Dr. Nemanja
Kaloper
UC Davis
We
show that the combined dimming of Type Ia supernovae
induced by both a cosmological constant and the conversion of photons into axions in extra-galactic magnetic
fields can impersonate dark energy with an equation of state w < -1. An
observer unaware of the presence of photon-axion
conversion would interpret the additional dimming as cosmic acceleration faster
than that induced by a cosmological constant alone. We find that this mechanism
can mimic equations of state as negative as w\simeq -
1.5. Our model does not have any ghosts, phantoms and the like. It is fully
consistent with the conventional effective field theory in curved space, and
all existing observational constraints on the axions
are obeyed.
References: hep-ph/0111311, hep-ph/0112212, astro-ph/0409596