928 research outputs found
Statistical challenges in the analysis of Cosmic Microwave Background radiation
An enormous amount of observations on Cosmic Microwave Background radiation
has been collected in the last decade, and much more data are expected in the
near future from planned or operating satellite missions. These datasets are a
goldmine of information for Cosmology and Theoretical Physics; their efficient
exploitation posits several intriguing challenges from the statistical point of
view. In this paper we review a number of open problems in CMB data analysis
and we present applications to observations from the WMAP mission.Comment: Published in at http://dx.doi.org/10.1214/08-AOAS190 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Constraints on CPT violation from WMAP three year polarization data: a wavelet analysis
We perform a wavelet analysis of the temperature and polarization maps of the
Cosmic Microwave Background (CMB) delivered by the WMAP experiment in search
for a parity violating signal. Such a signal could be seeded by new physics
beyond the standard model, for which the Lorentz and CPT symmetries may not
hold. Under these circumstances, the linear polarization direction of a CMB
photon may get rotated during its cosmological journey, a phenomenon also
called cosmological birefringence. Recently, Feng et al. have analyzed a subset
the WMAP and BOOMERanG 2003 angular power spectra of the CMB, deriving a
constraint that mildly favors a non zero rotation. By using wavelet transforms
we set a tighter limit on the CMB photon rotation angle \Delta\alpha= -2.5 \pm
3.0 (\Delta\alpha= -2.5 \pm 6.0) at the one (two) \sigma level, consistent with
a null detection.Comment: 7 pages, 4 figures, some modifications to match accepted (PRD)
version, results unchange
Constraining the general reheating phase in the -attractor inflationary cosmology
In this paper we constrain some aspects of the general postinflationary phase
in the context of superconformal -attractor models of inflation. In
particular, we provide constraints on the duration of the reheating process,
, and on the reheating temperature, , simulating possible and
future results given by the next-generation of cosmological missions. Moreover,
we stress what kinds of equation-of-state parameter, , are favored for
different scenarios. The analysis does not depend on the details of the
reheating phase and it is performed assuming different measurements of the
tensor-to-scalar ratio .Comment: 8 pages, 2 figure
Reconstruction of -attractor supergravity models of inflation
In this paper, we apply reconstruction techniques to recover the potential
parameters for a particular class of single-field models, the
-attractor (supergravity) models of inflation. This also allows to
derive the inflaton vacuum expectation value at horizon crossing. We show how
to use this value as one of the input variables to constrain the
postaccelerated inflationary phase. We assume that the tensor-to-scalar ratio
is of the order of , a level reachable by the expected
sensitivity of the next-generation CMB experiments.Comment: 10 pages, LaTeX, some typos correcte
Neutrinos and dark energy constraints from future galaxy surveys and CMB lensing information
We explore the possibility of obtaining better constraints from future
astronomical data by means of the Fisher information matrix formalism. In
particular, we consider how cosmic microwave background (CMB) lensing
information can improve our parameter error estimation. We consider a massive
neutrino scenario and a time-evolving dark energy equation of state in the
CDM framework. We use Planck satellite experimental specifications
together with the future galaxy survey Euclid in our forecast. We found
improvements in almost all studied parameters considering Planck alone when CMB
lensing information is used. In this case, the improvement with respect to the
constraints found without using CMB lensing is of 93% around the fiducial value
for the neutrino parameter. The improvement on one of the dark energy parameter
reaches 4.4%. When Euclid information is included in the analysis, the
improvements on the neutrino parameter constraint is of approximately 128%
around its fiducial value. The addition of Euclid information provides smaller
errors on the dark energy parameters as well. For Euclid alone, the FoM is a
factor of 29 higher than that from Planck alone even considering CMB
lensing. Finally, the consideration of a nearly perfect CMB experiment showed
that CMB lensing cannot be neglected specially in more precise future CMB
experiments since it provided in our case a 6 times better FoM in respect to
the unlensed CMB analysis .Comment: Accepted for publication in PR
Constraining auto-interaction terms in α-attractor supergravity models of inflation
The inflationary mechanism has become the paradigm of modern cosmology over the last thirty years. However, there are several aspects of inflationary physics that are still to be addressed, like the shape of the inflationary potential. Regarding this, the so-called α-attractor models show interesting properties. In this work, the reconstruction of the effective potential around the global minimum of these particular potentials is provided, assuming a detection of permille-order for the tensor-to-scalar-ratio by forthcoming cosmic microwave background or gravitational waves experiments
Scaling Function, Universality and Analytical Solutions of Generalized One-Species Population Dynamics Models
We consider several one-species population dynamics model with finite and
infinite carrying capacity, time dependent growth and effort rates and solve
them analytically. We show that defining suitable scaling functions for a given
time, one is able to demonstrate that their ratio with respect to its initial
value is universal. This ratio is independent from the initial condition and
from the model parameters. Although the effort rate does not break the model
universality it produces a transition between the species extinction and
survival. A general formula is furnished to obtain the scaling functions.Comment: 8 pages and 4 figure
Polarization of Cosmic Microwave Background
In this work we present an extension of the ROMA map-making code for data
analysis of Cosmic Microwave Background polarization, with particular attention
given to the inflationary polarization B-modes. The new algorithm takes into
account a possible cross-correlated noise component among the different
detectors of a CMB experiment. We tested the code on the observational data of
the BOOMERanG (2003) experiment and we show that we are provided with a better
estimate of the power spectra, in particular the error bars of the BB spectrum
are smaller up to 20% for low multipoles. We point out the general validity of
the new method. A possible future application is the LSPE balloon experiment,
devoted to the observation of polarization at large angular scales.Comment: 6 pages, 4 figures, proceedings of the 6th Young Researchers Meeting,
L'Aquila, Oct 12th-14th 201
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