A Cosmic Miracle: A Remarkably Luminous Galaxy at <i>z</i> _spec = 14.44 Confirmed with JWST

JWST has revealed a stunning population of bright galaxies at surprisingly early epochs, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mi>z</mml:mi> <mml:mo>&gt;</mml:mo> <mml:mn>10</mml:mn> </mml:mrow> </mml:math> , where few such sources were expected. Here we present the most distant example of this class yet – MoM-z14, a luminous () source in the COSMOS legacy field at that expands the observational frontier to a mere 280 million years after the Big Bang. The redshift is confirmed with NIRSpec/prism spectroscopy through a sharp Lyman- <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>α</mml:mi> </mml:math> break and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mo>≈</mml:mo> <mml:mn>3</mml:mn> <mml:mi>σ</mml:mi> </mml:mrow> </mml:math> detections of five rest-UV emission lines. The number density of bright sources implied by our “Mirage or Miracle” survey spanning <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mo>≈</mml:mo> <mml:mn>350</mml:mn> </mml:mrow> </mml:math> arcmin is <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mo>&gt;</mml:mo> <mml:mn>100</mml:mn> <mml:mo>×</mml:mo> </mml:mrow> </mml:math> larger ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:msubsup> <mml:mn>182</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>105</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>329</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>×</mml:mo> </mml:mrow> </mml:math> ) than pre-JWST consensus models. The high EWs of UV lines ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mo>≈</mml:mo> <mml:mn>15</mml:mn> <mml:mo>−</mml:mo> <mml:mn>35</mml:mn> </mml:mrow> </mml:math> ) signal a rising star-formation history, with a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mo>≈</mml:mo> <mml:mn>10</mml:mn> <mml:mo>×</mml:mo> </mml:mrow> </mml:math> increase in the last 5 Myr (). The source is extremely compact (circularized pc), and yet elongated ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mi>b</mml:mi> <mml:mi>/</mml:mi> <mml:mi>a</mml:mi> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mn>0.25</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.06</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.11</mml:mn> </mml:mrow> </mml:msubsup> </mml:mrow> </mml:math> ), suggesting an AGN is not the dominant source of UV light. The steep UV slope ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mi>β</mml:mi> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:msubsup> <mml:mn>2.5</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.2</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.2</mml:mn> </mml:mrow> </mml:msubsup> </mml:mrow> </mml:math> ) implies negligible dust attenuation and a young stellar population. The absence of a strong damping wing provides tentative evidence that the immediate surroundings of MoM-z14 may be partially ionized at a redshift where virtually every reionization model predicts a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mo>≈</mml:mo> <mml:mn>100</mml:mn> <mml:mi>%</mml:mi> </mml:mrow> </mml:math> neutral fraction. The nitrogen emission and highly super-solar [N/C] <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mo>&gt;</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:math> hint at an abundance pattern similar to local globular clusters that may have once hosted luminous supermassive stars. Since this abundance pattern is also common among the most ancient stars born in the Milky Way, we may be directly witnessing the formation of such stars in dense clusters, connecting galaxy evolution across the entire sweep of cosmic time.