supermassive black hole Archives

June 15, 2018 by Matt Williams

The Black Hole Ultimate Solar System: a Supermassive Black Hole, 9 Stars and 550 Planets

Artist's impression of the "Black Hole Ultimate Solar System". Credit: planetplanet.net

Shortly after Einstein published his Theory of General Relativity in 1915, physicists began to speculate about the existence of black holes. These regions of space-time from which nothing (not even light) can escape are what naturally occur at the end of most massive stars’ life cycle. While black holes are generally thought to be voracious eaters, some physicists have wondered if they could also support planetary systems of their own.

Looking to address this question, Dr. Sean Raymond – an American physicist currently at the University of Bourdeaux – created a hypothetical planetary system where a black hole lies at the center. Based on a series of gravitational calculations, he determined that a black hole would be capable of keeping nine individual Suns in a stable orbit around it, which would be able to support 550 planets within a habitable zone.

He named this hypothetical system “The Black Hole Ultimate Solar System“, which consists of a non-spinning black hole that is 1 million times as massive as the Sun. That is roughly one-quarter the mass of Sagittarius A*, the super-massive black hole (SMBH) that resides at the center of the Milky Way Galaxy (which contains 4.31 million Solar Masses).

*Detection of an unusually bright X-Ray flare from Sagittarius A*, a supermassive black hole in the center of the Milky Way galaxy. Credit: NASA/CXC/Stanford/I. Zhuravleva et al.*

As Raymond indicates, one of the immediate advantages of having this black hole at the center of a system is that it can support a large number of Suns. For the sake of his system, Raymond chose 9, thought he indicates that many more could be sustained thanks to the sheer gravitational influence of the central black hole. As he wrote on his website:

“Given how massive the black hole is, one ring could hold up to 75 Suns! But that would move the habitable zone outward pretty far and I don’t want the system to get too spread out. So I’ll use 9 Suns in the ring, which moves everything out by a factor of 3. Let’s put the ring at 0.5 AU, well outside the innermost stable circular orbit (at about 0.02 AU) but well inside the habitable zone (from about 2.7 to 5.4 AU).”

Another major advantage of having a black hole at the center of a system is that it shrinks what is known as the “Hill radius” (aka. Hill sphere, or Roche sphere). This is essentially the region around a planet where its gravity is dominant over that of the star it orbits, and can therefore attract satellites. According to Raymond, a planet’s Hill radius would be 100 times smaller around a million-sun black hole than around the Sun.

This means that a given region of space could stably fit 100 times more planets if they orbited a black hole instead of the Sun. As he explained:

“Planets can be super close to each other because the black hole’s gravity is so strong! If planets are little toy Hot wheels cars, most planetary systems are laid out like normal highways (side note: I love Hot wheels). Each car stays in its own lane, but the cars are much much smaller than the distance between them. Around a black hole, planetary systems can be shrunk way down to Hot wheels-sized tracks. The Hot wheels cars — our planets — don’t change at all, but they can remain stable while being much closer together. They don’t touch (that would not be stable), they are just closer together.”

This is what allows for many planets to be placed with the system’s habitable zone. Based on the Earth’s Hill radius, Raymond estimates that about six Earth-mass planets could fit into stable orbits within the same zone around our Sun. This is based on the fact that Earth-mass planets could be spaced roughly 0.1 AU from each other and maintain a stable orbit.

Given that the Sun’s habitable zone corresponds roughly to the distances between Venus and Mars – which are 0.3 and 0.5 AU away, respectively – this means there is 0.8 AUs of room to work with. However, around a black hole with 1 million Solar Masses, the closest neighboring planet could be just 1/1000^th (0.001) of an AU away and still have a stable orbit.

Doing the math, this means that roughly 550 Earths could fit in the same region orbiting the black hole and its nine Suns. There is one minor drawback to this whole scenario, which is that the black hole would have to remain at its current mass. If it were to become any larger, it would cause the Hill radii of its 550 planets to shrink down further and further.

Once the Hill radius got down to the point where it was the same size as any of the Earth-mass planets, the black hole would begin to tear them apart. But at 1 million Solar masses, the black hole is capable of supporting a massive system of planets comfortably. “With our million-Sun black hole the Earth’s Hill radius (on its current orbit) would already be down to the limit, just a bit more than twice Earth’s actual radius,” he says.

*Illustration of tightly-packed orbits of Earth-mass planets in orbit around the Sun (in black) vs. around a supermassive black hole (green). Credit: Sean Raymond*

Lastly, Raymond considers the implications that living in such a system would have. For one, a year on any planet within the system’s habitable zone would be much shorter, owing to the fact their orbital periods would be much faster. Basically, a year would last roughly 1.6 days for planets at the inner edge of the habitable zone and 4.6 days for planets at the outer edge of the habitable zone.

