arXiv subjects

C. Burigana

Publications and source records attributed to C. Burigana.

At least 217 records · Page 12Linked to original sources

arXiv2009

Destriping CMB temperature and polarization maps

We study destriping as a map-making method for temperature-and-polarization data for cosmic microwave background observations. We present a particular implementation of destriping and study the residual error in output maps, using simulated data corresponding to the 70 GHz channel of the Planck satellite, but assuming idealized detector and beam properties. The relevant residual map is the difference between the output map and a binned map obtained from the signal + white noise part of the data stream. For destriping it can be divided into six components: unmodeled correlated noise, white noise reference baselines, reference baselines of the pixelization noise from the signal, and baseline errors from correlated noise, white noise, and signal. These six components contribute differently to the different angular scales in the maps. We derive analytical results for the first three components. This study is related to Planck LFI activities.

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arXiv2009

WMAP anomalous signal in the ecliptic plane

We report the detection of a high Galactic latitude, large scale, 7-sigma signal in WMAP 5yr and spatially correlated with the ecliptic plane. Two possible candidates are studied, namely unresolved sources and Zodiacal light emission. We determine the strength of the Zodiacal light emission at WMAP frequencies and estimate the contribution from unresolved extragalactic sources. Neither the standard Zodiacal light emission nor the unresolved sources alone seem to be able to explain the observed signal. Other possible interpretations like Galactic foregrounds and diffuse Sunyaev-Zel'dovich effect also seem unlikely. We check if our findings could affect the low-l anomalies which have been reported in the WMAP data. Neither Zodiacal light emission nor unresolved point source residuals seem to affect significantly the quadrupole and octupole measurements. However, a signal with a quasi-blackbody spectrum and with a spatial distribution similar to the Zodiacal light emission, could explain both the anomalous signal and the low-ell anomalies. Future data (Planck) will be needed in order to explain the origin of this signal.

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arXiv2008

Cosmic Radiative Feedback from Reionization

We explore the effect of cosmic radiative feedback from the sources of reionization on the thermal evolution of the intergalactic medium. We find that different prescriptions for this feedback predict quite different thermal and reionization histories. In spite of this, current data can not discriminate among different reionization scenarios. We find that future observations both from 21-cm and CMB experiments can be used to break the degeneracy among model parameters provided that we will be able to remove the foreground signal at the percent (or better) level.

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arXiv2008

The impact of Galactic synchrotron emission on CMB anisotropy measurements. I. Angular power spectrum analysis of total intensity all-sky surveys

Galactic foreground emission is a limiting factor for precise cosmic microwave background (CMB) anisotropy measurements. We perform an angular power spectrum analysis (APS) of all-sky total intensity maps at 408 MHz and 1420 MHz, which are dominated by synchrotron emission out of the Galactic plane. We subtract the brighter sources from the maps. We study the APS as a function of Galactic latitude by considering various cuts and as a function of sky position by dividing the sky into patches of about 15 deg x 15 deg in size. The APS of the Galactic radio diffuse synchrotron emission is best fitted by a power law, $C_{\ell} \sim k \ell^α$, with $α\in [-3.0,-2.6]$, where the lower values of $α$ typically correspond to the higher latitudes. Nevertheless, the analysis of the patches reveals that strong local variations exist. The mean APS for $\ell \in [20,40]$ is used to determine the mean spectral index between 408 MHz and 1420 MHz, which is then adopted to extrapolate the synchrotron APS results to the microwave range. A simple extrapolation to 23 GHz of the synchrotron emission APS found at 408 and 1420 MHz does not explain all the power in the WMAP synchrotron component even at middle/high Galactic latitudes. This suggests a significant microwave contribution (of about 50% of the signal) by other components such as free-free or spinning dust emission. The comparison between the extrapolated synchrotron APS and the CMB APS shows that a mask excluding the regions with $|b_{gal}| \lesssim 5^{\circ}$ would reduce the foreground fluctuations to about half of the cosmological ones at 70 GHz even at the lowest multipoles. We discuss the main implications of our analysis for the cosmological exploitation of microwave temperature anisotropy maps.

