A new study of a rare and short-lived type of galaxy has found that such objects harbor dormant supermassive black holes that briefly wake up and tear apart a massive star, devouring its remains as a giant cosmic breakfast.
“Compact Symmetric Objects,” or CSOs, are active galaxies where two jets explode at nearly the speed of light. These jets are common for active galactic nuclei (AGN), which have supermassive black holes at their hearts that feed on surrounding gas and dust; but CSOs’ jets are different.
While jets from AGNs can extend up to 230,000 light-years in either direction, CSO jets are stunted and extend only about 1,500 light-years.
Scientists have previously theorized that CSO jets are short because they are newly formed or young. Now a team led by California Institute of Technology (Caltech) scientists has determined that these jets have a short lifespan.
Relating to: New view of the supermassive black hole at the heart of the Milky Way points to an exciting hidden feature (image)
“These CSOs are not young. You can’t call a 12-year-old dog a teenager even though it has lived a shorter life than an adult human,” said study team leader Anthony Readhead, a professor emeritus of astronomy at Caltech. An idiom. “These objects are a distinct species all their own, living and dying over thousands of years, rather than the millions of years common in galaxies with larger jets.”
Snack black holes give galaxies the life of a dog
To demystify CSOs and uncover their true nature, Readhead and colleagues spent two years researching 3,000 CSO candidates from past literature and astronomical data from the Very Long Baseline Array (VLBA) and other high-resolution radio telescopes.
“VLBA observations are the most detailed in astronomy, providing images with detail equivalent to measuring the width of a human hair from a distance of 100 miles.” [160 kilometers]” said Readhead.
The team confirmed that 64 of these candidates were CSOs and also identified 15 more of these rare galaxies. By analyzing these CSOs, the team concluded that these rare types of galaxies only expel jets for 5,000 years or less and then disappear.
“The CSO jets are very energetic jets, but they seem to be shutting down,” said team member Vikram Ravi, an assistant professor at Caltech. “Jets stop flowing from the source.”
The team has identified a suspect in the emission of these jets: They theorize that at the heart of the CSOs are supermassive black holes that tear apart stars that get too close to them, called “tidal disruption events,” or TDEs.
When stars come very close to a black hole, the black hole’s immense gravity creates strong tidal forces within the star body. These tidal forces compress the star horizontally and stretch it vertically; This process is called “spaghettification”.
This stellar noodle wraps around, forming a disk of material that is slowly eaten away by the supermassive black hole. But black holes are messy eaters, and some of this star matter is directed to the poles of these cosmic monsters. From here, some of the material is removed by spraying it in the form of jets. This TDE process is accompanied by incredibly bright light emissions that alert astronomers to these nurturing supermassive black holes.
“We think a single star is breaking apart and then all that energy is directed into jets along the axis around which the black hole rotates,” Readhead explained. “The giant black hole starts out invisible to us, and then when it consumes a star, boom! The black hole has fuel and we can see it.”
But as an NGO, it is not just any star that could be the messy cosmic meal that awakens the black hole. The team thinks that a CSO could only be created if a truly massive star were torn apart by a supermassive black hole in a TDE.
“The TDEs we saw before only lasted a few years,” Ravi explained. “We think the notable TDEs that power the CSOs last much longer because the decaying stars are either too large in size, too massive, or both.”
Readhead and his colleagues have also managed to create a “cosmic family album” showing how NGOs and their jets have evolved over time. Younger CSOs have shorter jets that extend closer to the central supermassive black hole, while older CSOs have longer jets that extend farther from the TDE region.
The team determined that the vast majority of CSOs will disappear, but 1% will continue to have long-lived events with long jets like those seen in Cygnus A, a distant supermassive black hole whose jets are aimed at Earth. object class called blazar.
In these 1 in 100 long-lived events, researchers suggest that the central black hole is fed by extra gas and dust from the host galaxy merging with another galaxy.
RELATED STORIES:
— Supermassive black hole’s mysterious ‘hiccup’ likely originates from neighboring black hole’s ‘punch’
— Brightest quasar ever seen is powered by black hole eating ‘a sun a day’
—Scientists think a spaghetti-effect black hole is very close to Earth
According to Readhead, these findings confirm the theory first proposed in the 1990s that only three NGOs were discovered. This idea was mostly unrecognized by the broader scientific community when it was first proposed, but is expected to gain traction with this new evidence.
“The hypothesis has been almost completely forgotten because it has been years since observational evidence for TDEs began to be collected,” Readhead said. said. “These objects are actually a separate population with their own distinct origins, and it is now up to us to learn more about them and how they came to be.
“Being able to study these objects over time spans of decades rather than millions of years has opened the door to a whole new laboratory for studying supermassive black holes and the many unexpected and unpredictable surprises they hold.”
The team’s research was published in three studies last month in The Astrophysical Journal.