In addition, on the surface of any planet in the system, the sky would be a lot more crowded! With so many planets in close orbit together, they would pass very close to one another. That essentially means that from the surface of any individual Earth, people would be able to see nearby Earths as clear as we see the Moon on some days. As Raymond illustrated:

“At closest approach (conjunction) the distance between planets is about twice the Earth-Moon distance. These planets are all Earth-sized, about 4 times larger than the Moon. This means that at conjunction each planet’s closest neighbor appears about twice the size of the full Moon in the sky. And there are two nearest neighbors, the inner and outer one. Plus, the next-nearest neighbors are twice as far away so they are still as big as the full Moon during conjunction. And four more planets that would be at least half the full Moon in size during conjunction.”

He also indicates that conjunctions would occur almost once per orbit, which would mean that every few days, there would be no shortage of giant objects passing across the sky. And of course, there would be the Sun’s themselves. Recall that scene in Star Wars where a young Luke Skywalker is watching two suns set in the desert? Well, it would a little like that, except way more cool!

According to Raymond’s calculations, the nine Suns would complete an orbit around the black hole every three hours. Every twenty minutes, one of these Suns would pass behind the black hole, taking just 49 seconds to do so. At this point, gravitational lensing would occur, where the black hole would focus the Sun’s light toward the planet and distort the apparent shape of the Sun.

To illustrate what this would look like, he provides an animation (shown above) created by @GregroxMun – a planet modeller who develops space graphics for Kerbal and other programs – using Space Engine.

While such a system may never occur in nature, it is interesting to know that such a system would be physically possible. And who knows? Perhaps a sufficiently advanced species, with the ability to tow stars and planets from one system and place them in orbit around a black hole, could fashion this Ultimate Solar System. Something for SETI researchers to be on the lookout for, perhaps?

This hypothetical exercise was the second installment in two-part series by Raymond, titled “Black holes and planets”. In the first installment, “The Black Hole Solar System“, Raymond considered what it would be like if our system orbited around a black hole-Sun binary. As he indicated, the consequences for Earth and the other Solar planets would be interesting, to say the least!

Raymond also recently expanded on the Ultimate Solar System by proposing The Million Earth Solar System. Check them all out at his website, PlanetPlanet.net.

Further Reading: PlanetPlanet

May 31, 2018 by Matt Williams

This is What Happens When a Black Hole Gobbles up a Star

Close-up of star near a supermassive black hole (artist’s impression). Credit: ESA/Hubble, ESO, M. Kornmesser

At the center of our galaxy resides a Supermassive Black Hole (SMBH) known as Sagittarius A. Based on ongoing observations, astronomers have determined that this SMBH measures 44 million km (27.34 million mi) in diameter and has an estimated mass of 4.31 million Solar Masses. On occasion, a star will wander too close to Sag A and be torn apart in a violent process known as a tidal disruption event (TDE).

These events cause the release of bright flares of radiation, which let astronomers know that a star has been consumed. Unfortunately, for decades, astronomers have been unable to distinguish these events from other galactic phenomena. But thanks to a new study from by an international team of astrophysicists, astronomers now have a unified model that explains recent observations of these extreme events.

The study – which recently appeared in the Astrophysical Journal Letters under the title “A Unified Model for Tidal Disruption Events” – was led by Dr. Jane Lixin Dai, a physicist with the Niels Bohr Institute’s Dark Cosmology Center. She was joined by members from University of Maryland’s Joint Space-Science Institute and the University of California Santa Cruz (UCSC).

*Illustration of the supermassive black hole at the center of the Milky Way. Credit: NRAO/AUI/NSF*

As Enrico Ramirez-Ruiz – the professor and chair of astronomy and astrophysics at UC Santa Cruz, the Niels Bohr Professor at the University of Copenhagen, and a co-author on the paper – explained in a UCSC press release:

“Only in the last decade or so have we been able to distinguish TDEs from other galactic phenomena, and the new model will provide us with the basic framework for understanding these rare events.”

In most galaxies, SMBHs do not actively consume any material and therefore do not emit any light, which distinguishes them from galaxies that have Active Galactic Nuclei (AGNs). Tidal disruption events are therefore rare, occurring only once about every 10,000 years in a typical galaxy. However, when a star does get torn apart, it results in the release of an intense amount of radiation. As Dr. Dai explained:

“It is interesting to see how materials get their way into the black hole under such extreme conditions. As the black hole is eating the stellar gas, a vast amount of radiation is emitted. The radiation is what we can observe, and using it we can understand the physics and calculate the black hole properties. This makes it extremely interesting to go hunting for tidal disruption events.”

