# Widespread Molecular Outflows in the Infrared Dark Cloud G28.37+0.07: Indications of Orthogonal Outflow-Filament Alignment

## TL;DR

This study uses ALMA observations to analyze molecular outflows in the infrared dark cloud G28.37+0.07, revealing a predominant east-west outflow orientation and a strong tendency for outflows to be orthogonal to their parent filaments, suggesting specific formation mechanisms.

## Contribution

It provides the first detailed statistical analysis of outflow-filament orientation in a massive IRDC, highlighting the orthogonal alignment pattern and its potential implications for star formation theories.

## Key findings

- Outflows predominantly oriented east-west.
- Most outflows are orthogonal to their parent filaments.
- Supports models involving filament fragmentation and magnetic fields.

## Abstract

We present ALMA CO(2-1) observations toward a massive infrared dark cloud G28.37+0.07. The ALMA data reveal numerous molecular (CO) outflows with a wide range of sizes throughout the cloud. Sixty-two 1.3 mm continuum cores were identified to be driving molecular outflows. We have determined the position angle in the plane-of-sky of 120 CO outflow lobes and studied their distribution. We find that the distribution of the plane-of-sky outflow position angles peaks at about 100 degree, corresponding to a concentration of outflows with an approximately east-west direction. For most outflows, we have been able to estimate the plane-of-sky angle between the outflow axis and the filament that harbors the protostar that powers the outflow. Statistical tests strongly indicate that the distribution of outflow-filament orientations is consistent with most outflow axes being mostly orthogonal to their parent filament in 3D. Such alignment may result from filament fragmentation or continuous mass transportation from filament to the embedded protostellar core. The latter is suggested by recent numerical studies with moderately strong magnetic fields.