An international team collected data from many radio telescopes to investigate the mechanism of star formation in a galaxy when the cosmos was less than 30% the age it is now.
They discovered that the features of the molecular gas reservoir are identical to those of our own Galaxy, which had previously been undetected in the distant cosmos.
The mechanism of star formation, or how efficient the conversion of cold gas into stars is, is a fundamental subject in the study of galaxies. Until now, galaxies in the early universe appear to create stars in a different way than our own Galaxy, which is perplexing. Radio telescopes are used to observe cold molecular gas, the fuel for star formation, in order to shed insight on this topic.
It cannot be viewed directly in the radio regime due to the physical features of molecular hydrogen gas (H2), but it can be traced via the carbon monoxide molecule (CO). That is exactly what the team led by Nikolaus Sulzenauer, a PhD student at the Max Planck Institute for Radio Astronomy, has accomplished.
First, the researchers chose a galaxy whose brightness is enhanced by an intervening cluster of galaxies due to gravitational lensing. They next looked for archived data from infrared space missions combined with Hubble Space Telescope imaging.
“The discovered galaxy is strongly lensed by a factor of about 10 and thus its morphology is distorted resembling a seahorse. Therefore its nickname is the Cosmic Seahorse” explained Sulzenauer.
Observations of carbon monoxide lines with the 30 m radio telescope of the Instituto de Radioastronoma Milimétrica (IRAM) in the Sierra Nevada determined the distance of this galaxy, the light travelled 9.6 billion years. Together with observations from the Yebes 40 m radio telescope, which is located 50 kilometers north-east of Madrid and is operated by the Instituto Geográfico Nacional (IGN), the physical parameters of the fuel of star formation could be obtained through measurements of numerous molecular gas lines.
“That it is the most distant galaxy detected with the Yebes 40 m radio telescope up to now” noted IAC researcher Helmut Dannerbauer who is also co-author of the paper: “The gravitational lensing virtually transforms the IRAM and Yebes telescopes into radio telescopes with sizes of single dishes of 300 resp. 400 m, impossible to construct.”
The researchers discovered the presence of a previously unknown star creation mechanism around cosmic noon, the universe’s peak period of star generation and black hole activity.
“Our research has shown that this is a so-called main-sequence galaxy with slowly evolving star formation at the epoch of maximum star formation in the Universe” added Bodo Ziegler from the University of Vienna and co-author of the article.
“This seems to be the missing link between systems with high and low star formation rate such as the Cosmic Seahorse” explained Anastasio Díaz Sánchez of the Universidad Politécnica de Cartagena who also participated in the study.
Likewise, Susana Iglesias Groth, IAC researcher and co-author of the article, emphasises the relevance of this discovery considering the difficulty of studying this type of galaxy: “Without the gravitational lensing it would have been impossible to detect this galaxy, with calm star formation activity, with these large radio telescopes.”
Image Credit: ESA / Hubble
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