The paper, published May 1 in the journal Monthly Notices of the Royal Astronomical Society, contradicts a 2015 study that theorized giant elliptical galaxies would be 10,000 times more likely than spiral disk galaxies such as the Milky Way to harbor planets that could nurture advanced, technological civilizations, Phys.org reported.

The increased likelihood, the authors of the 2015 study argued, would be because giant elliptical galaxies hold many more stars and have low rates of potentially lethal supernovae.

But Daniel Whitmire, a retired professor of astrophysics who is an instructor in the U of A Department of Mathematical Sciences, believes that the 2015 study contradicts a statistical rule called the principle of mediocrity, also known as the Copernican Principle, which states that in the absence of evidence to the contrary, an object or some property of an object should be considered typical of its class rather than atypical.

Historically, the principle has been employed several times to predict new physical phenomena, such as when Sir Isaac Newton calculated the approximate distance to the star Sirius by assuming that the sun is a typical star and then comparing the relative brightness of the two.

“The 2015 paper had a serious problem with the principle of mediocrity,” said Whitmire. “In other words, why don’t we find ourselves living in a large elliptical galaxy? To me, this raised a red flag. Any time you find yourself as an outlier, i.e. atypical, then that is a problem for the principle of mediocrity.”

He also had to show that most stars and therefore planets reside in large elliptical galaxies in order to nail down his argument that the earlier paper violated the principle of mediocrity.

According to the principle of mediocrity, Earth and its resident technological society should be typical, not atypical, of planets with technological civilizations elsewhere in the universe. That means that its location in a spiral-shaped disk galaxy should also be typical. But the 2015 paper suggests the opposite, that most habitable planets would not be located in galaxies similar to ours, but rather in large, spherical-shaped elliptical galaxies.

In his paper, Whitmire suggests a reason why large elliptical galaxies may not be cradles of life: They were awash in lethal radiation when they were younger and smaller, and they went through a series of the quasar and star-burst supernovae events at that time.

“The evolution of elliptical galaxies is totally different than the Milky Way,” said Whitmire. “These galaxies went through an early phase in which there is so much radiation that it would just completely have nuked any habitable planets in the galaxy and subsequently the star formation rate, and thus any new planets, went to essentially zero. There are no new stars forming and all the old stars have been irradiated and sterilized.”

If habitable planets hosting intelligent life are unlikely in large elliptical galaxies, where most stars and planets reside, then by default galaxies such as the Milky Way will be the primary sites of these civilizations, as expected by the principle of mediocrity, Whitmire said.

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According To Iran News, Astronomers have detected molecular oxygen in another galaxy over half a billion light-years away for the first time outside the Milky Way.

Oxygen is the third most abundant element in the Universe, behind hydrogen (naturally) and helium. So its chemistry and abundance in interstellar clouds are important for understanding the role of molecular gas in galaxies, Science Alert reported.

Astronomers have searched for oxygen again and again, using millimetre astronomy, which detects the radio wavelengths emitted by molecules; and spectroscopy, which analyses the spectrum to look for wavelengths absorbed or emitted by specific molecules.

But these searches have turned up a puzzling lack of oxygen molecules. Which means “a comprehensive picture of oxygen chemistry in different interstellar environments is still missing,” wrote a team of astronomers led by Junzhi Wang of the Chinese Academy of Sciences in a new paper.

One place molecular oxygen has been detected is the Orion nebula; it’s been hypothesised that out in space, oxygen is bound up with hydrogen in the form of water ice that is clinging to dust grains.

But the Orion nebula is a stellar nursery, and it’s possible that the intense radiation from very hot young stars shocks the water ice into sublimation and splits the molecules, releasing the oxygen.

Which brings us to a galaxy called Markarian 231.

Markarian 231 is special. It’s 561 million light-years away, and powered by a quasar. That’s an extremely luminous galactic nucleus with an active supermassive black hole in the centre. They’re the brightest objects in the Universe, and Markarian 231 contains the closest quasar to Earth.

In fact, astronomers think Markarian 231 might have two active supermassive black holes in its centre, whirling around each other at a furious rate.

An active galactic nucleus drives molecular outflows, producing continuous shocks of the kind that might release oxygen from water in molecular clouds. The molecular outflows in Markarian 231 are particularly high velocity, so Wang and colleagues went looking for oxygen.

Using the IRAM 30-metre radio telescope in Spain, they took observations of the galaxy for four days across a number of wavelengths. In those data, they found the spectral signature of oxygen, in line with the shock hypothesis.

