Few entities in the universe are as intricate as dark matter, an unseen and exotic “matter” believed to account for most of the mass within galaxies.
The hypothesis suggests that aligning our current physical theories with observed universe phenomena necessitates the presence of substantial volumes of invisible matter. Scientists are convinced that this “missing mass” is real due to its gravitational pull, although direct detection has eluded them; they can only infer its presence.
Nearly a century after dark matter was first hypothesized, Japanese astrophysicists claim to have found the first concrete evidence of its existence—gamma rays emanating in a halo-like formation near the heart of the Milky Way.
“Naturally, we’re extremely enthusiastic!” said Tomonori Toya, a professor in the astronomy department at the University of Tokyo, in an email to NBC News. “While the research aimed at detecting dark matter, I thought the chances of success felt akin to hitting the jackpot.”
Toya’s assertion of being the first to identify dark matter is met with skepticism by some experts. Nonetheless, the findings, published on Tuesday in the Journal of Cosmology and Astroparticle Physics, shed light on the relentless pursuit of dark matter and the challenges of investigating the unseen in space.
Dark matter is estimated to constitute around 27% of the universe, whereas ordinary matter (like humans, objects, stars, and planets) makes up roughly 5%, according to NASA. The remainder consists of another enigmatic component known as dark energy.
Toya’s research utilized data from NASA’s Fermi Gamma-ray Space Telescope, which is focused on the center of our galaxy. This telescope is adept at capturing a powerful form of electromagnetic radiation called gamma rays.
The idea of dark matter was first proposed by Swiss astronomer Fritz Zwicky in the 1930s when he detected anomalies in the mass and movement of galaxies within the gigantic Coma cluster. The galaxies’ velocities exceeded expectations, implying they were bound together rather than escaping the cluster.
The subsequent theory introduced a truly extraordinary form of matter. Dark matter is undetectable because it does not emit, absorb, or reflect light. However, given its theoretical mass and spatial occupation in the universe, its presence can be inferred from its gravitational effects.
Various models strive to elucidate dark matter, but scientists contend that it comprises exotic particles that exhibit different behaviors compared to familiar matter.
One widely considered theory posits that dark matter consists of hypothetical particles known as WIMPs (weakly interacting massive particles), which have minimal interaction with ordinary matter. However, when two WIMPs collide, they can annihilate and emit potent gamma rays.
In his investigation, Toya identified a gamma-ray emission equating to about one millionth of the brightness of the Milky Way. The gamma rays also appeared spread out in a halo-like formation across extensive sky areas. Should these emissions originate from a single source, it may indicate that black holes, stars, or other cosmic entities, rather than diffuse dark matter, generate the gamma rays.
“To my knowledge, there’s no cosmic phenomena that would cause radiation exhibiting the spherical symmetry and unique energy spectrum observed here,” Toya remarked.
However, certain scientists not associated with the study expressed doubts about the findings.
David Kaplan, a physics and astronomy professor at Johns Hopkins University, emphasized that our understanding of gamma rays is still incomplete, complicating efforts to reliably connect their emissions to dark matter particles.
“We don’t yet know all the forms of matter in the universe capable of generating gamma rays,” Kaplan indicated, adding that these high-energy emissions could also originate from rapidly spinning neutron stars or black holes that consume regular matter and emit energetic jets.
Thus, even when unusual gamma-ray emissions are identified, deriving meaningful interpretations is challenging, noted Eric Charles, a scientist at Stanford University’s SLAC National Accelerator Laboratory.
“There are numerous intricacies we don’t fully grasp, and we observe a plethora of gamma rays across extensive areas of the sky linked with galaxies. It’s particularly difficult to decipher what transpired there,” he explained.
Dillon Braut, an assistant professor at Boston University’s Department of Astronomy and Physics, remarked that the gamma-ray signals and halo-like formations discussed in the study appear in regions of the sky that are “incredibly challenging to model.”
“Therefore, any claims should be treated with utmost caution,” Braut communicated to NBC News via email. “And, naturally, extraordinary claims necessitate extraordinary proof.”
Kaplan labeled the study as “intriguing” and “meriting further investigation,” but remained uncertain if subsequent analyses would substantiate the findings. Nonetheless, he anticipates that future advancements will allow scientists to directly validate dark matter’s existence.
“It would be a monumental shift as it appears poised to dominantly influence the universe,” he stated. “It accounts for the evolution of galaxies and, consequently, stars, planets, us, and is crucial for comprehending the universe’s origin.”
Toya himself acknowledged that further exploration is necessary to authenticate or refute his assertions.
“If accurate, the outcomes would have such significance that the research community would earnestly evaluate their legitimacy,” he noted. “While I have confidence in my findings, I hope other independent scholars can verify these results.”
Source: www.nbcnews.com
