Distant Quasar Halts Star Formation in Nearby Galaxies

Astronomers have discovered that one of the most distant known quasars appears to have halted the creation of new stars in all the galaxies within its vicinity. A quasar, a powerful source of light, is generated by hot gas orbiting a massive black hole at the center of a galaxy. This particular quasar, named VIK J2348-3054, has likely stopped star formation in galaxies up to 16 million light-years away, according to a report by astronomer Trystan Lambert and colleagues, soon to be published in Astronomy and Astrophysics.

The quasar is so far away that its light has taken 13 billion years to reach Earth, allowing us to observe it as it was when the universe was only 770 million years old. Remarkably, by this early point in cosmic history, the black hole powering the quasar had already grown to a mass two billion times that of the sun. This suggests that the quasar’s host galaxy resides in a particularly dense region of the universe, likely at the center of a large galaxy cluster where many galaxies should be forming new stars.

However, contrary to expectations, this does not seem to be the case. “It was shocking,” said Lambert of the Universidad Diego Portales in Santiago, Chile. “You would expect more star-forming galaxies near the quasar than farther away, but we found the exact opposite. There’s a big hole around the quasar.” The closest star-forming galaxy is at least 16.8 million light-years away, a distance more than six times greater than that between the Milky Way and its neighboring Andromeda galaxy.

This surprising discovery was made possible because Lambert’s team searched a much larger area around this quasar for star-forming galaxies than previous studies had explored.

“Quasars aren’t quiet neighbors,” Lambert explained. “They are violent; they are bursting with energy, and that energy is influencing the nearby galaxies.” Lambert suspects that the quasar’s intense radiation heats the gas in surrounding galaxies, preventing it from cooling and collapsing to form new stars.

Nonetheless, further research is necessary to conclusively support this theory, according to Martin Rees, an astronomer at the University of Cambridge. The large number of star-forming galaxies found at greater distances from the quasar—38 in total—could merely reflect the larger volume of space at those distances. The volume of space around the quasar increases with the cube of the distance from it, so the absence of star-forming galaxies in the smaller volume near the quasar could simply be due to chance.

“It’s a fair point,” Lambert acknowledged, but he noted that no other similarly sized region near the quasar is devoid of star-forming galaxies. Rees added that if more sensitive observations find additional star-forming galaxies farther from the quasar but none near it, this would strengthen the statistical significance of the finding.

Interestingly, our own galaxy may have once been affected by a quasar. The enormous galaxy M87, located about 54 million light-years from the Milky Way, hosts a massive black hole that likely powered a quasar when the universe was young. At that time, this quasar was much closer to our galaxy. When the universe was a quarter of its current size, the distance between the Milky Way and M87 was likely only a quarter of what it is now. A quasar that close could have caused a temporary lull in star formation, which astronomers might eventually detect by measuring the precise ages of the Milky Way’s oldest stars.