ngVLA Synthetic Observations of Ionized Gas in Massive Protostars

Abstract

Massive star formation involves significant ionization in the innermost regions near the central object, such as gravitationally trapped H II regions, jets, ionized disks, or winds. Resolved observations of the associated continuum and recombination line emission are crucial for guiding theory. The next-generation Very Large Array (ngVLA) will enable unprecedented observations of thermal emission with 1 mas resolution, providing a new perspective on massive star formation at scales down to a few astronomical units at kiloparsec distances. This work presents synthetic interferometric ngVLA observations of the free-free continuum (93-GHz band), $H41\alpha$, and $H38\alpha$ recombination lines from ionized jets and disks around massive protostars. Using the sf3dmodels Python package, we generate gas distributions based on analytical models, which are then processed through the RADMC-3D radiative transfer code. Our results indicate that the ngVLA can easily resolve, both spatially and spectrally, the ionized jet from a 15 ${\mathrm{M}}_{\odot }$ protostar at 700 pc, distinguishing between collimated jets and wide-angle winds, and resolving their launching radii, widths, and any substructure down to a few astronomical units. Detailed studies of radio jets launched by massive protostars will be feasible up to distances of $\sim 2$ kpc. Furthermore, ngVLA will be able to study in detail the ionized disks around massive ($>10{\mathrm{M}}_{\odot }$) protostars up to distances from 4 to 12 kpc, resolving their kinematics and enabling the measurement of their central masses across the Galaxy. These observations can be conducted with on-source integrations of only a few hours.

Accepted for publication in ApJ

References in corpus (20)

• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• CASA, the Common Astronomy Software Applications for Radio Astronomy
• Understanding Spatial and Spectral Morphologies of Ultracompact H II Regions
• Weak and Compact Radio Emission in Early High-Mass Star Forming Regions: I. VLA Observations
• An Asymmetric Keplerian Disk Surrounding the O-type Protostar IRAS16547$-$4247
• Kinematics of the Outflow From The Young Star DG Tau B: Rotation in the vicinities of an optical jet
• ALMA-IMF II -- investigating the origin of stellar masses: Continuum Images and Data Processing
• Understanding hydrogen recombination line observations with ALMA and EVLA
• A Galactic survey of radio jets from massive protostars
• A Unified Model for Bipolar Outflows from Young Stars: Kinematic Signatures of Jets, Winds, and Their Magnetic Interplay with the Ambient Toroids
• Dynamics of a Massive Binary at Birth
• The evolution of temperature and density structures of OB cluster-forming molecular clumps
• Kinematics and stability of high-mass protostellar disk candidates at sub-arcsecond resolution -- Insights from the IRAM NOEMA large program CORE
• ALMA-IMF. VII. First release of the full spectral line cubes: Core kinematics traced by DCN J=(3-2)
• Zooming into the Collimation Zone in a Massive Protostellar Jet
• Discovery of a Photoionized Bipolar Outflow towards the Massive Protostar G45.47+0.05
• Simulated observations of star formation regions: infrared evolution of globally collapsing clouds
• Resolving the collimation zone of an intermediate-mass protostar
• Clustered Formation of Massive Stars within an Ionized Rotating Disk
• A high-resolution radio study of the L1551 IRS 5 and L1551 NE jets