Search Publications
Testing chirality of primordial gravitational waves with Planck and future CMB data: no hope from angular power spectra
Melchiorri, Alessandro; Shiraishi, Maresuke; Gerbino, Martina +2 more
We use the 2015 Planck likelihood in combination with the Bicep2/Keck likelihood (BKP and BK14) to constrain the chirality, χ, of primordial gravitational waves in a scale-invariant scenario. In this framework, the parameter χ enters theory always coupled to the tensor-to-scalar ratio, r, e.g. in combination of the form χ ṡ r. Thus, the capability…
Iron Kα line of boson stars
Cao, Zheng; Bambi, Cosimo; Zhou, Menglei +3 more
The present paper is a sequel to our previous work [1] in which we studied the iron Kα line expected in the reflection spectrum of Kerr black holes with scalar hair. These metrics are solutions of Einstein's gravity minimally coupled to a massive, complex scalar field. They form a continuous bridge between a subset of Kerr black holes and a family…
Cosmological constraint on the light gravitino mass from CMB lensing and cosmic shear
Osato, Ken; Yoshida, Naoki; Kamada, Ayuki +2 more
Light gravitinos of mass lesssim O (10) eV are of particular interest in cosmology, offering various baryogenesis scenarios without suffering from the cosmological gravitino problem. The gravitino may contribute considerably to the total matter content of the Universe and affect structure formation from early to present epochs. After the gravitino…
Inflation in the closed FLRW model and the CMB
Bonga, Béatrice; Gupt, Brajesh; Yokomizo, Nelson
Recent cosmic microwave background (CMB) observations put strong constraints on the spatial curvature via estimation of the parameter Ωk assuming an almost scale invariant primordial power spectrum. We study the evolution of the background geometry and gauge-invariant scalar perturbations in an inflationary closed FLRW model and calcula…
Cosmic microwave background and inflation in multi-fractional spacetimes
Calcagni, Gianluca; Kuroyanagi, Sachiko; Tsujikawa, Shinji
We use FIRAS and PLANCK 2015 data to place observational bounds on inflationary scenarios in multi-fractional spacetimes with q-derivatives. While a power-law expansion in the geometric time coordinate is subject to the usual constraints from the tensor-to-scalar ratio, model-independent best fits of the black-body and scalar spectra yield upper l…
Information gains from cosmological probes
Amara, A.; Refregier, A.; Grandis, S. +2 more
In light of the growing number of cosmological observations, it is important to develop versatile tools to quantify the constraining power and consistency of cosmological probes. Originally motivated from information theory, we use the relative entropy to compute the information gained by Bayesian updates in units of bits. This measure quantifies …
Constraints on cosmological birefringence from PLANCK and Bicep2/Keck data
Gruppuso, A.; Mandolesi, N.; Melchiorri, A. +4 more
The polarization of cosmic microwave background (CMB) can be used to constrain cosmological birefringence, the rotation of the linear polarization of CMB photons potentially induced by parity violating physics beyond the standard model. This effect produces non-null CMB cross correlations between temperature and B mode-polarization, and between E-…
Parameter splitting in dark energy: is dark energy the same in the background and in the cosmic structures?
Verde, Licia; Cuesta, Antonio J.; Bernal, José Luis
We perform an empirical consistency test of General Relativity/dark energy by disentangling expansion history and growth of structure constraints. We replace each late-universe parameter that describes the behavior of dark energy with two meta-parameters: one describing geometrical information in cosmological probes, and the other controlling the …
A comment on power-law inflation with a dark radiation component
Di Valentino, Eleonora; Bouchet, François R.
Tram et al. 2016 recently pointed out in [1] that power-law inflation in presence of a dark radiation component may relieve the 3.3 σ tension which exists within standard ΛCDM between the determination of the local value of the Hubble constant by Riess et al. (2016) [2] and the value derived from CMB anisotropy data [3] by the Planck collaboration…
Testing for new physics: neutrinos and the primordial power spectrum
Aslanyan, Grigor; Easther, Richard; Price, Layne C. +2 more
We test the sensitivity of neutrino parameter constraints from combinations of CMB and LSS data sets to the assumed form of the primordial power spectrum (PPS) using Bayesian model selection. Significantly, none of the tested combinations, including recent high-precision local measurements of H0 and cluster abundances, indicate a signal…