2010A&A...517A..11P


C.D.S. - SIMBAD4 rel 1.7 - 2020.01.28CET11:56:34

2010A&A...517A..11P - Astronomy and Astrophysics, volume 517, A11-11 (2010/7-1)

The HELLAS2XMM survey. XIII. Multi-component analysis of the spectral energy distribution of obscured AGN.

POZZI F., VIGNALI C., COMASTRI A., BELLOCCHI E., FRITZ J., GRUPPIONI C., MIGNOLI M., MAIOLINO R., POZZETTI L., BRUSA M., FIORE F. and ZAMORANI G.

Abstract (from CDS):

We combine near-to-mid-IR Spitzer data with shorter wavelength observations (optical to X-rays) to get insight into the properties of a sample of luminous, obscured active galactic nuclei (AGN). We aim at modelling their broad-band spectral energy distributions (SEDs) in order to estimate the main parameters related to the dusty torus that is assumed to be responsible for the reprocessed IR emission. Our final goal is to estimate the intrinsic nuclear luminosities and the Eddington ratios for our luminous, obscured AGN. The sample comprises 16 obscured high-redshift (0.9≲z≲2.1), X-ray luminous quasars (L2–10keV∼1044erg/s) selected from the HELLAS2XMM survey in the 2-10keV band. The optical-IR SEDs are described by a multi-component model that includes a stellar component to account for the optical and near-IR emission, an AGN component that dominates in the mid-IR (mainly emission from a dusty torus heated by nuclear radiation), and a starburst to reproduce the far-IR bump. A radiative transfer code to compute the spectrum and intensity of dust reprocessed emission was extensively tested against our multiwavelength data. While the torus parameters and the BH accretion luminosities are a direct output of the SED-fitting procedure, the BH masses were estimated indirectly by means of the local Mbulge-MBH relation. The majority (∼80%) of the sources show moderate optical depth (τ9.7µm≤3), and the derived column densities NH are consistent with the X-ray inferred values (1022≲NH≲3x1023cm–2) for most of the objects, confirming that the sources are moderately obscured Compton-thin AGN. Accretion luminosities in the range 5x1044≲Lbol≲4x1046erg/s are inferred from the multiwavelength fitting procedure. We compare model luminosities with those obtained by integrating the observed SED, finding that the latter are lower by a factor of ∼2 in the median. The discrepancy can be as high as an order of magnitude for models with high optical depth (τ9.7µm=10). The ratio between the luminosities obtained by the fitting procedure and from the observed SED suggest that, at least for type 2 AGN, observed bolometric luminosities are likely to underestimate intrinsic ones and the effect is more severe for highly obscured sources. Bolometric corrections from the hard X-ray band are computed and have a median value of k_2-10 keV_∼20. The obscured AGN in our sample are characterized by relatively low Eddington ratios (median λEdd∼0.08). On average, they are consistent with the Eddington ratio increasing at increasing bolometric correction.

Abstract Copyright:

Journal keyword(s): quasars: general - galaxies: nuclei - galaxies: active

Simbad objects: 24

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Number of rows : 24

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 ACO 2690 ClG 00 00 13.75 -25 11 11.5           ~ 23 0
2 NAME ACO 2690 29 Sy1 00 01 11.6 -25 12 03       25.1   ~ 9 0
3 EGGR 382 WD? 00 33 54.4629052338 -12 07 58.777597136 15.511 15.572 14.891 14.467 14.051 DC? 90 0
4 [VV2006] J003357.2-120038 Sy2 00 33 57.2 -12 00 38     21.80 21.8   ~ 8 0
5 HELLAS2XMM 15800062 Sy2 00 34 13.8 -11 56 00     23.30 23.3   ~ 6 0
6 NAME BPM 16274 69 LIN 00 50 30.9 -52 00 48           ~ 9 0
7 M 77 GiP 02 42 40.771 -00 00 47.84 9.70 9.61 8.87 10.1 9.9 ~ 4023 2
8 HELLAS2XMM J031019.0-765958 X 03 10 18.96 -76 59 57.9       24.4   ~ 6 0
9 QSO J0311-7651 BLL 03 11 55.2500768688 -76 51 50.846014733 15.27 16.09 16.10 15.33   ~ 207 1
10 HELLAS2XMM J031343.5-765426 X 03 13 43.55 -76 54 26.3       24.6   ~ 6 0
11 HELLAS2XMM 05370123 Sy1 05 38 51.5 -28 39 49     23.10 23.1   ~ 7 0
12 HELLAS2XMM J053911.5-283717 X 05 39 11.5 -28 37 18       24.5   ~ 5 0
13 HELLAS2XMM 05370164 Sy2 05 39 17.1 -28 38 17     23.60 23.6   ~ 5 0
14 HELLAS2XMM J053920.5-283722 Sy2 05 39 20.5 -28 37 21     23.40 23.4   ~ 6 0
15 HELLAS2XMM J053945.3-284910 X 05 39 45.3 -28 49 11       25.0   ~ 5 0
16 QSO B0537-286 QSO 05 39 54.28147645 -28 39 55.9478122   19.70 20.0 18.789   ~ 235 2
17 HELLAS2XMM J054021.2-285038 X 05 40 21.2 -28 50 38       23.7   ~ 5 0
18 HELLAS2XMM 05370043 Sy2 05 40 22.1 -28 31 40     22.70 22.7   ~ 8 0
19 NAME COSMOS Field reg 10 00 28.60 +02 12 21.0           ~ 1939 0
20 NGC 4151 Sy1 12 10 32.5771747733 +39 24 21.057727323   12.18 11.48     ~ 3337 2
21 HELLAS2XMM 50900013 Sy2 20 43 49.5 -10 32 40     23.20 23.2   ~ 7 0
22 Mrk 509 Sy1 20 44 09.7504131334 -10 43 24.724854084   13.35 13.12 10.7   ~ 1106 0
23 HELLAS2XMM 50900001 Sy2 20 44 28.4 -10 56 33     23.90 23.9   ~ 6 0
24 NAME ACO 2690 75 Sy2 23 59 56.6 -25 10 20       24.6   ~ 10 0

    Equat.    Gal    SGal    Ecl

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2020.01.28-11:56:34

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