Starlight-polarization-based tomography of the magnetized ISM: PASIPHAE's line-of-sight inversion method
Journal article, 2023

We present the first Bayesian method for tomographic decomposition of the plane-of-sky orientation of the magnetic field with the use of stellar polarimetry and distance. This standalone tomographic inversion method presents an important step forward in reconstructing the magnetized interstellar medium (ISM) in three dimensions within dusty regions. We develop a model in which the polarization signal from the magnetized and dusty ISM is described by thin layers at various distances, a working assumption which should be satisfied in small-angular circular apertures. Our modeling makes it possible to infer the mean polarization (amplitude and orientation) induced by individual dusty clouds and to account for the turbulence-induced scatter in a generic way. We present a likelihood function that explicitly accounts for uncertainties in polarization and parallax. We develop a framework for reconstructing the magnetized ISM through the maximization of the log-likelihood using a nested sampling method. We test our Bayesian inversion method on mock data, representative of the high Galactic latitude sky, taking into account realistic uncertainties from Gaia and as expected for the optical polarization survey PASIPHAE according to the currently planned observing strategy. We demonstrate that our method is effective at recovering the cloud properties as soon as the polarization induced by a cloud to its background stars is higher than ~0.1% for the adopted survey exposure time and level of systematic uncertainty. The larger the induced polarization is, the better the method's performance, and the lower the number of required stars. Our method makes it possible to recover not only the mean polarization properties but also to characterize the intrinsic scatter, thus creating new ways to characterize ISM turbulence and the magnetic field strength. Finally, we apply our method to an existing data set of starlight polarization with known line-of-sight decomposition, demonstrating agreement with previous results and an improved quantification of uncertainties in cloud properties.

polarization

ISM: magnetic fields

Astrophysics - Astrophysics of Galaxies

ISM: structure

dust

extinction

methods: statistical

Astrophysics - Cosmology and Nongalactic Astrophysics

Author

Vincent Pelgrims

University of Crete

Foundation for Research and Technology Hellas (FORTH)

Georgia Panopoulou

California Institute of Technology (Caltech)

Konstantinos Tassis

University of Crete

Foundation for Research and Technology Hellas (FORTH)

Vasiliki Pavlidou

University of Crete

A. Basyrov

University of Oslo

Dmitriy Blinov

University of Crete

E. Gjerlow

University of Oslo

S. Kiehlmann

University of Crete

N. Mandarakas

University of Crete

A. Papadaki

University of Crete

Raphael Skalidis

Foundation for Research and Technology Hellas (FORTH)

University of Crete

A. Tsouros

University of Crete

R. M. Anche

Inter-University Centre for Astronomy and Astrophysics

H. K. Eriksen

University of Oslo

Tuhin Ghosh

National Institute of Science Education and Research

J. A. Kypriotakis

University of Crete

Siddharth Maharana

University of Crete

E. Ntormousi

University of Crete

Foundation for Research and Technology Hellas (FORTH)

T. J. Pearson

California Institute of Technology (Caltech)

S. B. Potter

South African Astronomical Observatory

Astronomy and Astrophysics

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

Vol. 670 id.A164

Subject Categories

Computational Mathematics

Astronomy, Astrophysics and Cosmology

DOI

10.1051/0004-6361/202244625

More information

Latest update

4/5/2024 8