Radio, optical and infrared observations of CLASS B0128+437

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dc.creatorBiggs, A. D.
dc.creatorBrowne, I. W. A.
dc.creatorJackson, N. J.
dc.creatorYork, T.
dc.creatorNorbury, M. A.
dc.creatorMcKean, J. P.
dc.creatorPhillips, P. M.
dc.date2004-02-05
dc.date.accessioned2026-07-07T06:30:44Z
dc.date.available2026-07-07T06:30:44Z
dc.descriptionWe present new observations of the gravitational lens system CLASS B0128+437. HST observations detect a very faint, extended object in I-band with no emission from the lensed images visible; no detection at all is made in V-band. The lens system is detected with much higher signal to noise with UKIRT in K-band, but the resolution is not sufficient to allow the lensed images and the lens galaxy to be separated. A careful astrometric calibration, however, suggests that the peak of the infrared emission corresponds to the two merging images A and B and therefore that the lensed images dominate at infrared wavelengths. The new radio data consist of VLBI radio images at three frequencies, 2.3, 5 and 8.4GHz, made with the VLBA and the 100-m Effelsberg telescope. The lensed source consists of three well-defined sub-components embedded in a more extended jet. Due to the fact that the sub-components have different spectral indices it is possible to determine which part of each image corresponds to the same source sub-component. Our main finding is that one of the images, B, looks very different to the others, there being no obvious division into separate sub-components and the image being apparently both broader and smoother. This is a consequence we believe of scatter-broadening in the ISM of the lensing galaxy. The large number of multiply-imaged source sub-components also provide an abundance of modelling constraints and we have attempted to fit an SIE+external shear model to the data, as well as utilising the novel method of Evans & Witt. It proves difficult in both cases, however, to obtain a satisfactory fit which strongly suggests the presence of sub-structure in the mass distribution of the lensing galaxy, perhaps of the kind that is predicted by CDM theories of structure formation.
dc.descriptionAccepted for publication in MNRAS. 13 pages, 8 figures. Full resolution versions of Figures 1, 2, 3, 4 and 5 are obtainable from ftp://ftp.jive.nl/pub/biggs/0128_highres.tar.gz
dc.identifierhttps://arxiv.org/abs/astro-ph/0402128
dc.identifierhttp://arxiv.org/abs/astro-ph/0402128
dc.identifierMon.Not.Roy.Astron.Soc. 350 (2004) 949
dc.identifierdoi:10.1111/j.1365-2966.2004.07701.x
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/98411
dc.subjectAstrophysics
dc.titleRadio, optical and infrared observations of CLASS B0128+437
dc.typetext

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