An upper limit on [O III] 88 μm and 1.2 mm continuum emission from a JWSTz  ≈  12–13 galaxy candidate with ALMA

Abstract

A number of new z > 11 galaxy candidates have recently been identified based on public James Webb Space Telescope (JWST) NIRCam observations. Spectroscopic confirmation of these candidates is necessary to robustly measure their redshift and put them in the context of our understanding of the buildup of galaxies in the early Universe. GLASS-z13 is one of these candidates, with a reported photometric redshift z > 11.9. I present publicly available Atacama Large Millimeter/submillimeter Array (ALMA) band 6 Director’s Discretionary Time observations (project 2021.A.00020.S; PI T. Bakx), taken to acquire a spectroscopic redshift for GLASS-z13 by searching for [O III] 88 μm line emission in the redshift range z = 11.9 − 13.5. No [O III] 88 μm emission is detected in integrated spectra extracted within an aperture around GLASS-z13, nor when using an automated line finding algorithm (applying different uv-weighting strategies for the imaging). In addition, 1.2 mm continuum emission associated with GLASS-z13 is not detected either. If GLASS-z13 is at z ≈ 12 − 13, this implies a 3-σ upper limit on the [O III] 88 μm and rest-frame ∼90 μm continuum emission of ∼1 × 108 L⊙ and 10.8 μJy, respectively. The non-detection of [O III] 88 μm and continuum emission does not necessarily imply that GLASS-z13 is not at z ≈ 12 − 13. It can also be explained by a low metallicity (∼0.2 Z⊙ or lower) and/or high-density (at least 100 cm−3) interstellar medium. This work demonstrates the synergy between ALMA and JWST to study the properties of the first galaxies; although, JWST/NIRSpec spectroscopy will be necessary to confirm or reject the high photometric redshift of GLASS-z13.

To see or not to see a z ∼ 13 galaxy, that is the question

“…Ceverino et al 2018;Pallottini et al 2022). While multiple ALMA DDT programmes have now been conducted with the aim of confirming/rejecting z > 12 galaxy candidates identified using HST or JWST photometry, there are no conclusive results yet (Bakx et al 2023;Popping 2023;Yoon et al 2022). Thus, the interstellar medium (ISM) of these youngest of galaxies is yet to be observed with ALMA.…”

NOEMA reveals the true nature of luminous red JWST z > 10 galaxy candidates

“…There, expensive redshift looking for rest-frame FIR emission lines must be conducted as the continuum is likely too faint to be detected and does not significantly constrain the redshift of the galaxy (e.g. Kaasinen et al 2023;Bakx et al 2023;Popping 2023;Fujimoto et al 2023).…”

“…For objects with blue rest-frame UV colours, the situation is different as the presence of strong continuum dust emission is not expected (e.g. Kaasinen et al 2023;Bakx et al 2023;Popping 2023;Fujimoto et al 2023). L3, page 8 of 8…”

New insights and predictions on high-redshift galaxies from wide-area infrared surveys

“…Striking numbers of z > 12 Lyman break candidate galaxies are currently being discovered with JWST, but some are found to be incredibly dusty star-forming galaxies or AGN host galaxies at z ≲ 7 through ALMA sub-mm detections (Fujimoto et al 2022;Zavala et al 2023). Even if no significant ALMA detection is found, its absence and therefrom derived upper limits on sub-mm continuum and line emission can lead to conclusions on the galaxy metallicity or ISM density (Popping 2023;Kaasinen et al 2023). On the other hand, JWST has been able to probe the < 2 µm fluxes of ALMA/sub-mm galaxies that were previously undetected in the deepest HST imaging, shedding new light on the importance of extremely dust-obscured galaxies at z > 4 .…”