2007ApJ...657...95W

Query : 2007ApJ...657...95W

2007ApJ...657...95W - Astrophys. J., 657, 95-101 (2007/March-1)

Most hard-X-ray-selected quasars in the Chandra Deep Fields are obscured.

WANG J.X., JIANG P., ZHENG Z.Y., TOZZI P., NORMAN C., GIACCONI R., GILLI R., HASINGER G., KEWLEY L., MAINIERI V., NONINO M., ROSATI P., STREBLYANSKA A., SZOKOLY G., ZIRM A. and ZHENG W.

Abstract (from CDS):

Measuring the population of obscured quasars is one of the key issues in understanding the evolution of active galactic nuclei (AGNs). With a redshift completeness of 99%, the X-ray sources detected in the Chandra Deep Field South (CDF-S) provide the best sample for this issue. In this paper, we study the population of obscured quasars in CDF-S by choosing the 4-7 keV selected sample, which is less biased by the intrinsic X-ray absorption. The 4-7 keV band-selected samples also filter out most of the X-ray-faint sources with too few counts, for which the measurements of NHand LXhave very large uncertainties. Simply adopting the best-fit L_2-10 keV_ and NH, we find that 71%±19% (20 out of 28) of the quasars (with intrinsic L_2-10 keV_>1044 ergs/s) are obscured with NH>1022/cm2. Taking into account the uncertainties in the measurements of both NH and LX, conservative lower and upper limits for the fraction are 54% (13 out 24) and 84% (31 out 37). In the Chandra Deep Field North, the number is 29%; however, this is mainly due to the redshift incompleteness. We estimate a fraction of ∼50%-63% after correcting for the redshift incompleteness with a straightforward approach. Our results robustly confirm the existence of a large population of obscured quasars.

Abstract Copyright: ∼

Journal keyword(s): Galaxies: Active - Galaxies: Quasars: General - Surveys - X-Rays: Galaxies

