TY - JOUR

T1 - Demonstration of Magnetic Field Tomography with Starlight Polarization toward a Diffuse Sightline of the ISM

AU - Panopoulou, Georgia V.

AU - Tassis, Konstantinos

AU - Skalidis, Raphael

AU - Blinov, Dmitriy

AU - Liodakis, Ioannis

AU - Pavlidou, Vasiliki

AU - Potter, Stephen B.

AU - Ramaprakash, Anamparambu N.

AU - Readhead, Anthony C.S.

AU - Wehus, Ingunn K.

PY - 2019/2/10

Y1 - 2019/2/10

N2 - The availability of large data sets with stellar distance and polarization information will enable a tomographic reconstruction of the (plane-of-the-sky-projected) interstellar magnetic field in the near future. We demonstrate the feasibility of such a decomposition within a small region of the diffuse interstellar medium (ISM). We combine measurements of starlight (R-band) linear polarization obtained using the RoboPol polarimeter with stellar distances from the second Gaia data release. The stellar sample is brighter than 17 mag in the R-band and reaches out to several kiloparsecs from the Sun. H i emission spectra reveal the existence of two distinct clouds along the line of sight. We decompose the line-of-sight-integrated stellar polarizations to obtain the mean polarization properties of the two clouds. The two clouds exhibit significant differences in terms of column density and polarization properties. Their mean plane-of-the-sky magnetic field orientation differs by 60°. We show how our tomographic decomposition can be used to constrain our estimates of the polarizing efficiency of the clouds as well as the frequency dependence of the polarization angle of polarized dust emission. We also demonstrate a new method to constrain cloud distances based on this decomposition. Our results represent a preview of the wealth of information that can be obtained from a tomographic map of the ISM magnetic field.

AB - The availability of large data sets with stellar distance and polarization information will enable a tomographic reconstruction of the (plane-of-the-sky-projected) interstellar magnetic field in the near future. We demonstrate the feasibility of such a decomposition within a small region of the diffuse interstellar medium (ISM). We combine measurements of starlight (R-band) linear polarization obtained using the RoboPol polarimeter with stellar distances from the second Gaia data release. The stellar sample is brighter than 17 mag in the R-band and reaches out to several kiloparsecs from the Sun. H i emission spectra reveal the existence of two distinct clouds along the line of sight. We decompose the line-of-sight-integrated stellar polarizations to obtain the mean polarization properties of the two clouds. The two clouds exhibit significant differences in terms of column density and polarization properties. Their mean plane-of-the-sky magnetic field orientation differs by 60°. We show how our tomographic decomposition can be used to constrain our estimates of the polarizing efficiency of the clouds as well as the frequency dependence of the polarization angle of polarized dust emission. We also demonstrate a new method to constrain cloud distances based on this decomposition. Our results represent a preview of the wealth of information that can be obtained from a tomographic map of the ISM magnetic field.

KW - ISM: clouds

KW - ISM: magnetic fields

KW - techniques: polarimetric Supporting material: machine-readable table

KW - VELOCITY

KW - CLOUD

KW - DENSITY

KW - DUST

KW - PLEIADES CLUSTER

KW - INTERSTELLAR POLARIZATION

KW - WAVELENGTH DEPENDENCE

KW - STARS

KW - STELLAR POLARIZATION

KW - techniques: polarimetric

KW - POSITION ANGLE

UR - http://www.scopus.com/inward/record.url?scp=85062034510&partnerID=8YFLogxK

UR - http://www.mendeley.com/research/demonstration-magnetic-field-tomography-starlight-polarization-toward-diffuse-sightline-ism

U2 - 10.3847/1538-4357/aafdb2

DO - 10.3847/1538-4357/aafdb2

M3 - Article

VL - 872

SP - 56

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

M1 - 56

ER -