Nadia Dachlythra
A5024923057- Radio Astronomy Observations and Technology
- Cosmology and Gravitation Theories
- Superconducting and THz Device Technology
- Geophysics and Gravity Measurements
- Galaxies: Formation, Evolution, Phenomena
- Adaptive optics and wavefront sensing
- Antenna Design and Optimization
- Geomagnetism and Paleomagnetism Studies
- Astronomy and Astrophysical Research
- Statistical and numerical algorithms
- Astrophysics and Cosmic Phenomena
- Satellite Communication Systems
- Advanced Optical Sensing Technologies
- Sparse and Compressive Sensing Techniques
- Pulsars and Gravitational Waves Research
- Seismic Imaging and Inversion Techniques
Stockholm University
2020-2024
AlbaNova
2020-2024
University of Copenhagen
2020
Abstract We present a study of the impact beam far side-lobe lack knowledge on measurement Cosmic Microwave Background B -mode signal at large scale. Beam side-lobes induce mismatch in transfer function Galactic foregrounds between dipole and higher multipoles which degrads performances component separation methods. This leads to foreground residuals CMB map. It is expected be one main source systematic effects future polarization observations. Thus, it becomes crucial for all-sky survey...
Current- and next-generation Cosmic Microwave Background (CMB) experiments will measure polarization anisotropies with unprecedented sensitivities. The need for high precision in these measurements underscores the importance of gaining a comprehensive understanding instrument properties, particular emphasis on study beam properties and, particular, their characteristics, measurement angle. In this context, major challenge lies scarcity millimeter polarized astrophysical sources sufficient...
Abstract Polarization of the cosmic microwave background (CMB) can probe new parity-violating physics such as birefringence (CB), which requires exquisite control over instrumental systematics. The non-idealities half-wave plate (HWP) represent a source systematics when used polarization modulator. We study their impact on CMB angular power spectra, is partially degenerate with CB and miscalibration angle. use full-sky beam convolution simulations including HWP to generate mock noiseless...
We use time-domain simulations of Jupiter observations to test and develop a beam reconstruction pipeline for the Simons Observatory Small Aperture Telescopes. The method relies on map maker that estimates subtracts correlated atmospheric noise fitting code designed compensate bias caused by maker. our performance four different frequency bands against various algorithmic parameters, conditions input beams. additionally show quality as function number available investigate how calibration...
We study systematic effects from half-wave plates (HWPs) for cosmic microwave background (CMB) experiments using full-sky time-domain beam convolution simulations. Using an optical model a fiducial spaceborne two-lens refractor telescope, we investigate how different HWP configurations optimized dichroic detectors centred at 95 and 150 GHz impact the reconstruction of primordial B-mode polarization. pay particular attention to possible biases arising interaction frequency dependent...
We present geometrical and physical optics simulation results for the Simons Observatory Large Aperture Telescope. This work was developed as part of general design process telescope; allowing us to evaluate impact various choices on performance metrics potential systematic effects. The primary goal simulations final reflectors cold which are now being built. describe non-sequential ray tracing used inform optics, including absorbers internal each tube. discuss telescope structure that allow...
LiteBIRD has been selected as JAXA's strategic large mission in the 2020s, to observe cosmic microwave background (CMB) $B$-mode polarization over full sky at angular scales. The challenges of are wide field-of-view (FoV) and broadband capabilities millimeter-wave measurements, which derived from system requirements. possible paths stray light increase with a wider FoV far sidelobe knowledge $-56$ dB is challenging optical requirement. A crossed-Dragone configuration was chosen for low...
LiteBIRD is a JAXA-led Strategic Large-Class mission designed to search for the existence of primordial gravitational waves produced during inflationary phase Universe, through measurements their imprint onto polarization cosmic microwave background (CMB). These measurements, requiring unprecedented sensitivity, will be performed over full sky, at large angular scales, and 15 frequency bands from 34 GHz 448 GHz. The instruments consist three telescopes, namely Low-, Medium-and High-Frequency...
We study the distribution functions of CMB polarization angle $\psi$, focusing on Planck 2018 maps. extend model Preece & Battye (2014) Gaussian correlated $Q$ and $U$ Stokes parameters to allow nonzero means. When variances are equal their covariance means zero, is uniformly distributed. Otherwise uniform will be modulated by harmonics with $2\psi$ $4\psi$ phases. These modulations visible in Furthermore, mean value peculiar compared power spectrum.
We present near-field radio holography measurements of the Simons Observatory Large Aperture Telescope Receiver optics. These demonstrate that complex millimeter-wave optical systems comprising cryogenic lenses, filters, and feed horns can provide detailed characterization wave propagation before deployment. used measured amplitude phase, at 4K, receiver beam pattern to predict two key performance parameters: 1) amount scattered light will spill past telescope 300K 2) expected from when...
Polarization of the cosmic microwave background (CMB) can probe new parity-violating physics such as birefringence (CB), which requires exquisite control over instrumental systematics. The non-idealities half-wave plate (HWP) represent a source systematics when used polarization modulator. We study their impact on CMB angular power spectra, is partially degenerate with CB and miscalibration angle. use full-sky beam convolution simulations including HWP to generate mock noiseless time-ordered...
Near-field radio holography is a common method for measuring and aligning mirror surfaces millimeter sub-millimeter telescopes. In instruments with more than single mirror, degeneracies arise in the measurement, requiring multiple measurements new fitting methods. We present HoloSim-ML, Python code beam simulation analysis of data from complex optical systems. This uses machine learning to efficiently determine position hundreds adjusters on mirrors few micron accuracy. apply this approach...