27 research outputs found
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
Optimization of the half wave plate configuration for the LSPE-SWIPE experiment
The search for the B-mode polarization of Cosmic Microwave Background (CMB)
is the new frontier of observational Cosmology. A B-mode detection would give
an ultimate confirmation to the existence of a primordial Gravitational Wave
(GW) background as predicted in the inflationary scenario. Several experiments
have been designed or planned to observe B-modes. In this work we focus on the
forthcoming Large Scale Polarization Explorer (LSPE) experiment, that will be
devoted to the accurate measurement of CMB polarization at large angular
scales. LSPE consists of a balloon-borne bolometric instrument, the Short
Wavelength Instrument for the Polarization Explorer (SWIPE), and a ground-based
coherent polarimeter array, the STRatospheric Italian Polarimeter (STRIP).
SWIPE will employ a rotating Half Wave Plate (HWP) polarization modulator to
mitigate the systematic effects due to instrumental non-idealities. We present
here preliminary forecasts aimed at optimizing the HWP configuration.Comment: 6 pages, 4 figures, proceedings of the 7th Young Researcher Meeting,
Torino, Oct 24th-26th 201
Optimal strategy for polarization modulation in the LSPE-SWIPE experiment
CMB B-mode experiments are required to control systematic effects with an
unprecedented level of accuracy. Polarization modulation by a half wave plate
(HWP) is a powerful technique able to mitigate a large number of the
instrumental systematics. Our goal is to optimize the polarization modulation
strategy of the upcoming LSPE-SWIPE balloon-borne experiment, devoted to the
accurate measurement of CMB polarization at large angular scales. We depart
from the nominal LSPE-SWIPE modulation strategy (HWP stepped every 60 s with a
telescope scanning at around 12 deg/s) and perform a thorough investigation of
a wide range of possible HWP schemes (either in stepped or continuously
spinning mode and at different azimuth telescope scan-speeds) in the frequency,
map and angular power spectrum domain. In addition, we probe the effect of
high-pass and band-pass filters of the data stream and explore the HWP response
in the minimal case of one detector for one operation day (critical for the
single-detector calibration process). We finally test the modulation
performance against typical HWP-induced systematics. Our analysis shows that
some stepped HWP schemes, either slowly rotating or combined with slow
telescope modulations, represent poor choices. Moreover, our results point out
that the nominal configuration may not be the most convenient choice. While a
large class of spinning designs provides comparable results in terms of pixel
angle coverage, map-making residuals and BB power spectrum standard deviations
with respect to the nominal strategy, we find that some specific configurations
(e.g., a rapidly spinning HWP with a slow gondola modulation) allow a more
efficient polarization recovery in more general real-case situations. Although
our simulations are specific to the LSPE-SWIPE mission, the general outcomes of
our analysis can be easily generalized to other CMB polarization experiments.Comment: 11 pages, 9 figures, accepted for publication in A&
Exploring Cosmic Origins with CORE: Cosmological Parameters
We forecast the main cosmological parameter constraints achievable with theCORE space mission which is dedicated to mapping the polarisation of the CosmicMicrowave Background (CMB). CORE was recently submitted in response to ESA'sfifth call for medium-sized mission proposals (M5). Here we report the resultsfrom our pre-submission study of the impact of various instrumental options, inparticular the telescope size and sensitivity level, and review the great,transformative potential of the mission as proposed. Specifically, we assessthe impact on a broad range of fundamental parameters of our Universe as afunction of the expected CMB characteristics, with other papers in the seriesfocusing on controlling astrophysical and instrumental residual systematics. Inthis paper, we assume that only a few central CORE frequency channels areusable for our purpose, all others being devoted to the cleaning ofastrophysical contaminants. On the theoretical side, we assume LCDM as ourgeneral framework and quantify the improvement provided by CORE over thecurrent constraints from the Planck 2015 release. We also study the jointsensitivity of CORE and of future Baryon Acoustic Oscillation and Large ScaleStructure experiments like DESI and Euclid. Specific constraints on the physicsof inflation are presented in another paper of the series. In addition to thesix parameters of the base LCDM, which describe the matter content of aspatially flat universe with adiabatic and scalar primordial fluctuations frominflation, we derive the precision achievable on parameters like thosedescribing curvature, neutrino physics, extra light relics, primordial heliumabundance, dark matter annihilation, recombination physics, variation offundamental constants, dark energy, modified gravity, reionization and cosmicbirefringence. (ABRIDGED
