25 research outputs found
From BeyondPlanck to Cosmoglobe: Preliminary -band analysis
We present the first application of the Cosmoglobe analysis framework by
analyzing 9-year time-ordered observations using similar
machinery as BeyondPlanck utilizes for LFI. We analyze only
the -band (41 GHz) data and report on the low-level analysis process
from uncalibrated time-ordered data to calibrated maps. Most of the existing
BeyondPlanck pipeline may be reused for analysis with minimal
changes to the existing codebase. The main modification is the implementation
of the same preconditioned biconjugate gradient mapmaker used by the
team. Producing a single 1-band
sample requires 22 CPU-hrs, which is slightly more than the cost of a
44 GHz sample of 17 CPU-hrs; this demonstrates that full
end-to-end Bayesian processing of the data is computationally
feasible. In general, our recovered maps are very similar to the maps released
by the team, although with two notable differences. In
temperature we find a quadrupole difference that most
likely is caused by different gain modeling, while in polarization we find a
distinct signal that has been previously called
poorly-measured modes by the team. In the Cosmoglobe
processing, this pattern arises from temperature-to-polarization leakage from
the coupling between the CMB Solar dipole, transmission imbalance, and
sidelobes. No traces of this pattern are found in either the frequency map or
TOD residual map, suggesting that the current processing has succeeded in
modelling these poorly measured modes within the assumed parametric model by
using information to break the sky-synchronous degeneracies
inherent in the scanning strategy.Comment: 11 figures, submitted to A&A. Includes updated instrument model and
changes addressing referee comment
BeyondPlanck IV. On end-to-end simulations in CMB analysis -- Bayesian versus frequentist statistics
End-to-end simulations play a key role in the analysis of any
high-sensitivity CMB experiment, providing high-fidelity systematic error
propagation capabilities unmatched by any other means. In this paper, we
address an important issue regarding such simulations, namely how to define the
inputs in terms of sky model and instrument parameters. These may either be
taken as a constrained realization derived from the data, or as a random
realization independent from the data. We refer to these as Bayesian and
frequentist simulations, respectively. We show that the two options lead to
significantly different correlation structures, as frequentist simulations,
contrary to Bayesian simulations, effectively include cosmic variance, but
exclude realization-specific correlations from non-linear degeneracies.
Consequently, they quantify fundamentally different types of uncertainties, and
we argue that they therefore also have different and complementary scientific
uses, even if this dichotomy is not absolute. Before BeyondPlanck, most
pipelines have used a mix of constrained and random inputs, and used the same
hybrid simulations for all applications, even though the statistical
justification for this is not always evident. BeyondPlanck represents the first
end-to-end CMB simulation framework that is able to generate both types of
simulations, and these new capabilities have brought this topic to the
forefront. The Bayesian BeyondPlanck simulations and their uses are described
extensively in a suite of companion papers. In this paper we consider one
important applications of the corresponding frequentist simulations, namely
code validation. That is, we generate a set of 1-year LFI 30 GHz frequentist
simulations with known inputs, and use these to validate the core low-level
BeyondPlanck algorithms; gain estimation, correlated noise estimation, and
mapmaking
Planck intermediate results : LVII. Joint Planck LFI and HFI data processing
We present the NPIPE processing pipeline, which produces calibrated frequency maps in temperature and polarization from data from the Planck Low Frequency Instrument (LFI) and High Frequency Instrument (HFI) using high-performance computers. NPIPE represents a natural evolution of previous Planck analysis efforts, and combines some of the most powerful features of the separate LFI and HFI analysis pipelines. For example, following the LFI 2018 processing procedure, NPIPE uses foreground polarization priors during the calibration stage in order to break scanning-induced degeneracies. Similarly, NPIPE employs the HFI 2018 time-domain processing methodology to correct for bandpass mismatch at all frequencies. In addition, NPIPE introduces several improvements, including, but not limited to: inclusion of the 8% of data collected during repointing manoeuvres; smoothing of the LFI reference load data streams; in-flight estimation of detector polarization parameters; and construction of maximally independent detector-set split maps. For component-separation purposes, important improvements include: maps that retain the CMB Solar dipole, allowing for high-precision relative calibration in higher-level analyses; well-defined single-detector maps, allowing for robust CO extraction; and HFI temperature maps between 217 and 857 GHz that are binned into 0 ' .9 pixels (N-side = 4096), ensuring that the full angular information in the data is represented in the maps even at the highest Planck resolutions. The net effect of these improvements is lower levels of noise and systematics in both frequency and component maps at essentially all angular scales, as well as notably improved internal consistency between the various frequency channels. Based on the NPIPE maps, we present the first estimate of the Solar dipole determined through component separation across all nine Planck frequencies. The amplitude is (3366.6 +/- 2.7) mu K, consistent with, albeit slightly higher than, earlier estimates. From the large-scale polarization data, we derive an updated estimate of the optical depth of reionization of tau =0.051 +/- 0.006, which appears robust with respect to data and sky cuts. There are 600 complete signal, noise and systematics simulations of the full-frequency and detector-set maps. As a Planck first, these simulations include full time-domain processing of the beam-convolved CMB anisotropies. The release of NPIPE maps and simulations is accompanied with a complete suite of raw and processed time-ordered data and the software, scripts, auxiliary data, and parameter files needed to improve further on the analysis and to run matching simulations.Peer reviewe
Inclusion of photoautotrophic cultivated diatom biomass in salmon feed can deter lice
