JWST and the Rethink of Cosmology Theory

Sunday - May 7 2023, 06:26 UTC - 1 year ago

A new paper has shown data from six galaxies spotted by the James Webb Space Telescope that suggests it is possible that the universe was expanding faster after the Big Bang than what is currently understood in the leading model of cosmology. The implications of this could lead to changes in cosmological theory, requiring more matter was available for forming stars and galaxies in the early universe than is currently understood.

Launched at the end of 2021, the James Webb Space Telescope (JWST) continues to rack up impressive paradigm-shifting finds.

A new paper describes the discovery of a number of galaxies that appear to have grown very massive incredibly quickly after the Big Bang, so quickly, in fact, that this fact goes against the standard model of cosmology. If future data corroborates such information, the leading model would most likely need to be revised.

In the study,published in Nature Astronomy, author Mike Boylan-Kolchin, an associate professor of astronomy at The University of Texas at Austin, shows how data from six of the most massive and earliest galaxies spotted by JWST goes against the current thinking about the birth of galaxies.

The galaxies are much more massive than theoretical predictions would indicate for the age they are estimated to be, which is between 500 and 700 million years old. The researchers estimate that in order for the galaxies to reach their size in this time period, they would need to be converting nearly 100% of their available gas into stars. In contrast, astronomers typically see no more than 10% of gas converted into stars.

In a news release, Boylan-Kolchin pointed out that "If the masses are right, then we are in uncharted territory." Accounting for the differences between the predictions and reality would likely require changes in cosmological theory, possibly reinventing how we understand galaxy formation. The leading model of cosmology dates from the late 1990s and is termed the ΛCDM (Lambda CDM, or LCDM), also known as the dark energy + cold dark matter (ΛCDM) paradigm.

What might be possible, for example, is that new forces and particles exist which would explain how the universe expanded faster than we currently think right after the Big Bang. Another possibility is that more matter was available for forming stars and galaxies in the early universe than is currently understood.

The data on the galaxies used in the study was obtained from the Cosmic Evolution Early Release Science Survey (CEERS).

Interesting Engineering (IE) reached out to Professor Boylan-Kolchin for more insight into his paper. The following exchange has been lightly edited for clarity and flow. Interesting Engineering: What are the implications of the possibility that the universe was expanding faster after the Big Bang than prevailing theories suggest? .

Professor Boylan-Kolchin: If the Universe expanded faster early in its history (the models typically have this happening for a short period near redshift of 3500 or near ~50,000 years after the big bang), then one implication is that the Universe would be somewhat younger than we currently believe. We now have a precise measurement of 13.8 Gyr (with an error of < 0.2%) for the age of the Universe in the standard 6-parameter dark energy + cold dark matter (LCDM) model, but faster expansion would be an extension to this model and would require an age of closer to 12.8 or 13.0 billion years. This is one tangible example. [The] structure would also grow faster, somewhat paradoxically, because we’d require extra matter to ‘balance out’ that early expansion and this would help promote earlier growth of galaxies (perhaps matching JWST observations better).

These models for faster early expansion — some go by the name “early dark energy” — have been around for a while and are quite suggestive of some kind of new physics. For example, some models have an extra scalar field or ‘dark energy-like’ medium fill the universe that would ‘decay away’ at early times, leaving behind extra matter and faster early expansion.