INTEGRAL 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

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

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

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

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

AGN seen by INTEGRAL >20 keV ● Blazars are variable – preferentially ToO objects: S (Pian et al. 2005), 3C (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 keV ? ● Can we explain the CXB using INTEGRAL detected AGN?

INTEGRAL AGN survey public data, imager IBIS/ISGRI, 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, L X = 43.3 ergs/sec  Luminosity function: complete subsample of 38 AGN (no blazars)

INTEG Differential luminosity function of AGN with (log Lx) = 0.5 binning. γ 1 =0.8, γ 2 =2.1, L * = ergs/sec

AGN luminosity function > 20 keV ●  1 = 0.8,  2 =2.1 ● L * = 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?

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

INTEG Emissivity of INTEGRAL AGN in the local Universe: W(>10 41 ergs/sec) = ergs/s Mpc -3

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

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 ± 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 - paper: Beckmann, Soldi, Shrader, Gehrels & Produit, 2006, ApJ 652, 126 (astro-ph/ )

Additional material

INTEG Cumulative AGN luminosity function for 21 absorbed (N H > cm -2 ; red) and 13 unabsorbed sources (blue)

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

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

INTEGRAL AGN survey ● absorbed : N H >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 N H information highly absorbed?

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

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

INTEG The total survey area with respect to the 5 sigma flux limit in the keV energy band

INTEG The INTEGRAL AGN sample is complete above 5 sigma

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

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