We use the constraints set by the solar dipole seen with high signal to noise by all bolometers (100 to 353 GHz) to set with high accuracy the zero level of the HFI dust maps. This improves significantly the dust removal residuals.
The Planck satellite has measured CMB anisotropies on the full sky with unprecedented accuracy allowing pour cent precision on the measurement of cosmological parameters. This accuracy required
important mitigation of systematic effects which for some of the dominant effects were not anticipated before launch. In this presentation I will focus on Planck High Frequency Instrument (HFI)...
In this presentation I review the lessons learned from measuring and analyzing the microwave polarized sky with Planck, to extract the information encoded in the cosmic microwave background (CMB). I focus, in particular, on the challenge to control instrumental effects and calibration at the sensitivity level. This is crucial especially on large angular scales, where the noise is smaIl and the...
I will summarize some of the main lessons learned from Planck regarding efficient identification and mitigation of systematic effects, which will be essential for future CMB B-mode experiments. I will in particular highlight the tight relationship between instrumental systematics and astrophysical modelling, and the importance of addressing both of these aspects jointly. The presentation will...
The BeyondPlanck collaboration recently published the results from mapping out the global Bayesian posterior of instrumental and observational parameters jointly for LFI time-ordered data. These results are the first of their kind, providing an unique new perspective on the calibration process, and in this talk I will share some of the things we learned, and how that can be applied to future...
A methodology to provide the polarization angle requirements for the different frequency channels of a given CMB B-mode experiment is presented. The component separation procedure used to separate the CMB from the foreground signals is considered in order to establish those requirements. In addition, it is also considered possible instrumental correlations among the different measured...
I will discuss foreground and instrument systematic modeling for upcoming ground-based B-mode searches with the Simons Observatory (SO). I will begin by summarizing the power-spectrum domain foreground and systematic cleaning pipeline for SO. Using this framework we have quantified calibration requirements on bandpass and polarization angle systematics for the SO target of $\sigma_r\approx...
Balloon-borne instruments have long played an important role in CMB observation. Their unique vantage point provides a nearly unobstructed view of the sky at millimeter wavelengths, largely free of the atmospheric fluctuations and absorption that constrain terrestrial observations. By deploying modern instruments to a space-like environment, they also provide a critical technological proving...
Small-aperture ground-based telescopes are a well-demonstrated method for achieving high sensitivity to degree-scale CMB polarization. Current and future experiments including BICEP Array, Simons Observatory, and CMB-S4 will all use similar designs in their effort to detect primordial
gravitational waves. I will review the experience gained from the long-running BICEP/Keck program at the South...
I will present a review of LiteBIRD systematics. LiteBIRD aims for measuring the tensor-to-scalar ratio, r, with an accuracy less than 0.001. Given the current sensitivity of the observation devices, the systematic effects yield the dominant contribution in the error of r. I will present an overview of the possible systematic sources, and the procedure to evaluate the effects and to give...
Future experiments, like the LiteBIRD space-borne mission, aim at measuring the CMB B-mode signal with high accuracy in order to measure the tensor-to-scalar ratio r at the 10^{−3} level. I will present a study of the photometric calibration and bandpass resolution requirements to minimize the leakage of polarized Galactic foreground signals into CMB polarization maps for a multi-frequency CMB...
The Simons Observatory (SO) is a next generation Cosmic Microwave Background (CMB) experiment aimed to measure evidence of primordial gravitational waves and put constraints on the sum of the neutrino masses. SO is developing a high angular resolution 6 m class Large Aperture Telescope (LAT) for small angular scale measurements, and three wide field-of-view 0.42 m class Small Aperture...
The Simons Observatory (SO), currently under construction, will deploy one large-aperture (6 m) and four small-aperture (42 cm) telescopes to the Chajnantor Plateau of the Atacama Desert in Chile in the coming years. The small-aperture telescopes feature continuously-rotating half-wave plates (CRHWP) at cryogenic stages in order to modulate incoming polarization from the sky. In this talk, I...
In the last years, the Unmanned Aerial Vehicles (UAVs) produced significant innovations in in-situ antenna measurements. UAV-mounted radio-frequency generators have been initially exploited at low frequencies to characterize the radiation pattern of receiving antennas and arrays (e.g. HF radars, VHF radio telescopes), and up to the X-band for radar characterization. Within the Italian...
A calibration for polarization responses (i.e. angle and gain) is an important subject for sucess of CMB polarization experiments. We (I and my colleagues) have developed calibration systems using sparse wire grid. Wires in ambient make a blackbody signal which is linearly polarized. Focal plane detectors measure the polarization signal when we set the wires in front of receiver or telescope...
