The first degree-scale starlight-polarization-based tomography map of the magnetized interstellar medium
Journal article, 2024

We present the first degree-scale tomography map of the dusty magnetized interstellar medium (ISM) from stellar polarimetry and distance measurements. We used the RoboPol polarimeter at Skinakas Observatory to conduct a survey of the polarization of starlight in a region of the sky of about four square degrees. We propose a Bayesian method to decompose the stellar-polarization source field along the distance to invert the three-dimensional (3D) volume occupied by the observed stars. We used this method to obtain the first 3D map of the dusty magnetized ISM. Specifically, we produced a tomography map of the orientation of the plane-of-sky component of the magnetic field threading the diffuse, dusty regions responsible for the stellar polarization. For the targeted region centered on Galactic coordinates (l, b) (103.3, 22.3), we identified several ISM clouds. Most of the lines of sight intersect more than one cloud. A very nearby component was detected in the foreground of a dominant component from which most of the polarization signal comes and which we identified as being an intersection of the wall of the Local Bubble and the Cepheus Flare. Farther clouds, with a distance of up to 2 kpc, were similarly detected. Some of them likely correspond to intermediate-velocity clouds seen in H I spectra in this region of the sky. We found that the orientation of the plane-of-sky component of the magnetic field changes along distance for most of the lines of sight. Our study demonstrates that starlight polarization data coupled to distance measures have the power to reveal the great complexity of the dusty magnetized ISM in 3D and, in particular, to provide local measurements of the plane-of-sky component of the magnetic field in dusty regions. This demonstrates that the inversion of large data volumes, as expected from the PASIPHAE survey, will provide the necessary means to move forward in the modeling of the Galactic magnetic field and of the dusty magnetized ISM as a contaminant in observations of the cosmic microwave background polarization.

ISM: structure

ISM: magnetic fields

Dust, extinction

Polarization

Methods: statistical

Author

V. Pelgrims

University of Crete

Foundation for Research and Technology Hellas (FORTH)

Université libre de Bruxelles (ULB)

N. Mandarakas

Foundation for Research and Technology Hellas (FORTH)

University of Crete

R. Skalidis

California Institute of Technology (Caltech)

Konstantinos Tassis

Foundation for Research and Technology Hellas (FORTH)

University of Crete

Georgia Virginia Panopoulou

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

V. Pavlidou

Foundation for Research and Technology Hellas (FORTH)

University of Crete

D. Blinov

Foundation for Research and Technology Hellas (FORTH)

University of Crete

S. Kiehlmann

Foundation for Research and Technology Hellas (FORTH)

University of Crete

S. E. Clark

Stanford University

Kavli Institute for Particle Astrophysics and Cosmology

Brandon S. Hensley

California Institute of Technology (Caltech)

S. Romanopoulos

University of Crete

Foundation for Research and Technology Hellas (FORTH)

A. Basyrov

University of Oslo

H. K. Eriksen

University of Oslo

M. Falalaki

Foundation for Research and Technology Hellas (FORTH)

University of Crete

T. Ghosh

Homi Bhabha National Institute (HBNI)

Inter-University Centre for Astronomy and Astrophysics

E. Gjerløw

University of Oslo

J. A. Kypriotakis

University of Crete

Foundation for Research and Technology Hellas (FORTH)

S. Maharana

South African Astronomical Observatory

A. Papadaki

University of Crete

Foundation for Research and Technology Hellas (FORTH)

Institute of Computer Science Crete

T. J. Pearson

California Institute of Technology (Caltech)

S. B. Potter

University of Johannesburg

South African Astronomical Observatory

A. N. Ramaprakash

Université libre de Bruxelles (ULB)

California Institute of Technology (Caltech)

Inter-University Centre for Astronomy and Astrophysics

A. C.S. Readhead

California Institute of Technology (Caltech)

I. K. Wehus

University of Oslo

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 684

Subject Categories

Astronomy, Astrophysics and Cosmology

DOI

10.1051/0004-6361/202349015

More information

Latest update

5/13/2024