2008ApJ...687..111D


C.D.S. - SIMBAD4 rel 1.7 - 2021.04.19CEST15:51:40

2008ApJ...687..111D - Astrophys. J., 687, 111-132 (2008/November-1)

Spitzer's contribution to the AGN population.

DONLEY J.L., RIEKE G.H., PEREZ-GONZALEZ P.G. and BARRO G.

Abstract (from CDS):

Infrared selection is a potentially powerful way to identify heavily obscured AGNs missed in even the deepest X-ray surveys. Using a 24 µm-selected sample in GOODS-S, we test the reliability and completeness of three infrared AGN selection methods: (1) IRAC color-color selection, (2) IRAC power-law selection, and (3) IR-excess selection; we also evaluate a number of IR-excess approaches. We find that the vast majority of non-power-law IRAC color-selected AGN candidates in GOODS-S have colors consistent with those of star-forming galaxies. Contamination by star-forming galaxies is most prevalent at low 24 µm flux densities (∼100 µJy) and high redshifts (z∼2), but the fraction of potential contaminants is still high (∼50%) at 500 µJy, the highest flux density probed reliably by our survey. AGN candidates selected via a simple, physically motivated power-law criterion (``power-law galaxies'', or PLGs), however, appear to be reliable. We confirm that the IR-excess methods successfully identify a number of AGNs, but we also find that such samples may be significantly contaminated by star-forming galaxies. Adding only the secure Spitzer-selected PLG, color-selected, IR-excess, and radio/IR-selected AGN candidates to the deepest X-ray-selected AGN samples directly increases the number of known X-ray AGNs (84) by 54%-77%, and implies an increase to the number of 24 µm-detected AGNs of 71%-94%. Finally, we show that the fraction of MIR sources dominated by an AGN decreases with decreasing MIR flux density, but only down to f24µm=300 µJy. Below this limit, the AGN fraction levels out, indicating that a nonnegligible fraction (∼10%) of faint 24 µm sources (the majority of which are missed in the X-ray) are powered not by star formation, but by the central engine. The fraction of all AGNs (regardless of their MIR properties) exceeds 15% at all 24 µm flux densities.

Abstract Copyright:

Journal keyword(s): Galaxies: Active - Infrared: Galaxies - X-Rays: Galaxies

Simbad objects: 20

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Number of rows : 20

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9761 1
2 NAME Chandra Deep Field-South reg 03 32 28.0 -27 48 30           ~ 1872 1
3 NAME GOODS Southern Field reg 03 32 28.0 -27 48 30           ~ 1118 1
4 NGC 1614 AGN 04 34 00.027 -08 34 44.57   14.66 13.99     ~ 614 0
5 NGC 2639 Sy1 08 43 38.093 +50 12 19.94 12.90 12.56 11.65     ~ 391 2
6 M 82 IG 09 55 52.430 +69 40 46.93 9.61 9.30 8.41     ~ 5446 6
7 NGC 3256 IG 10 27 51.284 -43 54 13.55   11.83 11.33 10.62 11.9 ~ 771 2
8 ESO 320-30 H2G 11 53 11.722 -39 07 48.72   13.30   11.86   ~ 159 1
9 LEDA 39024 LIN 12 13 46.107 +02 48 41.50           ~ 315 1
10 NGC 4194 AGN 12 14 09.615 +54 31 35.93   13.79 13.30     ~ 422 2
11 NAME Chandra Deep Field-North reg 12 36.8 +62 13           ~ 623 0
12 Mrk 231 Sy1 12 56 14.2340989340 +56 52 25.238555193   14.68 13.84     ~ 1827 3
13 2MASX J14373831-1500239 Sy1 14 37 38.317 -15 00 23.97   16.58 16.40     ~ 248 1
14 IC 4553 SyG 15 34 57.22396 +23 30 11.6084   14.76 13.88     ~ 2741 4
15 NGC 6090 PaG 16 11 40.3 +52 27 21   14.0       ~ 402 2
16 NGC 6240 Sy2 16 52 58.861 +02 24 03.55   14.31 13.37     ~ 1515 2
17 6dFGS gJ172322.0-001701 LIN 17 23 21.943 -00 17 00.96   15.1       ~ 379 0
18 NAME Superantennae Sy2 19 31 21.4252803168 -72 39 21.448768732   17.39 16.37 14.65   ~ 280 2
19 ESO 286-19 LIN 20 58 26.8182983654 -42 38 59.418569678   14.79 14.79 14.20   ~ 254 0
20 NAME South America H2G 22 51 49.307 -17 52 23.96   16.97       ~ 291 3

    Equat.    Gal    SGal    Ecl

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