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Spectroscopic confirmation of a large and luminous galaxy with weak emission lines at $\mathbf{z = 13.53}$

Callum T. Donnan, Derek J. McLeod, Ross J. McLure, James S. Dunlop, Fergus Cullen, Mark Dickinson, Pablo Arrabal Haro, Anthony J. Taylor, Cecilia Bondestam, Feng-Yuan Liu, Karla Z. Arellano-Córdova, Laia Barrufet, Ryan Begley, Adam C. Carnall, Hanna Golawska, Ho-Hin Leung, Dirk Scholte, Thomas M. Stanton

Abstract

We present JWST/NIRSpec PRISM observations of a robust galaxy candidate at $z\simeq14$, selected from pure-parallel NIRCam imaging; PAN-z14-1. The NIRSpec spectrum allows confirmation of this source at $z_{\rm spec}=13.53^{+0.05}_{-0.06}$ through modeling of the Lyman-$α$ break. PAN-z14-1 is the fourth most distant galaxy known to date and is extremely luminous ($M_{\rm UV}=-20.6\pm0.2$), with a blue UV-continuum slope ($β=-2.26\pm0.08$) and a large physical size ($r_{\rm c}=233\pm10\, \rm pc$). We fail to detect any rest-frame UV emission lines at $\geq 2σ$ significance, with upper limits sufficiently constraining to exclude the possibility of strong line emission. In terms of its physical properties, PAN-z14-1 is remarkably similar to the previously confirmed $z_{\rm spec}=14.18$ galaxy GS-z14-0. The lack of strong emission lines and large physical size is consistent with an emerging picture of two potentially distinct galaxy populations at $z>10$, distinguished by star-formation rate surface density. In this scenario, PAN-z14-1 is a second example of a ``normal'', extended, luminous, star-forming galaxy at $z \simeq 14$, and differs markedly from the other class of extremely compact galaxies with strong emission lines recently uncovered at extreme redshifts with JWST. These results highlight the importance of further spectroscopic confirmation of $z>10$ galaxy candidates in order to fully understand the diversity of properties displayed by the first galaxies.

Spectroscopic confirmation of a large and luminous galaxy with weak emission lines at $\mathbf{z = 13.53}$

Abstract

We present JWST/NIRSpec PRISM observations of a robust galaxy candidate at , selected from pure-parallel NIRCam imaging; PAN-z14-1. The NIRSpec spectrum allows confirmation of this source at through modeling of the Lyman- break. PAN-z14-1 is the fourth most distant galaxy known to date and is extremely luminous (), with a blue UV-continuum slope () and a large physical size (). We fail to detect any rest-frame UV emission lines at significance, with upper limits sufficiently constraining to exclude the possibility of strong line emission. In terms of its physical properties, PAN-z14-1 is remarkably similar to the previously confirmed galaxy GS-z14-0. The lack of strong emission lines and large physical size is consistent with an emerging picture of two potentially distinct galaxy populations at , distinguished by star-formation rate surface density. In this scenario, PAN-z14-1 is a second example of a ``normal'', extended, luminous, star-forming galaxy at , and differs markedly from the other class of extremely compact galaxies with strong emission lines recently uncovered at extreme redshifts with JWST. These results highlight the importance of further spectroscopic confirmation of galaxy candidates in order to fully understand the diversity of properties displayed by the first galaxies.
Paper Structure (16 sections, 9 figures)

This paper contains 16 sections, 9 figures.

Table of Contents

  1. Introduction
  2. Data
  3. NIRSpec data
  4. NIRCam data
  5. Data Analysis
  6. Spectroscopic redshift
  7. UV properties
  8. SED fitting
  9. Emission lines
  10. Morphology
  11. Discussion
  12. The photometric selection of galaxies at $z\geq14$
  13. Inferring the physical properties of galaxies at $z>10$ with SED modeling
  14. Are there two distinct galaxy populations at $z>10$?
  15. Similarity to GS-z14-0
  16. ...and 1 more sections

Figures (9)

  • Figure 1: The 2D (top) and 1D (bottom) spectra of PAN-z14-1. The black data points show the measured NIRCam photometry and the red line shows the best-fitting model of the Lyman-$\alpha$ break and UV continuum. A $3.15\times3.15$ arcsec cutout image of the source in the F277W filter is shown in the inset with the NIRSpec slit overlayed.
  • Figure 2: Left: The $M_{\rm UV}-z_{\rm spec}$ plane for spectroscopically-confirmed galaxies at $z>10$, with the location of PAN-z14-1 highlighted by the red star. Right: The corresponding $\beta-z_{\rm spec}$ plane for spectroscopically-confirmed $z>10$ galaxies.
  • Figure 3: Left: The best-fitting spectral energy distribution (SED) models to the NIRSpec and NIRCam data for PAN-z14-1 using bagpipes with a constant (red), delayed-$\tau$ (green), double power-law (blue) and continuity-bursty non-parametric (purple) star-formation history (SFH) model. Right: The corresponding SFH for each best-fitting bagpipes SED model. There is significant scatter ($\simeq1.3\, \rm dex$) in the inferred stellar mass depending on the choice of model for the SFH.
  • Figure 4: Properties derived from spectro-photometric modeling of PAN-z14-1.
  • Figure 5: Emission-line flux limits for PAN-z14-1.
  • ...and 4 more figures