GASS High Velocity Clouds in the Region of the Magellanic Leading Arm

TL;DR

This paper catalogs 419 high-velocity clouds in the Magellanic Leading Arm using GASS data, analyzing their distribution, morphology, and implications for the Magellanic System's dynamics and formation processes.

Contribution

It provides a comprehensive catalog and analysis of high-velocity clouds in the Magellanic Leading Arm, highlighting the role of ram-pressure stripping over tidal forces.

Findings

Presence of numerous head-tail clouds suggests ram-pressure effects.

Identification of a new diffuse bridge-like feature between cloud complexes.

Different environmental conditions may explain morphological differences.

Abstract

We present a catalog of high-velocity clouds in the region of the Magellanic Leading Arm. The catalog is based on neutral hydrogen (\HI) observations from the Parkes Galactic All-Sky Survey (GASS). Excellent spectral resolution allows clouds with narrow-line components to be resolved. The total number of detected clouds is 419. We describe the method of cataloging and present the basic parameters of the clouds. We discuss the general distribution of the high-velocity clouds and classify the clouds based on their morphological type. The presence of a significant number of head-tail clouds and their distribution in the region is discussed in the context of Magellanic System simulations. We suggest that ram-pressure stripping is a more important factor than tidal forces for the morphology and formation of the Magellanic Leading Arm and that different environmental conditions might explain the morphological difference between the Magellanic Leading Arm and Magellanic Stream. We also discuss a newly identified population of clouds that forms the LA IV and a new diffuse bridge-like feature connecting the LA II and III complexes.