Search Publications
Confronting Kähler moduli inflation with CMB data
Bhattacharya, Sukannya; Dutta, Koushik; Gangopadhyay, Mayukh Raj +1 more
In models of inflation obtained from string compactification, moduli vacuum misalignment leads to an epoch in the postinflationary history of the Universe when the energy density is dominated by cold moduli particles. This effect leads to a modification in the number of e -foldings (Npivot) between the horizon exit of the CMB modes and …
Dark energy constraints in light of Pantheon SNe Ia, BAO, cosmic chronometers and CMB polarization and lensing data
Wang, Deng
To explore whether there is new physics going beyond the standard cosmological model or not, we constrain seven cosmological models by combining the latest and largest Pantheon Type Ia supernovae sample with the data combination of baryonic acoustic oscillations, cosmic microwave background radiation, Planck lensing and cosmic chronometers. We fin…
EDGES result versus CMB and low-redshift constraints on ionization histories
Mena, Olga; Gariazzo, Stefano; Witte, Samuel +2 more
We examine the results from the Experiment to Detect the Global Epoch of Reionization Signature (EDGES), which has recently claimed the detection of a strong absorption in the 21 cm hyperfine transition line of neutral hydrogen, at redshifts demarcating the early stages of star formation. More concretely, we study the compatibility of the shape of…
Inflation with Planck data: A survey of some exotic inflationary models
Gomes, Cláudio; Bertolami, Orfeu; Rosa, João G.
We examine some inflationary models based on modifications of gravity in the light of Planck 2015 data, such as the generalized Chaplygin inspired inflation, models based in N =1 supergravity and braneworld scenarios. We also show that, conversely, potentials with a very flat plateau yield a primordial spectrum similar to that of the Starobinsky m…
Test of general relativity during the BepiColombo interplanetary cruise to Mercury
Schettino, Giulia; Serra, Daniele; Tommei, Giacomo +1 more
The theory of general relativity first introduced the concept that space-time is curved by the presence of masses. As a consequence, any signal between two sources passing by a massive body is deflected and therefore experiences a transmission time delay with respect to the straight-line propagation. In the parametrized Post-Newtonian formalism—wh…
Effects of a caustic ring of dark matter on the distribution of stars and interstellar gas
Chakrabarty, Sankha S.; Sikivie, Pierre
Caustic rings of dark matter with tricusp cross section were predicted to lie in the galactic disk. Their radii increase on cosmological time scales at a rate of order 1 kpc /Gyr . When a caustic ring passes through the orbit of a star, the orbit is strongly perturbed. We find that a star moving in a nearly circular orbit is first attracted toward…
Closing in on the large-scale CMB power asymmetry
Moss, A.; Scott, D.; Contreras, D. +2 more
Measurements of the cosmic microwave background (CMB) temperature anisotropies have revealed a dipolar asymmetry in power at the largest scales, in apparent contradiction with the statistical isotropy of standard cosmological models. The significance of the effect is not very high, and is dependent on a posteriori choices. Nevertheless, a number o…
Observational constraints on warm quasi-exponential inflation
Videla, Nelson; Panotopoulos, Grigorios
In the present work, we study a warm inflationary model defined by a quasi-exponential inflaton potential and an inflaton decay rate proportional to the Hubble rate. The model is characterized by three free parameters. We compute the power spectrum, the scalar spectral index, as well as the tensor-to-scalar ratio within the framework of the model,…
Astrometric test of the weak equivalence principle
Xie, Yi
Weak equivalence principle (WEP) is, for the first time, tested by astrometry on quasars in the sky measured in two wavelengths. Compared to previous WEP tests based on the Shapiro time delay of massless particles, this one has profound superiority that nearly 1 700 quasars with best measured positions commonly in the optical and radio bands are a…
Gravitational wave effects on astrometric observables
Bini, Donato; Geralico, Andrea
Observational data from the European Space Agency astrometric mission Gaia determining the positions of celestial objects within an accuracy of a few microarcseconds will be soon fully available. Other satellite-based space missions are currently planned to significantly improve such precision in the next years. The data reduction process needs hi…