July 17, 2024
1 Solar System Way, Planet Earth, USA

First pair of merging quasars seen in Cosmic Dawn

Merging quasars: two spiral disks that glow yellow to orange, from which jets emerge.  The discs are very close together.
Artist's concept of a pair of quasars – bright and active galaxies – merging. Scientists saw these quasars merging just 900 million years after the big Bang, in a period of time known as the Cosmic Dawn. This makes the merging quasars the most distant merging pair known and the first pair astronomers have seen in Cosmic Dawn. Image via Gemini International Observatory/ NOIRLab/ NSF/ AURA/ M. Garlick.

Quasar merger in Cosmic Dawn

Quasars They are believed to be young, active, and extremely bright galaxies in the distant, early universe. Astronomers saying On June 17, 2024, they detected two quasars merging just 900 million years after the big Bang. This places these merged quasars in a time period known as the Cosmic Dawn, when the first stars and galaxies were beginning to illuminate the universe.

Thus, these quasars hold the titles of the most distant pair of merged quasars ever found and the first merged pair seen in Cosmic Dawn. The scientists published his study in peer reviewed diary The letters from the astrophysical diary on June 17, 2024. A complementary document accepted by the AAS Magazine is also available in arXiv.

At first

As far as we know, the universe began with a big Bang About 13.8 billion years ago. The universe expanded after the Big Bang, so in the early years objects were much closer together. For that reason, astronomers expected to see quasars close together as galaxies merged. But this is the first time astronomers have detected quasars merging in the early universe.

This period of time, the Cosmic Dawn, lasted from about 50 million years to one billion years after the Big Bang. Astronomers say this is the period when the stars began to light up and the universe went from a dark place to one dotted with light. As the stars and galaxies grew, their ultraviolet light spread throughout the universe. In doing so, he interacted with the intergalactic mediumor the diffuse gas of atoms and plasma between galaxies. The effect of ultraviolet light on this gas was to strip the atoms of their electrons, in what is called ionization. Thus, about 400 million years after the Big Bang, we obtain the Reionization epoch.

Reionization epoch

During the Epoch of Reionization, the universe gained the seeds it needed to create the large-scale structures of visible matter we see today. Previously, astronomers knew about 300 quasars from the epoch of reionization. But the discovery of merging quasars from this period is a first. And it allows astronomers to better understand what was happening in our universe back then. Primary author Yoshiki Matsuoka from Ehime University in Japan said:

The statistical properties of quasars in the Reionization Epoch tell us many things, such as the progress and origin of reionization, the formation of supermassive black holes during the Cosmic Dawn, and the earliest evolution of quasar host galaxies.

The discovery of merging quasars

Scientists found the pair of quasars while reviewing images of the Subaru Telescope, located in Hawaii. Matsuoka said:

While examining images of quasar candidates, I noticed two similar, extremely red sources, side by side. The discovery was purely fortuitous.

When astronomers look back at the early universe, they see that the light from these objects has been stretched due to the expansion of the universe. So the light from these objects is shifted to the red end of the spectrum. Therefore, seeing a reddish object often means that it existed a long time ago and has traveled across a greater expanse of the universe.

Astronomers needed to be sure that what they were seeing were two separate objects and not a single object. gravitational lens. Sometimes light from a closer massive object can cause the light behind it to bend and appear in more than one place in the sky.

Follow-up observations

So, to make sure the objects they saw were merging quasars and not foreground stars or something else, the astronomers made follow-up observations. They used the weak object camera and the spectrograph (SEALS) at the Subaru Telescope and the Gemini Near Infrared Spectrograph (GNIRS) in Gemini North.

What they found were two huge black holes that fed the quasars. Each black hole has about 100 million times the mass of the sun. Additionally, a bridge of gas extends between the two quasars, confirming the idea that they are a merging pair.

Matsuoka said:

The existence of merging quasars at the time of reionization has been anticipated for a long time. It has now been confirmed for the first time.

Dark square with many small galaxies and a box showing 2 red dots close to each other.
He Subaru Telescope I captured this image showing the high run to the red objects – 2 quasars merging – in Cosmic Dawn. Image via NOIRLab/ NSF/ AURA/ TA Provost (University of Alaska Anchorage/NSF NOIRLab), D. de Martin (NSF NOIRLab) and M. Zamani (NSF NOIRLab).

Bottom line: For the first time, scientists have discovered two quasars merging at the Cosmic Dawn, about 900 million years after the Big Bang. These are the most distant merged quasars seen yet.

Source: Discovery of twin quasar merger at z = 6.05

Source: Merger of gas-rich galaxies hosting low-luminosity twin quasars at z = 6.05: a promising progenitor of the most luminous quasars


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