RIOJA. Complex Dusty Starbursts in a Major Merger B14-65666 at z=7.15
Artikel i vetenskaplig tidskrift, 2025

We present JWST NIRCam imaging of B14-65666 ("Big Three Dragons"), a bright Lyman-break galaxy system (MUV = -22.5 mag) at z = 7.15. The high angular resolution of NIRCam reveals the complex morphology of two galaxy components: galaxy E has a compact core (E-core), surrounded by diffuse, extended, rest-frame optical emission, which is likely to be tidal tails; and galaxy W has a clumpy and elongated morphology with a blue UV slope (beta UV = -2.2 +/- 0.1). The flux excess, F356W - F444W, peaks at the E-core ( 1.05-0.09+0.08 mag), tracing the presence of strong [O iii] lambda lambda 4960,5008 emission. Atacama Large Millimeter/submillimeter Array archival data show that the bluer galaxy W is brighter in dust continua than the redder galaxy E, while the tails are bright in [O iii] 88 mu m. The UV/optical and submillimeter spectral energy distribution (SED) fitting confirms that B14-65666 is a major merger in a starburst phase as derived from the stellar mass ratio (3:1 to 2:1) and the star formation rate, similar or equal to 1 dex higher than the star formation main sequence at the same redshift. Galaxy E is a dusty (AV = 1.2 +/- 0.1 mag) starburst with a possible high dust temperature (>= 63-68 K). Galaxy W would have a low dust temperature (<= 27-33 K) or patchy stellar-and-dust geometry, as suggested by the IR excess and beta UV diagram. The high optical-to-far-IR [O iii] line ratio of the E-core shows its lower gas-phase metallicity (similar or equal to 0.2-0.4 Z circle dot) than galaxy W. These results agree with a scenario where major mergers disturb morphology and induce nuclear dusty starbursts triggered by less-enriched inflows. B14-65666 shows a picture of complex stellar buildup processes during major mergers in the epoch of reionization.

High-redshift

Big 3 dragons

Stellar feedback

Line ratios

Star-forming galaxy

Infrared-emission

Mass-metallicity relation

Luminosity function

Ionized-gas

Lyman-break galaxy

Författare

Yuma Sugahara

National Astronomical Observatory of Japan

Waseda University

Javier Álvarez-Márquez

Consejo Superior de Investigaciones Científicas (CSIC)

Takuya Hashimoto

University of Tsukuba

Luis Colina

Consejo Superior de Investigaciones Científicas (CSIC)

Akio K. Inoue

Waseda University

Luca Constantin

Consejo Superior de Investigaciones Científicas (CSIC)

Yoshinobu Fudamoto

Chiba University

Waseda University

National Astronomical Observatory of Japan

Ken Mawatari

University of Tsukuba

Yi W. Ren

Waseda University

Santiago Arribas

Consejo Superior de Investigaciones Científicas (CSIC)

Tom Bakx

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

Carmen Blanco-Prieto

Consejo Superior de Investigaciones Científicas (CSIC)

Daniel Ceverino

Universidad Autonoma de Madrid (UAM)

Alejandro Crespo Gomez

Consejo Superior de Investigaciones Científicas (CSIC)

Masato Hagimoto

Nagoya University

Takeshi Hashigaya

Kyoto University

Rui Marques-Chaves

Université de Genève

Hiroshi Matsuo

The Graduate University for Advanced Studies (SOKENDAI)

National Astronomical Observatory of Japan

Yurina Nakazato

University of Tokyo

Miguel Pereira-Santaella

Consejo Superior de Investigaciones Científicas (CSIC)

Yoichi Tamura

Nagoya University

Mitsutaka Usui

University of Tsukuba

Naoki Yoshida

University of Tokyo

Astrophysical Journal

0004-637X (ISSN) 1538-4357 (eISSN)

Vol. 981 2 135

Ämneskategorier (SSIF 2025)

Astronomi, astrofysik och kosmologi

DOI

10.3847/1538-4357/adb02a

Mer information

Senast uppdaterat

2025-03-21