Simbad objects: 109

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Number of rows : 109
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 [LBX2017] 19 AGN 03 31 47.27 -27 53 13.3   25.88 25.52 25.55 25.25 ~ 24 0
2 [LBX2017] 49 QSO 03 31 52.472 -27 50 17.34   25.22 24.83 24.46 23.87 ~ 29 0
3 [LBX2017] 50 QSO 03 31 52.53 -27 46 42.6   22.804 22.33 21.592 20.73 ~ 29 0
4 CXOCDFS J033155.4-275448 Sy2 03 31 55.35 -27 54 48.2   22.07 21.65 20.712 20.00 ~ 31 0
5 [LBX2017] 72 AGN 03 31 56.850 -27 51 00.84   25.27 25.21 25.29 25.68 ~ 17 0
6 [LBX2017] 79 AGN 03 31 58.102 -27 48 33.81   23.6447 22.8522 22.061 21.1009 ~ 31 0
7 CXOCDFS J033158.3-275043 rG 03 31 58.29 -27 50 42.0   25.33 25.11 25.16 24.37 ~ 41 0
8 CXOCDFS J033200.4-274320 Sy1 03 32 00.37 -27 43 20.0 22.76 22.7055 22.335 22.1283 22.2135 ~ 57 0
9 [LBX2017] 91 AGN 03 32 00.531 -27 53 53.01       26.79   ~ 29 0
10 ATCDFS J033201.44-274647.5 rG 03 32 01.547 -27 46 47.84   25.08 24.62 23.821 23.02 ~ 45 1
11 [VV2006] J033201.6-274327 QSO 03 32 01.59 -27 43 27.3 24.86 24.5724 24.07 23.405 23.9921 ~ 52 0
12 CXOCDFS J033202.5-274601 Sy1 03 32 02.45 -27 46 00.5   24.291 24.5944 22.425 23.7324 ~ 48 0
13 ACS-GC 90046082 Sy2 03 32 03.66 -27 46 03.7   23.5861   20.778 20.2362 ~ 62 0
14 [LBX2017] 120 AGN 03 32 03.875 -27 53 28.83   26.48 26.19 26.01 25.14 ~ 30 0
15 ATCDFS J033204.81-274125.8 Sy2 03 32 04.85 -27 41 27.7   24.050   24.284 24.0258 ~ 39 0
16 [LBX2017] 134 AGN 03 32 05.169 -27 53 54.56   24.89 24.48 23.91 23.46 ~ 26 0
17 [SWM2014] GOODS-S 28908 AGN 03 32 05.3468 -27 46 44.100   27.9053     25.816 ~ 45 0
18 [LBX2017] 145 AGN 03 32 06.14 -27 49 28.4   24.925 25.07 24.66 23.573 ~ 30 0
19 CXOCDFS J033207.7-275214 AGN 03 32 07.620 -27 52 13.60   25.47 25.06 24.78 23.82 ~ 32 0
20 [LBX2017] 168 AGN 03 32 07.94 -27 37 32.1   23.65 23.35 24.030 22.08 ~ 25 0
21 [LBX2017] 170 AGN 03 32 07.99858 -27 46 57.2578   25.6308   24.931 25.0534 ~ 46 0
22 CXOCDFS J033208.5-274047 rG 03 32 08.383 -27 40 46.75   28.32 27.71   25.87 ~ 36 0
23 2MASS J03320855-2746483 rG 03 32 08.538 -27 46 48.55   21.0851 20.1035 19.224 18.9552 ~ 63 0
24 [VV2006] J033208.7-274735 QSO 03 32 08.6729857488 -27 47 34.647814356 19.78 19.4713 19.11 18.665 18.6210 ~ 93 0
25 [VV2006] J033209.5-274807 QSO 03 32 09.4575891792 -27 48 07.049493144 22.94 21.4745 21.07 20.422 20.4857 ~ 66 0
26 CXOCDFS J033210.6-274309 QSO 03 32 10.50 -27 43 09.2   24.551 23.16 21.53 22.316 ~ 39 0
27 2XMM J033210.9-274415 Sy1 03 32 10.91 -27 44 15.1 23.35 22.500 22.882 22.50 22.3707 ~ 83 0
28 ATCDFS9 J033211.01-274053.7 rG 03 32 11.00 -27 40 53.8       23.560 23.8290 ~ 38 0
29 [LBX2017] 214 AGN 03 32 11.382 -27 52 13.45       26.8   ~ 42 0
30 [SWM2014] GOODS-S 29954 AGN 03 32 11.78 -27 46 28.5   26.64   26.27 25.531 ~ 52 0
31 CXOCDFS J033213.0-275238 Sy2 03 32 12.96 -27 52 36.5       24.040 23.899 ~ 52 0
32 CXOCDFS J033213.3-275530 Sy2 03 32 13.200 -27 55 28.47   24.50 24.08 22.97 21.41 ~ 33 0
33 ACS-GC 90045613 Sy2 03 32 13.257 -27 42 40.65   21.6424 20.820 20.164 19.8240 ~ 87 0
34 CXOCDFS J033213.5-274857 AGN 03 32 13.405 -27 48 56.01   27.219 27.07   26.338 ~ 28 0
35 CXOCDFS J033214.1-275101 Sy2 03 32 13.98 -27 51 00.3   23.9234   22.61 21.809 ~ 50 0
36 ACS-GC 90045314 Sy2 03 32 14.42141 -27 51 10.7305   24.3772   24.246 23.3772 ~ 59 0
37 [LBX2017] 260 Sy2 03 32 14.55 -27 54 21.1   25.65   25.47   ~ 35 0