“With deep observations toward Markarian 231 using the IRAM 30 meter telescope and NOEMA, we detected (molecular oxygen) emission in (an) external galaxy for the first time,” the researchers wrote in their paper.

“The detected O2 emission is located in regions about 10 kpc (32,615 light-years) away from the center of Markarian 231 and may be caused by the interaction between the active galactic nucleus-driven molecular outflow and the outer disc molecular clouds.”

The team’s measurements revealed that the abundance of oxygen compared to hydrogen was around 100 times higher than that found in the Orion nebula, so the galaxy could be undergoing a more intense version of the same molecule-splitting process.

As Markarian is a starburst galaxy, undergoing furious star formation, this could be possible. Just one region in the galaxy is forming new stars at a rate of over 100 solar masses a year. The Milky Way, by contrast, is pretty quiet, with a star formation rate of around 1 to two solar masses.

On the other hand,these findings could also mean that more observations need to be taken to confirm that the astronomers are correct in interpreting their results as oxygen.

If the results hold, the phenomenon could be used to understand more about both molecular oxygen in galaxies, and the molecular outflow from an active galactic nucleus, the researchers said.

“This first detection of extragalactic molecular oxygen provides an ideal tool to study active galactic nucleus-driven molecular outflows on dynamic timescales of tens of megayears,” they wrote.

“O2 may be a significant coolant for molecular gas in such regions affected by active galactic nucleus-driven outflows.”

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According To Iran News, Researchers have simulated the formation of galaxies in a universe without dark matter for the first time.

To replicate this process on the computer, they have instead modified Newton’s laws of gravity. The galaxies that were created in the computer calculations are similar to those we actually see today. According to the scientists, their assumptions could solve many mysteries of modern cosmology.

Cosmologists today assume that matter was not distributed entirely evenly after the Big Bang. The denser places attracted more matter from their surroundings due to their stronger gravitational forces. Over the course of several billion years, these accumulations of gas eventually formed the galaxies we see today, Phys reported.

An important ingredient of this theory is the so-called dark matter. On the one hand, it is said to be responsible for the initial uneven distribution that led to the agglomeration of the gas clouds. It also explains some puzzling observations. For instance, stars in rotating galaxies often move so fast that they should actually be ejected. It appears that there is an additional source of gravity in the galaxies that prevents this—a kind of “star putty” that cannot be seen with telescopes: dark matter.

However, there is still no direct proof of its existence. “Perhaps the gravitational forces themselves simply behave differently than previously thought,” explains Prof. Dr. Pavel Kroupa from the Helmholtz Institute for Radiation and Nuclear Physics at the University of Bonn and the Astronomical Institute of Charles University in Prague. This theory bears the abbreviation MOND (Modified Newtonian Dynamics). According to the theory, the attraction between two masses obeys Newton’s laws only up to a certain point. Under very low accelerations, as is the case in galaxies, it becomes considerably stronger. This is why galaxies do not break apart as a result of their rotational speed.

Results close to reality

“In cooperation with Dr. Benoit Famaey in Strasbourg, we have now simulated for the first time whether galaxies would form in a MOND universe and if so, which ones,” says Kroupa’s doctoral student Nils Wittenburg. To do this he used a computer program for complex gravitational calculations which was developed in Kroupa’s group. Because with MOND, the attraction of a body depends not only on its own mass, but also on whether other objects are in its vicinity.

The scientists then used this software to simulate the formation of stars and galaxies, starting from a gas cloud several hundred thousand years after the Big Bang. “In many aspects, our results are remarkably close to what we actually observe with telescopes,” explains Kroupa. For instance, the distribution and velocity of the stars in the computer-generated galaxies follow the same pattern that can be seen in the night sky. “Furthermore, our simulation resulted mostly in the formation of rotating disk galaxies like the Milky Way and almost all other large galaxies we know,” says the scientist. “Dark matter simulations, on the other hand, predominantly create galaxies without distinct matter disks—a discrepancy to the observations that is difficult to explain.”

Calculations based on the existence of dark matter are also very sensitive to changes in certain parameters, such as the frequency of supernovae and their effect on the distribution of matter in galaxies. In the MOND simulation, however, these factors hardly played a role.

Yet the recently published results from Bonn, Prague and Strasbourg do not correspond to reality in all points. “Our simulation is only a first step,” emphasizes Kroupa. For example, the scientists have so far only made very simple assumptions about the original distribution of matter and the conditions in the young universe. “We now have to repeat the calculations and include more complex influencing factors. Then we will see if the MOND theory actually explains reality.”

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