The First Detection of Abundant Carbon in the Early Universe
A research team of astronomers, mainly from Ehime University and Kyoto University in Japan, has successfully detected a carbon emission line (CIV1549) in the most distant radio galaxy known so far in the early universe. Using the Faint Object Camera and Spectrograph (FOCAS) on the Subaru Telescope, the team observed the radio galaxy TN J0924-2201, which is 12.5 billion light years away, and was able to measure its chemical composition for the first time. Their investigation of the detected carbon line showed that a significant amount of carbon existed as early as 12.5 billion years ago, less than a billion years after the Big Bang. This important finding contributes to our understanding of the chemical evolution of the universe and may provide clues about the chemical nature of humans, who are composed of various elements such as carbon and oxygen. Read more
Title: Chemical properties in the most distant radio galaxy Authors: Kenta Matsuoka, Tohru Nagao, Roberto Maiolino, Alessandro Marconi, Yoshiaki Taniguchi
We present a deep optical spectrum of TN J0924-2201, the most distant radio galaxy at z = 5.19, obtained with FOCAS on the Subaru Telescope. We successfully detect, for the first time, the CIV1549 emission line from the narrow-line region (NLR). In addition to the emission-line fluxes of Ly alpha and CIV, we set upper limits on the NV and HeII emissions. We use these line detections and upper limits to constrain the chemical properties of TN J0924-2201. By comparing the observed emission-line flux ratios with photoionisation models, we infer that the carbon-to-oxygen relative abundance is already [C/O] > -0.5 at a cosmic age of ~ 1.1 Gyr. This lower limit on [C/O] is higher than the ratio expected at the earliest phases of the galaxy chemical evolution, indicating that TN J0924-2201 has already experienced significant chemical evolution at z = 5.19.