Basic Precept of Cosmology Solid in Doubt by Compelling New Examine

Examine by the Universities of Bonn and Harvard raises doubts about fundamental assumption for the universe.

Regardless of the place we glance, the identical guidelines apply in every single place in area: numerous calculations of astrophysics are based mostly on this fundamental precept. A current research by the Universities of Bonn and Harvard, nonetheless, has thrown this precept into query. Ought to the measured values be confirmed, this may toss many assumptions in regards to the properties of the universe overboard. The outcomes are revealed within the journal Astronomy & Astrophysics, however are already accessible on-line.

Because the massive bang, the universe has swollen like a freshly fashioned raisin roll put in a heat place to rise. Till lately, it was thought that this improve in measurement was occurring evenly in all instructions, as with yeast dough. Astrophysicists name this “isotropy.” Many calculations on the elemental properties of the universe are based mostly on this assumption. It’s potential that they’re all improper — or at the least, inaccurate — thanks to forcing observations and analyses of the scientists from the Universities of Bonn and Harvard.

The sky distribution of the 313 clusters analyzed by the authors in galactic coordinates. 4 galaxy clusters as noticed by the Chandra telescope are displayed as examples. Credit score: © NASA/Chandra

For they’ve put the isotropy speculation to the take a look at for the primary time with a brand new methodology that enables extra dependable statements than earlier than. With an sudden outcome: In response to this methodology, some areas in area broaden quicker than they need to, whereas others broaden extra slowly than anticipated. “In any case, this conclusion is recommended by our measurements,” states Konstantinos Migkas, from the Argelander Institute for Astronomy on the College of Bonn.

Migkas and his colleagues have developed a brand new, environment friendly isotropy take a look at of their research. It’s based mostly on the remark of so-called galaxy clusters — in a way, the raisins within the yeast bun. The clusters emit X-ray radiation that may be collected on Earth (on this case, this was finished by the satellite-based telescopes Chandra and XMM-Newton). The temperature of the galaxy clusters will be calculated based mostly on sure traits of the radiation. Additionally, their brightness will be measured. The warmer they’re, the brighter they glow.

In an isotropic universe, a easy rule applies. The additional away a celestial object is from us, the quicker it strikes away from us. From its velocity, we are able to subsequently deduce its distance from us, whatever the route wherein the thing lies. At the least that’s what we thought till now. “In actuality, nonetheless, our brightness measurements appear to disagree with the above distance calculation,” Migkas emphasizes.

It is because the quantity of sunshine that reaches the earth decreases with rising distance. So, anybody who is aware of the unique luminosity of a celestial physique and its distance is aware of how vibrant it ought to shine within the telescope picture. And it’s exactly at this level that scientists have come throughout discrepancies which might be tough to reconcile with the isotropy speculation: that some galaxy clusters are a lot fainter than anticipated. Their distance from Earth might be a lot larger than calculated from their velocity. And for some others, nonetheless, the other is the case.

“There are solely three potential explanations for this,” states Migkas, who’s doing his doctorate within the analysis group of Prof. Dr. Thomas Reiprich on the Argelander Institute. “Firstly, it’s potential that the X-ray radiation, whose depth we’ve measured, is attenuated on its method from the galaxy clusters to Earth. This might be on account of as but undiscovered gasoline or mud clouds inside or exterior the Milky Way. In preliminary tests, however, we find this discrepancy between measurement and theory not only in X-rays but also at other wavelengths. It is extremely unlikely that any kind of matter nebula absorbs completely different types of radiation in the same way. But we won’t know for sure for several months.”

A second possibility are so-called “bulk flows.” These are groups of neighboring galaxy clusters that move continuously in a certain direction — for example, due to some structures in space that generate strong gravitational forces. These would therefore attract the galaxy clusters to themselves and thus change their speed (and thus also their derived distance). “This effect would also mean that many calculations on the properties of the local universe would be imprecise and would have to be repeated,” explains Migkas.

The third possibility is the most serious: What if the universe is not isotropic at all? What if — metaphorically speaking — the yeast in the galactic raisin roll is so unevenly distributed that it quickly bulges in some places while it hardly grows at all in other regions? Such an anisotropy could, for example, result from the properties of the mysterious “dark energy,” which acts as an additional driving force for the expansion of the universe. However, a theory is still missing that would make the behavior of the Dark Energy consistent with the observations. “If we succeed in developing such a theory, it could greatly accelerate the search for the exact nature of this form of energy,” Migkas is certain.

The current study is based on data from more than 800 galaxy clusters, 300 of which were analyzed by the authors. The remaining clusters come from previously published studies. The analysis of the X-ray data alone was so demanding that it took several months. The new satellite-based eROSITA X-ray telescope is expected to record several thousand more galaxy clusters in the coming years. At the latest then it will become clear whether the isotropy hypothesis really has to be abandoned.

Reference: “Probing cosmic isotropy with a new X-ray galaxy cluster sample through the L X – T scaling relation” by K. Migkas, G. Schellenberger, T. H. Reiprich, F. Pacaud, M. E. Ramos-Ceja and L. Lovisari, 8 April 2020, Astronomy & Astrophysics.
DOI: 10.1051/0004-6361/201936602