Research press release





今回、Ivo Labbéたちは、JWSTによって観測された高赤方偏移(z = 6.5からz = 9.1まで)の銀河候補を選び出して、宇宙誕生直後の約7億5000万年間に形成された大質量銀河を探索した。その結果、赤方偏移がz = 7.5からz = 9.1までの位置に6つの大質量銀河候補が同定され、その恒星質量が太陽質量の100億倍を超えることが判明した。そのうちの1つの銀河は、恒星質量が太陽質量の約1000億倍である可能性がある。


Observations of a population of candidate massive galaxies that formed around 500–700 million years after the Big Bang are published in Nature today. These galaxies are more massive than has been expected for this early point in time. The observations, part of the first release of data from the James Webb Space Telescope (JWST), offer insights into early galaxy formation.

Massive galaxies with stellar masses as high as 100 billion times that of the Sun have been identified at redshifts z ~ 6, approximately one billion years after the Big Bang, but it has been difficult to find massive galaxies at even earlier times. Redshift is a measure of the age of an astronomical object: due to the expansion of the Universe, light from distant objects shifts to wavelengths towards the red end of the spectrum — the redder the image, the more distant the object is.

Ivo Labbé and colleagues searched for massive galaxies in the first 750 million years of cosmic history by selecting candidates at high redshifts (z = 6.5 and z = 9.1), as observed by the JWST. The authors identify six candidate massive galaxies with redshifts between z = 7.5 and z = 9.1 with masses up to ten billion times that of our Sun, including one galaxy with a possible stellar mass 100 billion times that of the Sun.

The mass of the observed galaxies exceeds expected values. If verified with spectroscopy, these findings provide evidence to suggest that galaxies grew massive quicker than expected early in the history of the Universe.

doi: 10.1038/s41586-023-05786-2

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