Alexandre Adler
A5038549833- Radio Astronomy Observations and Technology
- French Urban and Social Studies
- Superconducting and THz Device Technology
- Cosmology and Gravitation Theories
- French Historical and Cultural Studies
- Political and Social Issues
- Multiculturalism, Politics, Migration, Gender
- Galaxies: Formation, Evolution, Phenomena
- Historical Studies and Socio-cultural Analysis
- Antenna Design and Optimization
- Adaptive optics and wavefront sensing
- Astronomy and Astrophysical Research
- Geophysics and Gravity Measurements
- Aerospace Engineering and Energy Systems
- African history and culture analysis
- Spacecraft and Cryogenic Technologies
- Advanced Thermodynamic Systems and Engines
- Pulsars and Gravitational Waves Research
- Communism, Protests, Social Movements
- Spacecraft Design and Technology
- Astrophysics and Cosmic Phenomena
- Satellite Communication Systems
- African Studies and Geopolitics
- Advanced Optical Sensing Technologies
- Philosophy, Sociology, Political Theory
Stockholm University
2020-2024
AlbaNova
2021-2024
Hanalei Watershed Hui
1980
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...
LiteBIRD, the Lite (Light) satellite for study of B-mode polarization and Inflation from cosmic background Radiation Detection, is a space mission primordial cosmology fundamental physics. JAXA selected LiteBIRD in May 2019 as strategic large-class (L-class) mission, with its expected launch late 2020s using JAXA's H3 rocket. plans to map microwave (CMB) over full sky unprecedented precision. Its main scientific objective carry out definitive search signal inflation, either making discovery...
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...
Abstract We simulate a variety of optical systematics for Taurus, balloon-borne cosmic microwave background (CMB) polarisation experiment, to assess their impact on large-scale E -mode measurements and constraints the depth reionisation τ . model one-month flight Taurus from Wanaka, New Zealand aboard super-pressure balloon (SPB). night-time scans both CMB dust foregrounds in 150 GHz band, one Taurus's four observing bands. consider possible that may affect observations, including...
We describe the cryogenic system being developed for Taurus: a super-pressure balloon-borne microwave polarimeter scheduled to fly in 2027. The Taurus consists of 660L liquid helium cryostat which achieves base temperature <100mK with help capillary-fed superfluid tank and closed cycle dilution refrigerator. main is supported fiberglass flexures encased two layers vapor-cooled shields allow make full use extended flight time offered by balloon platform. projected hold over 50 days while...
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...
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...
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...
Taurus is a balloon-borne cosmic microwave background (CMB) experiment optimized to map the E-mode polarization and Galactic foregrounds at largest angular scales ($\ell$ $\lt$ 30) improve measurements of optical depth reionization ($\tau$). This will pave way for improved sum neutrino masses in combination with high-resolution CMB data while also testing $\Lambda CDM$ model on large providing high-frequency maps polarized dust community. These take advantage low-loading environment found...
We simulate a variety of optical systematics for Taurus, balloon-borne cosmic microwave background (CMB) polarisation experiment, to assess their impact on large-scale E-mode measurements and constraints the depth reionisation {\tau}. model one-month flight Taurus from Wanaka, New Zealand aboard super-pressure balloon (SPB). night-time scans both CMB dust foregrounds in 150GHz band, one Taurus's four observing bands. consider possible that may affect observations, including non-gaussian...
Accurate optical modeling is important for the design and characterisation of current next-generation experiments studying Cosmic Microwave Background (CMB). Geometrical Optics (GO) cannot model diffractive effects. In this work, we discuss two methods that incorporate diffraction, Physical (PO) Theory Diffraction (GTD). We simulate response a ground-based two-lens refractor shielded by ground screen with time-reversed simulations. particular, use GTD to determine interplay between...