Search Publications
CDM/baryon isocurvature perturbations in a sneutrino curvaton model
Kawasaki, Masahiro; Harigaya, Keisuke; Hayakawa, Taku +1 more
Matter isocurvature perturbations are strictly constrained from cosmic microwave background observations. We study a sneutrino curvaton model where both cold dark matter (CDM)/baryon isocurvature perturbations are generated. In our model, total matter isocurvature perturbations are reduced since the CDM/baryon isocurvature perturbations compensate…
Superimposed oscillations in brane inflation
Martin, Jérôme; Ávila, Santiago; Steer, Danièle A.
In canonical scalar field inflation, the Starobinsky model (with a linear potential but discontinuous slope) is remarkable in that though slow-roll is violated, both the power-spectrum and bi-spectrum can be calculated exactly analytically. The two-point function is characterised by different power on large and small scales, and a burst of small a…
PLANCK and WMAP constraints on generalised Hubble flow inflationary trajectories
Contaldi, Carlo R.; Horner, Jonathan S.
We use the Hamilton-Jacobi formalism to constrain the space of possible single field, inflationary Hubble flow trajectories when compared to the WMAP and PLANK satellites Cosmic Microwave Background (CMB) results. This method yields posteriors on the space of Hubble Slow Roll (HSR) parameters that uniquely determine the history of the Hubble param…
The kinetic Sunyaev-Zel'dovich effect from the diffuse gas in the Local Group
Loeb, Abraham; Rubin, Douglas
Since the Local Group (LG) of galaxies moves with a bulk velocity with respect to the cosmic microwave background radiation (CMB), free electrons in its gaseous halo should imprint large-scale non-primordial temperature shifts in the CMB via the kinetic Sunyaev-Zel'dovich (kSZ) effect. By modeling the distribution of gas in the LG halo and using i…
Constraining primordial vector mode from B-mode polarization
Saga, Shohei; Shiraishi, Maresuke; Ichiki, Kiyotomo
The B-mode polarization spectrum of the Cosmic Microwave Background (CMB) may be the smoking gun of not only the primordial tensor mode but also of the primordial vector mode. If there exist nonzero vector-mode metric perturbations in the early Universe, they are known to be supported by anisotropic stress fluctuations of free-streaming particles …
BICEP's acceleration
Contaldi, Carlo R.
The recent Bicep2 [1] detection of, what is claimed to be primordial B-modes, opens up the possibility of constraining not only the energy scale of inflation but also the detailed acceleration history that occurred during inflation. In turn this can be used to determine the shape of the inflaton potential V(ϕ) for the first time - if a single, sca…
The Atacama Cosmology Telescope: Sunyaev-Zel'dovich selected galaxy clusters at 148 GHz from three seasons of data
Hilton, Matt; Hasselfield, Matthew; Sifón, Cristóbal +41 more
We present a catalog of 68 galaxy clusters, of which 19 are new discoveries, detected via the Sunyaev-Zel'dovich effect (SZ) at 148 GHz in the Atacama Cosmology Telescope (ACT) survey on the celestial equator. With this addition, the ACT collaboration has reported a total of 91 optically confirmed, SZ detected clusters. The 504 square degree surve…
A lower bound on the mass of cold thermal dark matter from Planck
Dolan, Matthew J.; Bœhm, Céline; McCabe, Christopher
We show that the new measurement of the effective number of neutrinos (Neff) by the Planck satellite can be used to set a robust lower bound on the mass of cold thermal dark matter of Script O(MeV). Our limit applies if the dark matter remains in thermal equilibrium by coupling to electrons and photons or through interactions with neutr…
A new life for sterile neutrinos: resolving inconsistencies using hot dark matter
Hamann, Jan; Hasenkamp, Jasper
Within the standard ΛCDM model of cosmology, the recent Planck measurements have shown discrepancies with other observations, e.g., measurements of the current expansion rate H0, the galaxy shear power spectrum and counts of galaxy clusters. We show that if ΛCDM is extended by a hot dark matter component, which could be interpreted as a…
Planck constraints on holographic dark energy
Zhang, Xin; Li, Miao; Ma, Yin-Zhe +2 more
We perform a detailed investigation on the cosmological constraints on the holographic dark energy (HDE) model by using the Plank data. We find that HDE can provide a good fit to the Plank high-l (l gtrsim 40) temperature power spectrum, while the discrepancy at l simeq 20-40 found in the ΛCDM model remains unsolved in the HDE model. The Plank dat…