Exploring cosmic origins with CORE : Effects of observer peculiar motion
We discuss the effects on the cosmic microwave background (CMB), cosmic infrared background (CIB), and thermal Sunyaev-Zeldovich effect due to the peculiar motion of an observer with respect to the CMB rest frame, which induces boosting effects. After a brief review of the current observational and theoretical status, we investigate the scientific perspectives opened by future CMB space missions, focussing on the Cosmic Origins Explorer (CORE) proposal. The improvements in sensitivity offered by a mission like CORE, together with its high resolution over a wide frequency range, will provide a more accurate estimate of the CMB dipole. The extension of boosting effects to polarization and cross-correlations will enable a more robust determination of purely velocity-driven effects that are not degenerate with the intrinsic CMB dipole, allowing us to achieve an overall signal-to-noise ratio of 13; this improves on the Planck detection and essentially equals that of an ideal cosmic variance-limited experiment up to a multipole l similar or equal to 2000. Precise inter-frequency calibration will offer the opportunity to constrain or even detect CMB spectral distortions, particularly from the cosmological reionization epoch, because of the frequency dependence of the dipole spectrum, without resorting to precise absolute calibration. The expected improvement with respect to COBE-FIRAS in the recovery of distortion parameters (which could in principle be a factor of several hundred for an ideal experiment with the CORE configuration) ranges from a factor of several up to about 50, depending on the quality of foreground removal and relative calibration. Even in the case of similar or equal to 1% accuracy in both foreground removal and relative calibration at an angular scale of 1 degrees, we find that dipole analyses for a mission like CORE will be able to improve the recovery of the CIB spectrum amplitude by a factor similar or equal to 17 in comparison with current results based on COBE-FIRAS. In addition to the scientific potential of a mission like CORE for these analyses, synergies with other planned and ongoing projects are also discussed.Peer reviewe
Point Source Detection and False Discovery Rate Control on CMB Maps
We discuss a new procedure to search for point sources in Cosmic Microwave
background maps; in particular, we aim at controlling the so-called False
Discovery Rate, which is defined as the expected value of false discoveries
among pixels which are labelled as contaminated by point sources. We exploit a
procedure called STEM, which is based on the following four steps: 1) needlet
filtering of the observed CMB maps, to improve the signal to noise ratio; 2)
selection of candidate peaks, i.e., the local maxima of filtered maps; 3)
computation of \emph{p-}values for local maxima; 4) implementation of the
multiple testing procedure, by means of the so-called Benjamini-Hochberg
method. Our procedures are also implemented on the latest release of Planck CMB
maps
Maternal Immune Activation Induced by Prenatal Lipopolysaccharide Exposure Leads to Long-Lasting Autistic-like Social, Cognitive and Immune Alterations in Male Wistar Rats
Several studies have supported the association between maternal immune activation (MIA) caused by exposure to pathogens or inflammation during critical periods of gestation and an increased susceptibility to the development of various psychiatric and neurological disorders, including autism and other neurodevelopmental disorders (NDDs), in the offspring. In the present work, we aimed to provide extensive characterization of the short- and long-term consequences of MIA in the offspring, both at the behavioral and immunological level. To this end, we exposed Wistar rat dams to Lipopolysaccharide and tested the infant, adolescent and adult offspring across several behavioral domains relevant to human psychopathological traits. Furthermore, we also measured plasmatic inflammatory markers both at adolescence and adulthood. Our results support the hypothesis of a deleterious impact of MIA on the neurobehavioral development of the offspring: we found deficits in the communicative, social and cognitive domains, together with stereotypic-like behaviors and an altered inflammatory profile at the systemic level. Although the precise mechanisms underlying the role of neuroinflammatory states in neurodevelopment need to be clarified, this study contributes to a better understanding of the impact of MIA on the risk of developing behavioral deficits and psychiatric illness in the offspring