Year: 2006
Type: article
Abstract: The central 2 × 1 kpc of the starburst galaxy NGC 253 have been imaged using the Submillimeter Array at a 60 pc resolution in the J = 2-1 transitions of 12 CO, 13 CO, and C 18 O, as well as in the 1.3 mm continuum. Molecular gas and dust are distributed mainly in a circumnuclear disk of ~500 pc radius, with warm (~40 K) and high area filling factor gas in its central part. Two gas shells or cavities have been discovered in the circumnuclear disk. They have ~100 pc diameters and have large velocity widths of 80-100 km s -1 , suggestive of expansion at ~50 km s -1 . Modeled as an expanding bubble, each shell has an age of ~0.5 Myr and needed kinetic energy of ~1 × 10 46 J, as well as mean mechanical luminosity of ~1 × 10 33 W, for its formation. The large energy allows each to be called a superbubble. A ~10 6 M ☉ super star cluster can provide the luminosity and could be a building block of the nuclear starburst in NGC 253. Alternatively, a hypernova can also be the main source of energy for each superbubble, not only because it can provide the mechanical energy and luminosity but also because the estimated rate of superbubble formation and that of hypernova explosions are comparable. Our observations indicate that the circumnuclear molecular disk harboring the starburst is highly disturbed on 100 pc or smaller scales, presumably by individual young clusters and stellar explosions, in addition to being globally disturbed in the form of the well-known superwind.
Source: The Astrophysical Journal
DOI: 10.1086/498075
Authors: Kazushi Sakamoto, Paul T. P. Ho, Daisuke Iono, Eric R. Keto, Rui‐Qing Mao, Satoki Matsushita, Alison B. Peck, Martina C. Wiedner, David J. Wilner, Jun‐Hui Zhao
Institutions: Harvard University, Smithsonian Astrophysical Observatory, Center for Astrophysics Harvard & Smithsonian, National Astronomical Observatory of Japan, Chinese Academy of Sciences, Purple Mountain Observatory, Institute of Astronomy and Astrophysics, Academia Sinica, Academia Sinica, University of Cologne
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W1997630701