VLBA observations of the gravitational lens system B0218+357

Patnaik, A. R.; Porcas, R. W.; Browne, I. W. A.

doi:10.1093/mnras/274.1.l5

Cited by 70 publications

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“…Previous VLBI observations at high frequencies (Biggs et al 2003;Kemball et al 2001;Patnaik et al 1995) show that Patnaik & Porcas (1999). b Patnaik et al (1993).…”

Section: Introductionmentioning

confidence: 91%

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

Mittal

Porcas

Wucknitz

et al. 2006

A&A

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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 1.65 GHz to 15.35 GHz. 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. (2004, MNRAS, 349, 14), show that shifts of the image peaks and centroids are too small to account for the observed frequency-dependent ratio.

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“…Previous VLBI observations at high frequencies (Biggs et al 2003;Kemball et al 2001;Patnaik et al 1995) show that Patnaik & Porcas (1999). b Patnaik et al (1993).…”

Section: Introductionmentioning

confidence: 91%

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

Mittal

Porcas

Wucknitz

et al. 2006

A&A

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“…Each image reveals intricate substructures at very high angular resolution (Patnaik et al 1995;Biggs et al 2003). The constraints provided by the complex image pattern and by the time variability of the background source flux, make of B0218+357 one of the best objects to measure H 0 at intermediate redshifts (Biggs et al 2003;Wucknitz et al 2004;York et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Distribution of the molecular absorption in front of the quasar B0218+357

Müller¹,

Guèlin

Combes

et al. 2007

A&A

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The line of sight to the quasar B0218+357, one of the most studied lensed systems, intercepts a z = 0.68 spiral galaxy, which splits its image into two main components A and B, separated by ca. 0.3 , and gives rise to molecular absorption. Although the main absorption component has been shown to arise in front of image A, it is not established whether some absorption from other velocity components is also occuring in front of image B. To tackle this question, we have observed the HCO + (2-1) absorption line during the commissioning phase of the new very extended configuration of the Plateau de Bure Interferometer, in order to trace the position of the absorption as a function of frequency. Visibility fitting of the self-calibrated data allowed us to achieve position accuracy between ∼12 and 80 mas per velocity component. Our results clearly demonstrate that all the different velocity components of the HCO + (2-1) absorption arise in front of the south-west image A of the quasar. We estimate a flux ratio f A / f B = 4.2 +1.8 −1.0 at 106 GHz.

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“…Stickel et al (1994) added three sources to their original sample: 0218+357, 2029+121 and 2150+173. In particular 0218+357 is a well known gravitational lens (O'Dea et al 1992;Patnaik et al 1993Patnaik et al , 1995. Since our work started when these three additional sources were not included, and furthermore, in the literature the "1 Jy sample of BL Lac sources" refers to the 34 objects in Stickel et al (1991), we will not consider the forementioned additional sources.…”

Section: Introductionmentioning

confidence: 99%

Extended radio emission in BL Lac objects

Cassaro

Stanghellini

Bondì

et al. 1999

Astron. Astrophys. Suppl. Ser.

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Abstract.We have observed 28 sources selected from the 1Jy sample of BL Lac objects (Stickel et al. 1991) with the Very Large Array (VLA) in A, B and D configurations at 1.36, 1.66 and 4.85 GHz, and/or with the Westerbork Synthesis Radio Telescope (WSRT) at 1.40 GHz. In this paper we present high sensitivity images at arcsecond resolution of the 18 objects showing extended structure in our images, and of another source from the FIRST (Faint Images of the Radio Sky at Twenty-cm) survey (Becker et al. 1995). In general our high sensitivity images reveal an amount of extended emission larger than previously reported. In some objects the luminosity of the extended structure is comparable with that of FR II radio sources. A future paper will be devoted to the interpretation of these results.

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VLBA observations of the gravitational lens system B0218+357

Cited by 70 publications

References 0 publications

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

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

Distribution of the molecular absorption in front of the quasar B0218+357

Extended radio emission in BL Lac objects

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