Oral Presentation
Spectroscopic observation of massive quenching galaxy at z=4.53.
Presenter: Takumi Kakimoto (The Graduate University for Advanced Studies (SOKENDAI))
A large fraction of massive galaxies in the local Universe are elliptical galaxies. Detailed spectroscopic studies of these galaxies suggest that they experienced an intense burst of star formation in the early Universe followed by passive evolution. The physical drivers of the starburst and subsequent quenching remain unclear, which is one of the outstanding issues in the field of galaxy evolution. To address this issue, a lot of efforts have been put into the search for progenitors of the local ellipticals in the distant Universe. With the advent of sensitive near-IR spectrographs, massive quiescent galaxies have been identified up to z~4. However, higher redshift objects have not yet been securely identified. Furthermore, recent hydrodynamical simulations cannot reproduce massive quiescent galaxies at such high redshifts.
We carry out a spectroscopic follow-up campaign to observe massive quiescent galaxies at z>~4 with Keck/MOSFIRE. Here we report a spectroscopic confirmation of a quenching galaxy at z=4.5 in the COSMOS field. The spectrum shows a weak [OII] emission and the Balmer break. We perform SED fitting using both photometry and spectrum to infer the physical properties of the galaxy. In this presentation, we will summarize the inferred properties and discuss the star formation history of the galaxy.
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