[SEMINARI] Polarisation observations of Compact Steep Spectrum Sources at sub-arcsecond resolution

[Enric Marco]

Polarisation observations of Compact Steep Spectrum Sources at
sub-arcsecond resolution

Franco Mantovani

Istituto di Radioastronomia - INAF, Bologna, Italy

Seminari del departament d'Astronomia i Astrofísica

Dilluns 08 novembre 2010

12:00

Resum

Measurements of the polarised emission from Compact Steep-Spectrum
(CSS) sources can provide important information about the physical
conditions inside and around the region of radio emission. CSS sources
are physically small objects with radio sizes smaller than 15 kpc that
reside inside their host galaxies. The most widely accepted
interpretation is that CSS galaxies are young radio sources of ages <
10^6 yr. The measurement of the physical properties of CSS sources can
provide insight into the conditions at the birth of a powerful radio
source and those of sources developing in dense interstellar
environments. An effect on the synchrotron polarised emission produced
by this magnetized thermal plasma is Faraday rotation, which is
proportional to the product of electron density and the magnetic field
component parallel to the direction of propagation integrated along
the line of sight. The magnetized plasma responsible for Faraday
rotation and depolarisation can be situated either within the source,
in a foreground screen, or in both. However, there are several
indications, such as the magnitudes of the RMs, the total rotation of
the electric vector position angle > 90 deg without very high
depolarisation, that most of the observable effects are not internal
to the source, but are produced in foreground material in the vicinity
of the radio synchrotron source. A model to describe the
depolarisation behaviour in external screens has been discussed by
Burn (1966) and later generalized by Tribble (1991). Many CSS sources
have been observed mainly with radio interferometers like the VLA and
the VLBA. Our investigations have provided very interesting results
about the polarised state of the radio emission CSS sources. 
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Dr. Enric Marco
Departament d'Astronomia i Astrofísica
Facultat de Física
Universitat de València
C/  Dr. Moliner, 50
46100 Burjassot, Spain
Phone: (34)-96-354-3069
Fax:(34)-96-354-3084
enric.marco en uv.es
www.uv.es/marco
www.uv.es/aia2009
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