2015A&A...578A..67H

Query : 2015A&A...578A..67H

2015A&A...578A..67H - Astronomy and Astrophysics, volume 578A, 67-67 (2015/6-1)

Active galactic nuclei cores in infrared-faint radio sources. Very long baseline interferometry observations using the Very Long Baseline Array.

HERZOG A., MIDDELBERG E., NORRIS R.P., SPITLER L.R., DELLER A.T., COLLIER J.D. and PARKER Q.A.

Abstract (from CDS):

Infrared-faint radio sources (IFRS) form a new class of galaxies characterised by radio flux densities between tenths and tens of mJy and faint or absent infrared counterparts. It has been suggested that these objects are radio-loud active galactic nuclei (AGNs) at significant redshifts (z>2). Whereas the high redshifts of IFRS have been recently confirmed based on spectroscopic data, the evidence for the presence of AGNs in IFRS is mainly indirect. So far, only two AGNs have been unquestionably confirmed in IFRS based on very long baseline interferometry (VLBI) observations. In this work, we test the hypothesis that IFRS contain AGNs in a large sample of sources using VLBI. We observed 57 IFRS with the Very Long Baseline Array (VLBA) down to a detection sensitivity in the sub-mJy regime and detected compact cores in 35 sources. Our VLBA detections increase the number of VLBI-detected IFRS from 2 to 37 and provide strong evidence that most - if not all - IFRS contain AGNs. We find that IFRS have a marginally higher VLBI detection fraction than randomly selected sources with mJy flux densities at arcsec-scales. Moreover, our data provide a positive correlation between compactness - defined as the ratio of milliarcsec- to arcsec-scale flux density - and redshift for IFRS, but suggest a decreasing mean compactness with increasing arcsec-scale radio flux density. Based on these findings, we suggest that IFRS tend to contain young AGNs whose jets have not formed yet or have not expanded, equivalent to very compact objects. We found two IFRS that are resolved into two components. The two components are spatially separated by a few hundred milliarcseconds in both cases. They might be components of one AGN, a binary black hole, or the result of gravitational lensing.

Abstract Copyright: ∼

Journal keyword(s): techniques: interferometric - galaxies: active - galaxies: high-redshift - galaxies: nuclei - radio continuum: galaxies

