2011A&A...532A..38S


C.D.S. - SIMBAD4 rel 1.7 - 2020.01.24CET10:37:13

2011A&A...532A..38S - Astronomy and Astrophysics, volume 532A, 38-38 (2011/8-1)

A VLBA survey of the core shift effect in AGN jets. I. Evidence of dominating synchrotron opacity.

SOKOLOVSKY K.V., KOVALEV Y.Y., PUSHKAREV A.B. and LOBANOV A.P.

Abstract (from CDS):

The effect of a frequency dependent shift of the VLBI core position (known as the ``core shift'') was predicted more than three decades ago and has since been observed in a few sources, but often within a narrow frequency range. This effect has important astrophysical and astrometric applications. To achieve a broader understanding of the core shift effect and the physics behind it, we conducted a dedicated survey with NRAO's Very Long Baseline Array (VLBA). We used the VLBA to image 20 pre-selected sources simultaneously at nine frequencies in the 1.4-15.4GHz range. The core position at each frequency was measured by referencing it to a bright, optically thin feature in the jet. A significant core shift has been successfully measured in each of the twenty sources observed. The median value of the core shift is found to be 1.21mas if measured between 1.4 and 15.4GHz, and 0.24mas between 5.0 and 15.4GHz. The core position, rc, as a function of frequency, ν, is found to be consistent with an rc ∝ν–1 law. This behavior is predicted by the Blandford & Koenigl (1979ApJ...232...34B) model of a purely synchrotron self-absorbed conical jet in equipartition. No systematic deviation from unity of the power law index in the rc(ν) relation has been convincingly detected. We conclude that neither free-free absorption nor gradients in pressure and/or density in the jet itself and in the ambient medium surrounding the jet play a significant role in the sources observed within the 1.4-15.4GHz frequency range. These results support the interpretation of the parsec-scale core as a continuous Blandford-Koenigl type jet with smooth gradients of physical properties along it.

Abstract Copyright:

Journal keyword(s): galaxies: active - galaxies: jets - quasars: general - radio continuum: general

Simbad objects: 29

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Number of rows : 29

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 [VV98] J015127.1+274442 QSO 01 51 27.14618081 +27 44 41.7936492   20.6   20.42   ~ 42 0
2 NGC 1052 GiP 02 41 04.79851 -08 15 20.7517 11.84 11.41 10.47 10.71   ~ 1118 2
3 ICRF J034506.4+145349 QSO 03 45 06.41654424 +14 53 49.5582021       20.00   ~ 39 1
4 QSO J0427+0457 QSO 04 27 47.57053172 +04 57 08.3256492   20.0       ~ 49 1
5 QSO B0507+179 QSO 05 10 02.36912982 +18 00 41.5816534   20.0 19.0 19.09   ~ 288 1
6 3C 154.0 QSO 06 13 50.13917401 +26 04 36.7198424           ~ 145 0
7 QSO B0839+187 QSO 08 42 05.09417058 +18 35 40.9905528   16.63 16.36 16.56   ~ 161 2
8 4C 58.17 QSO 08 54 41.99641123 +57 57 29.9390674   18.56 18.18 17.43   ~ 206 1
9 ICRF J092703.0+390220 Sy1 09 27 03.0139516273 +39 02 20.847968628   17.17 17.00 16.486   ~ 922 1
10 QSO B0952+179 QSO 09 54 56.82361250 +17 43 31.2222114   17.31 17.23     ~ 191 1
11 QSO J1007+1356 QSO 10 07 41.49808563 +13 56 29.6008672     19.0 18.59   ~ 103 1
12 Ton 490 QSO 10 13 53.42876682 +24 49 16.4407698   16.59 16.57 15.85   ~ 167 1
13 QSO B1038+528B QSO 10 41 48.8978503414 +52 33 55.609777399   18.38 18.23     ~ 94 0
14 4C 21.28 QSO 10 51 48.78907490 +21 19 52.3138145     18.5 17.72   ~ 123 1
15 7C 1219+2830 BLL 12 21 31.6902446545 +28 13 58.500383827   16.81 16.11 14.24   ~ 771 1
16 QSO B1406-076 QSO 14 08 56.48120036 -07 52 26.6664200   20.3 18.4     ~ 258 1
17 6C 141804+543700 BLL 14 19 46.5976435439 +54 23 14.787308481   16.17 15.65 14.16   ~ 532 1
18 ICRF J145907.5+714019 Sy1 14 59 07.5831170610 +71 40 19.867413302   17.24 16.78 17.2   ~ 445 1
19 6C 164218+690201 QSO 16 42 07.84850549 +68 56 39.7564973   19.723   19.219   ~ 280 1
20 3C 345 QSO 16 42 58.8100340220 +39 48 36.999540578   16.81 16.59 16.84   ~ 1537 2
21 4C 39.49 BLL 16 53 52.21668494 +39 45 36.6089458 14.09 14.15 13.29 8.26   ~ 1889 2
22 QSO J1658+0741 QSO 16 58 09.01146700 +07 41 27.5405227   19.993 19.5 19.598   ~ 152 1
23 8C 1803+784 BLL 18 00 45.6831135718 +78 28 04.017792333   16.4 16.4 15.46   ~ 652 1
24 4C 28.45 QSO 18 32 50.18562512 +28 33 35.9552936   16.91 17.16     ~ 120 1
25 ICRF J184208.9+794617 Sy1 18 42 08.9910523393 +79 46 17.129210139   16.06 15.38     ~ 1197 0
26 8C 2007+777 BLL 20 05 30.9981060951 +77 52 43.245329882     16.5 17.36   ~ 399 1
27 NAME BL Lac BLL 22 02 43.2913773726 +42 16 39.978417860   15.66 14.72     ~ 1981 1
28 4C 31.63 BLL 22 03 14.9758020 +31 45 38.269707   15.85 15.58 14.33   ~ 455 1
29 ICRF J232225.9+505751 QSO 23 22 25.98218320 +50 57 51.9636985       18.6   ~ 53 1

    Equat.    Gal    SGal    Ecl

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2020.01.24-10:37:13

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