Dark Sector: A Tale of Two Components

Speaker: Manuel Buen Abad Najar

When: October 5, 2016 (Wed), 12:10PM to 01:10PM (add to my calendar)
Location: PRB 261

This event is part of the Preliminary Oral Exam.

Examining Committee: Martin Schmaltz, Emanuel Katz, Claudio Chamon, Edward Kearns (Chair)


The recent measurements of the Cosmic Microwave Background (CMB) from the Planck telescope, and of the Large Scale Structure (LSS) from different experiments, have confirmed the standard model of cosmology, or ΛCDM. Nevertheless, many alternative cosmological models are also consistent with this data. Some mild tensions between Planck and these LSS experiments about the measurements of the Hubble constant (H0) and of the Matter Power Spectrum for sizes of 8h−1Mpc (σ8) hint to models beyond ΛCDM.

In this talk I present a recent proposal for a Dark Sector which consists of two components: a cold Dark Matter one, and another of Dark Radiation, along with their mutual interactions. The presence of the Dark Radiation resolves the tension in the measurement of H0, while the interactions address the discrepancy in σ8.

I describe in detail the mechanism with which this model deals with the mentioned tensions, using the equations for the evolution of the cosmological anisotropies. In addition, I present a simple analytical solution for the limit case in which the Dark Matter and the Dark Radiation form a tightly coupled plasma throughout the history of the Universe. Finally, I show that the fit of this new model to the cosmological data is better than ΛCDM’s.