Speaker
Agnieska Cieplak
(Brookhaven National Laboratory, United States)
Description
With the recent progress of Lyman-alpha forest power spectrum
measurements, understanding of the bias between the measured flux and
the underlying matter power spectrum is becoming crucial to the
percent level cosmological interpretation of these measurements.
Previous theoretical studies of this bias have used N-body and
hydro-PM simulations and inferred large-scale bias parameters that are
in reasonable agreement with observations. In this work we attempt to
develop a deeper understanding of the physical origin of the
large-scale biasing of the forest. We have run a series of
hydrodynamic N-body simulations in order to compare numerically
measured bias factors with analytical predictions from formulae
derived by Seljak (2012) using second-order perturbation theory. We
demonstrate the success of this theory in a fluctuating Gunn-Peterson
approximation (FGPA) framework for certain regimes, and characterise
its limitations due to hydrodynamic effects, such as thermal
broadening, with the hope of improving future theoretical
models. Deeper understanding of the large-scale Lyman-alpha biasing
will help us in using the large-scale clustering of the forest as a
cosmological probe beyond baryon acoustic oscillations.
