By the 1920s, astronomers discovered the Universe was expanding as Einstein’s Theory of General Relativity predicted. This resulted in a debate among astrophysicists in between people who thought the Universe began with a huge Bang and people who believed the Universe existed in a constant State. By the 1960s, the very first measurements of the Cosmic Microwave Background (CMB) suggested the former was probably the most probable scenario. And by the 1990s, the Hubble Deep Fields provided probably the deepest pictures of the Universe actually considered, revealing galaxies while they came out only a couple of 100 thousand years after the Big Bang.
As time passes, these discoveries resulted in an astounding realization: the speed at that the Universe is expanding (aka. the Hubble Constant) hasn’t been constant after a while! This resulted in the principle of Dark Energy, an invisible force which counteracts gravity and leads to this particular expansion to accelerate. In a number of papers, an international team of scientists led by the Faculty of Hawaii found that black holes in dormant and ancient galaxies have been growing much more than anticipated. This constitutes (they claim) the very first proof that black holes may be the source of Dark Energy.
The study was comprised of astrophysicists and astronomers from the Faculty of Hawai’i, the Kavli Institute for Cosmological Physics, the Enrico Fermi Institute, the European Southern Observatory (ESO), the Netherlands Institute for Space Research (SRON), the National Radio Astronomy Observatory (NRAO), the Instituto de Astrofísica e Ciências do Espaço (IA), the Mitchell Institute for Fundamental Astronomy and Physics, along with numerous universities. Their findings appeared in 2 papers published in the Astronomical Journal as well as the Astronomical Journal Letters.
Based on the most accepted model of the universe, Dark Energy accounts for 68% of all mass Energy in the universe. This particular concept revived an idea Einstein had proposed, but later rejected, that there was a cosmic constant (represented by the scientific symbol delta) that held back gravity and prevented the Universe from collapsing. the force and Dark Matter (which accounts for 26.8% of the mass-energy content) are essential to the most commonly held cosmological model these days, known as the Lambda-Cold Dark Matter (LCDM) model.
The main argument for Dark Energy exists that there is a particular kind of Energy inside spacetime (called vacuum Energy) that is separating the Universe. However there’s no direct evidence for this mysterious energy, and there’re a number of issues with this theory. In addition, while this vacuum energy is consistent with quantum mechanics, all efforts to calculate it using quantum field theory have failed. There is also the issue of exactly how this power interacts with supermassive black holes (SMBHs) in our Universe.
Astronomers had established by the 1970s that the persistent radio source in the center of our universe (Sagittarius A *) was a black hole with a mass of 40 million Suns. Further observations showed that most massive galaxies had SMBHs within their primary region, which had been the reason for the presence of Active Galactic Nuclei (AGNs) or quasars. The incredibly powerful gravity of SMBHs can cause the surrounding matter to infall around them, creating accretion disks and powerful relativistic jets, in which matter is sped up to close to the speed of light (and releasing enormous amounts of radiation).
In the center of nearly all significant galaxies, the presence of these mammoths would require a very powerful force to counter them. This’s particularly true when it comes to the singularities that are supposed to occur at their cores, where the laws of physics break down and become indistinguishable. This resulted in an unusual theory known as “cosmological coupling,” which says that SMBHs might have tremendous vacuum energy and that they are the reason why the Universe expands.
Within their papers, the team headed by Duncan Farrah (an astronomer with the University of Hawai’i at Manoa as well as a former Ph.D. with Imperial College report the very first observational proof that black holes gain mass in a way in keeping with them containing vacuum energy. Astrophysicists have been searching for a theoretical solution to the issue of dark energy and Black Holes, the findings of the team constitute the first observational evidence that Black Holes are the source of dark energy.
When the resultant finding is correct, it removes the need for singularities to form in the middle of black holes, resolving a long held debate. Additionally, it means that for our cosmological models to make sense, nothing more is required (no new forces or altered gravity theories). Dr. Chris Pearson, a researcher from RAL Space, a research council overseen by the UK’s Science and Technology Facilities Council (STFC), and Dr. Dave Clements of the Department of Physics at Imperial College were co-authors on the research.
