New diagnostics of astrophysical magnetic field based on atomic alignment
Huirong Yan
Postdoctoral Fellow Canadian Institute for Theoretical Astrophysics
I shall present a new technique of studying magnetic fields in diffuse
astrophysical media, e.g. interstellar and intergalactic gas/plasma.
This technique is based on the angular momentum alignment of atoms
and ions in their ground or metastable states. As their life-time in
such states is long, the alignment induced by anisotropic radiation
is susceptible to weak magnetic fields in diffuse medium. The alignment
reveals itself in terms of the polarization of the absorbed and emitted
light. A variety of atomic species with fine or hyperfine splitting of
the ground or metastable states exhibit the alignment and the resulting
polarization degree in some cases exceeds 20 %. A unique feature of
these studies is that they can reveal the 3D orientation of magnetic
field.
In addition, I shall demonstrate that the polarization of the far
IR or radio radiation arising from the transitions between fine and
hyperfine states of the ground level can provide yet another promising
diagnostics of magnetic fields, including the magnetic fields in the
Early Universe. I shall outline several cases of interplanetary,
circumstellar and interstellar magnetic fields for which the studies
of magnetic fields using ground state atomic alignment effect are
promising.
Date: | Jeudi, le 4 septembre 2008 |
Heure: | 12:30 |
Lieu: | Université de Montréal |
| Pavillon Roger-Gaudry, Local D-460 |
Contact: | Pierre Bergeron |
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