Supermassive black holes influence star formation in large galaxies

A new study shows that supermassive black holes influence large galaxy star formation.
By Joseph Scalise | Jan 03, 2018
Supermassive black holes sitting at the center of large galaxies dictate when the systems stop forming new stars, a new study published in the journalNaturereports.

This research -- which comes from scientists at various U.S. universities -- could help explain why young galaxies are hotbeds for star formation, and why that process slows down over time.

Researchers typically detect supermassive black holes because they have a major gravitational influence on their galaxy's stars. However, there are also times where such stars can be observed by studying energetic radiation from the active galactic nucleus. That means the the energy radiating from the AGN -- the compact region at the center of a galaxy from where the intensity of radiation across the electromagnetic spectrum is much higher than the rest of the galaxy -- could heat and dissipate gas that would have otherwise cooled and condensed into stars.

The idea that the AGN disrupts star formation is recent, but it has not had any observational evidence to back the theory until now.

The team in the study analyzed massive galaxies whose central black holes was already known. They then looked at the spectra from those galaxies and analyzed differently aged populations of stars to see how formation differed from system to system.

"For galaxies with the same mass of stars but different black hole mass in the center, those galaxies with bigger black holes were quenched earlier and faster than those with smaller black holes," said lead author Ignacio Martn-Navarro, apostdoctoral researcher at the University of California, Santa Cruz, in astatement. "So star formation lasted longer in those galaxies with smaller central black holes."

After thorough analysis, scientists found that the only factor that seemed to play a significant role in star formation was the black holes' mass. Everything else, from size to composition, did not seem important.

This research could affect future studies because ones seeking to explain the evolution of galaxies need to account for the feedback from the supermassive black hole at the center. In addition, recent observations do not create a picture of how the feedback stops or limits star formation. Researchers plan to expand on the recent study in order to see if they can find answers to such questions.

 

"There are different ways a black hole can put energy out into the galaxy, and theorists have all kinds of ideas about how quenching happens, but there's more work to be done to fit these new observations into the models," said study co-author Aaron Romanowsky, an astronomer at San Jose State University, according toInternational Business Times.

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