Large Interstellar Polarisation Survey (LIPS)

Bagnulo, S.; Cox, Nicholas; Cikota, Aleksandar; Siebenmorgen, R.; Вощинников, Н. В.; Patat, F.; Smith, Keith T.; Smoker, J. V.; Taubenberger, S.; Kaper, L.; Cami, J.

doi:10.1051/0004-6361/201731459

Cited by 33 publications

(40 citation statements)

References 51 publications

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“…Some of these objects are clustered closely on the sky, suggesting that the wavelength dependence is due to the effects of multiple dust clouds along the line of sight. We also confirm the result of Bagnulo et al (2017) that large |k| values have a weak inverse relationship with P IS,max (Fig. 6).…”

Section: Discussionsupporting

confidence: 90%

“…The recent ISP survey by Bagnulo et al (2017) found that stars with strong wavelength dependence in the ISP position angles (large |k|) tend to have low interstellar polarization overall (small P IS,max ). Our data confirm this trend, as shown in Figure 6, which displays a weak inverse relationship between P IS,max and |k|.…”

Section: The Wavelength Dependence Of the Isp Position Anglementioning

confidence: 99%

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A Multiwavelength Search for Intrinsic Linear Polarization in Wolf–Rayet Winds

Fullard

St-Louis

Moffat

et al. 2020

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Wolf-Rayet stars have strong, hot winds, with mass-loss rates at least a factor of ten greater than their O-star progenitors, although their terminal wind speeds are similar. In this paper we use the technique of multiband linear polarimetry to extract information on the global asymmetry of the wind in a sample of 47 bright Galactic WR stars. Our observations also include time-dependent observations of 17 stars in the sample. The path to our goal includes removing the dominating component of wavelength-dependent interstellar polarization (ISP), which normally follows the wellknown Serkowski law. We include a wavelength-dependent ISP position angle parameter in our ISP law and find that 15 stars show significant results for this parameter. We detect a significant component of wavelength-independent polarization due to electron scattering in the wind for 12 cases, with most WR stars showing none at the ∼0.05% level precision of our data. The intrinsically polarized stars can be explained with binary interaction, large-scale wind structure, and clumping. We also found that 5 stars out of 19 observed with the Strömgren b filter (probing the complex λ4600-4700 emission line region) have significant residuals from the ISP law and propose that this is due to binary illumination or wind clumping. We provide a useful catalogue of ISP for 47 bright Galactic WR stars and upper limits on the possible level of intrinsic polarization.

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Section: Discussionsupporting

confidence: 90%

Section: The Wavelength Dependence Of the Isp Position Anglementioning

confidence: 99%

A Multiwavelength Search for Intrinsic Linear Polarization in Wolf–Rayet Winds

Fullard

St-Louis

Moffat

et al. 2020

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“…They suggested that the poor R V -λ max correlation can be explained by dust grain size dependent variations in alignment capabilities of the dust grains. Also the LIPS data (Bagnulo et al 2017) do not follow any R V -λ max relationship.…”

Section: Comparison To Supernovae Ia and Normal Galactic Starsmentioning

confidence: 88%

“…Comparison of our sample of stars with anomalous extinction sightlines (blue symbols) to the Whittet et al (1992) sample (gray squares) and the LIPS sample (Bagnulo et al (2017), red circles). The gray ellipses represent 1-5σ confidence levels for the Whittet et al (1992) sample.…”

