Key results from DEXS • Large optically selected luminous quasars • PLE (Pure luminosity Evolution) • Moderate-luminosity AGN • LDDE (luminosity-dependent density evolution)

  37. Comoving space density

  38. X-ray constraints • Sky density • Bottom line (z > 4) ~ 30-150 deg-2 • AGN contribution to reionization at z ~ 6 is small • Accretion[z>4] ~ Accretion[local] • Infrared and sub-millimeter • star-forming processes • AGN/sub-mm galaxies >=40%. • X-ray survey should remain an effective way to find AGN at the highest redshift

  39. Future prospects • Detailed cosmic history of SMBH accretion • The nature of AGN activity in young, forming galaxies • X-ray measurements of clustering and large-scale structure • The X-ray properties of cosmologically distant starburst and normal galaxies

  40. Main CATAlog High significant Chandra sources Supplementary CATAlog Lower significance Chandra sources The 2Ms CDF-N 20 observations 447.8 arcmin2 Flux limit=2.5×10-17 erg cm-2 s-1 (0.5-2.0 keV) Flux limit=1.4 ×10-16 erg cm-2 s-1 (2.0-8.0 keV)

  41. CIAO Chandra Interactive Analysis of Observations Radiation damage Quantum Efficiency Losses Bad column Bad pixel Cosmic ray afterglow Standard pixel randomization Potential background events Data reduction

  42. Technique feature Matched filter Accuracy of the X-ray source position Correlation of optically bright sources with lower significance Chandra sources Production of CATAlogs

  43. Image and Exposure Map Creation

  44. FB HB SB1 SB SB2 HB1 HB2 keV Standard Bands

  45. False positive probability 1×10-7 main CATAlog 1×10-5 supplementary optically bright source CATAlog Point-source Detection • Key criterion

  46. Source Position Refinement X –ray 1.4GHz Radio 503 sources

  47. Position of sources in main138 NEW!

  48. Supplementary Optically Bright Chandra Source CATA X –ray Optical R-band 79 sources

  49. Primary analysis of S

  50. X-ray Band ratio