The 21-cm line as a new probe of magnetic fields in the pre-reionization epoch
Teja Venumadhav
Caltech
Mapping neutral hydrogen using the 21cm line is one of the next big
observational frontiers in cosmology. Its main advantage is that it
provides redshift information, and enables access to many more modes than
the CMB does. I will highlight another feature of the line which makes
it possible to extract even more interesting cosmological information
from high-resolution 21cm observations, when they are realized in the
future. This is the spin-degeneracy of the triplet excited state of
the transition, which is spin-polarized by anisotropies in the incident
radiation. In this talk, I will focus on fluctuations in the brightness
temperature seen by a present-day observer, and show that they encode
information about magnetic fields which are coherent on large scales
in the early universe. This technique will be naturally sensitive
to extremely weak field strengths of order 10^-19 G, which opens the
possibility of probing primordial magnetic fields in neutral gas prior
to reionization. I will also briefly touch upon the exciting, if even
more speculative possibility of studying tensor modes using the 21cm line.
Date: | Lundi, le 24 novembre 2014 |
Heure: | 12:00 |
Lieu: | Université McGill |
| 3550 University, Conference Room |
Contact: | Robert Rutledge |
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