# First results from BISTRO -- a SCUBA-2 polarimeter survey of the Gould Belt

## TL;DR

This paper presents initial findings from the BISTRO survey using SCUBA-2 polarimetry to study magnetic fields in star-forming regions, revealing their orientation relative to dense filaments and supporting theoretical models.

## Contribution

First observational results from the BISTRO survey demonstrating magnetic field morphologies in star-forming filaments and their alignment with theoretical predictions.

## Key findings

- Magnetic fields are perpendicular to dense filaments in the Orion Molecular Cloud.
- An hour-glass magnetic field morphology extends beyond dense regions.
- Field orientations are consistent with models predicting parallel fields in low-density filaments.

## Abstract

We present the first results from the B-fields In STar-forming Region Observations (BISTRO) survey, using the Sub-millimetre Common-User Bolometer Array 2 (SCUBA-2) camera, with its associated polarimeter (POL-2), on the James Clerk Maxwell Telescope (JCMT) in Hawaii. We discuss the survey's aims and objectives. We describe the rationale behind the survey, and the questions which the survey will aim to answer. The most important of these is the role of magnetic fields in the star formation process on the scale of individual filaments and cores in dense regions. We describe the data acquisition and reduction processes for POL-2, demonstrating both repeatability and consistency with previous data. We present a first-look analysis of the first results from the BISTRO survey in the OMC 1 region. We see that the magnetic field lies approximately perpendicular to the famous 'integral filament' in the densest regions of that filament. Furthermore, we see an 'hour-glass' magnetic field morphology extending beyond the densest region of the integral filament into the less-dense surrounding material, and discuss possible causes for this. We also discuss the more complex morphology seen along the Orion Bar region. We examine the morphology of the field along the lower-density north-eastern filament. We find consistency with previous theoretical models that predict magnetic fields lying parallel to low-density, non-self-gravitating filaments, and perpendicular to higher-density, self-gravitating filaments.