38 ACS-GC 90041713 Sy1 03 32 14.95 -27 51 26.9   21.913   22.751 20.751 ~ 53 0
39 ACS-GC 90043493 rG 03 32 14.98 -27 42 25.2   23.814 23.50 23.004 22.8916 ~ 56 0
40 [VV2006] J033216.2-273931 QSO 03 32 16.2096967968 -27 39 30.684107772 20.74 20.29 20.03 19.72 19.66 ~ 49 0
41 ACS-GC 90042334 Sy1 03 32 17.15 -27 43 03.6 23.16 22.5303 22.1603 21.068 20.8398 ~ 88 0
42 ACS-GC 90041108 Sy2 03 32 17.16 -27 52 20.6   23.445   23.572 22.283 ~ 71 0
43 ACS-GC 90045885 Sy2 03 32 18.39 -27 50 55.3   24.8876 24.190 23.82 23.039 ~ 85 0
44 CXOCDFS J033218.5-274557 AGN 03 32 18.44318 -27 45 55.8709   22.344 23.35 25.010 21.2672 ~ 49 1
45 CXOCDFS J033218.9-275136 Sy2 03 32 18.8321 -27 51 35.476   25.15   24.51 25.128 ~ 83 0
46 ACS-GC 90043051 Sy2 03 32 19.02 -27 47 55.7   26.460   24.525 23.664 ~ 51 0
47 CXOCDFS J033219.9-274519 AGN 03 32 19.811 -27 45 18.90   26.270 25.77 23.870 25.671 ~ 35 0
48 ACS-GC 90042601 Sy2 03 32 20.05005 -27 44 47.1529   22.941   25.050 24.7064 ~ 55 0
49 ACS-GC 90044373 Sy2 03 32 20.47022 -27 47 32.3484   22.743 23.88 24.752 21.863 ~ 56 0
50 ACS-GC 90042090 rG 03 32 22.52 -27 46 04.2   25.2790   24.91 24.424 ~ 63 0
51 ACS-GC 90042565 rG 03 32 24.26 -27 41 26.8   23.4284 21.661 20.832 20.6072 ~ 51 0
52 ACS-GC 90040743 AGN 03 32 24.84558 -27 55 59.9693   25.2158 24.752 24.65 23.523 ~ 46 0
53 ACS-GC 90043946 Sy2 03 32 24.98108 -27 41 01.5074   23.4535   21.973 21.4414 ~ 47 0
54 ACS-GC 90040981 Sy2 03 32 25.157 -27 54 50.10   23.166   23.17 22.1691 ~ 66 0
55 [PBM2009] s124624 Sy1 03 32 25.21 -27 42 18.8   24.7725 23.75 23.21 22.6063 ~ 92 0
56 CANDELS UDS F160W J033225.68-274305.6 Sy2 03 32 25.74 -27 43 05.6   26.617 25.773 26.13 25.3679 ~ 76 0
57 CANDELS UDS F160W J033225.95-274514.3 AGN 03 32 25.9457 -27 45 14.347   27.8578   26.040 25.8074 ~ 37 0
58 [VV2006] J033226.5-274036 QSO 03 32 26.4998939520 -27 40 35.910988680 20.34 20.0691   20.091 19.7666 ~ 81 0
59 CXOCDFS J033226.7-274013 AGN 03 32 26.69 -27 40 13.6   23.8628 23.80 23.826 23.4188 ~ 39 0
60 [VV2006] J033227.0-274105 QSO 03 32 27.0132796944 -27 41 05.357500044 19.93 19.3746   19.003 19.1163 ~ 93 1
61 ACS-GC 90045964 Sy2 03 32 27.623 -27 41 44.91   24.0498 23.2945 22.252 21.6131 ~ 61 0
62 NAME Chandra Deep Field-South reg 03 32 28.0 -27 48 30           ~ 2282 1
63 [LBX2017] 546 AGN 03 32 29.722 -27 51 45.54   27.255 27.831 23.440 26.669 ~ 26 0
64 [VV2006] J033229.9-275106 Sy2 03 32 29.8487 -27 51 05.879   27.5675 25.05 23.970 24.5370 ~ 101 0
65 2XMM J033229.9-274528 Sy1 03 32 29.976 -27 45 29.77 21.66 21.1307 21.33 21.298 21.1036 ~ 80 1
66 ACS-GC 90042078 Sy1 03 32 30.0611 -27 45 23.526 23.96 23.2871 23.0874 22.5697 22.010 ~ 70 0
67 ACS-GC 90042521 Sy1 03 32 30.2159 -27 45 04.590 23.17 22.5984 22.2969 21.958 21.7127 ~ 71 0
68 CXOCDFS J033232.2-274652 AGN 03 32 32.170 -27 46 51.49   28.3350 27.2830   26.411 ~ 50 0
69 CXOCDFS J033233.1-274548 rG 03 32 32.99 -27 45 47.5   21.1633 22.930 22.12 21.436 ~ 52 0
70 CXOCDFS J033233.4-274236 rG 03 32 33.285 -27 42 36.01   27.6501 27.187   25.5120 ~ 47 0
71 CXOCDFS J033234.4-273914 QSO 03 32 34.42 -27 39 13.3   25.4750 25.17 24.60 23.6590 ~ 33 0
72 ACS-GC 90040296 Sy2 03 32 34.947 -27 55 11.16   23.7556   22.920 22.1896 ~ 59 0
73 [SWM2014] GOODS-S 5001 AGN 03 32 35.2075 -27 53 18.019   27.5835     26.282 ~ 39 0
74 ACS-GC 90044174 AGN 03 32 35.842 -27 40 59.49   24.4130   22.471 21.7624 ~ 49 0
