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SUMMARY:The history of radio astronomy polarisation measurements - Richard
  Wielebinski (MPI fur Radioastronomie\, Bonn) 
DTSTART:20131029T163000Z
DTEND:20131029T173000Z
UID:TALK47325@talks.cam.ac.uk
CONTACT:David Titterington
DESCRIPTION:While intensity of electromagnetic radiation (radio\, infrared
 \, light\, or X-ray) gives us primary information about the distribution o
 f the baryonic matter in the Universe\, polarisation is a parameter that e
 nables us to investigate many additional details.  Polarisation at radio f
 requencies gives us details of emission processes since the non-thermal sy
 nchrotron process dominates at low radio frequencies in emission regions. 
  The studies can be inverted and by means of polarisation observations the
  details of Cosmic Magnetic Fields in the emission regions can be delineat
 ed.  The Zeeman Effect is based on polarisation observations and gives a m
 ethod of direct determination of magnetic field.  In addition polarised ra
 dio sources can be used as probes of the intervening medium through which 
 the radio waves are propagated.  Faraday Rotation effects are observed and
  in conjunction with known thermal emission can be used to determine magne
 tic fields.  Some of the earliest radio polarisation observations were mad
 e in Cambridge in 1960-1963.  For me the year 1963 was crucial: my PhD exa
 mination.  From these early beginnings a whole research area has developed
 : the study of Cosmic Magnetic Fields.  I will describe the technology nee
 ded for polarisation observations and show the early observations but in a
 ddition I will follow the developments up to the present day.\n
LOCATION:Martin Ryle Seminar Room\, Kavli Institute
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