The Far-Infrared Polarization Spectrum of OMC-1 using HAWC+/SOFIA Observations
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Joe Michail
Northwestern University
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Since far-infrared polarimetry is a key tool in studying the role of magnetic fields in star formation, understanding grain alignment is critical. The polarization fraction as a function of wavelength, referred to as the polarization spectrum, is used as a probe to physics of how grains are magnetically aligned. Polarization spectra analyzed with polarimeters like Stokes, SHARP, and SCUPol gave us a first look at this diagnostic tool. HAWC+ expands this capability by providing unprecedented spectral coverage in the far-infrared and is able to test a wider variety of environments. Here, I present our analysis of the polarization spectrum in the Orion Molecular Cloud-1 (OMC-1) region using all four HAWC+ wavelengths. We find the far-infrared polarization spectrum is negatively-sloped (decreasing with increasing wavelength) in regions with cool temperatures and positively-sloped or flat in warmer regions. We do not find a correlation between column density and slope, unlike the analysis completed in rho Oph A, also using HAWC+. We argue that the radiative environment, traced by dust temperature, determines the degree to which grains are aligned. This result is consistent with Radiative Torque alignment theory.

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