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Galaxies Going Bananas: Inferring the 3D Geometry of High-redshift Galaxies with JWST-CEERS

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Peer-reviewed

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Abstract

jats:titleAbstract</jats:title> jats:pThe 3D geometries of high-redshift galaxies remain poorly understood. We build a differentiable Bayesian model and use Hamiltonian Monte Carlo to efficiently and robustly infer the 3D shapes of star-forming galaxies in James Webb Space Telescope Cosmic Evolution Early Release Science observations with jats:inline-formula jats:tex-math

</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> mml:milog</mml:mi> mml:msub mml:mrow mml:miM</mml:mi> </mml:mrow> mml:mrow mml:mo*</mml:mo> </mml:mrow> </mml:msub> mml:mrow <mml:mo stretchy="true">/</mml:mo> </mml:mrow> mml:msub mml:mrow mml:miM</mml:mi> </mml:mrow> mml:mrow mml:mo⊙</mml:mo> </mml:mrow> </mml:msub> mml:mo=</mml:mo> mml:mn9.0</mml:mn> mml:mo–</mml:mo> mml:mn10.5</mml:mn> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjad1a13ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> at jats:italicz</jats:italic> = 0.5–8.0. We reproduce previous results from the Hubble Space Telescope Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey in a fraction of the computing time and constrain the mean ellipticity, triaxiality, size, and covariances with samples as small as ∼50 galaxies. We find high 3D ellipticities for all mass–redshift bins, suggesting oblate (disky) or prolate (elongated) geometries. We break that degeneracy by constraining the mean triaxiality to be ∼1 for jats:inline-formula jats:tex-math

</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> mml:milog</mml:mi> mml:msub mml:mrow mml:miM</mml:mi> </mml:mrow> mml:mrow mml:mo*</mml:mo> </mml:mrow> </mml:msub> mml:mrow <mml:mo stretchy="true">/</mml:mo> </mml:mrow> mml:msub mml:mrow mml:miM</mml:mi> </mml:mrow> mml:mrow mml:mo⊙</mml:mo> </mml:mrow> </mml:msub> mml:mo=</mml:mo> mml:mn9.0</mml:mn> mml:mo–</mml:mo> mml:mn9.5</mml:mn> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjad1a13ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> dwarfs at jats:italicz</jats:italic> > 1 (favoring the prolate scenario), with significantly lower triaxialities for higher masses and lower redshifts indicating the emergence of disks. The prolate population traces out a “banana” in the projected jats:inline-formula jats:tex-math

</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> mml:mib</mml:mi> mml:mrow <mml:mo stretchy="true">/</mml:mo> </mml:mrow> mml:mia</mml:mi> mml:mo–</mml:mo> mml:milog</mml:mi> mml:mia</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjad1a13ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> diagram with an excess of low-jats:italicb</jats:italic>/jats:italica</jats:italic>, large-jats:inline-formula jats:tex-math

</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> mml:milog</mml:mi> mml:mia</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjad1a13ieqn4.gif" xlink:type="simple" /> </jats:inline-formula> galaxies. The dwarf prolate fraction rises from ∼25% at jats:italicz</jats:italic> = 0.5–1.0 to ∼50%–80% at jats:italicz</jats:italic> = 3–8. Our results imply a second kind of disk settling from oval (triaxial) to more circular (axisymmetric) shapes with time. We simultaneously constrain the 3D size–mass relation and its dependence on 3D geometry. High-probability prolate and oblate candidates show remarkably similar Sérsic indices (jats:italicn</jats:italic> ∼ 1), nonparametric morphological properties, and specific star formation rates. Both tend to be visually classified as disks or irregular, but edge-on oblate candidates show more dust attenuation. We discuss selection effects, follow-up prospects, and theoretical implications.</jats:p>

Description

Keywords

5109 Space Sciences, 51 Physical Sciences

Journal Title

Astrophysical Journal

Conference Name

Journal ISSN

0004-637X
1538-4357

Volume Title

963

Publisher

American Astronomical Society