*Illustration of emissions from a tidal disruption event shows in cross section what happens when the material from a disrupted star is devoured by a black hole. Credit: Jane Lixin Dai*

In the past few years, a few dozen candidates for tidal disruption events (TDEs) have been detected using wide-field optical and UV transient surveys as well as X-ray telescopes. While the physics are expected to be the same for all TDEs, astronomers have noted that a few distinct classes of TDEs appear to exist. While some emit mostly x-rays, others emit mostly visible and ultraviolet light.

As a result, theorists have struggled to understand the diverse properties observed and create a coherent model that can explain them all. For the sake of their model, Dr. Dai and her colleagues combined elements from general relativity, magnetic fields, radiation, and gas hydrodynamics. The team also relied on state-of-the-art computational tools and some recently-acquired large computer clusters funded by the Villum Foundation for Jens Hjorth (head of DARK Cosmology Center), the U.S. National Science Foundation and NASA.

Using the model that resulted, the team concluded that it is the viewing angle of the observer that accounts for the differences in observation. Essentially, different galaxies are oriented randomly with respect to observers on Earth, who see different aspects of TDEs depending on their orientation. As Ramirez-Ruiz explained:

“It is like there is a veil that covers part of a beast. From some angles we see an exposed beast, but from other angles we see a covered beast. The beast is the same, but our perceptions are different.”

*Artist’s impression of the Large Synoptic Survey Telescope. Credit: lsst.org*

In the coming years, a number of planned survey projects are expected to provide much more data on TDEs, which will help expand the field of research into this phenomena. These include the Young Supernova Experiment (YSE) transient survey, which will be led by the DARK Cosmology Center at the Niels Bohr Institute and UC Santa Cruz, and the Large Synoptic Survey Telescopes (LSST) being built in Chile.

According to Dr. Dai, this new model shows what astronomers can expect to see when viewing TDEs from different angles and will allow them to fit different events into a coherent framework. “We will observe hundreds to thousands of tidal disruption events in a few years,” she said. “This will give us a lot of ‘laboratories’ to test our model and use it to understand more about black holes.”

This improved understanding of how black holes occasionally consume stars will also provide additional tests for general relativity, gravitational wave research, and help astronomers to learn more about the evolution of galaxies.

Further Reading: UCSC, Astrophysical Journal Letters

February 27, 2018 by Matt Williams

Amazing High Resolution Image of the Core of the Milky Way, a Region with Surprisingly Low Star Formation Compared to Other Galaxies

NASA's Spitzer Space Telescope captured this stunning infrared image of the center of the Milky Way Galaxy, where the black hole Sagitarrius A resides. Credit: NASA/JPL-Caltech

Compared to some other galaxies in our Universe, the Milky Way is a rather subtle character. In fact, there are galaxies that are a thousands times as luminous as the Milky Way, owing to the presence of warm gas in the galaxy’s Central Molecular Zone (CMZ). This gas is heated by massive bursts of star formation that surround the Supermassive Black Hole (SMBH) at the nucleus of the galaxy.

The core of the Milky Way also has a SMBH (Sagittarius A*) and all the gas it needs to form new stars. But for some reason, star formation in our galaxy’s CMZ is less than the average. To address this ongoing mystery, an international team of astronomers conducted a large and comprehensive study of the CMZ to search for answers as to why this might be.

The study, titled “Star formation in a high-pressure environment: an SMA view of the Galactic Centre dust ridge” recently appeared in the Monthly Notices of the Royal Astronomical Society. The study was led by Daniel Walker of the Joint ALMA Observatory and the National Astronomical Observatory of Japan, and included members from multiple observatories, universities and research institutes.

*A false color Spitzer infrared image of the Milky Way’s Central Molecular Zone (CMZ). Credit: Spitzer/NASA/CfA*

For the sake of their study, the team relied on the Submillimeter Array (SMA) radio interferometer, which is located atop Maunakea in Hawaii. What they found was a sample of thirteen high-mass cores in the CMZ’s “dust ridge” that could be young stars in the initial phase of development. These cores ranged in mass from 50 to 2150 Solar Masses and have radii of 0.1 – 0.25 parsecs (0.326 – 0.815 light-years).

They also noted the presence of two objects that appeared to be previously unknown young, high-mass protostars. As they state in their study, all of this indicated that stars in CMZ had about the same rate of formation as those in the galactic disc, despite their being vast pressure differences:

“All appear to be young (pre-UCHII), meaning that they are prime candidates for representing the initial conditions of high-mass stars and sub-clusters. We compare all of the detected cores with high-mass cores and clouds in the Galactic disc and find that they are broadly similar in terms of their masses and sizes, despite being subjected to external pressures that are several orders of magnitude greater.”

