2011A&A...531A.116G


Query : 2011A&A...531A.116G

2011A&A...531A.116G - Astronomy and Astrophysics, volume 531A, 116-116 (2011/7-1)

X-ray observations of highly obscured τ_9.7 µm_>1 sources: an efficient method for selecting Compton-thick AGN?.

GEORGANTOPOULOS I., DASYRA K.M., ROVILOS E., POPE A., WU Y., DICKINSON M., COMASTRI A., GILLI R., ELBAZ D., ARMUS L. and AKYLAS A.

Abstract (from CDS):

Observations with the IRS spectrograph onboard Spitzer have found many sources with very deep Si features at 9.7µm, that have optical depths of τ>1. Since it is believed that a few of these systems in the local Universe are associated with Compton-thick active galactic nuclei (hereafter AGN), we set out to investigate whether the presence of a strong Si absorption feature is a good indicator of a heavily obscured AGN. We compile X-ray spectroscopic observations available in the literature on the optically-thick (τ9.7µm>1) sources from the 12µm IRAS Seyfert sample. We find that the majority of the high-τ optically confirmed Seyferts (six out of nine) in the 12µm sample are probably Compton-thick. Thus, we provide direct evidence of a connection between mid-IR optically-thick galaxies and Compton-thick AGN, with the success rate being close to 70% in the local Universe. This is at least comparable to, if not better than, other rates obtained with photometric information in the mid to far-IR, or even mid-IR to X-rays. However, this technique cannot provide complete Compton-thick AGN samples, i.e., there are many Compton-thick AGN that do not display significant Si absorption, with the most notable example being NGC1068. After assessing the validity of the high 9.7µm optical-depth technique in the local Universe, we attempt to construct a sample of candidate Compton-thick AGN at higher redshifts. We compile a sample of seven high-τ Spitzer sources in the Great Observatories Origins Deep Survey (GOODS) and five in the Spitzer First-Look Survey. All these have been selected to have no PAH features (EW6.2µm<0.3µm) to maximise the probability that they are bona-fide AGN. Six out of the seven GOODS sources have been detected in X-rays, while for the five FLS sources only X-ray flux upper limits are available. The high X-ray luminosities (LX>1042erg/s) of the detected GOODS sources corroborates that these are AGN. For FLS, ancillary optical spectroscopy reveals hidden nuclei in two more sources. SED fitting can support the presence of an AGN in the vast majority of sources. Owing to the limited photon statistics, we cannot derive useful constraints from X-ray spectroscopy on whether these sources are Compton-thick. However, the low LX/L6µm luminosity ratios, suggest that at least four out of the six detected sources in GOODS may be associated with Compton-thick AGN.

Abstract Copyright:

Journal keyword(s): X-rays: general - X-rays: diffuse background - X-rays: galaxies - infrared: galaxies

