Interstellar polarization at high galactic latitudes from distant stars

Berdyugin, A.; Piirola, V.; Teerikorpi, P.

doi:10.1051/0004-6361/201322604

Cited by 76 publications

(89 citation statements)

References 14 publications

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“…Foreground and background structures are difficult to distinguish when the shadowing interstellar material consists of magnetically organized dust structures with sub-parsec filaments and collapsing clouds. The Aquila Rift set of molecular clouds shadows the North Polar Spur X-ray emission [87,88] but do not negate the optical polarization data that show a local origin for the Loop I magnetic field [74,90]. Loop I and Loop IV are prominent high-latitude radio bubbles in galactic quadrants IV and I.…”

Section: Line-of-sight Blending Of Loop I and Loop Iv With Galactic Cmentioning

confidence: 81%

Effect of Supernovae on the Local Interstellar Material

Frisch¹,

Dwarkadas²

2016

Handbook of Supernovae

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A range of astronomical data indicates that ancient supernovae created the galactic environment of the Sun and sculpted the physical properties of the interstellar medium near the heliosphere. In this paper we review the characteristics of the local interstellar medium that have been affected by supernovae. The kinematics, magnetic field, elemental abundances, and configuration of the nearest interstellar material support the view that the Sun is at the edge of the Loop I superbubble, which has merged into the low density Local Bubble. The energy source for the higher temperature X-ray emitting plasma pervading the Local Bubble is uncertain. Winds from massive stars and nearby supernovae, perhaps from the Sco-Cen Association, may have contributed radioisotopes found in the geologic record and galactic cosmic ray population. Nested supernova shells in the Orion and Sco-Cen regions suggest spatially distinct sites of episodic star formation. The heliosphere properties vary with the pressure of the surrounding interstellar cloud. A nearby supernova would modify this pressure equilibrium and thereby severely disrupt the heliosphere as well as the local interstellar medium.

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Section: Line-of-sight Blending Of Loop I and Loop Iv With Galactic Cmentioning

confidence: 81%

Effect of Supernovae on the Local Interstellar Material

Frisch¹,

Dwarkadas²

2016

Handbook of Supernovae

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“…The 20th century data sets used in this analysis included the discovery of the ISMF within 40 pc of the Sun in the fourth galactic quadrant (ℓ = 270°-360°, Piirola 1977;Tinbergen 1982). More recently, high sensitivity polarimeters capable of 3σ detections of polarization strengths <0.01% have become available (Pereyra & Magalhães 2007;Wisniewski et al 2007;Bailey et al 2010Bailey et al , 2015Berdyugin et al 2014;Piirola et al 2014;.…”

Section: Polarization Data Used To Determine the Magnetic Field Direcmentioning

confidence: 99%

CHARTING THE INTERSTELLAR MAGNETIC FIELD CAUSING THEINTERSTELLAR BOUNDARY EXPLORER(IBEX) RIBBON OF ENERGETIC NEUTRAL ATOMS

Frisch

Berdyugin

Piirola

et al. 2015

ApJ

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The interstellar magnetic field (ISMF) near the heliosphere is a fundamental component of the solar galactic environment that can only be studied using polarized starlight. The results of an ongoing survey of the linear polarizations of local stars are analyzed with the goal of linking the ISMF that shapes the heliosphere to the nearby field in interstellar space. We present new results on the direction of the magnetic field within 40 pc obtained from analyzing polarization data using a merit function that determines the field direction that provides the best fit to the polarization data. Multiple magnetic components are identified, including a dominant interstellar field, B POL , that is aligned with the direction ℓ, b = 36°.2, 49°.0 (±16°.0). Stars tracing B POL have the same mean distance as stars that do not trace B POL , but show weaker average polarizations consistent with a smaller column density of polarizing material. B POL is aligned with the ISMF traced by the IBEX Ribbon to within 7.6 7.6 14.9 -+ degrees. The variations in the polarization position angle directions derived from the data that best match B POL indicate a low level of magnetic turbulence, ∼9°±1°. The direction of B POL is obtained after excluding polarization data tracing a separate magnetic structure that appears to be associated with interstellar dust deflected around the heliosphere. The velocities of local interstellar clouds relative to the Local Standard of Rest (LSR) increase with the angles between the LSR velocities and B POL , indicating that the kinematics of local interstellar material is ordered by the ISMF. The Loop I superbubble that extends close to the Sun contains dust that reddens starlight and whose distance is determined by the color excess E(B − V) of starlight. Polarizations caused by grains aligned with respect to B POL are consistent with the location of the Sun in the rim of the Loop I superbubble. An angle of 76.8 27.6 23.5 -+ between B POL and the bulk LSR velocity the local interstellar material indicates a geometry that is consistent with an expanding superbubble. The efficiency of grain alignment in the local interstellar medium has been assessed using stars where both polarization data and hydrogen column density data are available. Nearby stars appear to have larger polarizations than expected based on reddened sightlines, which is consistent with previous results, but uncertainties are large. Optical polarization and color excess E(B − V) data indicate the presence of nearby interstellar dust in the BICEP2 field. Color excess E(B − V) indicates an optical extinction of A V >0.6 in the BICEP2 field, while the polarization data indicate that A V >0.09 mag. The IBEX Ribbon ISMF extends to the boundaries of the BICEP2 region.

