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Large amount of dark matter may be missing from the Milky Way

It turns out our galaxy is not as heavy as we previously believed. A new study indicates that we may be missing a fifth of the Milky Way’s weight, suggesting the disappearance of a considerable amount of dark matter.

The research is scheduled for publishing in the Astronomy and Astrophysics journal.

What is dark matter?

Dark matter is a hypothetical form of matter believed to make up a significant portion of the total mass of the universe. 

Unlike ordinary matter – including atoms and particles making up the stars, planets, and other things we see and touch – dark matter is invisible and undetectable. It does not interact with the electromagnetic field.  

Weight of the Milky Way 

Based on data from the Gaia telescope, the researchers determined that the Milky Way is 200 billion times heavier than the sun. This challenges existing estimates, which put the previous mass at between 890 billion and a little above one trillion solar masses.

The discovery also challenges previous assumptions that dark matter has six times more abundance than ordinary matter. 

This could mean that ordinary matter makes up a third of all the matter in the galaxy. After all, the popular opinion is that ordinary matter is equivalent to the mass of around 600 million suns.

Many questions remain

The findings are profound, no doubt. But they are very different from everything we have known about the matter content of the galaxy. This has led to skepticism among scientists.

Professor Andrew Pontzen of University College London believes that the study needs to provide more evidence to firmly establish the results.

Professor Andrew told The Times: “If our galaxy really has as little mass as this work suggests, one would have to explain why previous works based on different techniques all came up with a higher number.”

Exceptional findings

In their defense, the researchers acknowledge that their findings are “quite exceptional.” 

Their conclusion was made possible through the study of the Milky Way’s rotational curve.

The team explained that the difference in the Milky Way’s rotational curve compared to other spiral galaxies “could be due to the extraordinarily quiet history of our galaxy.” 

For example, it’s been nine billion years since the Milky Way’s last major merger. The time frame is six billion years for its counterparts. 

This new discovery is set to reshape how we have perceived our galaxy in the last 13 billion years.

More about dark matter

As discussed above, dark matter is the elusive cosmic enigma that continues to baffle scientists and astronomers alike. While it doesn’t emit, absorb, or reflect light, its profound influence on the universe is undeniable.

Defining dark matter

Unlike ordinary matter, which comprises atoms and everything we can see and touch, dark matter remains hidden from our senses. Scientists have known of its existence for decades, primarily through its gravitational effects on visible matter, such as galaxies and galaxy clusters.

Why dark matter matters

The significance of dark matter lies in its gravitational pull. While it may not emit or interact with light, it exerts a gravitational force that affects the motion of galaxies and galaxy clusters.

Without dark matter, galaxies would not have enough gravitational pull to hold their stars together, and the universe would be vastly different from what we observe today.

The hunt for dark matter

Unraveling the mysteries of dark matter is a scientific frontier that has captivated researchers for years. Various experiments and observations are underway to detect and understand this enigmatic substance.

Particle physics experiments

Some scientists believe that dark matter could consist of yet-undiscovered particles. Experiments such as the Large Hadron Collider (LHC) at CERN are searching for these elusive particles, aiming to recreate conditions present in the early universe when dark matter may have been formed.

Direct detection experiments

Deep underground laboratories house experiments designed to directly detect dark matter particles as they pass through Earth. These detectors are highly sensitive and aim to capture the faintest signals of dark matter interactions.

Cosmic microwave background

The cosmic microwave background radiation, a relic of the early universe, is another tool in the quest for dark matter. Precise measurements of this radiation can provide clues about the distribution and properties of dark matter.

Gravitational lensing

Astronomers use gravitational lensing, a phenomenon where the gravitational pull of dark matter bends and distorts light from distant objects, to map the distribution of dark matter in the universe.

Unfinished puzzle

Despite decades of research and numerous experiments, dark matter remains an unsolved puzzle. While we have strong evidence for its existence, we have yet to directly observe or identify its constituents. Understanding dark matter is crucial not only for piecing together the universe’s history but also for shedding light on fundamental questions about the nature of the cosmos.

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