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

Integrative analysis of ecosystem processes in the littoral zone of lower Chesapeake Bay: A modeling study of the Goodwin Islands National Estuarine Research Reserve

Approximately 40% of the bottom of Chesapeake Bay is less than 2.0 m in depth and many of these broad shoal environments are bordered by wetlands. The vegetated and nonvegetated subtidal and intertidal environment is a dynamic mosaic of highly productive estuarine habitats linked by the exchange of waterborne materials. This study developed simulation models of primary production and material exchange for four littoral zone habitats of the Goodwin Islands National Estuarine Research Reserve (NERR) in lower Chesapeake Bay. Field studies were conducted to determine the sediment biogeochemical and biomass characteristics of sandy shoal, seagrass, silt-mud, and marsh habitats. Ecological models were developed for each habitat based upon their position and ecological characteristics. The models simulate the dynamics of phytoplankton, particulate and dissolved organic carbon, dissolved inorganic nitrogen, sediment microalgae, Zostera marina, and Spartina alterniflora. Following sensitivity analysis and validation the models were used to estimate annual primary production, nitrogen processes, and material exchange. The net annual rate of phytoplankton production was 66.0, sediment microalgae ranged 101-169, Zostera marina community production was approximately 350 gC m&\sp{lcub}-2{rcub}& yr&\sp{lcub}-1{rcub}&, and Spartina alterniflora shoots and root-rhizomes produced 1150 gC m&\sp{lcub}-2{rcub}& yr&\sp{lcub}-1{rcub}& (gC m&\sp{lcub}-2{rcub}& yr&\sp{lcub}-1{rcub}&). Nitrogen uptake was in excess of demand in phytoplankton while the reverse was true for the macrophytes. The marsh habitat accounted for 43% of the total annual primary production for the ecosystem despite being the smallest habitat while the largest habitat (nonvegetated subtidal) required 52% of the total ecosystem nitrogen demand. All four habitats imported phytoplankton, particulate organic carbon, and dissolved inorganic nitrogen annually. While the intertidal habitats imported dissolved organic carbon the subtidal habitats showed net annual export. These models were developed to assess ecosystem structure, function, and change in the littoral zone of Chesapeake Bay. Ecosystem structure was assessed through field research and model development. Ecosystem function was assessed by using the model to generate annual producer, habitat, and ecosystem carbon and nitrogen budgets. The model is currently being used to investigate the interactive effects of water quality, primary production, and habitat composition in order to assess potential change in the estuary

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&

Optimal strategy for polarization modulation in the LSPE-SWIPE experiment

Context. Cosmic microwave background (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. Aims. 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. Methods. We departed from the nominal LSPE-SWIPE modulation strategy (HWP stepped every 60 s with a telescope scanning at around 12 deg/s) and performed 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 probed the effect of high-pass and band-pass filters of the data stream and explored the HWP response in the minimal case of one detector for one operation day (critical for the single-detector calibration process). We finally tested the modulation performance against typical HWP-induced systematics. Results. 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. Conclusions. 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