The universe may be younger than we thought, based on the movements of satellite galaxies, revealing how recently they have been included in a galaxy group.
According to the measurements made cosmic microwave background radiation by (SPK) European Space AgencyPlanck mission, The universe is approximately 13.8 billion years old. This calculation is based on what is known as the Standard Model. cosmologyIt describes a flat universe dominated by dark energy And dark matter and which one is expanding at an increasing rate.
Standard Model It is then used as a basis for supercomputer simulations that can depict the growth of large-scale structure. Universe — galaxies, galaxy clusters and great chains and walls of galaxies.
But these patterns are now contradicted by new measurements of the couples’ movements. galaxies These do not match what the simulations tell us.
Relating to: How old is the universe?
In a new study, astronomers led by Guo Qi of the National Astronomical Observatory of the Chinese Academy of Sciences examined pairs of moons in galaxy groups.
Galaxy groups are collections of small galaxies, such as our own Local Group, where several large galaxies are joined by a swarm of smaller galaxies. Like larger galaxy clusters, these galaxy groups form where filaments are present in the galaxy. cosmic web The amount of matter that covers the universe clumps together and moves along the filaments before falling into a group of smaller galaxies.
Using observations made by the Sloan Digital Sky Survey (SDSS) of 813 galaxy groups out of approximately 600 million galaxies light years from SoilQi’s team focused on the largest galaxy in each group and measured how galaxy pairs form. satellites he moved on opposite sides of the galaxy.
They found that the proportion of satellite galaxies that rotate in opposite directions relative to each other (in other words, orbiting in opposite directions around the larger galaxy) is higher than predicted by computer simulations of large-scale structure such as the Millennium Simulation. The Illustris TNG300 model is based on the Standard Model, both described in the Planck mission.
This is natural if the moons have just fallen into orbit around the group’s larger galaxy. But it’s over timeGalaxy groups and clusters must reach a dynamically comfortable state where most moons orbit together. If galaxy groups and clusters merge at the time suggested by the Standard Model, the proportion of counter-rotating moons will be smaller. The fact that these are a larger proportion than satellites is a problem for the Standard Model.
“In the SDSS data, we found that satellite galaxies accrete/fall into large groups and that a stronger accretion signal persists compared to simulations with Planck parameters,” Qi told Space.com in an email.
In other words, satellite galaxies appear to have only recently entered their respective groups.
“This suggests that the universe is younger than CMB’s Planck observations suggest,” Qi said. “Unfortunately, this study cannot quantitatively estimate the age of the universe.”
This is because there is still too much leeway in the motions of satellite pairs and models of how groups form for these results to give an accurate figure for how much younger the universe is than 13.8 billion years.
If true, the new findings suggest that something is wrong with the Standard Model and that some of our assumptions about the universe are wrong. In fact, a cosmic paradox that scientists are currently investigating may be the answer to this question.
Relating to: Our expanding universe: Age, history and other facts
The expansion rate of the universe is described by a number called Hubble constant. Planck measured the Hubble constant as 67.8 kilometers per second per megaparsec, or the volume of each megaparsec. space expanding 67.8 kilometers (42.1 miles) every second. (One megaparsec is approximately (3.26 million light-years).) Based on this expansion rate, cosmologists can turn back the clock and calculate the age of the universe as 13.8 billion years.
But observations redshift Type Ia supernovaexploding white dwarfsGive the value of the Hubble constant as 73.2 kilometers (45.5 miles) per second per megaparsec. Turning back the clock at this rate of expansion would reveal a younger age of 12.6 billion years.
Both measurements of the Hubble constant are considered perfect, but they still differ greatly. This paradox became known as: “Hubble voltage“
“This could of course be related to the Hubble tension problem,” Qi said when asked whether the younger age suggested by satellite pairs in galaxy groups supports the faster expansion rate obtained from supernova measurements.
But there are other obstacles to overcome. If we underestimate the age of the universe too much, then astronomers will find themselves in an odd situation. stars known to be older than the universe itself.
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Perhaps the explanation lies in other aspects of the Standard Model. For example, the model is heavily dependent on dark matter, but so far scientists do not know what dark matter is. Other researchers suggest that dark matter does not exist at all and that its gravitational effects can be explained by an event. changing the laws of gravity at low accelerations such as those experienced by satellite galaxies orbiting at greater distances. Qi’s team found that pairs of satellites with larger orbital radii were more likely to rotate in the opposite direction.
More data would be welcome at this time. The same phenomenon should be true for larger galaxy clusters, Qi said, but the clusters tend to be farther away and the limited sample size and lower data quality make any measurements inconclusive at the moment.
Whatever age value is correct, the universe is very old; but these new results suggest he may be able to regain some of his youth.
The new findings were published January 22 in the journal Nature Astronomy.