Candidate C <scp>iii</scp>] Emission in a Massive, Compact, <i>z</i> ∼ 4.5 Galaxy

Abstract We report candidate C iii ]1907,1909 Å emission at 3.6 σ at z = 4.521 using MultiObject Spectrometer for Infra-Red Exploration Y -band spectroscopy of COS J100029.9+021142.5. The galaxy was a filler target for the Web Epoch of Reionization Lyman-alpha Survey, a large spectroscopic campaign targeting Ly α in the Epoch of Reionization. Based on Bayesian Spectral Energy Distribution fitting, we find consistency between the photometric ( z p = 4.46 ± 0.09) and spectroscopic ( z spec = 4.521 ± 0.002) redshifts and measure the stellar mass to be <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>(</mml:mo> <mml:mn>1</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.6</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.7</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>)</mml:mo> <mml:mo>×</mml:mo> <mml:mn>1</mml:mn> <mml:msup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>9</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width="0.25em"/> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> </mml:math> .