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- Dachlythra, Konstantina, 1993-
(författare)
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Beam Prepared : Modeling optical systematics for current- and next-generation CMB experiments
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The polarization of the Cosmic Microwave Background (CMB) is at the center of attention of the cosmological community, as the observable possibly offers a view of primordial gravitational waves. A signature from an early-universe gravitational wave background would be imprinted on the parity-odd pattern of the CMB polarization, namely the B-modes. Achieving a non-zero primordial B-mode detection would serve as indirect evidence of the current most favorable scenario describing the initial perturbations of the universe, referred to as cosmic inflation. Several current- and next-generation telescopes are targetting high-accuracy measurements of the polarized microwave sky, with a particular emphasis on probing the inflationary paradigm. This effort faces two key challenges. The first is the impact of the galactic contaminants on the cosmological signal, which may be tackled by telescopes with increased frequency and sky coverage. The second concern refers to systematic errors arising from the instrument itself, highlighting the necessity of establishing a robust framework for their modeling. This thesis focuses on the modeling of a leading category of systematics that is associated with the telescope’s optics in the context of CMB analysis. A part of the thesis discusses the impact that combining non-ideal beams with a specific type of realistic polarization modulators, namely Half-Wave-Plates (HWPs), has on the reconstructed CMB B-mode spectra of a simulated satellite experiment. The rest of the analysis refers to the Simons Observatory (SO) Small Aperture Telescopes (SATs) that are currently being deployed from the Atacama Desert in Chile. Specifically, I first assess our expected beam calibration capabilities during science observations of the SO SATs in terms of the telescope’s scientific objective. I then expand on the calibration strategy optimization and pipeline infrastructure I developed for the commissioning phase of the first deployed SAT. This study aimed to assess the telescope’s anticipated pointing and beam reconstruction accuracy during its initial observations. Finally, I investigate how natural variations in beam patterns across the SO observing frequency bands influence the large-scale B-mode spectra of the SATs.
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| 2. |
- Dachlythra, Konstantina, 1993-
(författare)
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Modelling optical systematics for current and next-generation CMB experiments : Facilitating the quest for primordial B-modes
- 2022
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The polarization of the Cosmic Microwave Background (CMB) is at the centre of attention of the cosmological community, as the observable possibly offers a view of primordial gravitational waves. This effort faces two key challenges. The first is the impact of the Galactic contaminants on the cosmological signal, which may be tackled by telescopes with increased frequency and sky coverage. The second refers to systematics arising from the instrument itself. In this thesis, which focuses on optical systematics, I describe 1) the detailed time-domain simulations of a non-ideal polarization modulator, 2) the beam characterization of the Simons Observatory Small Aperture Telescopes.
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| 3. |
- Hasebe, T., et al.
(författare)
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Sensitivity Modeling for LiteBIRD
- 2023
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Ingår i: Journal of Low Temperature Physics. - : Springer Science and Business Media LLC. - 0022-2291 .- 1573-7357. ; 211:5-6, s. 384-397
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Tidskriftsartikel (refereegranskat)abstract
- LiteBIRD is a future satellite mission designed to observe the polarization of the cosmic microwave background radiation in order to probe the inflationary universe. LiteBIRD is set to observe the sky using three telescopes with transition-edge sensor bolometers. In this work we estimated the LiteBIRD instrumental sensitivity using its current design. We estimated the detector noise due to the optical loadings using physical optics and ray-tracing simulations. The noise terms associated with thermal carrier and readout noise were modeled in the detector noise calculation. We calculated the observational sensitivities over fifteen bands designed for the LiteBIRD telescopes using assumed observation time efficiency.
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