Ionized Gas Kinematics with FRESCO: An Extended, Massive, Rapidly Rotating Galaxy at z = 5.4

Nelson, E, Brammer, G, Giménez-Arteaga, C, Oesch, PA, Naidu, RP, Übler, H, Matharu, J, Shapley, AE, Whitaker, KE, Wisnioski, E, Förster Schreiber, NM, Smit, R ORCID: 0000-0001-8034-7802, van Dokkum, P, Chisholm, J, Endsley, R, Hartley, AI, Gibson, J, Giovinazzo, E, Illingworth, G, Labbe, I et al (2024) Ionized Gas Kinematics with FRESCO: An Extended, Massive, Rapidly Rotating Galaxy at z = 5.4. Astrophysical Journal Letters, 976 (2). ISSN 2041-8205

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Abstract

With the remarkable sensitivity and resolution of JWST in the infrared, measuring rest-optical kinematics of galaxies at z > 5 has become possible for the first time. This study pilots a new method for measuring galaxy dynamics for highly multiplexed, unbiased samples by combining FRESCO NIRCam grism spectroscopy and JADES medium-band imaging. Here we present one of the first JWST kinematic measurements for a galaxy at z > 5. We find a significant velocity gradient, which, if interpreted as rotation, yields V rot = 305 ± 70 km s−1, and we hence refer to this galaxy as Twister-z5. With a rest-frame optical effective radius of r e = 2.25 kpc, the high rotation velocity in this galaxy is not due to a compact size, as may be expected in the early Universe, but rather to a high total mass, log ( M dyn / M ⊙ ) = 11.2 ± 0.2 . This is a factor of roughly 10× higher than the stellar mass within r e . We also observe that the radial Hα equivalent width profile and the specific star formation rate map from resolved stellar population modeling are centrally depressed by a factor of ∼1.5 from the center to r e . Combined with the morphology of the line-emitting gas in comparison to the continuum, this centrally suppressed star formation is consistent with a star-forming disk surrounding a bulge growing inside out. While large, rapidly rotating disks are common to z ∼ 2, the existence of one after only 1 Gyr of cosmic time, shown for the first time in ionized gas, adds to the growing evidence that some galaxies matured earlier than expected in the history of the Universe.

Item Type:	Article
Uncontrolled Keywords:	5101 Astronomical Sciences; 51 Physical Sciences; 0201 Astronomical and Space Sciences; Astronomy & Astrophysics; 5101 Astronomical sciences; 5109 Space sciences
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute
Publisher:	American Astronomical Society
Date of acceptance:	12 September 2024
Date of first compliant Open Access:	25 April 2025
Date Deposited:	25 Apr 2025 14:49
Last Modified:	03 Jul 2025 13:45
DOI or ID number:	10.3847/2041-8213/ad7b17
URI:	https://researchonline.ljmu.ac.uk/id/eprint/26264

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