The measurement of the primordial B-mode polarization in the cosmic microwave background (CMB) is a major challenge of future CMB experiments. However, as B-mode polarization is dominated by foregrounds at all scales and frequencies, the detectability of this cosmological signal solely depends on our ability to remove foregrounds. We present the of B-mode polarization forecast in the...
A prototype version of the Q & U Bolometric Interferometer for Cosmology (QUBIC) underwent a campaign of testing in the laboratory at Astroparticle Physics and Cosmology in Paris. Characterization of QUBIC includes the measurement of the synthesized beam, the measurement of interference fringes, and the measurement of polarization performance. A modulated and frequency tunable...
We present the optical calibration strategy of the Medium-High Frequency Telescope on-board the LiteBIRD satellite, the JAXA’s space mission targeting the detection of the imprint of primordial gravitational waves on the Cosmic Microwave Background.
For its purpose, LiteBIRD is endowed with unprecedent sensitivity, guaranteed by two independent instruments, the Low Frequency Telescope (LFT)...
We present the analysis of the optical system of the STRIP instrument, the ground-based telescope of the Large Scale Polarization (LSPE) experiment, which aims at polarization measurements of the Cosmic Microwave Background on large angular scales.
STRIP will observe the polarized emission from the ``Observatorio del Teide” in Tenerife, starting in late 2021. The instrument consists of an...
The weak gravitational lensing of the CMB is an important cosmological tool that allows us to learn more about the structure, composition and evolution of the Universe. Upcoming CMB experiments, such as the Simons Observatory, will provide the most high-resolution and low-noise CMB measurements to date, from which we could reconstruct the lensing potential to unparalleled precision. To achieve...
Astrophysical observations at (sub-)mm wavelengths (λ from ~300 μm to ~3mm) allow us to study the cold and dense material in the Universe, hence probing the formation of stars and planets, and the interstellar and circumgalactic medium of galaxies across all cosmic times. The current generation of 10-meter-class single dish telescopes has delivered some of the first surveys at (sub-)mm...
Experiments to measure the polarization of the CMB require an exquisite characterization and control of optical systematics to achieve their scientific goals. Relevant parameters are the polarized co- and cross-polar beam shape, absolute and relative polarization angle among detector pairs, polarization frequency dependence across the bandpass, and polarization properties of far sidelobes. In...
The BICEP/Keck telescopes are a suite of CMB polarimeters located at the South Pole searching for evidence of inflationary gravitational waves. We invest much of our effort in acquiring high-fidelity calibrations of the optical performance to mitigate systematics in our results. To that end, we map far-field optical response using ground-based, non-thermal, finely-polarized Broad Spectrum...
Calibrating raw detector time-ordered data (TOD) to a standard unit is often the first step in processing data sets acquired by large arrays of detectors over many months of observations. The calibration method must be accurate, to suppress systematic errors in the final results, and robust, to be applicable to a vast majority of observations.
The raw calibration method developed for the CLASS...
The LiteBIRD Low Frequency Telescope (LFT) is a crossed-Dragone telescope that observes 34-161 GHz with a field of view of 18 x 9 degrees. We developed a 1/4-scaled model of the LFT and measured its far-sidelobes and polarization angles at multiple positions on the focal plane at accordingly scaled wavelength. The near-field measurements were consistent with physical optics simulation down to...
LiteBIRD is an upcoming JAXA-led cosmology space mission which has the scientific goal of measuring polarised CMB B-modes. LiteBIRD will fly at an L2 orbit, and thus will be subject to cosmic rays owing to the radiative environment. We present an end-to-end simulator for evaluating the effect of cosmic rays on the science outcomes of the LiteBIRD space mission, taking into account the...
LiteBIRD low-frequency telescope (LFT) employs a polarization modulation unit (PMU) based on a continuously rotating half-wave plate (HWP) at the telescope aperture. The PMU significantly suppresses 1/f noise and mitigates differential systematics. Therefore, the control and calibration of PMU intrinsic systematics are critical to achieving the scientific goal of LiteBIRD. The LFT PMU consists...
Located in the Atacama Desert of Chile, the Simons Observatory consists of one Large Aperture Telescope (LAT) and 3 Small Aperture Telescopes (SATs). The latter of these are optimized to observe the polarization in the CMB at large angular scales ( 30 < ℓ < 300), and as such we require a high degree of stability in our observations. To accomplish this we employ rapidly rotating sapphire...
The next generation of CMB polarisation experiments needs to have sufficient sensitivity and frequency coverage to detect and characterise the primordial B-modes signal, and to distinguish it from foregrounds contamination. This requires the deployment of detectors arrays of many thousands of multichroic detectors, along with new technologies for polarisation modulation, antennas, readout,...