The aim of this study was to evaluate the potential of diatom (microalgae) biomass as a lice-reducing ingredient in salmon feed. The original hypothesis was based on the fact that polyunsaturated aldehydes (PUAs), e.g. 2-trans, 4-trans decadenial (A3) produced by diatoms can function as grazing deterrents and harm copepod development. Salmon lice (Lepeophtheirus salmonis) is a copepod, and we intended to test if inclusion of diatom biomass in the feed could reduce the infestation of lice on salmon. We performed experiments where salmon kept in tanks were offered four different diets, i.e. basic feed with diatoms, fish oil, Calanus sp. oil or rapeseed oil added. After a feeding period of 67 days a statistically representative group of fishes, tagged with diet group origin, were pooled in a 4000L tank and exposed to salmon lice copepodites whereafter lice infestation was enumerated. Salmon from all four diet groups had good growth with SGR values from 1.29 to 1.44% day-1 (increase from ca. 130 g to 350 g). At the termination of the experiment the number of lice on salmon offered diatom feed were statistically significantly lower than on salmon fed the other diets. Mean lice infestation values increased from diatom feed through Calanus and fish oil to standard feed with terrestrial plant ingredients. Analysis of the chemical composition of the different diets (fatty acids, amino acids) failed to explain the differences in lice infestation. The only notable result was that diatom and Calanus feed contained more FFA (free fatty acids) than feed with fish oil and the control feed. None of the potential deleterious targeted polyunsaturated aldehydes could be detected in skin samples of the salmon. What was exclusive for salmon that experienced reduced lice was diatom inclusion in the feed. This therefore still indicates the presence of some lice deterring ingredient, either in the feed, or an ingredient can have triggered production of an deterrent in the fish. An obvious follow up of this will be to perform experiments with different degrees of diatom inclusion in the feeds, i.e. dose response experiments combined with targeted PUA analyses, as well as to perform large scale experiments under natural conditions in aquaculture pens
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BEYONDPLANCK
We describe the BEYONDPLANCK project in terms of our motivation, methodology, and main products, and provide a guide to a set of companion papers that describe each result in more detail. Building directly on experience from ESA's Planck mission, we implemented a complete end-to-end Bayesian analysis framework for the Planck Low Frequency Instrument (LFI) observations. The primary product is a full joint posterior distribution P(Ă Ăą ÂŁd), where Ă represents the set of all free instrumental (gain, correlated noise, bandpass, etc.), astrophysical (synchrotron, free-free, thermal dust emission, etc.), and cosmological (cosmic microwave background -CMB -map, power spectrum, etc.) parameters. Some notable advantages of this approach compared to a traditional pipeline procedure are seamless end-to-end propagation of uncertainties; accurate modeling of both astrophysical and instrumental effects in the most natural basis for each uncertain quantity; optimized computational costs with little or no need for intermediate human interaction between various analysis steps; and a complete overview of the entire analysis process within one single framework. As a practical demonstration of this framework, we focus in particular on low-Ăą CMB polarization reconstruction with Planck LFI. In this process, we identify several important new effects that have not been accounted for in previous pipelines, including gain over-smoothing and time-variable and non-1/f correlated noise in the 30 and 44 GHz channels. Modeling and mitigating both previously known and newly discovered systematic effects, we find that all results are consistent with the Ă CDM model, and we constrained the reionization optical depth to Ă Ăą =Ăą 0.066±0.013, with a low-resolution CMB-based Ă 2 probability to exceed of 32%. This uncertainty is about 30% larger than the official pipelines, arising from taking a more complete instrumental model into account. The marginal CMB solar dipole amplitude is 3362.7±1.4Ăą ÎŒK, where the error bar was derived directly from the posterior distribution without the need of any ad hoc instrumental corrections. We are currently not aware of any significant unmodeled systematic effects remaining in the Planck LFI data, and, for the first time, the 44 GHz channel is fully exploited in the current analysis. We argue that this framework can play a central role in the analysis of many current and future high-sensitivity CMB experiments, including LiteBIRD, and it will serve as the computational foundation of the emerging community-wide COSMOGLOBE effort, which aims to combine state-of-the-art radio, microwave, and submillimeter data sets into one global astrophysical model
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BEYONDPLANCK
We present the intensity foreground algorithms and model employed within the BEYONDPLANCK analysis framework. The BEYONDPLANCK analysis is aimed at integrating component separation and instrumental parameter sampling within a global framework, leading to complete end-to-end error propagation in the Planck Low Frequency Instrument (LFI) data analysis. Given the scope of the BEYONDPLANCK analysis, a limited set of data is included in the component separation process, leading to foreground parameter degeneracies. In order to properly constrain the Galactic foreground parameters, we improve upon the previous Commander component separation implementation by adding a suite of algorithmic techniques. These algorithms are designed to improve the stability and computational efficiency for weakly constrained posterior distributions. These are: (1) joint foreground spectral parameter and amplitude sampling, building on ideas from MIRAMARE; (2) component-based monopole determination; (3) joint spectral parameter and monopole sampling; and (4) application of informative spatial priors for component amplitude maps. We find that the only spectral parameter with a significant signal-to-noise ratio using the current BEYONDPLANCK data set is the peak frequency of the anomalous microwave emission component, for which we find Μpa =a 25.3±0.5a GHz; all others must be constrained through external priors. Future works will be aimed at integrating many more data sets into this analysis, both map and time-ordered based, thereby gradually eliminating the currently observed degeneracies in a controlled manner with respect to both instrumental systematic effects and astrophysical degeneracies. When this happens, the simple LFI-oriented data model employed in the current work will need to be generalized to account for both a richer astrophysical model and additional instrumental effects. This work will be organized within the Open Science-based COSMOGLOBE community effort