“If the principle holds, then this can revolutionize the field of cosmology, because at last we have a fix for the origin of dark energy that is been perplexing cosmologists and theoretical physicists for over twenty years,” said Pearson in a RAL Space news release. “This result is genuinely surprising. “I believe we may have found the answer to one of the biggest issues in cosmology, starting off looking at just how black holes grow over time,” Clements said.
Require Extraordinary Evidence
This conclusion was attained by checking out the evolutionary history of SMBHs in the center of gigantic elliptical galaxies. This refers to a kind of early galaxy which formed at the start of the Universe and has since ceased creating stars (also known as Dormant galaxies). Black holes may improve their mass in 2 ways, because years of observations have demonstrated: Simply by accreting material or by merging with dark holes. The team examined huge elliptical galaxies with redshifts of under z2 (as they came out nine billion years ago), as indicated in their very first paper.
These dormant galaxies have very little material remaining for their SMBHs to accrete, which means even further growth can’t be explained by the 2 mechanisms stated previously. After that, the team evaluated observations of these elliptical galaxies, which still look younger, with neighborhood galaxies dating to ca. 6.6 billion years back, that have now turned dormant. These observations demonstrated SMBHs had been seven to 20 times bigger than they were 9 billion years ago, a greater expansion compared to what’s predicted by mergers or accretion.
In their second paper, they further explain exactly how measurements of associated populations of galaxies at different points in their development (ca. An equivalent link between the mass of SMBHs and the size of the Universe was discovered, 7.2 billion years ago. This is the first proof of “cosmological coupling” by showing that expansion of the Universe and development of SMBHs are related. If more observations confirm this, it might redefine our understanding of the Universe and black holes. Farrah concluded:
“We are actually saying two things at the identical time: that there is evidence the regular black hole methods don’t work for you on a long, long timescale, and we’ve the pioneer proposed astrophysical source for dark energy. What meaning, though, is not that other people haven’t proposed sources for dark energy, but this’s the 1st observational paper in which we are not including anything new to the Universe as a supply for dark energy: “the black holes are the deep energy in Einstein’s theory of gravity,” he wrote.
Correlation, not Coupling?
These statements had been naturally met with some skepticism from the astronomical / astrophysical community. Specifically, the authors ‘claim that their observations constitute proof of coupling has been challenged for conflating correlation with causation. The astrophysicist, author, science communicator and Forbes senior contributor Ethan Siegel addressed this in a recent installment of Ask Ethan, a special series in his column Starts off with a Bang, where he responds to inquiries from his readers. Siegel discusses in his post how the authors ‘conclusions rest upon a major assumption.
The notion is that there’s a common connection between the mass of the central black hole and also the mass of stars within a galaxy, which may evolve over cosmic time, but ought to be universal at any particular time. Because of this, they evaluated the SMBHs they selected for their sample information to figure out whether there’s a “coupling parameter” (represented as k) that has the same value throughout cosmic time. The team concluded that k has a non-zero value, having a confidence of 99.8 %. This conclusion is based on an assumed relationship, though this conclusion is ostensibly convincing. Ethan concluded:
The authors are assuming the presence of a coupling which is not there, and ascribing the seen evolution of black hole to stellar mass ratios to some coupling, when what is taking place is these galaxies and their black holes developing. ” Because we are only measuring each galaxy at a snapshot in time, we have not a clue how each object is evolving, and this’s just the way the post authors fool themselves and everybody who believes them.
At the risk of repeating the old saying, “extraordinary claims call for extraordinary evidence.” Among the most important qualifications for sound evidence will be the capability to repeatedly verify the results. Quite simply, the results should be demonstrable over and over and (preferably) with varying methods. The contributors recognize this and wish repeating observations will support them. But the claim continues to be extraordinary and demands further investigation, due to the implications.
Original article Universe Today