To determine that the external pressure in the CMZ was greater, the team observed spectral lines of the molecules formaldehyde and methyl cyanide to measure the temperature of the gas and its kinetics. These indicated that the gas environment was highly turbulent, which led them to the conclusion that the turbulent environment of the CMZ is responsible for inhibiting star formation there.

*A radio image from the NSF’s Karl G. Jansky Very Large Array showing the center of our galaxy. Credit: NSF/VLA/UCLA/M. Morris et al.*

As they state in their study, these results were consistent with their previous hypothesis:

“The fact that >80 percent of these cores do not show any signs of star-forming activity in such a high-pressure environment leads us to conclude that this is further evidence for an increased critical density threshold for star formation in the CMZ due to turbulence.”

So in the end, the rate of star formation in a CMZ is not only dependent on their being a lot of gas and dust, but on the nature of the gas environment itself. These results could inform future studies of not only the Milky Way, but of other galaxies as well – particularly when it comes to the relationship that exists between Supermassive Black Holes (SMBHs), star formation, and the evolution of galaxies.

For decades, astronomers have studied the central regions of galaxies in the hopes of determining how this relationship works. And in recent years, astronomers have come up with conflicting results, some of which indicate that star formation is arrested by the presence of SMBHs while others show no correlation.

In addition, further examinations of SMBHs and Active Galactic Nuclei (AGNs) have shown that there may be no correlation between the mass of a galaxy and the mass of its central black hole – another theory that astronomers previously subscribed to.

As such, understanding how and why star formation appears to be different in galaxies like the Milky Way could help us to unravel these other mysteries. From that, a better understanding of how stars and galaxies evolved over the course of cosmic history is sure to emerge.

Further Reading: CfA, MNRAS

February 22, 2018 by Matt Williams

Maybe There’s no Connection Between Supermassive Black Holes and Their Host Galaxies?

Artist's impression of an ionized gas outflow (green) driven by the central supermassive black hole does not affect the star formation of its host galaxy. This situation may occur if the ionized gas is outflowing perpendicularly to the molecular gas. Credit: ALMA (ESO/NAOJ/NRAO)

For decades, astrophysicists have puzzled over the relationship between Supermassive Black Holes (SMBHs) and their respective galaxies. Since the 1970s, it has been understood the majority of massive galaxies have an SMBH at their center, and that these are surrounded by rotating tori of gas and dust. The presence of these black holes and tori are what cause massive galaxies to have an Active Galactic Nucleus (AGN).

However, a recent study conducted by an international team of researchers revealed a startling conclusion when studying this relationship. Using the Atacama Large Millimeter/submillimeter Array (ALMA) to observe an active galaxy with a strong ionized gas outflow from the galactic center, the team obtained results that could indicate that there is no relationship between a an SMBH and its host galaxy.

The study, titled “No sign of strong molecular gas outflow in an infrared-bright dust-obscured galaxy with strong ionized-gas outflow“, recently appeared in the Astrophysical Journal. The study was led by Yoshiki Toba of the Academia Sinica Institute of Astronomy and Astrophysics in Taiwan and included members from Ehime University, Kogakuin University, and the National Astronomical Observatory of Japan, The Graduate University for Advanced Studies (SOKENDAI), and Johns Hopkins University.

*Images from the Sloan Digital Sky Survey (SDSS) (left), and mid-infrared image from WISE (right), respectively. Credit: Sloan Digital Sky Survey/NASA/JPLCaltech*

The question of how SMBHs have affected galactic evolution remains one of the greatest unresolved questions in modern astronomy. Among astrophysicists, it is something of a foregone conclusion that SMBHs have a significant impact on the formation and evolution of galaxies. According to this accepted notion, SMBHs significantly influence the molecular gas in galaxies, which has a profound effect on star formation.

Basically, this theory holds that larger galaxies accumulate more gas, thus resulting in more stars and a more massive central black hole. At the same time, there is a feedback mechanism, where growing black holes accrete more matter on themselves. This results in them sending out a tremendous amount of energy in the form of radiation and particle jets, which is believed to curtail star formation in their vicinity.

However, when observing an infrared (IR)-bright dust-obscured galaxy (DOG) – WISE1029+0501 – Yoshiki and his colleagues obtained results that contradicted this notion. After conducting a detailed analysis using ALMA, the team found that there were no signs of significant molecular gas outflow coming from WISE1029+0501. They also found that star-forming activity in the galaxy was neither more intense or suppressed.