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arXiv2007

CMB polarization constraints on radiative feedback

We compute the imprints left on the CMB by two cosmic reionization models consistent with current observations but characterized by alternative radiative feedback prescriptions (suppression and filtering) resulting in a different suppression of star formation in low-mass halos. The models imply different ionization and thermal histories and 21 cm background signals. The derived Comptonization, u, and free-free distortion, y_B, parameters are below current observational limits for both models. However, the value of u = 1.69 * 10^-7 (9.65 * 10^-8) for the suppression (filtering) model is in the detectability range of the next generation of CMB spectrum experiments. Through the dedicated Boltzmann code CMBFAST, modified to include the above ionization histories, we compute the CMB angular power spectrum (APS) of the TT, TE, and EE modes. For the EE mode the differences between these models are significantly larger than the cosmic and sampling variance over the multipole range l = 5-15, leaving a good chance of discriminating between these feedback mechanisms with forthcoming/future CMB polarization experiments. The main limitations come from foreground contamination: it should be subtracted at per cent level in terms of APS, a result potentially achievable by novel component separation techniques and mapping of Galactic foreground.

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arXiv2007

Detectable Signatures of Cosmic Radiative Feedback

We use a semi-analytical model to study the impact of reionization, and the associated radiative feedback, on galaxy formation. Two feedback models have been considered: (i) a standard prescription, according to which star formation is totally suppressed in galaxies with circular velocity below a critical threshold (model CF06) and (ii) a characterization based on the filtering scale (model G00), allowing for a gradual reduction of the gas available for star formation in low-mass galaxies. In model CF06 reionization starts at z ~ 15-20, is 85% complete by z ~ 10; at the same z, the ionized fraction is 16% in model G00. The models match SDSS constraints on the evolution of the neutral hydrogen fraction at z < 7, but predict different Thomson optical depths, tau_e = 0.1017 (CF06), and 0.0631 (G00); such values are within 1 sigma of the WMAP 3-yr determination. Both models are in remarkable good agreement with additional existing data (evolution of Lyman-limit systems, cosmic star formation history, high-z galaxy counts, IGM thermal history), which therefore cannot be used to discriminate among different feedback models. Deviations among radiative feedback prescriptions emerge when considering the expected HI 21 cm background signal, where a ~ 15 mK absorption feature in the range 75-100 MHz is present in model G00 and a global shift of the emission feature preceding reionization towards larger frequencies occurs in the same model. Single dish observations with existing or forthcoming low-frequency radio telescopes can achieve mK sensitivity, allowing the identification of these features provided that foregrounds can be accurately subtracted.

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arXiv2007

The impact of dipole straylight contamination on the alignment of low multipoles of CMB anisotropies

We estimate the impact of the Dipole Straylight Contamination (DSC) for the {\it Planck} satellite on the alignments of vectors associated to the low multipoles of the pattern of the cosmic microwave background (CMB) anisotropies. In particular we study how the probability distributions of eighteen estimators for the alignments change when DSC is taken into account. We find that possible residual DSC should leave a non-negligible impact on low multipole alignments for effective values of the fractional far sidelobe integrated response, $p$, larger than $\sim {\rm few} \times 10^{-3}$. The effect is strongly dependent on the intrinsic sky amplitude and weakly dependent on the considered scanning strategy. We find a decrease of the alignment probability between the quadrupole and the dipole and an increase of the alignment probability between the hexadecapole and the dipole (larger is the intrinsic sky amplitude and lower is the contamination). The remaining estimators do not exhibit clear signatures, except, in some cases, considering the largest values of $p$ and the lowest sky amplitudes. Provided that the real sidelobes of the {\it Planck} receivers in flight conditions will correspond to $p \lsim {\rm few} \times 10^{-3}$, as realistically expected at least in the cosmological frequency channels, and will be known with accuracies better than $\sim {\rm few} \times 10$% allowing for a suitable cleaning during data reduction, {\it Planck} will be very weakly affected from DSC on the alignments of low multipoles.

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arXiv2006

An angular power spectrum analysis of the DRAO 1.4 GHz polarization survey: implications for CMB observations

