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INTEGRAL 20 - 40 keV AGN Survey and Luminosity Function

Volker Beckmann NASA Goddard Space Flight Center, Exploration of the Universe Division & Joint Center for Astrophysics, University of Maryland, Baltimore County & C. R. Shrader, N. Gehrels, S. Soldi, N. Produit Extragalactic Surveys Workshop, November 6, 2006.

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INTEGRAL 20 - 40 keV AGN Survey and Luminosity Function

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  1. Volker Beckmann NASA Goddard Space Flight Center, Exploration of the Universe Division & Joint Center for Astrophysics, University of Maryland, Baltimore County & C. R. Shrader, N. Gehrels, S. Soldi, N. Produit Extragalactic Surveys Workshop, November 6, 2006 INTEGRAL 20 - 40 keV AGN Survey and Luminosity Function

  2. Overview • The First INTEGRAL AGN catalog • Hard X-ray luminosity function (20-40 keV) • Obscured vs. unobscured AGN • Implications for the hard X-ray background • Conclusions ESA / V. Beckmann

  3. The CXB peaks around 30 keV (Gruber et al. 1999) INTEG

  4. IBIS/ISGRI: 20-400 keV fov: 9º x 9º 12 arcmin JEM-X: 2-30 keV fov: 5º, 3 arcmin FWHM ~0.3 keV SPI: 20-8000 keV fov: 16º 2º resolution 1.3 keV @ 1MeV OMC: V-band imaging INTEGRAL Graphic: ESA

  5. Example for INTEGRAL 400 ks spectrum of a bright AGN (compared to OSSE spectrum). Beckmann et al. 2005, ApJ 634, 939

  6. AGN seen by INTEGRAL >20 keV • Blazars are variable – preferentially ToO objects: S5 0716+714 (Pian et al. 2005), 3C 454.3 (Pian et al. 2006), 3C 279 (Collmar et al. 2004) , Mrk 421 • AGN observed so far: bright well known AGN (catalog paper Beckmann et al. 2006, ApJ 638, 642) • large field of view; additional AGN + new detections: IGR J… (e.g. Masetti et al. 2004, 2005, 2006) • How dominant are absorbed sources/Seyfert 2 at 20-40 keV ? • Can we explain the CXB using INTEGRAL detected AGN?

  7. INTEGRAL AGN survey public data, imager IBIS/ISGRI, 20 - 40 keV • extract images/spectra from data 10° around the source position • 71 AGN and 2 Clusters (Coma, Oph) • 11 new INTEGRAL sources, 7 blazars • Sazonov et al. (2006): 127 AGN, about 23 new INTEGRAL sources • Low redshift : z = 0.022, LX = 43.3 ergs/sec • Luminosity function: complete subsample of 38 AGN (no blazars)

  8. Differential luminosity function of AGN with (log Lx) = 0.5 binning. γ1=0.8, γ2=2.1, L*=2.4 1043 ergs/sec INTEG

  9. AGN luminosity function > 20 keV • 1 = 0.8, 2=2.1 • L* = 2.4 1043 ergs/sec • Consistent with XLF at 2-10 keV (Ueda et al. 2003, La Franca 2005) and 3 – 20 keV (Sazonov & Revnivtsev 2004) • Similar population? • 60% absorbed sources • < 10% Compton thick • 30 keV peak in the X-ray background?

  10. Intrinsic absorption. Shaded area: measured, open area: estimated from ISGRI/RASS flux comparison INTEG

  11. Emissivity of INTEGRAL AGN in the local Universe: W(>1041 ergs/sec) =2.8 1038 ergs/s Mpc-3 INTEG

  12. INTEGRAL AGN survey • Emissivity about a factor of ~1.5 too low to explain the cosmic X-ray background (CXB) • Where are the missing sources? • Compton thick? Up to now not seen (Swift/BAT; but see also next presentation by Lisa Winter) • Low luminosity? LINER, non-active galaxies, ULX, cluster of galaxies? • Redshift dependent? Increase of absorbed sources toward higher redshift (La Franca et al. 2005, but not in Ueda et al. 2003, Treister & Urry 2005) • careful: total flux of INTEGRAL AGN accounts for < 2% of CXB flux

  13. Conclusions - INTEGRAL good for detailed analysis of ~20 objects: Comptonisation features in AGN - 71 AGN + 2 GCluster in the INTEGRAL AGN catalogue - number counts slope: 1.66 ± 0.11 - luminosity function consistent with < 20 keV findings and with Swift/BAT AGN Survey (Tueller et al. 2007) - absorbed : unabsorbed ratio 1.5…2.0 (60%-70%) - up to now no new class of extragalactic sources found http://heasarc.gsfc.nasa.gov/docs/integral - paper: Beckmann, Soldi, Shrader, Gehrels & Produit, 2006, ApJ 652, 126 (astro-ph/0606687)

  14. Additional material

  15. Cumulative AGN luminosity function for 21 absorbed (NH > 1022 cm-2; red) and 13 unabsorbed sources (blue) INTEG

  16. Number flux distribution per steradian of INTEGRAL AGN (no blazars) with detection significance >5. The slope is 1.66 ± 0.11 INTEG

  17. Fraction of absorbed AGN as a function of X-ray luminosity INTEG

  18. INTEGRAL AGN survey • absorbed : NH >10²² cm-² • 21 absorbed, 13 unabsorbed (X=1.6) • Γ = 1.98 / 2.08 • 13 Seyfert 1, 9 Seyfert 1.5, 14 Seyfert 2 • Γ = 2.11 / 2.10 / 1.95 • 7 Blazars; Γ =2.07 • Sy2 : Sy 1.5 : Sy 1 = (1.1 : 0.7 : 1.0) • Are the AGNs for which we do not have NH information highly absorbed?

  19. The Ve/Va parameter Va zmax (fx,z,fluxlimit) Ve z <Ve/Va> = 0.5 for a homogeneous sample with no evolution in Eucledian space Avni & Bahcall 1980, ApJ 235, 694

  20. INTEGRAL AGN survey • Highly inhomogeneous survey • Instead of a flux limit, define a completeness significance limit • Determine for each source, in which survey fields it would have been detected • First: What is the significance limit? • Ve/Va test (Avni & Bahcall 1980) shows that sample complete at 5 sigma

  21. The total survey area with respect to the 5 sigma flux limit in the 20-40 keV energy band INTEG

  22. INTEG The INTEGRAL AGN sample is complete above 5 sigma

  23. Exposure map in Galactic coordinates. Contours indicate 2, 5, 10, 20, 100, 200, 500, 1000, 2000 ksec exposure time. INTEG

  24. The flux limit in the survey as a function of the exposure time. INTEG

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