This indicates that a strong ionized gas outflow coming from the SMBH in WISE1029+0501 did not significantly affect the surrounding molecular gas or star formation. As Dr. Yoshiki Toba explained, this result:

“[H]as made the co-evolution of galaxies and supermassive black holes more puzzling. The next step is looking into more data of this kind of galaxies. That is crucial for understanding the full picture of the formation and evolution of galaxies and supermassive black holes”.

*Emission from Carbon Monoxide (Left) and Cold Dust (Right) in WISE1029 Observed by ALMA (image). Credit: ALMA (ESO/NAOJ/NRAO), Toba et al.*

This not only flies in the face of conventional wisdom, but also in the face of recent studies that showed a tight correlation between the mass of central black holes and those of their host galaxies. This correlation suggests that supermassive black holes and their host galaxies evolved together over the course of the past 13.8 billion years and closely interacted as they grew.

In this respect, this latest study has only deepened the mystery of the relationship between SMBHs and their galaxies. As Tohru Nagao, a Professor at Ehime University and a co-author on the study, indicated:

“[W]e astronomers do not understand the real relation between the activity of supermassive black holes and star formation in galaxies. Therefore, many astronomers including us are eager to observe the real scene of the interaction between the nuclear outflow and the star-forming activities, for revealing the mystery of the co-evolution.”

The team selected WISE1029+0501 for their study because astronomers believe that DOGs harbor actively growing SMBHs in their nuclei. In particular, WISE1029+0501 is an extreme example of galaxies where outflowing gas is being ionized by the intense radiation from its SMBH. As such, researchers have been highly motivated to see what happens to this galaxy’s molecular gas.

The study was made possible thanks to ALMA’s sensitivity, which is excellent when it comes to investigating the properties of molecular gas and star-forming activity in galaxies. In fact, multiple studies have been conducted in recent years that have relied on ALMA to investigate the gas properties and SMBHs of distant galaxies.

And while the results of this study contradict widely-held theories about galactic evolution, Yoshiki and his colleagues are excited about what this study could reveal. In the end, it may be that radiation from a SMBH does not always affect the molecular gas and star formation of its host galaxy.

“[U]nderstanding such co-evolution is crucial for astronomy,” said Yoshiki. “By collecting statistical data of this kind of galaxies and continuing in more follow-up observations using ALMA, we hope to reveal the truth.”

Further Reading: ALMA Observatory, Astrophysical Journal

February 2, 2018 by Matt Williams

Outflows From Black Holes are Creating New Molecules Where There Should Only be Destruction

During the 1960s, scientists discovered a massive radio source (known as Sagittarius A*) at the center of the Milky Way, which was later revealed to be a Supermassive Black Holes (SMBH). Since then, they have learned that these SMBHs reside at the center of most massive galaxies. The presence of these black holes is also what allows the centers of these galaxies to have a higher than normal luminosity – aka. Active Galactic Nuclei (AGNs).

In the past few years, astronomers have also observed fast molecular outflows emanating from AGNs which left them puzzled. For one, it was a mystery how any particles could survive the heat and energy of a black hole’s outflow. But according to a new study produced by researchers from Northwestern University, these molecules were actually born within the winds themselves. This theory may help explain how stars form in extreme environments.

The study recently appeared in The Monthly Notices of the Royal Astronomical Society under the title “The origin of fast molecular outflows in quasars: molecule formation in AGN-driven galactic winds.” The study was conducted by Lindheimer post-doctoral fellow Alexander J Richings and assistant professor Claude-André Faucher-Giguère from Northwestern University’s Center for Interdisciplinary Research and Exploration in Astrophysics (CIERA).

*Artist’s impression of a black hole’s wind sweeping away galactic gas. Credit: ESA*

For the sake of their study, Richings developed the first-ever computer code capable of modeling the detailed chemical processes in interstellar gas which are accelerated by a growing SMBH’s radiation. Meanwhile, Claude-André Faucher-Giguère contributed his expertise, having spent his career studying the formation and evolution of galaxies. As Richings explained in a Northwestern press release:

“When a black hole wind sweeps up gas from its host galaxy, the gas is heated to high temperatures, which destroy any existing molecules. By modeling the molecular chemistry in computer simulations of black hole winds, we found that this swept-up gas can subsequently cool and form new molecules.”

The existence of energetic outflows form SMBHs was first confirmed in 2015, when researchers used the ESA’s Herschel Space Observatory and data from the Japanese/US Suzaku satellite to observe the AGN of a galaxy known as IRAS F11119+3257. Such outflows, they determined, are responsible for draining galaxies of their interstellar gas, which has an arresting effect on the formation of new stars and can lead to “red and dead” elliptical galaxies.