The aim of the present analysis is to improve the knowledge of the statistical properties of the Galactic diffuse synchrotron emission, which constrains sensitive CMB anisotropy measurements. We have analysed the new DRAO 1.4 GHz polarization survey together with the Stockert 1.4 GHz total intensity survey and derived the angular power spectra (APSs) of the total intensity, the polarized emission, and their cross-correlation for the entire surveys and for three low-intensity regions. The APSs of the diffuse synchrotron emission are modelled by power laws. For the $E$ and $B$ modes, a slope of $α\sim [-3.0,-2.5]$ for the multipole range $\sim [30,300]$ is found. By the extrapolation of these results to 70 GHz, we can estimate the Galactic synchrotron contamination of CMB anisotropies, and we find results that are compatible with the ones coming from WMAP 3-yr data. In the low-intensity regions, the cosmological primordial B~mode peak at $\ell \sim 100$ should be clearly observable for a tensor-to-scalar ratio $T/S \gsim 0.5$ and a synchrotron temperature spectral index $β\sim -3$. Its detection is also possible for $T/S \gsim 0.005$ and $β\sim -3$, in case a separation of the foreground from the CMB signal could be achieved with an accuracy of $\sim 5-10%$. For the TE mode, a mask excluding $|b_{gal}| \le 5^{\circ}$ (for $β\sim -3.0$) or $|b_{gal}| \le 20^{\circ}$ (for $β\sim -2.8$) from the surveys is sufficient to render the foreground contamination negligible, thus confirming the ability of WMAP to have a clear view of the temperature-polarization correlation peak and antipeak series.

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arXiv2006

A statistical analysis of a Galactic all sky survey at 1.4 GHz

Radio surveys at frequencies of about 1 GHz allow to map the synchrotron emission in a frequency range where (except for very low Galactic latitudes or towards localized regions) it dominates over the other radio components. New all sky total intensity and polarization data at 1.4 GHz have been recently collected. We focus on the Galactic radio emission correlation properties described in terms of angular power spectrum (APS). We present for the first time the APS, in both total intensity and polarization modes, for some representative Galactic cuts and suitable APS power law parametrizations.

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arXiv2006

Mapping the ionizing sources with CMB polarization measurements

We show that the delay of structure formation from WMAP3 can not fully account for the reduction of electron optical depth from WMAP1 to WMAP3 when the radiative transfer effects and feedback mechanisms are took into account in computing the reionization history of the Universe. As the ultimate limit in constraining the reionizatin history of the Universe with Planck will be placed by the our understanding of systematic effects and foregrounds removal, we discuss also these aspects.

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arXiv2006

Zodiacal Light Emission in the PLANCK mission

The PLANCK satellite, scheduled for launch in 2007, will produce a set of all sky maps in nine frequency bands spanning from 30 GHz to 857 GHz, with an unprecedented sensitivity and resolution. Planets, minor bodies and diffuse interplanetary dust will contribute to the (sub)mm sky emission observed by PLANCK, representing a source of foreground contamination to be removed before extracting the cosmological information. The aim of this paper is to assess the expected level of contamination in the survey of the forthcoming PLANCK mission. Starting from existing far-infrared (far-IR) models of the Zodiacal Light Emission (ZLE), we present a new method to simulate the time-dependent level of contamination from ZLE at PLANCK frequencies. We studied the possibility of PLANCK to detect and separate the ZLE contribution from the other astrophysical signals. We discuss the conditions in which PLANCK will be able to increase the existing information on the ZLE and IDP physical properties.

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arXiv2005

Radiative effects by high-z UV radiation background: Implications for the future CMB polarization measurements

We investigate the role of the radiative effects for the temporal evolution of the reionization fraction by using cosmological Smooth Particle Hydrodynamics (SPH) simulations. We find that the increase of photo-ionization and photo-heating rates due to optical depth effects results in a significantly contribute to the heating of the IGM before and during the reionization. The main effect of the UV radiation spectrum on the temporal evolution of the ionization fraction is given by the value of the reionization redshift and the redshift interval, in which the reionization is completed. We evaluate the effects of the UV radiation background on the CMB angular power spectrum taking into account different temporal evolutions of the ionization fraction. We show that through E-mode CMB polarization power spectrum measurements, the Planck experiment will have the sensitivity to distinguish between different reionization histories even when they imply the same optical depth to electron scattering and degenerated temperature anisotropy power spectra.

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arXiv2004

The Planck Low Frequency Instrument

Planck is the third generation of mm-wave instruments designed for space observations of the cosmic microwave background (CMB) anisotropies within the new Cosmic Vision 2020 ESA Science Program. Planck will map the whole sky with unprecedented sensitivity, angular resolution, and frequency coverage, and it likely leads us to the final comprehension of the CMB anisotropies. The Low Frequency Instrument (LFI), operating in the 30-70 GHz range, is one of the two instruments onboard Planck satellite, sharing the focal region of a 1.5 meter off-axis dual reflector telescope together with the High Frequency Instrument (HFI) operating at 100-857 GHz. We present LFI and discuss the major instrumental systematic effects that could degrade the measurements and the solutions adopted in the design and data analysis phase in order to adequately reduce and control them.

