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  <front>
    <journal-meta>
      <journal-title-group>
        <journal-title>Cosmological and Astrobiological Review</journal-title>
      </journal-title-group>
      <issn pub-type="ppub">0000-0000</issn>
      <issn pub-type="epub">0000-0000</issn>
      <publisher>
        <publisher-name>SAPCRAA</publisher-name>
        <publisher-loc>Banja Luka, Bosnia and Herzegovina</publisher-loc>
      </publisher>
    </journal-meta>
    <article-meta>
      <article-id pub-id-type="publisher-id">1515</article-id>
      <article-id pub-id-type="doi">https://doi.org/10.65932/CAR-2023-1-4</article-id>
      <title-group>
        <article-title>Jwst and the problem of prematurely-formed massive galaxies: pre-mission predictions, early observations, and the structure of the emerging tension with λcdm</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <name>
            <surname>Davis</surname>
            <given-names>Christopher</given-names>
          </name>
          <contrib-id contrib-id-type="orcid">https://orcid.org/0009-0000-4175-1458</contrib-id>
        </contrib>
      </contrib-group>
      <pub-date pub-type="epub">
        <day>30</day>
        <month>12</month>
        <year>2023</year>
      </pub-date>
      <volume>1</volume>
      <issue>1</issue>
      <fpage>48</fpage>
      <lpage>60</lpage>
      <self-uri xlink:href="https://www.sapcraa.com/article-preview/1515"/>
      <abstract>
        <p>The James Webb Space Telescope, operational from July 2022, was designed to test ΛCDM predictions for first-galaxy formation in the z = 8 to z = 20 window. Within six months, NIRCam imaging from the SMACS 0723, GLASS, and CEERS Early Release programmes returned an unexpected population of luminous galaxy candidates at z ≈ 10-16 with inferred stellar masses of 10^9-10^10 M_⊙ at cosmic times of 300-500 Myr after the Big Bang. The Naidu and colleagues (2022) GLASS-z10/z12 discovery, the Castellano and colleagues (2022) z ≈ 9-15 sample, and the converging Harikane and colleagues (2022) and Donnan and colleagues (2022) UV luminosity function analyses together established that the bright-end number density at z &gt; 10 exceeds pre-JWST Behroozi-Silk (2018) and Behroozi-UniverseMachine (2019) predictions by approximately 0.5-1 order of magnitude. Whether this excess reflects genuine over-formation of massive galaxies, contamination by lower-redshift interlopers, calibration systematics, or a ΛCDM breakdown remained unresolved at the December 2022 boundary of this review. I propose, as the original contribution, the Galaxy Formation Tension Index (GFTI), a normalised composite metric on [0,1] integrating five performance dimensions (observed-topredicted number-density ratio, inferred star formation efficiency, stellar-mass-density ratio, UVbright-fraction at z &gt; 10, cross-survey consistency). Applied to the December 2022 dataset, GFTI returns approximately 0.55 — the “significant tension” tier, well below the 0.75 refutation threshold.</p>
      </abstract>
      <kwd-group kwd-group-type="author">
        <kwd>James Webb Space Telescope</kwd>
        <kwd>high-redshift galaxies</kwd>
        <kwd>UV luminosity function</kwd>
        <kwd>ΛCDM</kwd>
        <kwd>cosmic dawn</kwd>
        <kwd>reionization</kwd>
        <kwd>galaxy formation</kwd>
        <kwd>Behroozi-Silk constraint</kwd>
        <kwd>prematurely-formed massive galaxies</kwd>
      </kwd-group>
    </article-meta>
  </front>
</article>
