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X-ORIGINAL-URL:https://www.oact.inaf.it
X-WR-CALDESC:Eventi per Osservatorio Astrofisico di Catania
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DTSTART:20250101T000000
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DTSTART;TZID=UTC:20250407T110000
DTEND;TZID=UTC:20250407T120000
DTSTAMP:20260405T045451
CREATED:20250405T091539Z
LAST-MODIFIED:20250405T091543Z
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SUMMARY:Non-standard signatures from CMB polarisation with an insight into the new technological challenges
DESCRIPTION:Recording: https://www.oact.inaf.it/seminars/ \nDATE:  Monday\, April 7\, 11:00 a.m. \nORGANIZER: INAF-OACT \nLOCATION: AULA OVEST (INAF-OACT) + remote \nLink for the remote audience:https://meet.google.com/wvf-uwxo-oyj \nSPEAKER: Dr. Matteo Billi (University of Catania) \nABSTRACT:In this seminar\, I will focus on non-standard signatures from CMB polarisation that may indicate the existence of new phenomena beyond the standard models of cosmology and particle physics\, from both theoretical and observational perspectives. ESA’s Planck mission has observed CMB temperature anisotropies at the cosmic variance limit\, but polarisation remains to be further investigated. CMB polarisation data are important not only because they contribute to provide tighter constraints on cosmological parameters but also because they allow the study of physical processes that would be excluded if only the CMB temperature maps were considered. I use polarisation data into account to assess the statistical significance of the anomalies currently observed only in the CMB temperature map\, and to constrain the Cosmic Birefringence (CB) effect\, which is expected in parity-violating extensions of the standard electromagnetism.Measuring CMB polarisation is technically challenging because the polarised signal is much fainter than the temperature signal\, and accurate polarisation estimates require exquisite control of systematic effects. To investigate the impact of spurious signals in upcoming CMB polarisation experiments\, I present a study of the interplay between half-wave plate (HWP) non-idealities and the beams of the instrument for the next generation of CMB experiments\, with an insight into how this instrumental contamination affects the measurement of the cosmic birefringence effect. \n  \nA few rules:— before joining\, make sure you are using your institutional inaf.it account if you have one (otherwise we will grant you permission to join)— please do not forget to mute your microphone and switch off your webcam when access the virtual room— for questions leave a message in the chat\, the answers at the end of the webinar— the seminar will be recorded\, so if you are interested in it\, please contact us to get the link to the registration.
URL:https://www.oact.inaf.it/event/non-standard-signatures-from-cmb-polarisation-with-an-insight-into-the-new-technological-challenges/
LOCATION:Sede A. Riccò\, Via Santa Sofia 78\, Catania
CATEGORIES:Eventi & Seminari
ATTACH;FMTTYPE=image/jpeg:https://www.oact.inaf.it/wp-content/uploads/2025/04/seminario_Billi.jpg
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DTSTART;TZID=UTC:20250430T110000
DTEND;TZID=UTC:20250430T120000
DTSTAMP:20260405T045451
CREATED:20250428T210420Z
LAST-MODIFIED:20250428T210924Z
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SUMMARY:Precision Meter-wavelength Polarimetry with the Very Large Array
DESCRIPTION:Recording: https://www.oact.inaf.it/seminars/ \nDATE: Wednesday\, April 30\, 11:00 a.m. \nORGANIZER: INAF-OACT \nLOCATION: AULA OVEST (INAF-OACT) + remote \nLink for the remote audience:https://meet.google.com/wvf-uwxo-oyj \nSPEAKER: Rick Perley (National Radio Astronomy Observatory – USA) \nABSTRACT:Accurate imaging polarimetry at meter wavelengths requires removal of the highly variable ionospheric Faraday rotation (IFRM) with an accuracy of 0.1 rad/m^2 or better. Models to estimate the VTEC using GNSS timing data\, combined with global terrestrial magnetic field models have been developed over the past 25 years.  Estimating the accuracy of these models requires observations of a source of known intrinsic electric vector position angle (EVPA) over a wide rage of ionospheric conditions.Using eight VLA polarimetric observations of the moon spanning ten years using the VLA’s P-band (295 — 445 MHz) receivers\, we have tested the accuracy of seven global IONEX models produced by the AIPS program TECOR\, and the regional model derived by ALBUS.All seven global models overestimate the IFRM\, typically by 0.5 to 1.0 rad/m^2 — a value which remains constant over many hours\, including day — night transitions.  The ‘ALBUS’ model\, which uses GNSS ground station data within ~300 km of the requested site\, generates predictions which are always the closest — usually with 0.2 rad/m^2— to the observed values. \n  \nA few rules:— before joining\, make sure you are using your institutional inaf.it account if you have one (otherwise we will grant you permission to join)— please do not forget to mute your microphone and switch off your webcam when access the virtual room— for questions leave a message in the chat\, the answers at the end of the webinar— the seminar will be recorded\, so if you are interested in it\, please contact us to get the link to the registration.
URL:https://www.oact.inaf.it/event/precision-meter-wavelength-polarimetry-with-the-very-large-array/
LOCATION:Sede A. Riccò\, Via Santa Sofia 78\, Catania
CATEGORIES:Eventi & Seminari
ATTACH;FMTTYPE=image/jpeg:https://www.oact.inaf.it/wp-content/uploads/2025/04/Locandine-eventi-OACT-2.jpg
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