TY - JOUR

T1 - Chaotic and Clumpy Galaxy Formation in an Extremely Massive Reionization-era Halo

AU - Spilker, Justin S.

AU - Hayward, Christopher C.

AU - Marrone, Daniel P.

AU - Aravena, Manuel

AU - Bethermin, Matthieu

AU - Burgoyne, James

AU - Chapman, Scott C.

AU - Greve, Thomas R.

AU - Gururajan, Gayathri

AU - Hezaveh, Yashar D.

AU - Hill, Ryley

AU - Litke, Katrina C.

AU - Lovell, Christopher C.

AU - Malkan, Matthew A.

AU - Murphy, Eric J.

AU - Narayanan, Desika

AU - Phadke, Kedar A.

AU - Reuter, Cassie

AU - Stark, Antony A.

AU - Sulzenauer, Nikolaus

AU - Vieira, Joaquin D.

AU - Vizgan, David

AU - Weiss, Axel

PY - 2022/4/1

Y1 - 2022/4/1

N2 - The SPT 0311-58 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 mu m emission in the central pair of galaxies and reach physical resolutions of similar to 100-350 pc, among the most detailed views of any reionization-era system to date. The observations resolve the source into at least a dozen kiloparsecsize 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 similar to 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 similar to 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.

AB - The SPT 0311-58 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 mu m emission in the central pair of galaxies and reach physical resolutions of similar to 100-350 pc, among the most detailed views of any reionization-era system to date. The observations resolve the source into at least a dozen kiloparsecsize 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 similar to 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 similar to 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.

KW - High-redshift galaxies

KW - Starburst galaxies

KW - STAR-FORMING GALAXIES

KW - MOLECULAR GAS

KW - DUSTY

KW - REDSHIFT

KW - CATALOGS

U2 - 10.3847/2041-8213/ac61e6

DO - 10.3847/2041-8213/ac61e6

M3 - Letter

VL - 929

JO - The Astrophysical Journal Letters

JF - The Astrophysical Journal Letters

SN - 2041-8205

IS - 1

M1 - 3

ER -