In brief...
I am a cosmologist, which means I use the universe as a laboratory
for testing the laws of Nature. My interests include dark energy and
modified gravity, cosmic microwave background (CMB), structure
formation, cosmic magnetic fields, cosmic strings and other
topological defects and their implications for particle physics and
cosmology.
Origin of Cosmic Acceleration
The observed acceleration of cosmic expansion could be caused by
Dark Energy or be a manifestation of Gravity obeying different laws
on cosmological scales. My work involves developing tests of Dark
Energy and Modified Gravity theories that can be performed with
current and future astronomical data. This line of research requires
understanding the capabilities of planned and proposed observations
and the extent to which they will help us be distinguish between
different theories.
Fundamental Physics from CMB
The Cosmic Microwave Background (CMB) radiation is a snapshot of our
Universe at the age of 400,000 years and bears signatures of events
that happened before and after. I use the CMB data to gain insight
into the fundamental physics in the early and late universe. For
example, measurements of the so-called B-mode polarization help us
infer information about inflation, primordial magnetic fields and
cosmic strings, which could have been created in the aftermath of
Inflation or subsequent phase transitions. I am also interested in
examining CMB maps for any non-Gaussian features of primordial
origin. If found, they would be of profound significance to our
understanding of the earliest instants in the history of our
universe.
Topological Defects
Topological defects, such as magnetic monopoles, cosmic strings and
domain walls, are observed in condensed matter systems and may have
been formed during phase transitions at the early stages in the
history of the universe. I study magnetic monopoles and domain
walls, and their interactions, in the context of grad unified
theories (GUTs). Even if we never manage to observe cosmic
topological defects, just the fact of their existence as solutions
of a field theory is important when working out implications of that
theory for the real world.