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Title: Near-infrared polarimetry of the edge-on galaxy NGC 891

The edge-on galaxy NGC 891 was probed using near-infrared (NIR) imaging polarimetry in the H band (1.6 μm) with the Mimir instrument on the 1.8 m Perkins Telescope. Polarization was detected with a signal-to-noise ratio greater than three out to a surface brightness of 18.8 mag arcsec{sup –2}. The unweighted average and dispersion in polarization percentage (P) across the full disk were 0.7% and 0.3%, respectively, and the same quantities for polarization position angle (P.A.) were 12° and 19°, respectively. At least one polarization null point, where P falls nearly to zero, was detected in the northeast disk but not the southwest disk. Several other asymmetries in P between the northern and southern disk were found and may be related to spiral structure. Profiles of P and P.A. along the minor axis of NGC 891 suggest a transition from magnetic (B) field tracing dichroic polarization near the disk mid-plane to scattering dominated polarization off the disk mid-plane. A comparison between NIR P.A. and radio (3.6 cm) synchrotron polarization P.A. values revealed similar B-field orientations in the central-northeast region, which suggests that the hot plasma and cold, star-forming interstellar medium may share a common B-field. Disk-perpendicular polarizations previously seen at opticalmore » wavelengths are likely caused by scattered light from the bright galaxy center and are unlikely to be tracing poloidal B-fields in the outer disk.« less
Authors:
;  [1]
  1. Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States)
Publication Date:
OSTI Identifier:
22357012
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 786; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASYMMETRY; BRIGHTNESS; COMPARATIVE EVALUATIONS; DISPERSIONS; GALAXIES; HOT PLASMA; MAGNETIC FIELDS; NEAR INFRARED RADIATION; OXYGEN 12; OXYGEN 19; POLARIMETRY; POLARIZATION; SCATTERING; SIGNAL-TO-NOISE RATIO; STARS; SURFACES; SYNCHROTRONS; TELESCOPES; VISIBLE RADIATION