Speaker
Description
Model independent equations can be derived for gravitational waves (GW) and curvature perturbations in terms of an appropriately defined effective sound speed. The effective sound speed encodes the effects of the source terms in the equations of motion associated to the interactions terms in the Lagrangian, related to the coupling with other fields. The effects of the interaction terms can be modeled by introducing an effective metric, in terms of which the equations of motion reduce to the covariant d'Álembert operator.
For GWs the effective sound speed depends on the transverse-traceless anisotropic part of the stress-energy tensor, and for curvature perturbation on the entropy and anisotropy. The effective action is derived in both the Einstein's and Jordan's frame.
We show applications to multi-fields inflationary models, and GW propagation in presence of dark energy or dark matter. For GW the effective speed can be polarization and frequency dependent, and we obtain a model independent relation between electromagnetic and gravitational luminosity distance, $d_L^{GW}(z)=\tilde{c}_T(z)\, d_L^{EM}(z)$.
We discuss the implications for constraining dark energy and inflation models with gravitational waves, CMB, large structure observations and other cosmological probes.
Faculty position
Professor
| Topic Field | Cosmology |
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