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外文期刊>The Astrophysical journal
>WITNESSING THE BIRTH OF THE RED SEQUENCE: ALMA HIGH-RESOLUTION IMAGING OF [C II] AND DUST IN TWO INTERACTING ULTRA-RED STARBURSTS AT z = 4.425
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WITNESSING THE BIRTH OF THE RED SEQUENCE: ALMA HIGH-RESOLUTION IMAGING OF [C II] AND DUST IN TWO INTERACTING ULTRA-RED STARBURSTS AT z = 4.425
Exploiting the sensitivity and spatial resolution of the Atacama Large Millimeter/submillimeter Array, we have studied the morphology and the physical scale of the interstellar medium—both gas and dust—in SGP?38326, an unlensed pair of interacting starbursts at z = 4.425. SGP?38326 is the most luminous star bursting system known at z??4, with a total IR luminosity of L IR?~?2.5?×?1013 L ⊙ and a star formation rate of?~?4500 M ⊙ yr?1. SGP?38326 also contains a molecular gas reservoir among the most massive yet found in the early universe, and it is the likely progenitor of a massive, red-and-dead elliptical galaxy at z?~?3. Probing scales of ~01 or ~800 pc we find that the smooth distribution of the continuum emission from cool dust grains contrasts with the more irregular morphology of the gas, as traced by the [C ii] fine structure emission. The gas is also extended over larger physical scales than the dust. The velocity information provided by the resolved [C ii] emission reveals that the dynamics of the two interacting components of SGP?38326 are each compatible with disk-like, ordered rotation, but also reveals an ISM which is turbulent and unstable. Our observations support a scenario where at least a subset of the most distant extreme starbursts are highly dissipative mergers of gas-rich galaxies.
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