Refined modelling of the gravitationally lensed quasar PKS 1830-211
Typ
Examensarbete för masterexamen
Program
Physics and astronomy (MPPAS), MSc
Publicerad
2019
Författare
Subramanyam, Jaswanth
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
PKS 1830-211 is a well studied radio-loud quasar with a flat spectrum undergoing
strong gravitational lensing by a foreground galaxy. At cm-wavelengths the structure
of PKS 1830-211 consists of two lensed images separated by 1 arcsecond and
connected by an Einstein ring. High-resolution radio continuum observations have
revealed structural changes in both the NE and the SW images. The absorption
spectra arising from the foreground galaxy, at z = 0.89, show temporal variations.
It is very likely that the variations in the lines of sight are related to changes in the
structure of the background source.
In this thesis we use a core-jet model of the background source and examine how
variations in the illumination affect the absorption spectra. For this purpose, the
lens system was divided into three parts: the source, the lens, and an absorption
screen in the lens galaxy. The position of the jet was varied while keeping the lens
and the absorption screen parameters constant. Temporal variations of the order
of 1% in the absorption spectra over a time scale of 1 yr corresponding to a
physical scale of about 0.3 pc, for a jet travelling at speed of light at the redshift
of the source, could be reproduced with the model. This supports the claim that
variations in the source structure can explain the observed temporal variations in
the absorption spectra.
Beskrivning
Ämne/nyckelord
Gravitational lensing, Einstein ring, PKS 1830-211, Absorption spectra,GravLens, modelling.