Galaxies fling out matter much more violently than we thought

Violent activity from black holes could explain the ongoing mystery surrounding missing cosmic matter.

The universe is largely made up of dark matter, yet the distribution of ordinary matter still baffles astronomers. Certain baryonic material seemed to have vanished over time; however, recent investigations led by Boryana Hadzhiyska and her team at the University of California, Berkeley have unveiled its hidden locations and how black holes influence its dispersal.

“Matter is composed of dark matter, predominantly, alongside baryonic matter or gas. A mere fraction of this gas forms stars; the majority exists as diffuse gas,” she explains. This diffuse gas is faint and challenging to detect, but through integrating several observational data sets, her team tracked it down.

One of the utilized data sets illustrates how baryonic matter impacts the cosmic microwave background radiation from the big bang. Furthermore, analyzing gravitational distortions in this afterglow provided crucial insights. Combining these analyses, the team pinpointed areas where dark and baryonic matter overlap and where they diverge within and between galaxies.

Hadzhiyska expressed enthusiasm about discovering that baryonic matter is significantly more dispersed than dark matter, hinting that supermassive black holes at galaxy centers might be expelling it with surprising intensity.

“Understanding how this matter ejection occurs and its strength remains ambiguous. The extent of matter expelled from any given galaxy is still unclear,” remarks Colin Hill from Columbia University, New York. Although researchers can model galaxies computationally, intricate analyses such as this one are essential for refining understanding. “This provides a complementary avenue to grasp the role of supermassive black holes in gas dispersal across galaxies,” asserts Alex Krolewski from the University of Waterloo in Canada.

Hadzhiyska also suggests that these analyses might help resolve ongoing debates regarding the universe’s clumpiness — specifically, how both ordinary and dark matter aggregate throughout space under gravity’s influence. Her team aims to include even more diverse observations, such as the effects of fleeting cosmic radio waves passing through the diffuse baryon gas. An improved “baryon census” with minimized uncertainties is still needed, according to Michael Shull from the University of Colorado Boulder.

Could these findings reveal peculiarities in matter distribution that prompt theorists to reconsider existing models? “We are hopeful for breakthroughs. My aspiration is for dark matter to be the area where we begin to detect variations from the standard cosmological model,” hopes Hadzhiyska.