Galaxy Swarm Discovered Orbiting Hyperluminous Galaxy

Sep. 12 () –

The Very Large Telescope and the ALMA radio telescope have revealed a swarm of galaxies in the vicinity of a hyperluminous and vigorously star-forming galaxy in the early universe.

The observation provides important clues about how exceptionally bright galaxies grow and evolve into energetic quasars. that emit light throughout most of the observable universe.

A fundamental topic in astronomy is the question of how galaxies form, grow and evolve. As part of their evolution, most galaxies seem to harbor a supermassive black hole at their center. These gravity monsters occasionally gobble up nearby gas and stars, spewing out excess energy in the form of powerful jets, a phenomenon known as a quasar.

Many details about the transition from “normal” galaxies to quasars are still unknown. But in a new study published in Nature Communicationsa team of astronomers led by Michele Ginolfi may have come one step closer to understanding this evolution.

“Before becoming a full-fledged quasar, some galaxies are thought to go through a phase of being very dusty and very ‘active’ in terms of star formation and gas accretion in their central supermassive black holes,” explains Ginolfi. it’s a statement. “We set out to design an experiment to learn more about this transition phase.”

Ginolfi and his collaborators focused on an already known galaxy, W0410-0913, one of the brightest, most massive and gas-rich galaxies in the distant universe, seen 12 billion years ago.

The dust is heated by light energy from stars and the central black hole, causing it to glow and cast the galaxy through its infrared light. This has led to these types of galaxies being called hot dust obscured galaxies. (also known colloquially as “hot dogs”).

Because the evolution of galaxies is intrinsically connected to their environment, Ginolfi and his team, whose core somewhat uncharacteristically consisted mainly of early-career researchers, decided to observe W0410-0913 with the “MUSE” instrument on the Very Large Telescope. (VLT) in Chile. This advanced tool allowed them to study a region 40 times wider than the galaxy itself.

Peter Laursen of the Cosmic Dawn Center in Copenhagen participated in the study. “The observations revealed that W0410-0913 is surrounded by a swarm of no fewer than 24 smaller galaxies. The beauty of the MUSE instrument is that we can measure not only its position in the sky, but also its distance along our line of sight. In other words, we can measure their positions in 3D“, Explain.

Although this implies that W0410-0913 resides in a region at least ten times denser than the average universe, this is not entirely unexpected, as hot dogs are thought to live in dense environments.

Furthermore, although W0410-0913 is seen at a time when the universe was 1/8 of its current age, it is already ten times more massive than our own Milky Way galaxy. Growing such a large galaxy in such a short time and fueling a supermassive black hole requires a substantial supply of fresh material. All of this fits well with the conventional picture that massive galaxies grow by accumulating gas and satellite galaxies, attracted from intergalactic space by its immense gravity.

Indeed, in such a dense environment, the rate of galaxy interaction and merging is expected to be very high. Exposed to such bombardment, astronomers anticipated that W0410-0913 would be a car accident of chaotically rotating clusters of gas and stars.

However, by delving into older observations obtained by ALMA radio antennas located just 300 km northeast of the VLT, Ginolfi and colleagues were able to measure the internal movement of gas within W0410-0913.

And here a completely different picture emerged. Surprisingly, the ALMA observations revealed that W0410-0913 does not appear to have been perturbed at all by interactions with companion galaxies. According to observations, this gas rotates in an orderly way around the central black hole.. Neat, but surprisingly fast, with speeds reaching 500 km/s.