Leviathan’s sprawling stars problem concept that dusty giants develop into compact galaxies

Astronomers utilizing the James Webb Area Telescope (JWST) have confirmed a large, dust-rich galaxy referred to as Leviathan within the early universe. Seen when the universe was roughly 1.5 billion years previous, the galaxy has its stars unfold out moderately than in a concentrated vogue. A paper, describing its unusual stellar distribution, was posted to the arXiv preprint server on Oct. 19.

Dusty vivid galaxies

Submillimeter galaxies are extraordinarily luminous, dust-obscured galaxies, sometimes at redshifts round 2 to three, forming stars at lots of to 1000’s of photo voltaic lots per yr. Mud absorbs their shorter-wavelength optical and ultraviolet mild and re-emits it, which is detected at submillimeter wavelengths. They’re considered doable progenitors of large quiescent galaxies (MQGs), that are immediately’s large elliptical galaxies.

Finding out them can check theories of how galaxies type, what number of stars they comprise and the way effectively they convert fuel into stars. Insights from these galaxies may also clarify how heavy their darkish matter halos are.

Huge quiescent galaxies, which have stopped forming stars, are very compact when seen 11.5 to 12.5 billion years in the past. With half-light radii of solely about 0.2 to 1 kiloparsec, they maintain tens of billions of the solar’s mass in stars. This implies their ancestors, that are considered submillimeter galaxies, will need to have constructed dense stellar cores in a short time.

Their mud emission is compact, with radii of about 1 to 2 kiloparsecs, nevertheless it exhibits solely the place stars are forming now, not the place current stars are. However now, JWST can detect galaxies’ faint glow, which comes from stars.

Leviathan: An historical large

The staff led by William M. Baker of the College of Copenhagen has now investigated the place the celebs are positioned in a large submillimeter galaxy and measured its mass. “Whether or not these galaxies are on the way in which to turning into compact MQGs due to this fact requires measuring the place their stellar mass (not simply their mild) is positioned,” the staff writes within the paper.

The staff measured the mass and redshift of Leviathan, a large submillimeter galaxy found in 2012. In its spectrum, they detected emissions from hydrogen and ionized nitrogen. Utilizing these strains, they measured the redshift of z = 4.0514 for the galaxy as a complete.

To measure its mass, the staff match 31 completely different bands of sunshine from Leviathan to fashions of the galaxy’s stars and dirt, revealing a stellar mass of about 219 billion suns. The derived mass, researchers say, makes it one of the crucial large spectroscopically confirmed galaxies past redshift 4.

Subsequent, researchers estimated that Leviathan varieties about 410 photo voltaic lots of stars per yr. This “locations Leviathan on the large finish of the star-forming most important sequence at z≈4,” the staff notes.

Compact or unfold out?

Shifting on to estimating its measurement, researchers discovered that Leviathan is larger than most submillimeter galaxies seen about 11.5 billion years in the past. They measured three forms of radii: the radius containing half of the galaxy’s mild, half of its stellar mass and half of its mud glow.

The half-light and half-mass radii are 4.3 and three.1 kiloparsecs, respectively, so the mass is extra concentrated than the sunshine. That is typical of “inside-out” progress, the place the middle fashioned first and is older and dustier, whereas the outskirts are youthful and brighter. The star formation is unfold throughout the disk. The mud was discovered to be solely barely extra compact than the celebs (about 2.2 to 2.5 kiloparsecs).

They calculated that even when all its fuel will get transformed into stars, it could solely shrink to about 2.8 kiloparsecs. Its central density is beneath that of compact quiescent galaxies. Thus, Leviathan is unlikely to develop into a compact quiescent galaxy.

“If its star formation continues with its current spatial distribution, Leviathan is due to this fact unlikely to develop the compact construction of the large quiescent galaxies at 3 < z < 5,” researchers say.

As a substitute, it might develop into an prolonged, disk-like quiescent galaxy. The research means that dusty galaxies within the early universe can comply with completely different paths as they develop.

© 2026 Science X Community