Oral Presentation

HINOTORI: A Statistical Study of Rejuvenated Galaxies with the SDSS/MaNGA Sample

Author(s): Takumi Tanaka (U. Tokyo), Kazuhiro Shimasaku (U. Tokyo), Makoto Ando (U. Tokyo), Kei Ito (U. Tokyo), Suin Matsui (U. Tokyo), Sandro Tacchella (Cambridge U./Cavendish Lab./KICC), Hassen Yesuf (IPMU)

Presenter: Takumi Tanaka (The University of Tokyo)

Rejuvenated galaxies (RGs) are galaxies restarting star formation (rejuvenate) and returning from quiescent galaxies (QGs) to star-forming galaxies (SFGs). However, the mechanism of rejuvenation and its role in galaxy evolution are still unclear. Statistical and comprehensive analysis for RGs is still challenging due to small sample sizes, different definitions of RGs, and biased selection methods (e.g., search from only QGs) in the previous studies. To address these issues and understand the nature of RGs, we have launched a systematic survey project of RGs, named the HINOTORI (star formation History INvestigatiOn TO find RejuvenatIon). Using “Prospector,” a Bayesian spectral energy distribution fitting code, we estimate star-formation histories (SFHs) of N~10000 galaxies from the SDSS/MaNGA sample (z~0.03). Then, based on the reconstructed SFHs, we construct the largest ever (N~1000) RG sample. We find that ~10% of the total sample and ~40% of the green valley galaxies, mainly massive galaxies, are classified as RGs. We also find that our RGs have a similar stellar mass distribution to QGs but show more disk-like morphologies. In this talk, we will present the results of the initial analysis of this sample and the prospects of the HINOTORI project.