New method sharpens distance measurements between merging quasar pairs

By the Everything Space news desk · 29 Sep 2026 · written from the sources below

Image: Universe Today

A refined technique using quasar light absorption could reduce errors in measuring how far apart merging supermassive black holes actually are.

Researchers at the University of Alberta have developed a more accurate way to measure the physical distance between pairs of quasars, the extremely bright cores of merging galaxies powered by supermassive black holes.

Traditionally, astronomers estimate distances using redshift, which tracks how fast light-emitting gas is moving away from Earth. But in quasar pairs, the intense radiation from active black holes pushes surrounding gas outward at high speeds, skewing velocity readings and introducing errors of up to tens of millions of light-years when estimating how far apart the two quasars truly are along the line of sight.

The new approach relies on something called the Quasar Proximity Effect, which examines hydrogen absorption features in gas heated and illuminated by a quasar's own light. By analyzing where this heated, transparent gas appears in a quasar's spectrum, researchers can infer the true separation between two quasars with far greater precision, likened by the lead researcher to using the visible glow between two light bulbs to gauge how far apart they are.

Using simulations, the team found this method could narrow the margin of error to as little as half a million light-years, a dramatic improvement over conventional redshift-based estimates.

Notably, the technique can be applied to quasar pair data already collected, rather than requiring new observations that can take years to obtain or may not be possible at all.

More precise separation measurements matter because they help scientists estimate how long it takes merging galaxies and their central black holes to coalesce, which in turn feeds into broader efforts to understand the relationship between cosmic distance and expansion.

The researchers plan to further test the method using finer details in real quasar spectra to see how much additional precision can be gained.

Written in Everything Space’s own words by our news-desk model from the sources above, and checked against them in code: every number in this report appears in its sources, and no sentence is copied from them.