Search for the Galactic Magnetic-field by All-sky Polarimetric survey

SGMAP is the Northern Hemisphere Optical Polarization Survey Project being conducted by Hiroshima Astrophysical Science Center in Hiroshima University.

Japanese version is here .

What's New

Survey region in Galactic coordinate

This project will use a 1 m class (semi)dedicated telescope and a newly developed multi-channel polarization imager to perform simultaneous polarization surveys (polarization measurement accuracy ~0.1-0.2%) in multiple two-bands on millions of stars, almost all brighter than ~14 mag, observable from the northern sky.

This research is complementary to the magnetic field measurements from polarimetric observations in the radio-submillimeter wave range, which have progressed significantly over the past 10-20 years, and is extremely compatible with the magnetic field measurements from ALMA and future SKA, as well as the distance measurements of individual stars in the Milky Way by the Gaia and Nano-JASMINE satellites.
This will allow us to broadly and in detail unravel the magnetic field structure in the northern sky region of the Milky Way Galaxy and elucidate the history of the formation of the Galactic structure.

The resulting polarization catalog is indeed more than 100 times larger in sample stars than the existing all-sky optical polarization catalog (compilation of previous catalogs; Heiles 2000). In addition, the number of measurement bands is not one, but a survey with multiple bands from which wavelength dependence can be derived, which is far superior to similar projects being undertaken overseas.

The overwhelming quantity and quality of polarization catalogs obtained from this project are expected to make a wide variety of astronomical contributions, including the following

Draft Observation Plan
  1. Phase 1 (3-band optical and near-infrared Galactic Plane Survey by modification of existing telescopes and instruments)
    • Sky survey range
      1. -3° ≦ galactic latitude b < +3°, +20° ≦ galactic diameter l < +200° (1080 square degrees)
      2. *Collaboration with SOUTH POL (Magalhaes et al.) on Nanten

    • Telescope Candidate
      • Hiroshima University's 1.5-m Kanata Telescope

    • Observation equipment
      • Field of view 25 arcmin x 25 arcmin φ (0.1736 square degrees) *Modified optics of HONIR (Akitaya et al. 2014) to achieve a wider field of view and added J-band channels (using 1.3k InGaAs arrays manufactured by Hamamatsu Photonics)
      • Optical and near-infrared 3 channels V, J, K
      • Polarization measurement accuracy Δp = 0.15% or better

  2. Phase 2 (2-band Optical all-sky survey with dedicated telescope and dedicated wide-field instrument)
    • Sky survey range
      1. -30° ≦ galactic latitude b < +30°, 0° ≦ galactic diameter l < +220° (12000 square degrees)
      2. +30°≦ galactic latitude b < +90° and -90°≦ galactic latitude b < -30°, +160°≦ galactic diameter l < +360° (13200 square degrees)
      3. *Collaboration with SOUTH POL (Magalhaes et al.) on Sathern Hemisphere

    • Telescope Candidate
      • Hiroshima University's 1.5-m Kanata Telescope (modified secondary mirror)

    • Specifications of Observation Equipment (Wide-field polarized light imager)
      • Field of view 50 arcminutes dia. x 50 arcminutes (0.6944 square degrees)
      • Optical 2 channels g', i'
      • Polarization measurement accuracy Δp=0.15% or better

Events History

Published documents, etc.

Other Optical and Infrared Polarization Survey Projects Catalog

SGMAP Project: Hiroshima Astrophysical Science Center Last update: Aug. 24, 2023