Astrophys. J., 829, L10-L10 (2016/September-3)
Clumpy and extended starbursts in the brightest unlensed submillimeter galaxies.
IONO D., YUN M.S., ARETXAGA I., HATSUKADE B., HUGHES D., IKARASHI S., IZUMI T., KAWABE R., KOHNO K., LEE M., MATSUDA Y., NAKANISHI K., SAITO T., TAMURA Y., UEDA J., UMEHATA H., WILSON G., MICHIYAMA T. and ANDO M.
Abstract (from CDS):
The central structure in three of the brightest unlensed z=3-4 submillimeter galaxies is investigated through 0.''015-0.''05 (120-360 pc) 860 µm continuum images obtained using the Atacama Large Millimeter/submillimeter Array (ALMA). The distribution in the central kiloparsec in AzTEC1 and AzTEC8 is extremely complex, and they are composed of multiple ∼200 pc clumps. AzTEC4 consists of two sources that are separated by ∼1.5 kpc, indicating a mid-stage merger. The peak star formation rate densities in the central clumps are ∼300-3000 M_☉ yr^-1 kpc^-2, suggesting regions with extreme star formation near the Eddington limit. By comparing the flux obtained by ALMA and Submillimeter Array, we find that 68%-90% of the emission is extended (>=1 kpc) in AzTEC4 and 8. For AzTEC1, we identify at least 11 additional compact (∼200 pc) clumps in the extended 3-4 kpc region. Overall, the data presented here suggest that the luminosity surface densities observed at <=150 pc scales are roughly similar to that observed in local ULIRGs, as in the eastern nucleus of Arp 220. Between 10% and 30% of the 860 µm continuum is concentrated in clumpy structures in the central kiloparsec, while the remaining flux is distributed over >=1 kpc regions, some of which could also be clumpy. These sources can be explained by a rapid inflow of gas such as a merger of gas-rich galaxies, surrounded by extended and clumpy starbursts. However, the cold mode accretion model is not ruled out.
© 2016. The American Astronomical Society. All rights reserved.
galaxies: evolution - galaxies: formation - galaxies: high-redshift - galaxies: starburst - galaxies: starburst
Table 3: clumps in AzTEC1 are not in SIMBAD.
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