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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.

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Presentation on theme: "INTEGRAL 20 - 40 keV AGN Survey and Luminosity Function Volker Beckmann NASA Goddard Space Flight Center, Exploration of the Universe Division & Joint."— Presentation transcript:

1 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

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

4 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

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: 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?

7 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)

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

9 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?

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

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

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 ± 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/ )

14 Additional material

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

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

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

18 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?

19 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

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

22 INTEG The INTEGRAL AGN sample is complete above 5 sigma

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

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


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