Search Publications
Strategy to minimize dust foregrounds in B -mode searches
Kovetz, Ely D.; Kamionkowski, Marc
The Planck satellite has identified several patches of sky with low polarized dust emission, obvious targets for searches for the cosmic microwave background B -mode signal from inflationary gravitational waves. Still, given the Planck measurement uncertainties, the polarized dust foregrounds in these different candidate patches may differ by an o…
Inflection point inflation and dark energy in supergravity
Guo, Zong-Kuan; Gao, Tie-Jun
We consider an inflection point inflationary model in supergravity with a single chiral superfield and show that the predicted values of the scalar spectral index and tensor-to-scalar ratio are consistent with the Planck 2015 results. In this model supersymmetry is strongly broken after inflation, which results in a non-supersymmetry de Sitter vac…
Possibility of observable signatures of leptonium from astrophysical sources
Bland-Hawthorn, Joss; Ellis, S. C.
The formation of positronium in our Galaxy is well measured, and has led to important and unanswered questions on the origin of the positrons. In principle it should be possible to form analogous systems from µ and τ leptons, viz. true muonium and true tauonium. However the probability of formation for these systems is greatly reduced due to…
Bayesian evidence of nonstandard inflation: Isocurvature perturbations and running spectral index
Komatsu, Eiichiro; Giannantonio, Tommaso
Bayesian model comparison penalizes models with more free parameters that are allowed to vary over a wide range, and thus offers the most robust method to decide whether some given data require new parameters. In this paper, we ask a simple question: do current cosmological data require extensions of the simplest single-field inflation models? Spe…
Consistency of the nonflat Λ CDM model with the new result from BOSS
Kumar, Suresh
Using 137,562 quasars in the redshift range 2.1 ≤z ≤3.5 from the data release 11 (DR11) of the baryon oscillation spectroscopic survey (BOSS) of Sloan Digital Sky Survey (SDSS)-III, the BOSS-SDSS collaboration estimated the expansion rate H (z =2.34 )=222 ±7 km /s /Mpc of the Universe, and reported that this value is in tension with the prediction…
Principal component analysis of the reionization history from Planck 2015 data
Cai, Rong-Gen; Guo, Zong-Kuan; Dai, Wei-Ming
The simple assumption of an instantaneous reionization of the Universe may bias estimates of cosmological parameters. In this paper a model-independent principal component method for the reionization history is applied to give constraints on the cosmological parameters from recent Planck 2015 data. We find that the Universe is not completely reion…
New geometric representations of the CMB two-point correlation function
Starkman, Glenn D.; Froes, Andre L. D.; Pereira, Thiago S. +1 more
When searching for deviations of statistical isotropy in the cosmic microwave background, a popular strategy is to write the two-point correlation function (2pcf) as the most general function of four spherical angles (i.e., two unit vectors) in the celestial sphere. Then, using a basis of bipolar spherical harmonics, statistical anisotropy will sh…
Revisiting the cosmological bias due to local gravitational redshifts
Huang, Zhiqi
A recent article by Wojtak et al. pointed out that the local gravitational redshift, despite its smallness (∼10-5 ), can have a noticeable (∼1 %) systematic effect on our cosmological parameter measurements. The authors studied a few extended cosmological models (nonflat Λ CDM , w CDM , and w0-waCDM ) with a mock s…
Improved cosmological model fitting of Planck data with a dark energy spike
Park, Chan-Gyung
The Λ cold dark matter (Λ CDM ) model is currently known as the simplest cosmology model that best describes observations with a minimal number of parameters. Here we introduce a cosmology model that is preferred over the conventional Λ CDM one by constructing dark energy as the sum of the cosmological constant Λ and an additional fluid that is de…