The Circumnuclear Star Formation Environment of NGC 6946: Br-gamma and H2 Results from Keck Integral Field Spectroscopy

Abstract

We present a 3-dimensional data cube of the K band continuum and the Br-gamma, H2 S(0) and S(1) lines within the central 18.5" x 13.8" (520 pc x 390 pc) region of NGC 6946. Data were obtained using OSIRIS, a near-infrared Integral Field Unit at Keck Observatory, with Laser Guide Star Adaptive Optics. The 0.3" resolution allows us to investigate the stellar bulge and the forming star clusters in the nuclear region on 10 parsec scales. We detect giant HII regions associated with massive young star clusters in the nuclear spiral/ring (R ~ 30pc) and in the principal shocks along the nuclear bar. Comparisons of the Br-gamma fluxes with Pa-alpha line emission and radio continuum indicate A_K ~ 3, A_V ~ 25 for the nuclear star forming regions. The most luminous HII regions are restricted to within 70pc of the center, despite the presence of high gas columns at larger radii (R ~ 200pc). H2 emission is restricted to clouds within R ~ 60pc of the center, and in this sense resembles the distribution of the HCN line emission. We propose that gas-assisted migration of the young star clusters is contributing to the buildup of the nuclear bar and nuclear star cluster (R < 30pc) in this galaxy.

16 pages in emulateapj format, including 2 tables and 11 figures. To be published in ApJ

References in corpus (7)

• Bulgeless Giant Galaxies Challenge our Picture of Galaxy Formation by Hierarchical Clustering
• Molecular Gas Dynamics in NGC 6946: a Bar-driven Nuclear Starburst "Caught in the Act"
• CO(1-0), CO(2-1) and Neutral Gas in NGC 6946: Molecular Gas in a Late-Type, Gas Rich, Spiral Galaxy
• Nuclear Bar Catalyzed Star Formation: 13^CO, C18^O and Molecular Gas Properties in the Nucleus of Maffei 2
• Bar-Driven Mass Build-Up within the Central 50pc of NGC6946
• Subarcsecond-Resolution Radio Maps of Nearby Spiral Galaxies
• Locating the Youngest HII Regions in M82 with 7 mm Continuum Maps

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• Star Formation Rate in late-type galaxies: I- The H(alpha) and FUV integrated values
• Pa$\beta$, H$\alpha$, and Attenuation in NGC 5194 and NGC 6946