(history of radio polarization) Cosmic magnetism (history of radio polarization) Richard Wielebinski MPI für Radioastronomie, Bonn IAU Hawaii, 05.08.2015

planetary motion is due to gravity Johannes Kepler suggests magnetic fields responsible for planetary motion ca. 1609 William Gilbert made experiments with magnets ca. 1600 Isaac Newton shows that planetary motion is due to gravity ca.1700 2

J. C. Maxwell , 1865 Cambridge Electromagnetic theory Heinrich Hertz 1885, Karlsruhe 1886, Bonn Dipoles must be aligned Polarization!

P. Zeeman, 1896 remote sensing of magnetic fields Polarization ! G.E.Hale - Zeeman Effect in Sunspots, 1908 H.W. Babcock - Zeeman Effect in stars, 1947 4

a pioneer of polarization Solar researchers were first to discover cosmic radio polarization 1946 Martyn: Polarization of Solar radio waves Appelton & Hey; Ryle & Vonberg: Circular polarization of Solar emission K.O.Kiepenheuer: Radio waves originate in magnetic fields Joe Pawsey a pioneer of polarization

Methods of measurement of cosmic magnetic fields Zeeman effect (optical and radio) Optical polarization (+ Davis-Greenstein Effect) Radio continuum total intensity linear polarization Faraday rotation radio continuum extragactic sources pulsars 6

Radio polarimetry ca. 1953 Naval Research Laboratory Washington D.C. 50 foot dish Pioneers of polarization 1957 Mayer McCullough Sloanaker, Detection of polarization In the Crab Nebula at 3.15 cm Simple rotating feed

Lebedev Physical institute Radio polarimetry in USSR confirmation of the polarization of Crab Nebula at 21 cm wavelength 31m dish of the Lebedev Physical institute Kuzmin Udalt’sov, 1957 Ferrite polarization tranducer

Polarization of Jupiter Radhakrishnan & Roberts, 1960 Jupiter has 30% linear polarization

Dwingeloo Westerhout et al. 1962 Detection of polarization in the Milky Way Galactic Faraday Rotation Muller et al. 1963 Correlation polarimeter

Cambridge Wielebinski et al. 1962, Detection of polarization In the Milky Way Wielebinski & Shakeshaft, 1962 Ionospheric Faraday Rotation Switching polarimeter, rotating feed and receiver

Magnetic fields in the Milky Way ←WMAP 32 GHZ Galactic Centre 32 GHz W.Reich Vertical field 21cm © MPIfR→

100 m dish Effelsberg 11cm polarization survey

M51 NGC7479 Magnetic fields in galaxies ©MPIfR NGC4631

Parkes Bracewell et al. 1962 Detection of polarization In Centaurus A Cooper & Price, 1962 Faraday Rotation in Cenaturus A Mayer et al. 1962 In Cygnus A

The catalogues of RM of sources made in 1960s allowed the compilations of RMs of the Galaxy 1980 Simrad-Normandin & Kronberg

The early source surveys avoided the Galactic plane Van Eck et al. J-A Brown et al. Haverkorn et al. The early source surveys avoided the Galactic plane At first pulsars closed the gap. Now EGRS data came.

A new method of displaying RM distribution

Single dish observations <— of Cas A © NRAO Tuffs et al. VLA Mayer et al. 1968

Westerbork Magnetic fields in radio galaxies 1970s Miley, 1973 Hœgbom 1974

VLA Studies of galaxies radio galaxies and jets in AGNs Magnetic phenomena 1980s

of polarization mapping 1968 1,2 cm 140 ft dish Mayer et al. Development of polarization mapping Cygnus A 1974 Hargrave & Ryle 2cm 6cm©NRAO

Centaurus A Parkes 2013 Shimwell Fein et al. ©.ATNF 1962 Cooper & Price 1990 Junkes

Intergalactic magnetic fields in Coma cluster Thierbach et al. 2003 Coma halo Kim et al. 1990 → Rotation Measure of quasars

Pulsar polarization 0° 90° Lyne & Smith, 1968 ↑ Pulsars have the most unusual polarization Karastergiou et al. →

Radio Zeeman Effect Bolton & Wild, 1957 suggest the use of the HI line For measurement of magnetic fields Verschuur, 1968 makes first detection Later other molecular lines are used.

Magnetic fields have been grossly neglected Waiting for SKA THANK YOU !!