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arXiv2004

Cosmological reionization after WMAP: perspectives from PLANCK and future CMB missions

The WMAP first year detection of a high redshift reionization through its imprints on CMB anisotropy T and TE mode angular power spectra calls for a better comprehension of the universe ionization and thermal history after the standard recombination. Different reionization mechanisms predict different signatures in the CMB, both in temperature and polarization anisotropies and in spectral distortions. The Planck capability to distinguish among different scenarios through its sensitivity to T, TE, and E mode angular power spectra is discussed. Perspectives open by future high sensitivity experiments on the CMB polarization anisotropy and spectrum are also presented.

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arXiv2004

Surveys of extragalactic sources with Planck

Although the primary goal of ESA's Planck mission is to produce high resolution maps of the temperature and polarization anisotropies of the Cosmic Microwave Background (CMB), its high-sensitivity all-sky surveys of extragalactic sources at 9 frequencies in the range 30--860 GHz will constitute a major aspect of its science products. In particular, Planck surveys will provide key information on several highly interesting radio source populations, such as Flat Spectrum Radio Quasars, BL Lac objects, and, especially, extreme GHz Peaked Spectrum sources, thought to correspond to the very earliest phases of the evolution of radio sources. Above 100 GHz, Planck will provide the first all-sky surveys, that are expected to supply rich samples of highly gravitationally amplified dusty proto-galaxies and large samples of candidate proto-clusters at z~2-3, thus shedding light on the evolution of large scale structure across the cosmic epoch when dark energy should start dominating the cosmic dynamics.

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arXiv2004

A maximum likelihood approach to the destriping technique

The destriping technique is a viable tool for removing different kinds of systematic effects in CMB related experiments. It has already been proven to work for gain instabilities that produce the so-called 1/f noise and periodic fluctuations due to e.g. thermal instability. Both effects when coupled with the observing strategy result in stripes on the observed sky region. Here we present a maximum-likelihood approach to this type of technique and provide also a useful generalization. As a working case we consider a data set similar to what the Planck satellite will produce in its Low Frequency Instrument (LFI). We compare our method to those presented in the literature and find some improvement in performance. Our approach is also more general and allows for different base functions to be used when fitting the systematic effect under consideration. We study the effect of increasing the number of these base functions on the quality of signal cleaning and reconstruction. This study is related to Planck LFI activities.

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arXiv2004

Diffuse radio emission from the Intracluster medium

An important aspect of the radio emission from galaxy clusters is represented by the diffuse radio sources associated with the intracluster medium: radio halos, relics and mini-halos. The radio halos and relics are indicators of cluster mergers, whereas mini-halos are detected at the center of cooling core clusters. SKA will dramatically improve the knowledge of these sources, thanks to the detection of new objects, and to detailed studies of their spectra and polarized emission. SKA will also provide the opportunity to investigate the presence of halos produced by radiation scattered by a powerful radio galaxy at the cluster centers.

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arXiv2004

Extracting cosmic microwave background polarisation from satellite astrophysical maps

We present the application of the Fast Independent Component Analysis ({\ica}) technique for blind component separation to polarized astrophysical emission. We study how the Cosmic Microwave Background (CMB) polarized signal, consisting of $E$ and $B$ modes, can be extracted from maps affected by substantial contamination from diffuse Galactic foreground emission and instrumental noise. {We implement Monte Carlo chains varying the CMB and noise realizations in order to asses the average capabilities of the algorithm and their variance.} We perform the analysis of all sky maps simulated according to the {\sc Planck} satellite capabilities, modelling the sky signal as a superposition of the CMB and of the existing simulated polarization templates of Galactic synchrotron. Our results indicate that the angular power spectrum of CMB $E$-mode can be recovered on all scales up to $\ell\simeq 1000$, corresponding to the fourth acoustic oscillation, while the $B$-mode power spectrum can be detected, up to its turnover at $\ell\simeq 100$, if the ratio of tensor to scalar contributions to the temperature quadrupole exceeds 30%. The power spectrum of the cross correlation between total intensity and polarization, $TE$, can be recovered up to $\ell\simeq 1200$, corresponding to the seventh $TE$ acoustic oscillation.

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