JWST MIRI Detections of H α and [O iii] and a Direct Metallicity Measurement of the z =10.17 Lensed Galaxy MACS0647-JD

• Published in: The Astrophysical journal 2024, Vol.973 (2)
• Main Authors: Hsiao, Tiger Yu-Yang, Alvarez-Marquez, Javier, Coe, Dan, Crespo Gomez, Alejandro, Dayal, Pratika, Larson, Rebecca L., Bik, Arjan, Blanco-Prieto, Carmen, Colina, Luis, Perez-Gonzalez, Pablo Guillermo, Costantin, Luca, Prieto-Jimenez, Carlota, Adamo, Angela, Bradley, Larry D., Conselice, Christopher J., Fujimoto, Seiji, Furtak, Lukas J., Hutchison, Taylor A., James, Bethan L., Jimenez-Teja, Yolanda, Jung, Intae, Kokorev, Vasily, Mingozzi, Matilde, Norman, Colin, Ricotti, Massimo, Rigby, Jane R., Sharon, Keren, Vanzella, Eros, Welch, Brian, Xu, Xinfeng, Zackrisson, Erik, Zitrin, Adi
• Format: Article
• Language: English
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ad6562

JWST spectroscopy has revolutionized our understanding of galaxies in the early Universe. Covering wavelengths up to 5.3 mu m, NIRSpec can detect rest-frame optical H alpha emission lines out to z = 7 and [O iii] to z = 9.5. Observing these lines in more distant galaxies requires longer wavelength spectroscopy with MIRI. Here we present MIRI Medium Resolution Spectrograph integral field unit observations of the lensed galaxy merger MACS0647-JD at z = 10.165. With exposure times of 4.2 hr in each of two bands (SHORT and LONG), we detect H alpha at 9 sigma, [O iii] lambda 5008 at 11 sigma, and [O iii] lambda 4960 at 3 sigma. Combined with previously reported NIRSpec spectroscopy that yielded seven emission lines including the auroral line [O iii] lambda 4363, we present the first direct metallicity measurement of a z > 10 galaxy: 12+log(O/H)=7.79 +/- 0.09, or 0.13(-0.03)(+0.02)Z(circle dot). This is similar to galaxies at z similar to 4-9 with direct metallicity measurements, though higher than expected given the high specific star formation rate log(sSFR/yr(-1)) = -7.4 +/- 0.3. We further constrain the ionization parameter log(U) = -1.9 +/- 0.1, ionizing photon production efficiency log(xi(ion)) = 25.3 +/- 0.1, and SFR = 5.0 +/- 0.6 M-circle dot yr(-1) within the past 10 Myr. These observations demonstrate the combined power of JWST NIRSpec and MIRI for studying galaxies in the first 500 million years.