This was followed-up in 2017 with observations that indicated that rapidly moving new stars formed in these outflows, something that astronomers previously thought to be impossible because of the extreme conditions present within them. By theorizing that these particles are actually the product of black hole winds, Richings and Faucher-Giguère have managed to address questions raised by these previous observations.

Artist's concept of Sagittarius A, the supermassive black hole at the center of our galaxy. Credit: NASA/JPL — *Artist’s concept of Sagittarius A, the supermassive black hole at the center of our galaxy. Credit: NASA/JPL*

Essentially, their theory helps explain predictions made in the past, which appeared contradictory at first glance. On the one hand, it upholds the prediction that black hole winds destroy molecules they collide with. However, it also predicts that new molecules are formed within these winds – including hydrogen, carbon monoxide and water – which can give birth to new stars. As Faucher-Giguère explained:

“This is the first time that the molecule formation process has been simulated in full detail, and in our view, it is a very compelling explanation for the observation that molecules are ubiquitous in supermassive black hole winds, which has been one of the major outstanding problems in the field.”

Richings and Faucher-Giguère look forward to the day when their theory can be confirmed by next-generation missions. They predict that new molecules formed by black hole outflows would be brighter in the infrared wavelength than pre-existing molecules. So when the James Webb Space Telescope takes to space in the Spring of 2019, it will be able to map these outflows in detail using its advance IR instruments.

One of the most exciting things about the current era of astronomy is the way new discoveries are shedding light on decades-old mysteries. But when these discoveries lead to theories that offer symmetry to what were once thought to be incongruous pieces of evidence, that’s when things get especially exciting. Basically, it lets us know that we are moving closer to a greater understanding of our Universe!

Further Reading: Northwestern University, MNRAS

May 13, 2017November 5, 2018 by Matt Williams

Astronomers Find a Rogue Supermassive Black Hole, Kicked out by a Galactic Collision

Using data from Chandra and other telescopes, astronomers have found a possible "recoiling" black hole. Credit: NASA/CXC/M.Weiss

When galaxies collide, all manner of chaos can ensue. Though the process takes millions of years, the merger of two galaxies can result in Supermassive Black Holes (SMBHs, which reside at their centers) merging and becoming even larger. It can also result in stars being kicked out of their galaxies, sending them and even their systems of planets into space as “rogue stars“.

But according to a new study by an international team of astronomers, it appears that in some cases, SMBHs could also be ejected from their galaxies after a merger occurs. Using data from NASA’s Chandra X-ray Observatory and other telescopes, the team detected what could be a “renegade supermassive black hole” that is traveling away from its galaxy.

According to the team’s study – which appeared in the Astrophysical Journal under the title A Potential Recoiling Supermassive Black Hole, CXO J101527.2+625911 – the renegade black hole was detected at a distance of about 3.9 billion light years from Earth. It appears to have come from within an elliptical galaxy, and contains the equivalent of 160 million times the mass of our Sun.

*Hubble data showing the two bright points near the middle of the galaxy. Credit: NASA/CXC/NRAO/D.-C.Kim/STScI*

The team found this black hole while searching through thousands of galaxies for evidence of black holes that showed signs of being in motion. This consisted of sifting through data obtained by the Chandra X-ray telescope for bright X-ray sources – a common feature of rapidly-growing SMBHs – that were observed as part of the Sloan Digital Sky Survey (SDSS).

They then looked at Hubble data of all these X-ray bright galaxies to see if it would reveal two bright peaks at the center of any. These bright peaks would be a telltale indication that a pair of supermassive black holes were present, or that a recoiling black hole was moving away from the center of the galaxy. Last, the astronomers examined the SDSS spectral data, which shows how the amount of optical light varies with wavelength.

From all of this, the researchers invariably found what they considered to be a good candidate for a renegade black hole. With the help data from the SDSS and the Keck telescope in Hawaii, they determined that this candidate was located near, but visibly offset from, the center of its galaxy. They also noted that it had a velocity that was different from the galaxy – properties which suggested that it was moving on its own.

The image below, which was generated from Hubble data, shows the two bright points near the center of the galaxy. Whereas the one on the left was located within the center, the one on the right (the renegade SMBH) was located about 3,000 light years away from the center. Between the X-ray and optical data, all indications pointed towards it being a black hole that was kicked from its galaxy.

*The bright X-ray source detected with Chandra (left), and data obtained from the SDSS and the Keck telescope in Hawaii. Credit: NASA/CXC/NRAO/D.-C.Kim/STScI*

In terms of what could have caused this, the team ventured that the back hole might have “recoiled” when two smaller SMBHs collided and merged. This collision would have generated gravitational waves that could have then pushed the black hole out of the galaxy’s center. They further ventured that the black hole may have formed and been set in motion by the collision of two smaller black holes.

