Chaotic and Clumpy Galaxy Formation in an Extremely Massive Reionization-era Halo uri icon

abstract

  • Abstract The SPT 031158 system at z = 6.900 is an extremely massive structure within the reionization epoch and offers a chance to understand the formation of galaxies at an extreme peak in the primordial density field. We present 70 mas Atacama Large Millimeter/submillimeter Array observations of the dust continuum and [C ii] 158 m emission in the central pair of galaxies and reach physical resolutions of 100350 pc, among the most detailed views of any reionization-era system to date. The observations resolve the source into at least a dozen kiloparsec-size clumps. The global kinematics and high turbulent velocity dispersion within the galaxies present a striking contrast to recent claims of dynamically cold thin-disk kinematics in some dusty galaxies just 800 Myr later at z 4. We speculate that both gravitational interactions and fragmentation from massive parent disks have likely played a role in the overall dynamics and formation of clumps in the system. Each clump individually is comparable in mass to other 6 < z < 8 galaxies identified in rest-UV/optical deep field surveys, but with star formation rates elevated by a factor of ~3-5. Internally, the clumps themselves bear close resemblance to greatly scaled-up versions of virialized cloud-scale structures identified in low-redshift galaxies. Our observations are qualitatively similar to the chaotic and clumpy assembly within massive halos seen in simulations of high-redshift galaxies.

published proceedings

  • ASTROPHYSICAL JOURNAL LETTERS

author list (cited authors)

  • Spilker, J. S., Hayward, C. C., Marrone, D. P., Aravena, M., Bethermin, M., Burgoyne, J., ... Weiss, A.

complete list of authors

  • Spilker, Justin S||Hayward, Christopher C||Marrone, Daniel P||Aravena, Manuel||Bethermin, Matthieu||Burgoyne, James||Chapman, Scott C||Greve, Thomas R||Gururajan, Gayathri||Hezaveh, Yashar D||Hill, Ryley||Litke, Katrina C||Lovell, Christopher C||Malkan, Matthew A||Murphy, Eric J||Narayanan, Desika||Phadke, Kedar A||Reuter, Cassie||Stark, Antony A||Sulzenauer, Nikolaus||Vieira, Joaquin D||Vizgan, David||Weiss, Axel

publication date

  • April 2022