In this talk I will discuss the optical modeling efforts used to inform the design of the Simons Observatory Large Aperture Telescope. I will present some general aspects of this new and exciting telescope design and review expected performance. I will discuss various techniques that we have used in the analysis of this telescope and compare those to similar work for past and current...
ArtDeco is beam-deconvolution code, designed for absolute CMB measurements.
Is has been successfully applied to beam analysis for the LFI instrument of the Planck mission up to multipole lmax=1500.
Given time-ordered data and known beam shapes as input, the code removes the effects of asymmetric beam shape, yielding as output a map with symmetrized effective beam.
In particular, the method...
Future CMB experiments will require an unprecedented control of systematics in order to constrain the B-mode polarisation power spectrum. There are a plethora of different systematics which effect the measurements of the CMB, but in this talk we shall concentrate on the effects of beam systematics resulting from optical imperfections that can lead to contamination of the observed signals. One...
One of the most powerful probes to understand the Universe’s evolution is the Cosmic Microwave Background (CMB). Lately the search for the CMB polarization B-modes has become one of the main objectives of observational cosmology, leading to active instrumental developments and to a large number of CMB experiments. Nowadays, it is widely recognised that any unambiguous detection of the B-modes...
The new generation of CMB $B$-mode experiments will reach limits of sensitivity never achieved before in order to detect the elusive primordial $B$-mode signal. However, all these efforts will be futile if we lack a tight control of the systematics. Here, we focus on the systematic that arises from the uncertainty of the polarization angles calibration. Miscalibrated polarization angles induce...
The POLARBEAR experiment has achieved B-mode measurements from degree angular scales to sub-degree angular scales for searching for primordial gravitational waves and measuring gravitational lensing effects of the large-scale structure. To achieve that, we implemented a blind analysis framework so-called "null test" in our analysis. In this talk, I explain our null test framework, which could...
The primary science goal of the vast majority of upcoming CMB experiments is the detection of B-modes sourced by primordial gravitational waves. While enhanced experimental sensitivity is essential to meet this target, diagnosing and removing sources of contamination that could potentially obscure the primordial B-mode signal will be equally important to claim a robust detection. This...
The characterization and modelling of polarized foregrounds has become a critical issue in the quest for primordial $B$-modes. A typical method to proceed is to factorize and parametrize the spectral properties of foregrounds and their scale dependence (i.e. assuming that foreground spectra are well described everywhere by their sky-averaged spectrum). Since in reality foreground properties...
The BICEP/Keck (BK) experiment is a series of small-aperture refracting telescopes observing degree-scale Cosmic Microwave Background (CMB) polarization from the South Pole in search of a primordial B-mode signature. This B-mode signal arises from inflationary gravitational waves interacting with the CMB, and has amplitude parametrized by the tensor-to-scalar ratio r. As a pair differencing...
In this talk, I will first present the systematics considered and their impact on the constraint on the tensor-to-scalar ratio r in delensing the BICEP/Keck data. Then, I will discuss systematics considerations for future delensing analyses.
CMB space missions are uniquely capable of probing the very largest angular scales for the primordial B-mode reionization bump which is the signal least susceptible to contamination from lensing.
A critical piece of this framework will necessarily be the ability of generating synthetic mission datasets of sufficient realism, both in their complexity and their size, to be truly...
Atmospheric fluctuation is one of the sources of low-frequency
noise in ground-based CMB experiments. Since atmospheric emissions are
almost unpolarized, they do not directly increase the noise of
polarization measurements as far as instruments are well-calibrated.
Tropospheric ice clouds, however, scatter upwelling thermal radiations
and produce polarized signals. In practice, most of the...
Distortions in the primordial cosmic microwave background polarization can correspond to real or conjectured cosmological signals such as gravitational lensing, patchy reionization, and cosmic birefringence, but they can also arise from instrumental systematics such as detector gain fluctuation, differential gain, differential pointing, polarization angle rotation. The distortion fields...
In a ground-based CMB experiment, the detection is contaminated by the atmosphere and ground emissions, and there are also temperature-to-polarization leakages. Thus, the time-ordered data (TOD) need to be filtered to reduce those contaminations. However, the filtering will inevitably remove some CMB signals and distort the rest. Especially, it causes additional E-to-B leakage and B-mode...
A crucial problem for part-sky analysis of CMB polarization is the E-B leakage problem. Such leakage arises from the presence of `ambiguous' modes that satisfy properties of both E and B modes. Solving this problem is critical for primordial polarization B mode detection in part-sky CMB polarization experiments. In this work we introduce a new method for reducing the leakage. We demonstrate...
