63 research outputs found
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
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
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
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
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
Real-time Cosmology
In recent years the possibility of measuring the temporal change of radial
and transverse position of sources in the sky in real time have become
conceivable thanks to the thoroughly improved technique applied to new
astrometric and spectroscopic experiments, leading to the research domain we
call Real-time cosmology. We review for the first time great part of the work
done in this field, analysing both the theoretical framework and some endeavor
to foresee the observational strategies and their capability to constrain
models. We firstly focus on real time measurements of the overall redshift
drift and angular separation shift in distant source, able to trace background
cosmic expansion and large scale anisotropy, respectively. We then examine the
possibility of employing the same kind of observations to probe peculiar and
proper acceleration in clustered systems and therefore the gravitational
potential. The last two sections are devoted to the short time future change of
the cosmic microwave background, as well as to the temporal shift of the
temperature anisotropy power spectrum and maps. We conclude revisiting in this
context the effort made to forecast the power of upcoming experiments like
CODEX, GAIA and PLANCK in providing these new observational tools.Comment: 44 pages, 23 figures. References added; revised text, tables and
plots. Accepted for publication in Physics Report
Harmonic Inpainting of the Cosmic Microwave Background Sky: Formulation and Error Estimate
We develop a new interpolation scheme, based on harmonic inpainting, for
reconstructing the cosmic microwave background temperature data within the
Galaxy mask from the data outside the mask. We find that, for scale-invariant
isotropic random Gaussian fluctuations, the developed algorithm reduces the
errors in the reconstructed map for the odd-parity modes significantly for
azimuthally symmetric masks with constant galactic latitudes. For a more
realistic Galaxy mask, we find a modest improvement in the even-parity modes as
well.Comment: 8 pages, 6 figures, Minor change, Discusssion about the Gaussian
noise in the WMAP data is added in footnote
Asymmetries in the local curvature of the WMAP data
We use the local curvature to investigate the possible existence of
non-Gaussianity/asymmetry in the WMAP data. Considering the full sky we find
results which are consistent with the Gaussian assumption. However, strong
non-Gaussian features emerge when considering the northern and southern
galactic hemisphere separately, particularly on scales between 1 and 5 degrees.
Quite interestingly, the maximum non-Gaussianity is found for hemispheres
centered near the ecliptic poles, which might suggest the presence of some
systematic effect. The direction of the asymmetry seems consistent with the
findings by Eriksen et al. 2004.Comment: Submitted to ApJ Letter
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