Search Publications
Do joint CMB and HST data support a scale invariant spectrum?
Benetti, Micol; Graef, Leila L.; Alcaniz, Jailson S.
We combine current measurements of the local expansion rate, H0, and Big Bang Nucleosynthesis (BBN) estimates of helium abundance with the latest cosmic microwave background (CMB) data from the Planck Collaboration to discuss the observational viability of the scale invariant Harrison-Zeldovch-Peebles (HZP) spectrum. We also analyze som…
Constraints on direction-dependent cosmic birefringence from Planck polarization data
Scott, Douglas; Contreras, Dagoberto; Boubel, Paula
Cosmic birefringence is the process that rotates the plane of polarization by an amount, α, as photons propagate through free space. Such an effect arises in parity-violating extensions to the electromagnetic sector, such as the Chern-Simons term common in axion models, quintessence models, or Lorentz-violating extensions to the standard model. Mo…
Inflation model selection meets dark radiation
Tram, Thomas; Vennin, Vincent; Vallance, Robert
We investigate how inflation model selection is affected by the presence of additional free-streaming relativistic degrees of freedom, i.e. dark radiation. We perform a full Bayesian analysis of both inflation parameters and cosmological parameters taking reheating into account self-consistently. We compute the Bayesian evidence for a few represen…
Narrowing down the possible explanations of cosmic acceleration with geometric probes
Dhawan, Suhail; Goobar, Ariel; Mörtsell, Edvard +2 more
Recent re-calibration of the Type Ia supernova (SNe Ia) magnitude-redshift relation combined with cosmic microwave background (CMB) and baryon acoustic oscillation (BAO) data have provided excellent constraints on the standard cosmological model. Here, we examine particular classes of alternative cosmologies, motivated by various physical mechanis…
Early cosmology constrained
Verde, Licia; Jimenez, Raul; Heavens, Alan F. +2 more
We investigate our knowledge of early universe cosmology by exploring how much additional energy density can be placed in different components beyond those in the ΛCDM model. To do this we use a method to separate early- and late-universe information enclosed in observational data, thus markedly reducing the model-dependency of the conclusions. We…
Testing predictions of the quantum landscape multiverse 2: the exponential inflationary potential
Di Valentino, Eleonora; Mersini-Houghton, Laura
The 2015 Planck data release tightened the region of the allowed inflationary models. Inflationary models with convex potentials have now been ruled out since they produce a large tensor to scalar ratio. Meanwhile the same data offers interesting hints on possible deviations from the standard picture of CMB perturbations. Here we revisit the predi…
CLASH-VLT: constraints on f(R) gravity models with galaxy clusters using lensing and kinematic analyses
Grillo, C.; Balestra, I.; Rosati, P. +10 more
We perform a maximum likelihood kinematic analysis of the two dynamically relaxed galaxy clusters MACS J1206.2-0847 at z=0.44 and RXC J2248.7-4431 at z=0.35 to determine the total mass profile in modified gravity models, using a modified version of the MAMPOSSt code of Mamon, Biviano and Bou&apose. Our work is based on the kinematic and lensin…
Power spectra based Planck constraints on compensated isocurvature, and forecasts for LiteBIRD and CORE space missions
Väliviita, Jussi
Compensated isocurvature perturbations (CIP), where the primordial baryon and cold dark matter density perturbations cancel, do not cause total matter isocurvature perturbation. Consequently, at the linear order in the baryon density contrast Δ, a mixture of CIP and the adiabatic mode leads to the same CMB spectra as the pure adiabatic mode. Only …
Testing non-minimally coupled inflation with CMB data: a Bayesian analysis
Benetti, Micol; Alcaniz, Jailson; Campista, Marcela
We use the most recent cosmic microwave background (CMB) data to perform a Bayesian statistical analysis and discuss the observational viability of inflationary models with a non-minimal coupling, ξ, between the inflaton field and the Ricci scalar. We particularize our analysis to two examples of small and large field inflationary models, namely, …
Testing predictions of the quantum landscape multiverse 1: the Starobinsky inflationary potential
Di Valentino, Eleonora; Mersini-Houghton, Laura
The 2015 Planck data release has placed tight constraints on the allowed class of inflationary models. The current data favors concave downwards inflationary potentials while offering interesting hints on possible deviations from the standard picture of CMB perturbations. We here test the predictions of the theory of the origin of the universe fro…