The Outer Scale of Turbulence in the Magnetoionized Galactic Interstellar Medium
By M. Haverkorn, Jo-Anne C. Brown, B. Gaensler, N. McClure-Griffiths. 2008
185 citations recorded by the source corpus.
We analyze Faraday rotation and depolarization of extragalactic radio point sources in the direction of the inner Galactic plane to determine the outer scale and amplitude of the rotation measure power spectrum. Structure functions of rotation measure show lower amplitudes than expected when extrapolating electron density fluctuations to large scales assuming a Kolmogorov spectral index. This implies an outer scale of those fluctuations on the order of a parsec, much smaller than commonly assumed. Analysis of the partial depolarization of point sources independently indicates a small outer scale of a Kolmogorov power spectrum. In the Galaxy’s spiral arms, no rotation measure fluctuations on scales above a few parsecs are measured. In the interarm regions fluctuations on larger scales than in spiral arms are present, and show power-law behavior with a shallow spectrum. These results suggest that in the spiral arms stellar sources such as stellar winds or protostellar outflows dominate the energy injection for the turbulent energy cascade on parsec scales, while in the interarm regions supernova and superbubble explosions are the main sources of energy on scales on the order of 100 pc.
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/fdc2c29f6025908ab446e600e848ca10458934ed
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In Astronomy and Astrophysics
Citations in the corpus
- THE GALACTIC MAGNETIC FIELD (2012, background): “The random fields are due to a number of phenomena including supernovae and other outflows, possibly compounded by hydrodynamic turbulence, which are expected to result in randomly-oriented fields with a coherence length λ of order 100 pc or less (Gaensler & Johnston 1995; Haverkorn et al. 2008).”
- A NEW MODEL OF THE GALACTIC MAGNETIC FIELD (2012, background): “The latter are due to a variety of phenomena including supernovae and other outflows, possibly compounded by hydrodynamic turbulence, which are expected to result in randomly-oriented fields with a coherence length λ of order 100 pc or less (Gaensler & Johnston 1995; Haverkorn et al. 2008).”
- ASTROPHYSICAL GYROKINETICS: KINETIC AND FLUID TURBULENT CASCADES IN MAGNETIZED WEAKLY COLLISIONAL PLASMAS (2007, background): “…in the arms and interarms has been attributed to smaller effective outer scale in the arms (∼ 1 pc, compared to∼ 102 pc in the interarms; see Haverkorn et al. 2008) or to the turbulence in the arms and interarms belonging to the two distinct asymptotic regimes described in § 1.3: closer…”
- An improved map of the Galactic Faraday sky (2011, methodology): “Haverkorn et al. (2006a) and Haverkorn et al. (2008) studied observations through interarm regions in the Galactic plane separately from observations along Galactic arms.”
- EXTENDING THE BIG POWER LAW IN THE SKY WITH TURBULENCE SPECTRA FROM WISCONSIN Hα MAPPER DATA (2009, methodology): “For instance, Haverkorn et al. (2008) used the Southern Galactic Plane Survey data and concluded that the injection scale of the turbulence in the spiral arms of the Galaxy should be rather small (e.g., on the order of a parsec) while a much larger (e.g., on the order of 100 pc) outer scale is…”
- Planck intermediate results. XIX. An overview of the polarized thermal emission from Galactic dust (2014, background): “Because a source’s degree of polarization anti-correlates with the standard deviation of the RM due to turbulent depolarization (Haverkorn et al. 2008), we might expect a positive correlation in the degree of polarization of the sources compared to the Galactic dust emission if the two observables…”
- COrE (Cosmic Origins Explorer) A White Paper (2011, unknown): “[172]) or dissipative scales will be challenging.”