The first degree-scale starlight-polarization-based tomography map of the magnetized interstellar medium

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Main Authors: Pelgrims, V., Mandarakas, N., Skalidis, R., Tassis, K., Panopoulou, G. V., Pavlidou, V., Blinov, D., Kiehlmann, S., Clark, S. E., Hensley, B. S., Romanopoulos, S., Basyrov, A., Eriksen, H. K., Falalaki, M., Ghosh, T., Gjerløw, E., Kypriotakis, J. A., Maharana, S., Papadaki, A., Pearson, T. J., Potter, S. B., Ramaprakash, A. N., Readhead, A. C. S., Wehus, I. K.
Format: Preprint
Published: 2024
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author Pelgrims, V.
Mandarakas, N.
Skalidis, R.
Tassis, K.
Panopoulou, G. V.
Pavlidou, V.
Blinov, D.
Kiehlmann, S.
Clark, S. E.
Hensley, B. S.
Romanopoulos, S.
Basyrov, A.
Eriksen, H. K.
Falalaki, M.
Ghosh, T.
Gjerløw, E.
Kypriotakis, J. A.
Maharana, S.
Papadaki, A.
Pearson, T. J.
Potter, S. B.
Ramaprakash, A. N.
Readhead, A. C. S.
Wehus, I. K.
author_facet Pelgrims, V.
Mandarakas, N.
Skalidis, R.
Tassis, K.
Panopoulou, G. V.
Pavlidou, V.
Blinov, D.
Kiehlmann, S.
Clark, S. E.
Hensley, B. S.
Romanopoulos, S.
Basyrov, A.
Eriksen, H. K.
Falalaki, M.
Ghosh, T.
Gjerløw, E.
Kypriotakis, J. A.
Maharana, S.
Papadaki, A.
Pearson, T. J.
Potter, S. B.
Ramaprakash, A. N.
Readhead, A. C. S.
Wehus, I. K.
contents 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 starlight polarization in a region of the sky of 4 square degrees. We propose a Bayesian method to decompose the stellar-polarization source field along the distance to invert the 3D volume occupied by the observed stars. We used it 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 (POS) component of the magnetic field threading the diffuse, dusty regions responsible for the stellar polarization. For the targeted region centered on Galactic coordinates $(l,b) \approx (103.3^\circ, 22.3^\circ)$, 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. Farther clouds, with a distance of up to 2~kpc, were similarly detected. Some of them likely correspond to intermediate-velocity clouds seen in HI spectra in this region of the sky. We found that the orientation of the POS 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 POS component of the magnetic field. 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.
format Preprint
id arxiv_https___arxiv_org_abs_2404_10821
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The first degree-scale starlight-polarization-based tomography map of the magnetized interstellar medium
Pelgrims, V.
Mandarakas, N.
Skalidis, R.
Tassis, K.
Panopoulou, G. V.
Pavlidou, V.
Blinov, D.
Kiehlmann, S.
Clark, S. E.
Hensley, B. S.
Romanopoulos, S.
Basyrov, A.
Eriksen, H. K.
Falalaki, M.
Ghosh, T.
Gjerløw, E.
Kypriotakis, J. A.
Maharana, S.
Papadaki, A.
Pearson, T. J.
Potter, S. B.
Ramaprakash, A. N.
Readhead, A. C. S.
Wehus, I. K.
Astrophysics of Galaxies
Instrumentation and Methods for Astrophysics
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 starlight polarization in a region of the sky of 4 square degrees. We propose a Bayesian method to decompose the stellar-polarization source field along the distance to invert the 3D volume occupied by the observed stars. We used it 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 (POS) component of the magnetic field threading the diffuse, dusty regions responsible for the stellar polarization. For the targeted region centered on Galactic coordinates $(l,b) \approx (103.3^\circ, 22.3^\circ)$, 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. Farther clouds, with a distance of up to 2~kpc, were similarly detected. Some of them likely correspond to intermediate-velocity clouds seen in HI spectra in this region of the sky. We found that the orientation of the POS 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 POS component of the magnetic field. 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.
title The first degree-scale starlight-polarization-based tomography map of the magnetized interstellar medium
topic Astrophysics of Galaxies
Instrumentation and Methods for Astrophysics
url https://arxiv.org/abs/2404.10821