Statistical Properties of Galactic Starlight Polarization

By Pablo Fosalba, A. Lazarian, S. Prunet, J. Tauber. 2001

132 citations recorded by the source corpus.

We present a statistical analysis of Galactic interstellar polarization from the largest compilation available of starlight data. The data comprises ~9300 stars, of which we have selected ~5500 for our analysis. We find a nearly linear growth of mean polarization degree with extinction. The amplitude of this correlation shows that interstellar grains are not fully aligned with the Galactic magnetic field, which can be interpreted as the effect of a large random component of the field. In agreement with earlier studies of more limited scope, we estimate the ratio of the uniform to the random plane-of-the-sky components of the magnetic field to be Bu/Br ≈ 0.8. Moreover, a clear correlation exists between polarization degree and polarization angle that provides evidence that the magnetic field geometry follows Galactic structures on large scales. The angular power spectrum Cℓ of the starlight polarization degree for Galactic plane data (|b| < 10°) is consistent with a power law, Cℓ ∝ ℓ-1.5 (where ℓ ≈ 180°/θ is the multipole order), for all angular scales θ ≳ 10′. An investigation of sparse and inhomogeneous sampling of the data shows that the starlight data analyzed traces an underlying polarized continuum that has the same power-spectrum slope, Cℓ ∝ ℓ-1.5. Our findings suggest that starlight data can be safely used for the modeling of Galactic polarized continuum emission at other wavelengths.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/1da20db5a1ba3e6af863eae170de0ffb0aec587b

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In Astronomy and Astrophysics

Citations in the corpus

Tracing Magnetic Fields with Aligned Grains (2007, background): “In fact, its potential for studies of magnetic fields in the Galaxy is enormous (see Fosalba et al. 2002, Cho & Lazarian 2002a).”
The pre-launch Planck Sky Model: a model of sky emission at submillimetre to centimetre wavelengths (2012, unknown): “The measured dust polarisation fraction is in rough agreement with what is expected from the polarisation of starlight (Fosalba et al. 2002).”
Planck2018 results (2018, background): “This upper limit is also smaller than the upper limit proposed by Fosalba et al. (2002) based”
The Spiral Arms and Interarm Separation of the Milky Way: An Updated Statistical Study (2005, background): “Fosalba et al. (2002) studied Galactic starlight polarization, with the vast majority of such measured stars being within 2 kpc of the Sun.”
Chemical similarities between Galactic bulge and local thick disk red giants: O, Na, Mg, Al, Si, Ca, and Ti (2010, background): “4.2 of Meléndez et al. 2006b; Ramı́rez et al. 2006) and polarization (e.g. Fosalba et al. 2002).”
Interstellar Turbulence II: Implications and Effects (2004, background): “It is also smaller than the integrated fluctuations found by scintillation on scales less than 3.5 pc, which give δB ∼ 0.9 µG and 〈B〉 ∼ 3 µG (Minter & Spangler 1997), and smaller than δB/B ∼ 1 from optical polarization (Heiles 1996, Fosalba et al. 2002).”
Three Year Wilkinson Microwave Anistropy Probe (WMAP) Observations: Polarization Analysis (2006, background): “Starlight Polarization and Polarized Dust Emission Measurements of starlight polarization serve as a template for the analysis of polarized microwave dust emission (Fosalba et al. 2002; Bernardi et al. 2003).”
Interstellar Turbulence I: Observations and Processes (2004, background): “Power spectra of optical starlight polarization over the whole sky have power-law structure too, with a slope of −1.5 for angles greater than ∼ 10 arcmin (Fosalba et al. 2002).”