تقرير
Observing the Sun with the Atacama Large Millimeter/submillimeter Array (ALMA): Polarization Observations at 3 mm
| العنوان: | Observing the Sun with the Atacama Large Millimeter/submillimeter Array (ALMA): Polarization Observations at 3 mm |
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| المؤلفون: | Shimojo, Masumi, Bastian, Timothy S., Kameno, Seiji, Hales, Antonio S. |
| المصدر: | Solar Physics 299, 20 (2024) |
| سنة النشر: | 2024 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics |
| الوصف: | The Atacama Large Millimeter-submillimeter Array (ALMA) is a general purpose telescope that performs a broad program of astrophysical observations. Beginning in late-2016, solar observations with ALMA became available, thereby opening a new window onto solar physics. Since then, the number of solar observing capabilities has increased substantially but polarimetric observations, a community priority, have not been available. Weakly circularly polarized emission is expected from the chromosphere where magnetic fields are strong. Hence, maps of Stokes V provide critical new constraints on the longitudinal component of the chromospheric magnetic field. Between 2019-2022, an ALMA solar development effort dedicated to making solar polarimetry at millimeter wavelengths a reality was carried out. Here, we discuss the development effort to enable solar polarimetry in the 3 mm band (ALMA Band 3) in detail and present a number of results that emerge from the development program. These include tests that validate polarization calibration, including evaluation of instrumental polarization: both antenna based "leakage" terms and off-axis effects (termed "beam squint" for Stokes V). We also present test polarimetric observations of a magnetized source on the Sun, the following sunspot in a solar active region, which shows a significant Stokes V signature in line with expectations. Finally, we provide some cautions and guidance to users contemplating the use of polarization observations with ALMA. Comment: 30 pages, 16 figures, Accepted for publication in Solar Physics |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1007/s11207-024-02265-3 |
| URL الوصول: | http://arxiv.org/abs/2401.06343 |
| رقم الأكسشن: | edsarx.2401.06343 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1007/s11207-024-02265-3 |
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