Section: Figmentioning

confidence: 99%

Spectropolarimetry of Galactic stars with anomalous extinction sightlines

Cikota

Hoang

Taubenberger

et al. 2018

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Highly reddened type Ia Supernovae (SNe Ia) with low total-to-selective visual extinction ratio values, R V , also show peculiar linear polarization wavelength dependencies with peak polarizations at short wavelengths (λ max 0.4µm). It is not clear why sightlines to SNe Ia display such different continuum polarization profiles from interstellar sightlines in the Milky Way with similar R V values. We investigate polarization profiles of a sample of Galactic stars with low R V values, along anomalous extinction sightlines, with the aim to find similarities to the polarization profiles that we observe in SN Ia sightlines. We undertook spectropolarimetry of 14 stars, and used archival data for three additional stars, and run dust extinction and polarization simulations (by adopting the picket-fence alignment model) to infer a simple dust model (size distribution, alignment) that can reproduce the observed extinction and polarization curves. Our sample of Galactic stars with low R V values and anomalous extinction sightlines displays normal polarization profiles with an average λ max ∼ 0.53µm, and is consistent within 3σ to a larger coherent sample of Galactic stars from literature. Despite the low R V values of dust towards the stars in our sample, the polarization curves do not show any similarity to the continuum polarization curves observed towards SNe Ia with low R V values. There is a correlation between the best-fit Serkowski parameters K and λ max , but we did not find any significant correlation between R V and λ max . Our simulations show that the K-λ max relationship is an intrinsic property of polarization. Furthermore, we have shown that in order to reproduce polarization curves with normal λ max and low R V values, a population of large (a ≥ 0.1µm) interstellar silicate grains must be contained in the dust's composition.

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“…The total optical polarization along arbitrary lines of sight toward galactic field stars can range from a fraction of a percent to several percent [102][103][104]. Previous work from the Large Interstellar Polarization Survey provided evidence that interstellar polarization (ISP) from multiple dust clouds along a given line of sight is smaller than from lines of sight passing through a single dust cloud [104,105]. Since the presence of two or more clouds would therefore depolarize the incoming radiation, we assume that the ISP along the line of sight toward a galactic field star represents a conservative upper limit to the true ISP toward an AGN source that would have been measured through the full dust column of the galaxy, the intergalactic medium, and the AGN host galaxy.…”

Section: A Observations and Systematicsmentioning

confidence: 99%

Constraints on Lorentz invariance and CPT violation using optical photometry and polarimetry of active galaxies BL Lacertae and S5 B0716+714

et al. 2019

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Various quantum gravity approaches that extend beyond the standard model predict Lorentz Invariance and Charge-Parity-Time Violation at energies approaching the Planck scale. These models frequently predict a wavelength dependent speed of light, which would result in time delays between promptly emitted photons at different energies, as well as a wavelength-dependent rotation of the plane of linear polarization for photons resulting from vacuum birefringence. Here, we describe a pilot program with an automated system of small telescopes that can simultaneously conduct high cadence optical photometry and polarimetry of Active Galactic Nuclei (AGN) in multiple passbands. We use these observations as a proof-of-principle to demonstrate how such data can be used to test various Lorentz Violation models, including special cases of the Standard Model Extension (SME). In our initial campaign with this system, the Array Photo Polarimeter, we observed two AGN sources, including BL Lacertae at redshift z = 0.069, and S5 B0716+714 at z = 0.31. We demonstrate that optical polarimetry with a broadband Luminance filter combined with simultaneous Ic-band observations yields SME parameter constraints that are up to ∼10 and ∼30 times more sensitive than with a standard Ic-band filter, for SME models with mass dimension d = 5 and d = 6, respectively. Using only a small system of telescopes with an effective 0.45-m aperture, we further demonstrate d = 5 constraints for individual lines of sight that are within a factor of ∼1-10 in sensitivity to comparable constraints from optical polarimetry with a 3.6-m telescope. Such an approach could significantly improve existing SME constraints via a polarimetric all-sky survey of AGN with multiple 1-meter class telescopes.

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Large Interstellar Polarisation Survey (LIPS)

Cited by 33 publications

References 51 publications

A Multiwavelength Search for Intrinsic Linear Polarization in Wolf–Rayet Winds

A Multiwavelength Search for Intrinsic Linear Polarization in Wolf–Rayet Winds

Spectropolarimetry of Galactic stars with anomalous extinction sightlines

Constraints on Lorentz invariance and CPT violation using optical photometry and polarimetry of active galaxies BL Lacertae and S5 B0716+714

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