Another possible explanation is that two SMBHs are located in the center of this galaxy, but one of them is not producing detectable radiation – which would mean that it is growing too slowly. However, the researchers favor the explanation that what they observed was a renegade black hole, as it seems to be more consistent with the evidence. For example, their study showed signs that the host galaxy was experiencing some disturbance in its outer regions.

This is a possible indication that the merger between the two galaxies occurred in the relatively recent past. Since SMBH mergers are thought to occur when their host galaxies merge, this reservation favors the renegade black hole theory. In addition, the data showed that in this galaxy, stars were forming at a high rate. This agrees with computer simulations that predict that merging galaxies experience an enhanced rate of star formation.

But of course, additional researches is needed before any conclusions can be reached. In the meantime, the findings are likely to be of particular interest to astronomers. Not only does this study involve a truly rare phenomenon – a SMBH that is in motion, rather than resting at the center of a galaxy – but the unique properties involved could help us to learn more about these rare and enigmatic features.

For one, the study of SMBHs could reveal more about the rate and direction of spin of these enigmatic objects before they merge. From this, astronomers would be able to better predict when and where SMBHs are about to merge. Studying the speed of recoiling black holes could also reveal additional information about gravitational waves, which could unlock additional secrets about the nature of space time.

And above all, witnessing a renegade black hole is an opportunity to see some pretty amazing forces at work. Assuming the observations are correct, there will no doubt be follow-up surveys designed to see where the SMBH is traveling and what effect it is having on the surrounding cosmic environment.

Ever since the 1970s, scientists have been of the opinion that most galaxies have SMBHs at their center. In the years and decades that followed, research confirmed the presence of black holes not only at the center of our galaxy – Sagittarius A* – but at the center of all almost all known massive galaxies. Ranging in mass from the hundreds of thousands to billions of Solar masses, these objects exert a powerful influence on their respective galaxies.

Be sure to enjoy this video, courtesy of the Chandra X-Ray Observatory:

Further Reading: Chandra X-ray Observatory, arXiv

April 26, 2017April 26, 2017 by Fraser Cain

What Are Fast Radio Bursts?

You might think you’re reading an educational website, where I explain fascinating concepts in space and astronomy, but that’s not really what’s going on here.

What’s actually happening is that you’re tagging along as I learn more and more about new and cool things happening in the Universe. I dig into them like a badger hiding a cow carcass, and we all get to enjoy the cache of knowledge I uncover.

Okay, that analogy got a little weird. Anyway, my point is. Squirrel!

Fast radio bursts are the new cosmic whatzits confusing and baffling astronomers, and now we get to take a front seat and watch them move through all stages of process of discovery.

Stage 1: A strange new anomaly is discovered that doesn’t fit any current model of the cosmos. For example, strange Boyajian’s Star. You know, that star that probably doesn’t have an alien megastructure orbiting around it, but astronomers can’t rule that out just yet?

Stage 2: Astronomers struggle to find other examples of this thing. They pitch ideas for new missions and scientific instruments. No idea is too crazy, until it’s proven to be too crazy. Examples include dark matter, dark energy, and that idea that we’re living in a

Stage 3: Astronomers develop a model for the thing, find evidence that matches their predictions, and vast majority of the astronomical community comes to a consensus on what this thing is. Like quasars and gamma ray bursts. YouTuber’s make their videos. Textbooks are updated. Balance is restored.

Today we’re going to talk about Fast Radio Bursts. They just moved from Stage 1 to Stage 2. Let’s dig in.

Fast radio bursts, or FRBs, or “Furbys” were first detected in 2007 by the astronomer Duncan Lorimer from West Virginia University.

He was looking through an archive of pulsar observations. Pulsars, of course, are newly formed neutron stars, the remnants left over from supernova explosions. They spin rapidly, blasting out twin beams of radiation. Some can spin hundreds of times a second, so precisely you could set your watch to them.

Lorimer’s archive of pulsar observations was captured at the Parkes radio dish in Australia. Credit: CSIRO (CC BY 3.0)

In this data, Lorimer made a “that’s funny” observation, when he noticed one blast of radio waves that squealed for 5 milliseconds and then it was gone. It didn’t match any other observation or prediction of what should be out there, so astronomers set out to find more of them.

Over the last 10 years, astronomers have found about 25 more examples of Fast Radio Bursts. Each one only lasts a few milliseconds, and then fades away forever. A one time event that can appear anywhere in the sky and only last for a couple milliseconds and never repeats is not an astronomer’s favorite target of study.

Actually, one FRB has been found to repeat, maybe.

The question, of course, is “what are they?”. And the answer, right now is, “astronomers have no idea.”

