Embedded Young Massive Star Clusters in the Antennae Merger

Abstract

The properties of young massive clusters (YMCs) are key to understanding the star formation mechanism in starburst systems, especially mergers. We present ALMA high-resolution ($\sim$10 pc) continuum (100 and 345 GHz) data of YMCs in the overlap region of the Antennae galaxy. We identify 6 sources in the overlap region, including two sources that lie in the same giant molecular cloud (GMC). These YMCs correspond well with radio sources in lower resolution continuum (100 and 220 GHz) images at GMC scales ($\sim$60 pc). We find most of these YMCs are bound clusters through virial analysis. We estimate their ages to be $\sim$1 Myr and to be either embedded or just beginning to emerge from their parent cloud. We also compare each radio source with Pa$\beta$ source and find they have consistent total ionizing photon numbers, which indicates they are tracing the same physical source. By comparing the free-free emission at $\sim$10 pc scale and $\sim$60 pc scale, we find that $\sim$50% of the free-free emission in GMCs actually comes from these YMCs. This indicates that roughly half of the stars in massive GMCs are formed in bound clusters. We further explore the mass correlation between YMCs and GMCs in the Antennae and find it generally agrees with the predictions of the star cluster simulations. The most massive YMC has a stellar mass that is 1% - 5% of its host GMC mass.

20 pages, 11 figures; accepted for publication in ApJ; added adjunct affliation

References in corpus (21)

• Theory of Star Formation
• ALMA Reveals the Molecular Medium Fueling the Nearest Nuclear Starburst
• Luminous Infrared Galaxies with the Submillimeter Array: I. Survey Overview and the Central Gas to Dust Ratio
• Star Cluster Demographics. I. A General Framework and Application to the Antennae Galaxies
• Studying the YMC population of M83: how long clusters remain embedded, their interaction with the ISM and implications for GC formation theories
• The molecular cloud lifecycle
• Super Star Cluster Velocity Dispersions and Virial Masses in the M82 Nuclear Starburst
• Modeling the Formation of Globular Cluster Systems in the Virgo Cluster
• ALMA Observations of the Antennae Galaxies: I. A New Window on a Prototypical Merger
• AUTO-MULTITHRESH: A General Purpose Automasking Algorithm
• Disruption of giant molecular clouds and formation of bound star clusters under the influence of momentum stellar feedback
• Radii of Young Star Clusters in Nearby Galaxies
• The Physical Conditions in a Pre Super Star Cluster Molecular Cloud in the Antennae Galaxies
• Star cluster formation in the most extreme environments: Insights from the HiPEEC survey
• H$\alpha$ Morphologies of Star Clusters: A LEGUS study of HII region evolution timescales and stochasticity in low mass clusters
• Emerging Massive Star Clusters Revealed: High Resolution Imaging of NGC 4449 from the Radio to the Ultraviolet
• Feedback in the Antennae Galaxies (NGC 4038/9): I. High-Resolution Infrared Spectroscopy of Winds from Super Star Clusters
• Probing Star Formation at Low Metallicity: The Radio Emission of Super Star Clusters in SBS0335-052
• Mass Functions of Giant Molecular Clouds and Young Star Clusters in Six Nearby Galaxies
• New Insights into the Physical Conditions and Internal Structure of a Candidate Proto-Globular Cluster
• Towards a More Complex Understanding of Natal Super Star Clusters with Multiwavelength Observations