2025/08/27 by S.-L. Kim, Kim, Seongjae, Woong-Seob Jeong +9 · 1 voice · 1 citation
Physics and Astronomy · #Active galactic nucleus #Dark Matter and Cosmic Phenomena #Emission spectrum #Galaxies: Formation, Evolution, Phenomena #Galaxy #Population #Scientific Research and Discoveries #Spectral energy distribution #Star formation #Stellar population #Supermassive black hole #Young stellar object
paper · doi:10.3847/1538-4357/adff59
published in The Astrophysical Journal 992(1), 70 (IOP Publishing)
openalex created_date 2025/10/10 · openalex publication_date 2025/10/10 · openalex updated_date 2026/06/11
Abstract We discovered a hyperluminous dust-obscured galaxy with mysterious blue-excess emission (BlueDOG) in the rest-frame UV of its spectral energy distribution (SED) from a multiwavelength survey in the AKARI Deep Field - South (ADF-S). We present the results of SED analysis with multiwavelength photometric data and spectroscopic analysis, observed with Gemini-S/GMOS, FLAMINGOS-2, to explore the origin of blue-excess emission of a hyperluminous BlueDOG, ADFS-KMTDOG-102, at z = 2.6. The SED analysis shows that this BlueDOG is a highly massive system (log M * / M ⊙ = 12.3) with substantial extinction. Additionally, the proportion of the old stellar population exceeds that of the young stellar population, which suggests stellar evolution cumulated from the early Universe. The mass of the supermassive black hole estimated using the extinction-corrected broad H α emission line yields log M BH / M ⊙ = 10.2. We discuss the similarity between the BlueDOG and “Little Red Dots” (LRDs), recently discovered with the James Webb Space Telescope, showing SED shapes remarkably similar to those of LRDs. The UV emission line ratios indicate that the emission lines are primarily powered by the central active galactic nuclei (AGN). In contrast, the origin of the blue-excess UV continuum remains ambiguous, since both recent star formation and AGN-induced scattered light are viable explanations, based on the results from the SED fitting and scattered light modeling.