Integrated Optical Polarization of Nearby Galaxies

Jones, Amy; Wang, Lifan; Krisciunas, K.; Freeland, Emily

doi:10.1088/0004-637x/748/1/17

Cited by 6 publications

(5 citation statements)

References 44 publications

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“…The integrated polarization level would be less than the level in polarization maps in Fendt et al (1996) and Scarrott (1996) due to partial cancellation of polarization vectors over the galaxy. The integrated polarization levels of 70 galaxies reported by Jones et al (2012) are mostly below 1% with several above 2%. Hence, we choose the fraction of polarized light emitted by an edge-on disk galaxy to be 2%.…”

Section: Selection Bias Estimation Processmentioning

confidence: 90%

“…The level of polarization is typically of order of several percent (Sofue et al 1986;Scarrott et al 1990;Draper et al 1995;Scarrott 1996;Jones et al 2012). For edge-on galaxies, the anisotropic scattering (Jura 1982) and alignment with the magnetic field (Fendt et al 1996;Scarrott et al 1990) under several µG of interstellar magnetic field both demonstrate polarization of order of 5%.…”

Section: Selection Bias Estimation Processmentioning

confidence: 99%

“…The toroidal magnetic field on the disc plane would generate polarizations parallel to the major axis for edge-on galaxies (since the grains align perpendicular to the disc and preferentially absorb that polarization), while the polarization by anisotropic scattering is perpendicular to the major axes (since the grains are in a radiation field where more light is coming from directions parallel to than perpendicular to the disc). In Jones et al (2012), the authors presented the integrated polarization survey of 70 nearby galaxies and suggested that the dust scattering is the dominant source of optical polarization. The magnitude of the polarization-dependence of the PSF is only affected by the polarization level rather than the polarization orientation, but the polarization orientation has a great impact on the selection bias.…”

Section: Optical/nir Polarization Of Galaxiesmentioning

confidence: 99%

“…For face-on disk galaxies, the light we observe on a whole is unpolarized. If we use the sin 2 i law for the dependence of polarization effect on inclination angle in Simmons & Audit (2000) and Jones et al (2012), we can then say that the random inclinations of the disk galaxies results in e1 being multiplied by a factor of 4 3π ≈ 0.42.…”

Section: Additional Correction Factorsmentioning

confidence: 99%

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The Impact of Light Polarization Effects on Weak Lensing Systematics

Lin,

Tan,

Mandelbaum

et al. 2019

Preprint

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A fraction of the light observed from edge-on disk galaxies is polarized due to two physical effects: selective extinction by dust grains aligned with the magnetic field, and scattering of the anisotropic starlight field. Since the efficiency of detectors and the response of optical devices depend on the polarization of incoming rays, this optical polarization produces both (a) a selection bias in favor of galaxies with specific orientations and (b) a polarization-dependent PSF. In this work we build toy models to obtain for the first time an estimate for the impact of polarization on PSF shapes and the impact of the selection bias due to the polarization effect on the measurement of the ellipticity used in shear measurements. In particular, we are interested in determining if this effect will be significant for WFIRST. We show that the systematic uncertainties in the ellipticity components are 7 × 10 −5 and 1.1 × 10 −4 due to the selection bias and PSF errors respectively. Both of these systematic uncertainties are close to the WFIRST tolerance level, and hence more detailed studies of the polarization effects or more stringent requirements on polarization-sensitive instrumentation for WFIRST are required.

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Section: Selection Bias Estimation Processmentioning

confidence: 90%

Section: Selection Bias Estimation Processmentioning

confidence: 99%

Section: Optical/nir Polarization Of Galaxiesmentioning

confidence: 99%

Section: Additional Correction Factorsmentioning

confidence: 99%

See 2 more Smart Citations

The Impact of Light Polarization Effects on Weak Lensing Systematics

Lin,

Tan,

Mandelbaum

et al. 2019

Preprint

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show abstract

“…However, polarimet-Current address: Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, Massachusetts 02421-6426 ric studies at these short wavelengths of diffuse sources such as galaxies can be affected by contamination from highly polarized, scattered starlight. This light originates with stars in the disk and the bulge, that subsequently scatters off dust grains in the interstellar medium (Jones et al 2012). The optical polarimetry vector map of M51 (Scarrott et al 1987) was claimed to trace the interstellar polarization in extinction and does indeed follow the spiral pattern.…”

Section: Introductionmentioning

confidence: 99%

HAWC+ Far-Infrared Observations of the Magnetic Field Geometry in M51 and NGC 891

Jones,

Kim,

Dowell

et al. 2020

Preprint

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SOFIA HAWC+ polarimetry at 154 µm is reported for the face-on galaxy M51 and the edge-on galaxy NGC 891. For M51, the polarization vectors generally follow the spiral pattern defined by the molecular gas distribution, the far-infrared (FIR) intensity contours, and other tracers of star formation. The fractional polarization is much lower in the FIR-bright central regions than in the outer regions, and we rule out loss of grain alignment and variations in magnetic field strength as causes. When compared with existing synchrotron observations, which sample different regions with different weighting, we find the net position angles are strongly correlated, the fractional polarizations are moderately correlated, but the polarized intensities are uncorrelated. We argue that the low fractional polarization in the central regions must be due to significant numbers of highly turbulent segments across the beam and along lines of sight in the beam in the central 3 kpc of M51. For NGC 891, the FIR polarization vectors within an intensity contour of 1500 MJy sr −1 are oriented very close to the plane of the galaxy. The FIR polarimetry is probably sampling the magnetic field geometry in NGC 891 much deeper into the disk than is possible with NIR polarimetry and radio synchrotron

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The impact of light polarization effects on weak lensing systematics

Lin

Tan

Mandelbaum

et al. 2020

Monthly Notices of the Royal Astronomical Society

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A fraction of the light observed from edge-on disc galaxies is polarized due to two physical effects: selective extinction by dust grains aligned with the magnetic field and scattering of the anisotropic starlight field. Since the reflection and transmission coefficients of the reflecting and refracting surfaces in an optical system depend on the polarization of incoming rays, this optical polarization produces both (a) a selection bias in favour of galaxies with specific orientations and (b) a polarization-dependent point spread function (PSF). In this work, we build toy models to obtain for the first time an estimate for the impact of polarization on PSF shapes and the impact of the selection bias due to the polarization effect on the measurement of the ellipticity used in shear measurements. In particular, we are interested in determining if this effect will be significant for Wide-Field Infrared Survey Telescope (WFIRST). We show that the systematic uncertainties in the ellipticity components are 8 × 10−5 and 1.1 × 10−4 due to the selection bias and PSF errors respectively. Compared to the overall requirements on knowledge of the WFIRST PSF ellipticity (4.7 × 10−4 per component), both of these systematic uncertainties are sufficiently close to the WFIRST tolerance level that more detailed studies of the polarization effects or more stringent requirements on polarization-sensitive instrumentation for WFIRST are required.

show abstract

Integrated Optical Polarization of Nearby Galaxies

Cited by 6 publications

References 44 publications

The Impact of Light Polarization Effects on Weak Lensing Systematics

The Impact of Light Polarization Effects on Weak Lensing Systematics

HAWC+ Far-Infrared Observations of the Magnetic Field Geometry in M51 and NGC 891

The impact of light polarization effects on weak lensing systematics

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