Simbad objects: 41

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Number of rows : 41
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 NGC 34 Sy2 00 11 06.612 -12 06 28.33   14.14 13.52     ~ 333 0
2 M 77 GiP 02 42 40.7091669408 -00 00 47.859690204 9.70 9.61 8.87 10.1 9.9 ~ 4348 2
3 NGC 1125 Sy2 02 51 40.3 -16 39 04   13.98 13.13 12.48   ~ 113 0
4 [WLF2008b] 1187 AGN 03 32 14.465 -27 52 33.77           ~ 10 0
5 GMASS 410 AGN 03 32 26.0050 -27 47 51.535   25.5214   25.75 24.9178 ~ 24 0
6 NAME Chandra Deep Field-South reg 03 32 28.0 -27 48 30           ~ 1962 1
7 NAME Extended Chandra Deep Field South reg 03 32 30.0 -27 48 20           ~ 708 0
8 ASPECS LP.1mm.C10 AGN 03 32 40.055 -27 47 55.42 25.2984 24.0577 23.690 23.701 23.084 ~ 57 0
9 NAME IRAS F08572+3915 NW LIN 09 00 25.364 +39 03 54.23     16.66     ~ 391 1
10 UGC 5101 Sy1 09 35 51.6045544584 +61 21 11.589382368   15.20 15.50     ~ 541 4
11 NGC 3079 Sy2 10 01 57.8789863992 +55 40 47.449758324 11.57 11.54 10.86     ~ 1320 3
12 NGC 3256 IG 10 27 51.284 -43 54 13.55   11.83 11.33 10.62 11.9 ~ 805 2
13 NGC 3628 GiP 11 20 17.018 +13 35 22.16   10.42 9.48 9.22   ~ 790 3
14 NAME SMM J123555.14+620901.7 AGN 12 35 55.14 +62 09 01.7 24.4 24.2 24.1 23.8 23.5 ~ 33 0
15 NAME SMM J123600.2+621047 QSO 12 36 00.15 +62 10 47.2 24.21 25.5874 25.35   24.6340 ~ 52 0
16 SDSS J123603.25+621111.1 G 12 36 03.26 +62 11 10.9 23.10 22.3841 21.664 20.72 20.3027 ~ 41 0
17 NAME SMM J123618+621554 rG 12 36 18.32 +62 15 50.5 25.84   25.58 25.07 25.0 ~ 63 0
18 NAME SMM J123621.3+621708 G 12 36 21.25 +62 17 08.3   25.1     25.0 ~ 54 0
19 SDSS J123622.50+621544.4 G 12 36 22.50 +62 15 44.5 22.30 22.0680   20.74 20.4127 ~ 37 0
20 GOODS J123637.03+620852.4 rG 12 36 37.04 +62 08 52.4 27.4 27.3 26.7     ~ 18 0
21 CXO J123646.7+621445 QSO 12 36 46.750 +62 14 45.95 23.87 24.19 24.10     ~ 10 0
22 NAME Chandra Deep Field-North reg 12 36.8 +62 13           ~ 641 0
23 NAME Hubble Deep Field reg 12 36 49.5 +62 12 58           ~ 1877 1
24 CXO J123653.3+621139 EmG 12 36 53.38 +62 11 39.6 24.11 23.4368 23.69 22.93 22.6310 ~ 63 0
25 GOODS J123656.47+621937.6 QSO 12 36 56.48 +62 19 37.7           ~ 15 0
26 NAME SMM J123711.32+621331.3 AG? 12 37 11.35 +62 13 31.0 25.3 24.9032   23.8 24.7226 ~ 55 1
27 CXO J123726.5+622026 AGN 12 37 26.5080 +62 20 26.840 26.7 27.4128   25.1 24.9925 ~ 21 0
28 GOODS J123734.52+621723.3 G 12 37 34.53 +62 17 23.2 24.90 23.8683 23.77 22.1 20.9187 ~ 22 0
29 NGC 5256 PaG 13 38 17.5 +48 16 37   14.1 13.42     ~ 417 1
30 Mrk 273 Sy2 13 44 42.1883001096 +55 53 13.596220932   15.68 14.91     ~ 864 3
31 IC 4553 SyG 15 34 57.22396 +23 30 11.6084   14.76 13.88     ~ 2835 4
32 NGC 6240 Sy2 16 52 58.861 +02 24 03.55   14.31 13.37     ~ 1564 2
33 [YSF2007] MIPS 283 AGN 17 14 58.27 +59 24 11.2       22.88   ~ 7 0
34 [YSF2007] SST24 J171510.28+600955.2 G 17 15 10.170 +60 09 54.54       22.67   ~ 11 0
35 [YSF2007] SST24 J171536.34+593614.8 G 17 15 36.34 +59 36 14.8       25.73   ~ 15 0
36 [YCA2005] IRS 2 QSO 17 15 38.244 +59 25 40.68       25.73   ~ 17 0
37 [DYH2009] MIPS 8550 G 17 18 14.6 +59 56 05       22.66   ~ 3 0
38 [YSF2007] MIPS 16080 IR 17 18 44.799 +60 01 15.69       23.09   ~ 15 0
39 NAME Super Antennae Sy2 19 31 21.4272801984 -72 39 21.442847832   17.39 16.37 14.65   ~ 285 2
40 NGC 7172 Sy2 22 02 01.897 -31 52 11.60   12.72 13.61 11.15   ~ 498 1
41 NGC 7582 GiP 23 18 23.621 -42 22 14.06 11.62 10.92 10.62     ~ 860 2

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2022.08.09-03:01:56

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