Monster black hole ‘reborn’ after 100 million years of silence: ‘Like watching a cosmic volcano erupt’
Scientists have observed a supermassive phenomenon black hole waking up from a nap of almost 100 million years.
The black hole is at the center of a gigantic galaxy emitting extremely powerful radio waves. A new analysis of these radio emissions reveals that the black hole once spewed gargantuan jets of plasma hundreds of thousands of light years into space, before suddenly shutting down in the distant past. These jets are now active again and interact in complex and chaotic ways with the superheated gas around them, according to the new study.
“It’s like watching a cosmic volcano erupt again after periods of calm, except this one is large enough to carve out structures spanning nearly a million light years across space,” co-author of the study. Shobha Kumarian astronomer from Midnapore City College in India, said in a statement.
Galactic engine problem
Only 10 to 20% of supermassive black holes have jets that emit radio signals. In these galaxies, a rotating disk of dust and plasma swirls around the black hole, steadily feeding it large quantities of matter. This foolproof material creates a tangle magnetic field which can throw matter away from the black hole in giant jets. Changes to the disk can cause these radio jets to turn off and on in rare cases.
In the new study, published January 15 in the journal Monthly Notices of the Royal Astronomical SocietyThe researchers used the Low-Frequency Array, an array of radio telescopes located primarily in the Netherlands, to find more than 20 galaxy clusters harboring radio galaxies with irregularly shaped jets. They focused on one of these galaxies, called J1007+3540, which has a particularly unusual footprint.
The giant galaxy has large lobes of diffuse plasma that indicate past jet activity dating back about 240 million years. But inside these lobes are smaller, brighter jets of plasma, only 140 million years old, the team found. This suggests that the active galactic core (AGN) – the central region that houses a galaxy’s supermassive black hole – has awakened after a period of silence.
“This spectacular superposition of young jets inside older, exhausted lobes is the signature of an episodic AGN – a galaxy whose central engine keeps turning on and off over cosmic timescales,” Kumari said.
The space between the galaxies in the cluster that includes J1007+3540 is filled with superheated gas called the intracluster environment. This gas interacts with the radio jets, bending and shaping them as they extend from the AGN. One of the two oldest lobes is crushed laterally and brought back towards its source by the surrounding gas. The other lobe has a long bent tail which suggests that the intracluster medium interacts with the jets in a different way.
“J1007+3540 is one of the clearest and most spectacular examples of episodic AGN with jet-cluster interaction, where the surrounding hot gas bends, compresses and deforms the jets,” co-author of the study. Surajit Palphysicist at the Manipal Center for Natural Sciences in India, said in the statement.
Observing J1007+3540 will help researchers determine how often AGNs turn on and off and how ancient planes interact with their environment. As part of future work, the team plans to collect high-resolution observations of the galaxy to map how jets propagate through the intracluster medium, according to the release.