75 ACS-GC 90041506 AGN 03 32 36.1574 -27 50 37.059   25.2232 26.32 25.89 24.433 ~ 42 0
76 ACS-GC 90043479 rG 03 32 36.70 -27 44 06.1   22.732 23.6511 22.6377 20.548 ~ 72 0
77 ACS-GC 90041753 Sy2 03 32 37.75 -27 52 12.3   25.2146 24.717 24.68 24.1108 ~ 87 0
78 ASPECS LP.1mm.C08 AGN 03 32 38.029 -27 46 26.31 28.2222 28.4300 27.60 27.04 26.106 ~ 70 1
79 ACS-GC 90043401 Sy1 03 32 38.1232741056 -27 39 45.158278032 20.89 20.9342 20.511 20.4095 20.6297 ~ 69 0
80 ATCDFS J033238.95-275700.6 rG 03 32 38.9187869184 -27 57 00.810546876   20.195 19.55 18.857 18.45 ~ 49 0
81 CXOCDFS J033239.1-274440 AGN 03 32 39.052 -27 44 39.32   27.8340     26.304 ~ 44 1
82 [VV2006] J033239.1-274602 QSO 03 32 39.0897389184 -27 46 02.044213860 21.11 21.413 21.157 20.68 20.812 ~ 82 0
83 ACS-GC 90045073 Sy2 03 32 39.670 -27 48 50.60   27.3148   25.18 24.512 ~ 108 0
84 ASPECS LP.3mm.05 rG 03 32 39.737 -27 46 11.25 25.2508 25.0913 25.00 24.94 23.902 ~ 97 0
85 ATCDFS J033240.82-275545.8 Sy2 03 32 40.83 -27 55 46.6   26.87 26.153 25.42 25.4033 ~ 64 0
86 [VV2006] J033241.9-275203 QSO 03 32 41.84 -27 52 02.3   24.3501 23.03 22.529 22.4031 ~ 68 1
87 CANDELS UDS F160W J033241.87-274359.9 AGN 03 32 41.87599 -27 43 59.9419   23.136   25.068 25.1361 ~ 44 0
88 CXOCDFS J033242.9-274703 Sy1 03 32 42.837 -27 47 02.53   25.6384 24.571 24.100 24.311 ~ 81 0
89 ACS-GC 90044579 rG 03 32 43.038 -27 48 45.09   26.3069 25.14 25.56 24.431 ~ 53 0
90 COMBO J0332433-274914 Sy1 03 32 43.25 -27 49 14.4 24.17 22.4055 22.6983 22.984 22.5427 ~ 74 0
91 ACS-GC 90039808 Sy2 03 32 44.44 -27 49 39.8   25.4428 24.5909 23.8157 23.0180 ~ 62 0
92 ACS-GC 90072761 rG 03 32 46.35 -27 46 32.2   26.4203   25.140 24.485 ~ 55 0
93 CXOCDFS J033247.2-275335 QSO 03 32 47.0589 -27 53 33.531   30.967   25.98 26.2117 ~ 38 0
94 BLAST J033247-274221 QSO 03 32 47.886 -27 42 32.82   22.51 22.12 21.65 20.51 ~ 49 0
95 CXOCDFS J033248.0-274148 Sy2 03 32 47.91 -27 41 47.9   22.913 22.55 22.113 21.11 ~ 41 0
96 [FPG2012] M3320 QSO 03 32 50.24688 -27 52 51.9384   26.5873 25.63   24.8575 ~ 41 0
97 ACS-GC 90040278 Sy1 03 32 52.89 -27 51 19.8   22.837   23.541 22.3247 ~ 56 0
98 [GZW2002] Main 267 AGN 03 32 54.899 -27 45 06.03   24.53 24.47 24.10 23.18 ~ 21 0
99 CXOCDFS J033259.1-274340 Sy2 03 32 59.05 -27 43 39.7 22.26 21.90 21.61 20.973 20.41 ~ 40 0
100 CXOCDFS J033259.4-274859 rG 03 32 59.314 -27 48 58.70   23.73 23.57 23.37 22.68 ~ 42 0
101 CXOCDFS J033259.8-275031 AGN 03 32 59.6818187880 -27 50 30.590830608   20.084   19.863 19.6215 ~ 32 0
102 [LBX2017] 937 AGN 03 32 59.762 -27 46 26.24   22.10 21.41 20.351 19.83 ~ 32 0
103 [VV2006] J033259.8-274749 QSO 03 32 59.8499816688 -27 47 48.381054396 22.29 22.0936 21.6616 21.9181 21.9483 ~ 47 0
104 COMBO J0333017-275819 QSO 03 33 01.7077508784 -27 58 18.887579508   20.34 20.37 20.32 20.04 ~ 32 0
105 CXOCDFS J033302.7-274823 rG 03 33 02.635 -27 48 22.82   25.39 25.07 25.09 24.68 ~ 28 0
106 CXOCDFS J033303.7-274519 Sy1 03 33 03.64 -27 45 18.5   23.7809 23.2970 22.9775 22.7093 ~ 32 0
107 CXOCDFS J033307.7-275127 AGN 03 33 07.60 -27 51 27.1   22.876 23.73 23.365 23.87 ~ 31 0
108 ATCDFS9 J033310.19-274842.2 QSO 03 33 10.21 -27 48 42.2 24.27 23.866 23.14 22.97 22.00 ~ 47 0
109 NAME Chandra Deep Field-North reg 12 36.8 +62 13           ~ 686 0

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