|
Cosmology and Astrophysics - Inflation
One of my main research interests concerns a very early phase in the
evolution of the Universe, the so-called inflationary phase. During
this phase the Universe expanded exponentially, which can explain why
the Universe looks so homogeneous in each direction even though it
might seem that two different parts of the sky in the opposite
direction had no chance to have known each other in the past. It also
solves the flatness problem and the monopole problem of the standard
big bang scenario.
In the past my research was mainly focused on the problem of
preheating. After the inflationary phase the Universe is very cold but
in order to make nucleosynthesis work the Universe has to be at a high
temperature. It reaches this temperature during the reheating
phase. This phase seems to be not efficient enough in standard
scenarios, therefore an additional preheating phase was introduced.
In collaboration with Jurgen Baacke and Carsten Patzold I worked on
the back reaction problem of quantum fluctuation in an FRW
cosmology. We also investigated the preheating phase for different
models such as fermionic and gauge field models. Later on together
with Daniel Cormier and Anupam Mazumdar I have worked on preheating in
coupled systems which is especially important for hybrid models of
inflation. More recently I have become interested in predicitions for
structure formation and CMB anisotropies from inflation. In
collaboration with
Salman Habib,
Andreas
Heinen, Gerard Jungman, and Carmen
Molina-Paris we have found an excellent analytic approximation for the
primordial power spectrum and the related spectral index. We have
extended this approximation up to second order and we implemented a
numerical code which calculates the primordial power spectrum exact,
in the uniform approximation, and in the traditional slow-roll
approximation (well, Andreas did most of the implementing part...).
We also developed a new way of reconstructing the inflationary
potential from a given power spectrum via inverse scattering theory.
By combining our two approached and with the upcoming new observations
of the cosmic microwave background we hope to be able to put
constrains on the inflationary model space.
Publications
-
Inflationary Perturbations and Precision Cosmology,
S. Habib, A. Heinen, K. Heitmann, and G. Jungman, Phys. Rev. D71, 043518
(2005),
astro-ph/0501130
- Inverse-Scattering Theory and the Density Perturbations from Inflation,
S. Habib, K. Heitmann, and G. Jungman,
Phys. Rev. Lett. 94, 061303 (2005),
astro-ph/0409599
- Characterizing Inflationary Perturbations: The Uniform
Approximation,
S. Habib, A. Heinen, K. Heitmann, G. Jungman, and C. Molina-Paris,
Phys. Rev. D70, 083507 (2004)
astro-ph/0406134
- The Inflationary Perturbation Spectrum,
S. Habib, K. Heitmann, G. Jungman, and C. Molina-Paris,
Phys. Rev. Lett. 89, 281301 (2002)
astro-ph/0208443
- Dynamics of Coupled Bosonic Systems with Application to Preheating,
D. Cormier, K. Heitmann, and A. Mazumdar, Phys. Rev. D65, 083521 (2002),
hep-ph/0105236
- Nonequilibrium Dynamics of Fermions in a Spatially
Homogeneous Scalar Background Field,
J. Baacke, K. Heitmann, and C. Patzold,
Phys. Rev. D58, 125013 (1998),
hep-ph/9806205
- Renormalization of Nonequilibrium Dynamics in FRW Cosmology,
J. Baacke, K. Heitmann, and C. Patzold,
Phys. Rev. D56, 6556, (1997),
hep-ph/9706274
- Nonequilibrium Dynamics: Preheating in the SU(2) Higgs Model,
J. Baacke, K. Heitmann, and C. Patzold,
Phys. Rev. D55, 7815 (1997),
hep-ph/9612264
|
|