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“…Studies using multi-wavelength observations of diffuse emission (Puspitarini et al 2014) show that the local bubble appears to be open-ended toward the south galactic pole (SGP). Polarimetry from stars can be a useful probe (Berdyugin & Teerikorpi 2001;Berdyugin et al 2004Berdyugin et al , 2014;however, these are sparsely sampled for stars within the local bubble region (a few tens of parsecs to ∼100 pc). Observations of pulsars can also be used to probe conditions in the line of sight to the source (Mao et al 2010); however,the density of such sources is low, even more so if only nearby sources are considered and for directions at mid or high Galactic latitudes.…”

Section: Introductionmentioning

confidence: 99%

Low-Frequency Observations of Linearly Polarized Structures in the Interstellar Medium Near the South Galactic Pole

Lenc

Gaensler

Sun

et al. 2016

ApJ

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We present deep polarimetric observations at 154 MHz with the Murchison Widefield Array (MWA), covering 625 deg 2 centered on α=0 h andδ=−27°. The sensitivity available in our deep observations allows an in-band, frequency-dependent analysis of polarized structure for the first time at long wavelengths. Our analysis suggests that the polarized structures are dominated by intrinsic emission but may also have a foreground Faraday screen component. At these wavelengths, the compactness of the MWA baseline distribution provides excellent snapshot sensitivity to large-scale structure. The observations are sensitive to diffuse polarized emission at ∼54′ resolution with a sensitivity of 5.9 mJy beam −1 and compact polarized sources at ∼2 4 resolution with a sensitivity of 2.3 mJy beam −1 for a subset (400 deg 2 ) of this field. The sensitivity allows the effect of ionospheric Faraday rotation to be spatially and temporally measured directly from the diffuse polarized background. Our observations reveal large-scale structures (∼1°-8°in extent) in linear polarization clearly detectable in ∼2 minute snapshots, which would remain undetectable by interferometers with minimum baseline lengths of >110 m at 154 MHz. The brightness temperature of these structures is on average 4 K in polarized intensity, peaking at 11 K. Rotation measure synthesis reveals that the structures have Faraday depths ranging from −2 to 10 rad m −2 with a large fraction peaking at approximately+1 rad m −2 . We estimate a distance of 51±20 pc to the polarized emission based on measurements of the in-field pulsar J2330-2005. We detect four extragalactic linearly polarized point sources within the field in our compact source survey. Based on the known polarized source population at 1.4 GHz and non-detections at 154 MHz, we estimate an upper limit on the depolarization ratio of 0.08 from 1.4 GHz to 154 MHz.

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Interstellar polarization at high galactic latitudes from distant stars

Cited by 76 publications

References 14 publications

Effect of Supernovae on the Local Interstellar Material

Effect of Supernovae on the Local Interstellar Material

CHARTING THE INTERSTELLAR MAGNETIC FIELD CAUSING THEINTERSTELLAR BOUNDARY EXPLORER(IBEX) RIBBON OF ENERGETIC NEUTRAL ATOMS

Low-Frequency Observations of Linearly Polarized Structures in the Interstellar Medium Near the South Galactic Pole

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