銀河進化の「ミッシングリンク」を発見か（An International Team of Astronomers Led by UMass Amherst May Have Just Found One of the Missing Links in Galaxy Evolution）

2026-02-17 マサチューセッツ大学アマースト校

マサチューセッツ大学アマースト校主導の国際研究チームは、宇宙進化の“ミッシングリンク”となり得る天体の証拠を発見した可能性を発表した。観測データの解析により、これまで理論上は予測されながら確認が難しかった中間的性質を持つ天体の特徴を捉えた。研究は多波長観測と高度な解析手法を組み合わせ、既存モデルを補完する結果を提示。銀河やブラックホール形成の過程理解を前進させ、宇宙構造の進化史解明に重要な手がかりを与える成果とされる。

＜関連情報＞

ALMAとJWSTによるz∼8までの微弱な塵星形成銀河の同定と他の銀河種族との関連性 ALMA and JWST Identification of Faint Dusty Star-forming Galaxies up to z ∼ 8 and Their Connection with Other Galaxy Populations

Jorge A. Zavala, Andreas L. Faisst, Manuel Aravena, Caitlin M. Casey, Jeyhan S. Kartaltepe, Felix Martinez III, John D. Silverman, Sune Toft, Ezequiel Treister, Hollis B. Akins,…
Astrophysical Journal Letters Published: 2026 February 11
DOI:10.3847/2041-8213/ae382a

Abstract

We exploit a new sample of around 400 bright dusty galaxies from the Atacama Large Millimeter/submillimeter Array (ALMA) CHAMPS Large Program, together with the rich JWST multiband data products in the COSMOS field, to explore and validate new selection methods for identifying dusty star-forming galaxies (DSFGs). Here we present an effective empirical selection criterion based on a newly defined parameter:I_*≡log₁₀(M_*)×log₁₀(SFR) . Incorporating the m_277W − m_444W color as a second parameter further improves the purity of the selection. We then apply this method to the COSMOS2025 catalog to search for fainter dusty galaxy candidates below the ALMA CHAMPS detection limit and, through a stacking technique, identify a population of high-redshift DSFG candidates with an average flux density of S_1.2mm ≈ 150 μJy and a space density of ∼6 × 10⁻⁶ Mpc⁻³. Three of these galaxies have been spectroscopically confirmed at z_spec = 7.20, 5.85, and 5.04. This faint population seems to have been missed by most of the previous submillimeter/millimeter surveys and ground- and space-based UV−near-IR observations. We then show evidence of a possible evolutionary connection between the z > 10 UV-bright galaxies recently discovered by JWST, the faint dusty z ≈ 6-8 galaxies identified here, and the population of z ≈ 3–5 massive quiescent galaxies; all of them are potentially linked as progenitor−descendant populations based on their abundance, redshifts, and stellar masses. Future spectroscopic campaigns will be essential to confirm the redshifts and physical properties of these massive, faint, high-redshift DSFG candidates.