3D structure of the Milky Way out to 10 kpc from the Sun

Catalogue of large molecular clouds in the Galactic Plane

¹ Max-Planck-Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
² Chalmers University of Technology, Department of Space, Earth and Environment, 412 93 Gothenburg, Sweden
³ Department of Physics, University of Wisconsin-Whitewater, Whitewater, WI 53190, USA
⁴ Physics Department and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge MA 02139, USA
⁵ Laboratoire de Physique de l’École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France
⁶ Observatorio Astronómico Nacional (IGN), C/Alfonso XII 3, 28014 Madrid, Spain
⁷ Centro de Desarrollos Tecnológicos, Observatorio de Yebes (IGN), 19141 Yebes, Guadalajara, Spain

^★ Corresponding author; s.rezaei.kh@gmail.com

Received: 17 January 2024
Accepted: 24 October 2024

Abstract

Understanding the 3D structure of the Milky Way is a crucial step in deriving properties of the star-forming regions, as well as the Galaxy as a whole. We present a novel 3D map of the Milky Way plane that extends to 10 kpc distance from the Sun. We leverage the wealth of information in the near-infrared dataset of the Sloan Digital Sky Survey’s Apache Point Observatory Galactic Evolution Experiment (APOGEE) and combine that with our state-of-the-art 3D mapping technique using Bayesian statistics and the Gaussian process to provide a large-scale 3D map of the dust in the Milky Way. Our map stretches across 10 kpc along both the X and Y axes, and 750 pc in the Z direction, perpendicular to the Galactic plane. Our results reveal multi-scale over-densities as well as large cavities in the Galactic plane and shed new light on the Galactic structure and spiral arms. We also provide a catalogue of large molecular clouds identified by our map with accurate distance and volume density estimates. Utilising volume densities derived from this map, we explore mass distribution across various galactocentric radii. A general decline towards the outer Galaxy is observed, followed by local peaks, some aligning with established features such as the molecular ring and segments of the spiral arms. Moreover, this work explores extragalactic observational effects on derived properties of molecular clouds by demonstrating the potential biases arising from column density measurements in inferring properties of these regions, and opens exciting avenues for further exploration and analysis, offering a deeper perspective on the complex processes that shape our galaxy and beyond.