INTEGRAL 20 - 40 keV AGN Survey INTEGRAL 20 - 40 keV AGN Survey and Luminosity Functionand 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

OverviewOverview

● 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:20-400 keVfov: 9º x 9º12 arcmin

JEM-X:2-30 keVfov: 5º, 3 arcminFWHM ~0.3 keV

SPI:20-8000 keVfov: 16º2º resolution1.3 keV @ 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 keVAGN 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?

INTEGRAL AGN surveyINTEGRAL 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)

INTEG

Differential luminosity function of AGN with (log Lx) = 0.5 binning. γ

1=0.8, γ

2=2.1, L

*=2.4 1043 ergs/sec

AGN luminosity function > 20 keVAGN 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?

INTEG

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

INTEG

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

INTEGRAL AGN surveyINTEGRAL 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

ConclusionsConclusions- 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)

Additional materialAdditional material

INTEG

Cumulative AGN luminosity function for 21 absorbed (NH > 1022 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 surveyINTEGRAL 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 N

H

information highly absorbed?

The Ve/Va parameterThe Ve/Va parameter

Ve

Va

z

zmax

(fx,z,fluxlimit)

<Ve/Va> = 0.5 for a homogeneous sample with no evolution in Eucledian space

Avni & Bahcall 1980, ApJ 235, 694

INTEGRAL AGN surveyINTEGRAL 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 20-40 keV energy band

INTEGThe 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.