Cosmology seminar: Mikjel Thorsrud: Doubly Coupled Quintessence
Mikjel Thorsrud is a phd student with David
Motivated by the couplings of the dilaton in four-dimensional effective
actions, we investigate the cosmological consequences of a scalar field
coupled both to matter and a Maxwell-type vector field. The vector field
has a background isotropy-violating component. New anisotropic scaling
solutions which can be responsible for the matter and dark energy dominated
epochs are identified and explored. For a large parameter region the
universe expands almost isotropically. Using that the CMB quadrupole is
extremely sensitive to shear, we constrain the ratio of the matter coupling
to the vector coupling to be less than 10^(-5). Moreover, we identify a
large parameter region, corresponding to a strong vector coupling regime,
yielding exciting and viable cosmologies close to the LCDM limit.
Published Feb. 21, 2012 2:34 PM
- Last modified May 29, 2012 9:18 PM