Polarization from Aligned Dust Grains in the β Pic Debris Disk

Hull, Charles L. H.; Yang, Haifeng; Cortés, Paulo C.; Dent, W. R. F.; Kral, Quentin; Li, Zhi-Yun; Gouellec, Valentin J. M. Le; Hughes, A. Meredith; Milli, J.; Wyatt, M. C.

doi:10.3847/1538-4357/ac6023

Cited by 6 publications

(3 citation statements)

References 105 publications

(121 reference statements)

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“…In most ISM cases, the grains align and cause polarization relative to the magnetic field direction; this referred to as "B-RAT." However, in the case of a strong anisotropic radiation field, RAT theory predicts that the alignment axis can change from the magnetic field to the radiation field (also called "k-RAT"; Lazarian & Hoang 2007;Tazaki et al 2017;Hull et al 2022). This effect is stronger for large grains and can affect large internally aligned grains located close to a strong radiation source, if rotating at thermal velocities.…”

Section: Introductionmentioning

confidence: 99%

The Origin of Dust Polarization in the Orion Bar

Gouellec¹,

Andersson²,

Soam

et al. 2023

ApJ

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The linear polarization of thermal dust emission provides a powerful tool to probe interstellar and circumstellar magnetic fields, because aspherical grains tend to align themselves with magnetic field lines. While the Radiative Alignment Torque (RAT) mechanism provides a theoretical framework for this phenomenon, some aspects of this alignment mechanism still need to be quantitatively tested. One such aspect is the possibility that the reference alignment direction changes from the magnetic field (“B-RAT”) to the radiation field k-vector (“k-RAT”) in areas of strong radiation fields. We investigate this transition toward the Orion Bar PDR, using multiwavelength SOFIA HAWC+ dust polarization observations. The polarization angle maps show that the radiation field direction is on average not the preferred grain alignment axis. We constrain the grain sizes for which the transition from B-RAT to k-RAT occurs in the Orion Bar (grains ≥ 0.1 μm toward the most irradiated locations), and explore the radiatively driven rotational disruption that may take place in the high-radiation environment of the Bar for large grains. While the grains susceptible to rotational disruption should be in suprathermal rotation and aligned with the magnetic field, k-RAT aligned grains would rotate at thermal velocities. We find that the grain size at which the alignment shifts from B-RAT to k-RAT corresponds to grains too large to survive the rotational disruption. Therefore, we expect a large fraction of grains to be aligned at suprathermal rotation with the magnetic field, and to potentially be subject to rotational disruption, depending on their tensile strength.

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Section: Introductionmentioning

confidence: 99%

The Origin of Dust Polarization in the Orion Bar

Gouellec¹,

Andersson²,

Soam

et al. 2023

ApJ

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“…Polarimetric observations of debris disks have been carried out using the Advanced Camera for Surveys coronagraph (ACS) in Hubble Space Telescope (HST) and current groundbased high-contrast imaging polarimeters in optical and NIR wavelength regions (Graham et al 2007;Maness et al 2009;Engler et al 2017;Milli et al 2017;Chen et al 2020;Esposito et al 2020;Hom et al 2020;Crotts et al 2021;Hull et al 2022). Using the Gemini Planet Imager (GPI) (Macintosh et al 2014) at the Gemini-South Telescope, Esposito et al (2020) conducted a four-year survey of 104 stars and obtained polarization observations of 35 debris disks at NIR wavelengths.…”

Section: Introductionmentioning

confidence: 99%

Simulation of High-contrast Polarimetric Observations of Debris Disks with the Roman Coronagraph Instrument

Anche,

Douglas,

Milani

et al. 2023

PASP

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The Nancy Grace Roman Space Telescope Coronagraph Instrument will enable the polarimetric imaging of debris disks and inner dust belts in the optical and near-infrared wavelengths, in addition to the high-contrast polarimetric imaging and spectroscopy of exoplanets. The Coronagraph uses two Wollaston prisms to produce four orthogonally polarized images and is expected to measure the polarization fraction with measurement errors <3% per spatial resolution element. To simulate the polarization observations through the Hybrid Lyot Coronagraph (HLC) and Shaped Pupil Coronagraph (SPC), we model disk scattering, the coronagraphic point-response function, detector noise, speckles, jitter, and instrumental polarization and calculate the Stokes parameters. To illustrate the potential for discovery and a better understanding of known systems with both the HLC and SPC modes, we model the debris disks around Epsilon Eridani and HR 4796A, respectively. For Epsilon Eridani, using astrosilicates with 0.37 ± 0.01 as the peak input polarization fraction in one resolution element, we recover the peak disk polarization fraction of 0.33 ± 0.01. Similarly, for HR 4796A, for a peak input polarization fraction of 0.92 ± 0.01, we obtain the peak output polarization fraction as 0.80 ± 0.03. The Coronagraph design meets the required precision, and forward modeling is needed to accurately estimate the polarization fraction.

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“…Polarization observations of debris disks enable us to constrain their structure and properties of the dust grains such as composition, size, shape, and distribution. [4][5][6][7] Polarization observation of several debris disks has been carried out using the Gemini Planet Imager (GPI) 8 at the Gemini Telescope, and SPHERE-ZIMPOL 9 at the Very Large Telescope (VLT) in the near IR wavelengths. Hubble Space Telescope Advanced Camera for Surveys coronograph has been used to observe the polarization of a few debris disks (HD61005, 10 and AU Mic 11 ) in the Johnson-Cousins V band filter.…”

Section: Introductionmentioning

confidence: 99%

Simulations of polarimetric observations of debris disks through the Roman Coronagraph Instrument

Anche¹,

Douglas²,

Milani³

et al. 2022

Preprint

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The Roman coronagraph instrument will demonstrate high-contrast imaging technology, enabling the imaging of faint debris disks, the discovery of inner dust belts, and planets. Polarization studies of debris disks provide information on dust grains' size, shape, and distribution. The Roman coronagraph uses a polarization module comprising two Wollaston prism assemblies to produce four orthogonally polarized images (I 0 , I 90 , I 45 , and I 135 ), each measuring 3.2 arcsecs in diameter and separated by 7.5 arcsecs in the sky. The expected RMS error in the linear polarization fraction measurement is 1.66% per resolution element of 3 by 3 pixels. We present a mathematical model to simulate the polarized intensity images through the Roman CGI, including the instrumental polarization and other uncertainties. We use disk modeling software, MCFOST, to model q, u, and polarization intensity of the debris disk, Epsilon-Eridani. The polarization intensities are convolved with the coronagraph throughput incorporating the PSF morphology. We include model uncertainties, detector noise, speckle noise, and jitter. The final polarization fraction of 0.4±0.0251 is obtained after the post-processing.

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Polarization from Aligned Dust Grains in the β Pic Debris Disk

Cited by 6 publications

References 105 publications

The Origin of Dust Polarization in the Orion Bar

The Origin of Dust Polarization in the Orion Bar

Simulation of High-contrast Polarimetric Observations of Debris Disks with the Roman Coronagraph Instrument

Simulations of polarimetric observations of debris disks through the Roman Coronagraph Instrument

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