VizieR on-line data: <Available at CDS (J/A+A/578/A67): table1.dat>

Simbad objects: 62

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Number of rows : 62
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024 		#notes
1 ELAIS S1 reg 00 34 44 -43 28.2           ~ 204 0
2 NVSS J014418-092158 Rad 01 44 18.196 -09 21 54.77           ~ 2 0
3 NVSS J021557-082517 Rad 02 15 57.080 -08 25 17.55           ~ 2 0
4 NVSS J022022-011017 Rad 02 20 22.049 -01 10 16.49           ~ 2 0
5 NVSS J023033-030909 Rad 02 30 33.4 -03 09 08           ~ 4 1
6 NVSS J024150-032011 Rad 02 41 50.196 -03 20 12.17           ~ 2 0
7 NVSS J024346-050737 Rad 02 43 46.9 -05 07 36           ~ 3 0
8 NVSS J024700+062831 Rad 02 47 00.457 +06 28 34.34           ~ 2 0
9 NAME Chandra Deep Field-South reg 03 32 28.0 -27 48 30           ~ 2086 1
10 NVSS J090337+515142 Rad 09 03 37.10 +51 51 42.2           ~ 3 0
11 NVSS J093243+521400 Rad 09 32 43.6 +52 14 00           ~ 4 0
12 NAME Lockman Hole reg 10 45 00.0 +58 00 00           ~ 840 0
13 NVSS J104946+531947 Rad 10 49 46.8 +53 19 49           ~ 3 0
14 SDSS J112623.72+375334.8 QSO 11 26 23.7288130008 +37 53 34.893139344           ~ 7 0
15 NVSS J113330+585506 Rad 11 33 29.982 +58 55 05.01           ~ 2 0
16 NVSS J114333+582209 Rad 11 43 33.395 +58 22 07.59           ~ 2 0
17 NVSS J115544+495437 Rad 11 55 44.9 +49 54 37           ~ 4 1
18 NVSS J115900+474005 Rad 11 59 00.6 +47 39 59           ~ 4 1
19 7C 115947.20+484202.00 AGN 12 02 21.2 +48 25 14           ~ 5 1
20 NVSS J121731+485954 Rad 12 17 31.8 +48 59 54           ~ 4 1
21 NVSS J121814+590516 Rad 12 18 14.1 +59 05 16           ~ 4 1
22 NVSS J122524+433439 Rad 12 25 24.776 +43 34 39.18           ~ 2 0
23 7C 122515.40+365935.00 QSO 12 27 43.486 +36 42 55.74           ~ 10 1
24 3C 273 BLL 12 29 06.6998257176 +02 03 08.597629980   13.05 14.830 14.11   ~ 5798 1
25 NVSS J123952+604958 Rad 12 39 52.6 +60 49 56           ~ 3 0
26 PMN J1251-0642 Rad 12 51 48.680 -06 42 17.01           ~ 2 0
27 NVSS J130316+481558 Rad 13 03 16.442 +48 15 57.70           ~ 3 0
28 NVSS J130748+555452 Rad 13 07 48.3 +55 54 50           ~ 3 0
29 7C 131101.89+323651.00 QSO 13 13 22.58 +32 21 10.1           ~ 5 1
30 NVSS J131551+512710 Rad 13 15 51.1 +51 27 10           ~ 3 0
31 7C 132553.70+432953.00 QSO 13 28 04.4179845696 +43 14 17.482279164           ~ 5 1
32 NVSS J133024+221800 Rad 13 30 24.725 +22 17 59.98           ~ 4 2
33 NVSS J133431+543930 Rad 13 34 31.8 +54 39 32           ~ 3 0
34 SDSS J133733.08+591837.6 QSO 13 37 33.0834971400 +59 18 37.674824616           ~ 11 1
35 NVSS J134921+081217 Rad 13 49 21.4 +08 12 16           ~ 3 0
36 NVSS J135248+093020 Rad 13 52 48.328 +09 30 16.60           ~ 2 0
37 NVSS J135601-012539 Rad 13 56 01.445 -01 25 38.70           ~ 2 0
38 NVSS J140707+285558 Rad 14 07 07.2 +28 55 56           ~ 4 1
39 FIRST J140730.5+040234 AG? 14 07 30.5901 +04 02 34.280           ~ 3 0
40 6C 140715+560633 QSO 14 08 55.0169362800 +55 52 17.955154920   20.36 20.22     ~ 29 1
41 PMN J1410+0241 Rad 14 10 04.764 +02 40 49.82           ~ 2 0
42 NVSS J142228+264716 Rad 14 22 28.909 +26 47 16.63           ~ 2 0
43 NVSS J142241+363956 Rad 14 22 41.7 +36 39 58           ~ 4 1
44 NVSS J143110+360317 Rad 14 31 10.8 +36 03 17           ~ 4 0
45 NVSS J144500+624605 Rad 14 45 00.769 +62 46 05.55           ~ 2 0
46 NVSS J144924+085628 Rad 14 49 24.799 +08 56 32.59           ~ 2 0
47 NVSS J145334-014513 Rad 14 53 34.184 -01 45 13.48           ~ 2 0
48 NVSS J150623+103048 Rad 15 06 23.3027 +10 30 47.451           ~ 8 1
49 NVSS J150649+422059 Rad 15 06 49.227 +42 20 58.93           ~ 4 1
50 NVSS J151557+201248 Rad 15 15 57.840 +20 12 47.13           ~ 2 0
51 NVSS J151817+042327 Rad 15 18 17.648 +04 23 26.84           ~ 2 0
52 NVSS J152348+321541 Rad 15 23 48.35 +32 15 43.8           ~ 2 0
53 SDSS J153826.90+145505.2 QSO 15 38 26.9070835032 +14 55 05.304849420           ~ 9 0
54 NVSS J160235+310832 Rad 16 02 35.668 +31 08 33.42           ~ 2 0
55 ELAIS N1 reg 16 10 01 +54 30.6           ~ 421 0
56 FIRST J161910.0+483713 AG? 16 19 10.0158 +48 37 13.140           ~ 3 0
57 NVSS J172102+333445 Rad 17 21 02.8 +33 34 47           ~ 3 0
58 NVSS J172923+390532 Rad 17 29 24.12 +39 05 31.5           ~ 2 0
59 NVSS J173019+460128 Rad 17 30 19.022 +46 01 28.48           ~ 3 1
60 NVSS J173517+474300 Rad 17 35 17.4 +47 42 59           ~ 4 1
61 FIRST J173702.9+494446 AG? 17 37 02.9363 +49 44 46.351           ~ 3 0
62 NVSS J174243+621908 Rad 17 42 43.6 +62 19 09           ~ 6 1

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