Galactic clusters may be key to testing competing theories of dark matter and dark energy
Scientists suggest a modified cosmological mannequin that challenges the existence of darkish matter and darkish power.
Our present understanding of the evolution and construction of the cosmos depends on the idea that gravity is described by Einstein’s basic concept of relativity, and that solely about 5% of the mass in the entire Universe consists of odd matter.
The remaining 95% is considered composed of darkish matter and darkish power. Darkish matter, comprising one third of the full mass, is accountable for the formation and progress of galaxies, whereas darkish power, which accounts for greater than two-thirds of the mass, is believed to drive the accelerated enlargement of the Universe.
This understanding falls beneath a mannequin referred to as ΛCDM, the place CDM stands for “chilly darkish matter” and Λ is the broadly used image for darkish power. In it, darkish matter particles are thought-about to be heavy and gradual shifting, very similar to particles that make up a chilly fuel.
Whereas the ΛCDM offers a superb description of astronomical observations, it nonetheless has some conceptual issues. For instance, though there ought to be rather more darkish matter than odd matter within the Universe, this mysterious entity has by no means been instantly noticed and so scientists nonetheless don’t know what it’s made or whether or not it exists in any respect. Darkish power has confirmed much more elusive, with no believable speculation concerning its composition and nature put forth so far.
A modified concept
These points have prompted researchers to search for alternate options to ΛCDM that may not require these unusual, undetectable entities. Some of the widespread of those is a cosmological concept based mostly on two postulates, the place the primary claims that gravity ought to really be described by a modification of Einstein’s concept that doesn’t require the introduction of darkish power to elucidate the accelerated enlargement of the Universe. The second is the assertion that darkish matter shouldn’t be composed of heavy, unknown particles, however of tiny, mild particles referred to as neutrinos.
“This mannequin is especially attention-grabbing as a result of it yields nearly an identical progress and enlargement histories to the ΛCDM, not like the opposite various fashions,” stated Jounghun Lee of the Seoul Nationwide College in an electronic mail. “In different phrases, this mannequin satisfies all of the constraints put by the usual diagnostics just like the cosmic microwave background radiation temperature energy spectrum.”
The truth that this mannequin offers such an correct description of observational information prompted Lee and his colleagues from Italy and Korea to conduct an in depth evaluation of the mannequin’s predictions, which may assist decide whether or not the ΛCDM or the brand new method thought-about by the authors of the research is appropriate.
Of their research printed in The Astrophysical Journal, they analyzed each cosmological fashions via theoretical and numerical computations to find out the orientation of galaxy clusters — which have an ellipsoidal form — inside galactic superclusters, the biggest gravitationally certain objects within the Universe. This evaluation will help decide which cosmological mannequin finest describes the true world, as a result of the outcomes of calculating the orientation of clusters rely each on which concept describes gravity and on what particles darkish matter is manufactured from.
“In our work, we’ve got give you an environment friendly diagnostics based mostly on the form alignments of galaxy clusters, with which this mannequin may be discriminated from the ΛCDM mannequin,” defined Lee.
Future experiments will present proof
What they discovered was fairly stunning. It seems that although for a lot of noticed and measured portions each theories give nearly an identical predictions. Nonetheless, when it comes to the orientation of clusters inside a supercluster, the predictions diverge — the orientation of particular person clusters are typically fairly totally different, which in precept ought to make it potential to search out out which description is appropriate via astronomical remark.
To truly research the orientation of galactic clusters, it’s essential to enhance observational devices, because the present degree of growth doesn’t permit scientists to probe these objects with the required accuracy to have the ability to present proof for both of those theories.
“To make use of our technique in observe and to really check the mannequin we thought-about, nonetheless, will probably be essential to give you a technique to find out the three dimensional shapes of galaxy clusters in actual area from observations,” concluded Lee. “That’s the essential issue.”
Hopefully, with the appearance of next-generation telescopes the theories explored on this research may be put to the check, probably resulting in a breakthrough in our understanding of the mysteries surrounding darkish matter and darkish power. This may be an enormous leap ahead in our understanding of how the Universe is organized.
Reference: Jounghun Lee, Suho Ryu, and Marco Baldi, Disentangling Modified Gravity and Large Neutrinos with Intrinsic Form Alignments of Large Halos, The Astrophysical Journal (2023). DOI: 10.3847/1538-4357/acabbc
Characteristic picture credit score: NASA
