A Diverse Population of z ∼ 2 ULIRGs Revealed by JWST Imaging

Journal article

Abstract Four ultraluminous infrared galaxies (ULIRGs) observed with JWST/NIRcam in the Cosmos Evolution Early Release Science program offer an unbiased preview of the z ∼ 2 ULIRG population. The objects were originally selected at 24 μ m and have strong polycyclic aromatic hydrocarbon emission features observed with Spitzer/Infrared Spectrometer. The four objects have similar stellar masses of ∼10 11 M ⊙ but otherwise are quite diverse. One is an isolated disk galaxy, but it has an active nucleus as shown by X-ray observations and by a bright point-source nucleus. Two others are merging pairs with mass ratios of 6–7:1. One has active nuclei in both components, while the other has only one active nucleus: the one in the less-massive neighbor, not the ULIRG. The fourth object is clumpy and irregular and is probably a merger, but there is no sign of an active nucleus. The intrinsic spectral energy distributions for the four active galactic nuclei in these systems are typical of type-2 QSOs. This study is consistent with the idea that even if internal processes can produce large luminosities at z ∼ 2, galaxy merging may still be necessary for the most luminous objects. The diversity of these four initial examples suggests that large samples will be needed to understand the z ∼ 2 ULIRG population.

Authors: Huang, J-S; Li, Z-J; Cheng, C; Hou, M; Yan, H

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Astronomical Society
• Journal: The Astrophysical Journal
• Volume: 949
• Issue: 2
• Pages: 83-83
• Publication date: 2023-06-01
• DOI: 10.3847/1538-4357/acc9c3
• EISSN: 1538-4357
• ISSN: 0004-637X
• Language: English
• Keywords: Physics; QSOS; Astrophysics; Active galactic nucleus; Population; Quasar; Galaxy; Luminous infrared galaxy; Astronomy; Luminosity