Study involving IUB researcher sharpens Hubble constant measurement

An international team of astronomers has produced one of the most precise direct measurements of the universe’s expansion rate, intensifying the long-standing “Hubble tension”.

The study, led by the H0 Distance Network (H0DN) collaboration, estimates the current expansion rate at 73.50 kilometres per second per megaparsec, with an uncertainty of ±0.81, says a press release.

Dr Syed Ashraf Uddin, associate professor of physical sciences at Independent University, Bangladesh (IUB), contributed to the research as part of the global collaboration.

The study, titled “The Local Distance Network: A community consensus report on the measurement of the Hubble constant at ~1% precision”, has been published in the journal Astronomy & Astrophysics.

Researchers said the findings add to evidence of a persistent gap between measurements of the universe’s present expansion rate and estimates based on observations of the early universe.

Dr Uddin said, “By showing that multiple independent methods converge on the same higher value, the new study makes it harder to attribute the discrepancy to a single flawed approach and strengthens the case that the tension may reflect deeper, unresolved physics.”

The team combined multiple distance measurement techniques, including observations of variable stars, supernovae and galaxy properties, into a unified framework.

Researchers said this “distance network” approach allowed cross-checking of methods and reduced uncertainties.

Nearly 40 researchers from different methodological backgrounds contributed to the study.

Dr Uddin said the findings suggest the discrepancy is unlikely to be due to measurement errors alone.

“When multiple independent approaches point to the same result, it strengthens our confidence that the discrepancy we see is real and not simply a measurement issue,” he said.

Dr Khan Muhammad Bin Asad, director of the Center for Astronomy, Space Science and Astrophysics at IUB, said the research reflects the university’s growing involvement in international scientific work.

The researchers said the study provides a framework for future investigations into whether new physics may be required to explain the mismatch.