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arXiv · 2412.03644

A nuclear spiral in a dusty star-forming galaxy at $z=2.78$

H. R. Stacey·M. Kaasinen·C. M. O'Riordan·J. P. McKean·D. M. Powell·F. Rizzo
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Abstract

The nuclear structure of dusty star-forming galaxies is largely unexplored but harbours critical information about their structural evolution. Here, we present long-baseline Atacama Large (sub-)Millimetre Array (ALMA) continuum observations of a gravitationally lensed dusty star-forming galaxy at $z=2.78$. We use a pixellated lens modelling analysis to reconstruct the rest-frame 230 $\rm\mu$m dust emission with a mean resolution of $\approx55$ pc and demonstrate that the inferred source properties are robust to changes in lens modelling methodology. The central 1 kpc is characterised by an exponential profile, a dual spiral arm morphology and an apparent super-Eddington compact central starburst. We find tentative evidence for a nuclear bar in the central 300 pc. These features may indicate that secular dynamical processes play a role in accumulating a high concentration of cold gas that fuels the rapid formation of a compact stellar spheroid and black hole accretion. We propose that the high spatial resolution provided by long-baseline ALMA observations and strong gravitational lensing will give key insights into the formation mechanisms of massive galaxies.

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H. R. Stacey, M. Kaasinen, C. M. O'Riordan, J. P. McKean, D. M. Powell, F. Rizzo. 2024-12-04. A nuclear spiral in a dusty star-forming galaxy at $z=2.78$. https://doi.org/10.1051/0004-6361%2F202452518

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