Some of the gas sent gas away from the supermassive black hole — which is located in the center of the galaxy cluster SDSS J1531+3414 (SDSS J1531 for short) — by the eruption eventually cooled enough to form numerous clusters of stars.
Multiwavelength image of the massive galaxy cluster SDSS J1531+3414. Image credit: NASA / CXC / SAO / Omoruyi et al. / STScI / Tremblay et al. / ASTRON / LOFAR / NASA / CXC / SAO / N. Wolk.
SDSS J1531 is a massive galaxy cluster containing hundreds of individual galaxies and huge reservoirs of hot gas and dark matter.
In the heart of SDSS J1531, two of the cluster’s largest galaxies are colliding with each other.
Surrounding these merging giants is a set of 19 large clusters of stars, called superclusters, arranged in an ‘S’ formation that resembles beads on a string.
Dr. Osase Omoruyi from the Harvard & Smithsonian’s Center for Astrophysics and her colleagues used NASA’s Chandra X-ray Observatory, the LOFAR radio network and other telescopes to unravel how this unusual chain of star clusters likely formed.
Their discovery of evidence for an ancient, titanic eruption in SDSS J1531 provided a vital clue.
The eruption likely occurred when the supermassive black hole in the center of one of the large galaxies produced an extremely powerful jet.
As the jet moved through space, it pushed the surrounding hot gas away from the black hole, creating a gigantic cavity.
“We are already looking at this system as it existed 4 billion years ago, not long after the Earth formed,” Dr. Omoruyi said.
“This ancient cavity, a fossil of the black hole’s effect on the host galaxy and its surroundings, tells us about a key event that happened nearly 200 million years earlier in the cluster’s history.”
The evidence for a cavity comes from ‘wings’ of bright X-ray emission, seen with Chandra, tracing dense gas near the center of SDSS J1531.
These wings make up the edge of the cavity and the less dense gas in between is part of the cavity.
LOFAR shows radio waves from the remains of the jet’s energetic particles filling in the giant cavity.
Together, these data provide compelling evidence of an ancient, massive explosion.
The astronomers also discovered cold and warm gas located near the opening of the cavity, detected with the Atacama Large Millimeter and submillimeter Array (ALMA) and the Gemini North Telescope, respectively.
They argue that some of the hot gas pushed away from the black hole eventually cooled to form cold and warm gas.
They think tidal effects from the two merging galaxies compressed the gas along curved paths, leading to the star clusters forming in the ‘beads on a string’ pattern.
“We’ve reconstructed a likely sequence of events in this cluster that occurred over a vast range of distances and times,” said Dr. Grant Tremblay, also from the Harvard & Smithsonian’s Center for Astrophysics.
“It began with the black hole a tiny fraction of a light-year across forming a cavity almost 500,000 light-years wide.”
“This single event set in motion the formation of the young star clusters nearly 200 million years later, each a few thousand light-years across.”
The authors only see radio waves and a cavity from one jet, but black holes usually fire two jets in opposite directions.
They also observed radio emission farther away from the galaxies that might be the leftovers from a second jet, but it is not associated with a detected cavity.
They surmise that the radio and X-ray signals from the other eruption might have faded to the point that they are undetectable.
“We think our evidence for this huge eruption is strong, but more observations with Chandra and LOFAR would clinch the case,” Dr. Omoruyi said.
“We hope to learn more about the origin of the cavity we’ve already detected, and find the one expected on the other side of the black hole.”
A paper on the findings will be published in the Astrophysical Journal.
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Osase Omoruyi et al. 2024. ‘Beads on a String’ Star Formation Tied to one of the most Powerful AGN Outbursts Observed in a Cool Core Galaxy Cluster. ApJ, in press; arXiv: 2312.06762
Source : Breaking Science News