2006A&A...447..515M


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.08CET20:46:33

2006A&A...447..515M - Astronomy and Astrophysics, volume 447, 515-524 (2006/2-4)

VLBI phase-reference observations of the gravitational lens JVAS B0218+357.

MITTAL R., PORCAS R., WUCKNITZ O., BIGGS A. and BROWNE I.

Abstract (from CDS):

We present the results of phase-referenced VLBA+Effelsberg observations at five frequencies of the double-image gravitational lens JVAS B0218+357, made to establish the precise registration of the A and B lensed image positions. The motivation behind these observations is to investigate the anomalous variation of the image flux-density ratio (A/B) with frequency - this ratio changes by almost a factor of two over a frequency range from 1.65GHz to 15.35GHz. We investigate whether frequency dependent image positions, combined with a magnification gradient across the image field, could give rise to the anomaly. Our observations confirm the variation of image flux-density ratio with frequency. The results from our phase-reference astrometry, taken together with the lens mass model of Wucknitz et al. (2004MNRAS.349...14W), show that shifts of the image peaks and centroids are too small to account for the observed frequency-dependent ratio.

Abstract Copyright:

Journal keyword(s): gravitational lensing - techniques: interferometric - quasars: individual: JVAS B0218+357

Simbad objects: 10

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Number of rows : 10

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 NVSS J021348+365234 Rad 02 13 48.1919210 +36 52 34.007332           ~ 8 1
2 7C 021548.00+362642.00 Bla 02 18 50.0451442570 +36 40 42.594858209           ~ 22 1
3 [PBK93] B0218+357 A2 LeI 02 21 +35.9           ~ 9 0
4 [PBK93] B0218+357 A1 LeI 02 21 +35.9           ~ 9 0
5 [PBK93] B0218+357 B1 LeI 02 21 +35.9           ~ 8 0
6 [PBK93] B0218+357 B2 LeI 02 21 +35.9           ~ 8 0
7 RORF 0218+35A LeI 02 21 05.4667 +35 56 13.730           ~ 33 0
8 QSO B0218+357 QSO 02 21 05.5 +35 56 14   20.0 20.0 19.60   ~ 513 2
9 RORF 0218+35B LeI 02 21 05.5 +35 56 14           ~ 30 0
10 7C 022224.00+365659.00 Bla 02 25 27.3267948625 +37 10 27.741998994   15.0   9.5   ~ 57 1

    Equat.    Gal    SGal    Ecl

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2021.03.08-20:46:34

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