Search Publications
Parametrized modified gravity constraints after Planck
Hu, Bin; Bartolo, Nicola; Liguori, Michele +1 more
We constrain f(R) and chameleon-type modified gravity in the framework of the Berstchinger-Zukin parametrization using the recently released Planck data, including both the cosmic mircowave background radiation (CMB) temperature power spectrum and the lensing potential power spectrum. Some other external data sets are included, such as baryon acou…
Equation of state of dark matter after Planck data
Xu, Lixin; Chang, Yadong
In this paper, we loosen the zero equation of state of dark matter to a constant wdm. By using the currently available cosmic observations, which include the type-Ia supernovae, the baryon acoustic oscillation, the WiggleZ measurements of matter power spectrum, and the cosmic microwave background radiation from the firs release of Planc…
Clusters of galaxies and variation of the fine structure constant
Galli, Silvia
We propose a new method to probe for variations in the fine structure constant α using clusters of galaxies, opening up a window on a new redshift range for such constraints. Hot clusters shine in the x-ray mainly due to bremsstrahlung, while they leave an imprint on the cosmic microwave background (CMB) frequency spectrum through the Sunyaev-Zel’…
Growth index after the Planck results
Xu, Lixin
The growth index γL was proposed to investigate the possible deviation from the standard ΛCDM model and Einstein’s gravity theory in a dynamical perspective. Recently, thanks to the measurement of the cosmic growth rate via the redshift-space distortion, one can understand the evolution of the density contrast through fσ8(z),…
Moduli dark matter and the search for its decay line using Suzaku x-ray telescope
Loewenstein, Michael; Kusenko, Alexander; Yanagida, Tsutomu T.
Light scalar fields called moduli arise from a variety of different models involving supersymmetry and/or string theory; thus their existence is a generic prediction of leading theories for physics beyond the standard model. They also present a formidable, long-standing problem for cosmology. We argue that an anthropic solution to the moduli probl…
MeV dark matter in the 3+1+1 model
Nelson, Ann E.; Huang, Jinrui
The existence of light sterile neutrinos in the eV mass range with relatively large mixing angles with the active neutrinos has been proposed for a variety of reasons, including to improve the fit to the LSND and MiniBooNE neutrino oscillation experiments, and reactor disappearance experiments. A. E. Nelson [Phys. Rev. D 84, 053001 (2011)] showed …
Planck constraints on Higgs modulated reheating of renormalization group improved inflation
Qiu, Taotao; Cai, Yi-Fu; Chang, Yu-Chiao +2 more
Within the framework of renormalization group improved inflationary cosmology motivated by asymptotically safe gravity, we study the dynamics of a scalar field which can be interpreted as the Higgs field. The background trajectories of this model can provide sufficient inflationary e-folds and a graceful exit to a radiation dominated phase. We stu…
Planck constraints on the effective neutrino number and the CMB power spectrum lensing amplitude
Di Valentino, Eleonora; Gerbino, Martina; Said, Najla
We present new constraints on the relativistic neutrino effective number Neff and on the cosmic microwave background power spectrum lensing amplitude AL from the recent Planck 2013 data release. Including observations of the cosmic microwave background large angular scale polarization from the Wilkinson microwave anisotropy p…
Updated constraints from the Planck experiment on modified gravity
Salvatelli, Valentina; Marchini, Andrea
A modification of the action of the general relativity produces a different pattern for the growth of the cosmic structures below a certain length scale leaving an imprint on the cosmic microwave background anisotropies. We reexamine the upper limits on the length-scale parameter B0 of f(R) models using the recent data from the Planck s…
Neutrino anisotropies after Planck
Di Valentino, Eleonora; Gerbino, Martina; Said, Najla
We present new constraints on the rest-frame sound speed, ceff2, and the viscosity parameter, cvis2, of the cosmic neutrino background from the recent measurements of the cosmic microwave background anisotropies provided by the Planck satellite. While broadly consistent with the expectations of ceff…