In fact, until very recently, astronomers weren’t ever certain they were coming from space at all. We’re surrounded by radio signals all the time, so a terrestrial source of fast radio bursts seems totally logical.

About a week ago, astronomers from Australia announced that FRBs are definitely coming from outside the Earth. They used the Molonglo Observatory Synthesis Telescope (or MOST) in Canberra to gather data on a large patch of sky.

Then they sifted through 1,000 terabytes of data and found just 3 fast radio bursts. Three.

Since MOST is farsighted and can’t perceive any radio signals closer than 10,000 km away, the signals had to be coming outside planet Earth. They were “extraterrestrial” in origin.

Right now, fast radio bursts are infuriating to astronomers. They don’t seem to match up with any other events we can see. They’re not the afterglow of a supernova, or tied in some way to gamma ray bursts.

In order to really figure out what’s going on, astronomers need new tools, and there’s a perfect instrument coming. Astronomers are building a new telescope called the Canadian Hydrogen Intensity Mapping Experiment (or CHIME), which is under construction near the town of Penticton in my own British Columbia.

CHIME under construction in Penticton, British Columbia. Credit: Mateus A. Fandiño (CC BY-SA 4.0)

It looks like a bunch of snowboard halfpipes, and its job will be to search for hydrogen emission from distant galaxies. It’ll help us understand how the Universe was expanding between 7 and 11 billion years ago, and create a 3-dimensional map of the early cosmos.

In addition to this, it’s going to be able to detect hundreds of fast radio bursts, maybe even a dozen a day, finally giving astronomers vast pools of signals to study.

What are they? Astronomers have no idea. Seriously, if you’ve got a good suggestion, they’d be glad to hear it.

In these kinds of situations, astronomers generally assume they’re caused by exploding stars in some way. Young stars or old stars, or maybe stars colliding. But so far, none of the theoretical models match the observations.

This artist’s conception illustrates one of the most primitive supermassive black holes known (central black dot) at the core of a young, star-rich galaxy. Image credit: NASA/JPL-Caltech

Another idea is black holes, of course. Specifically, supermassive black holes at the hearts of distant galaxies. From time to time, a random star, planet, or blob of gas falls into the black hole. This matter piles upon the black hole’s event horizon, heats up, screams for a moment, and disappears without a trace. Not a full on quasar that shines for thousands of years, but a quick snack.

The next idea comes with the only repeating fast radio burst that’s ever been found. Astronomers looked through the data archive of the Arecibo Observatory in Puerto Rico and found a signal that had repeated at least 10 times in a year, sometimes less than a minute apart.

Since the quick blast of radiation is repeating, this rules out a one-time collision between exotic objects like neutron stars. Instead, there could be a new class of magnetars (which are already a new class of neutron stars), that can release these occasional shrieks of radio.

An artist’s impression of a magnetar. Credit: ESO/L. Calçada

Or maybe this repeating object is totally different from the single events that have been discovered so far.

Here’s my favorite idea. And honestly, the one that’s the least realistic. What I’m about to say is almost certainly not what’s going on. And yet, it can’t be ruled out, and that’s good enough for my fertile imagination.

Avi Loeb and Manasvi Lingam at Harvard University said the following about FRBs:

“Fast radio bursts are exceedingly bright given their short duration and origin at distances, and we haven’t identified a possible natural source with any confidence. An artificial origin is worth contemplating and checking.”

Artificial origin. So. Aliens. Nice.

Loeb and Lingam calculated how difficult it would be to send a signal that strong, that far across the Universe. They found that you’d need to build a solar array with twice the surface area of Earth to power the radio wave transmitter.

And what would you do with a transmission of radio or microwaves that strong? You’d use it to power a spacecraft, of course. What we’re seeing here on Earth is just the momentary flash as a propulsion beam sweeps past the Solar System like a lighthouse.

But in reality, this huge solar array would be firing out a constant beam of radiation that would propel a massive starship to tremendous speeds. Like the Breakthrough Starshot spacecraft, but for million tonne spaceships.

In other words, we could be witnessing alien transportation systems, pushing spacecraft with beams of energy to other worlds.

And I know that’s probably not what’s happening. It’s not aliens. It’s never aliens. But in my mind, that’s what I’m imagining.

So, kick back and enjoy the ride. Join us as we watch astronomers struggle to understand what fast radio bursts are. As they invalidate theories, and slowly unlock one of the most thrilling mysteries in modern astronomy. And as soon as they figure it out, I’ll let you know all about it.

What do you think? Which explanation for fast radio bursts seems the most logical to you? I’d love to hear your thoughts and wild speculation in the comments.

August 15, 2016February 22, 2017 by Fraser Cain

Will Our Black Hole Eat the Milky Way?

Want to hear something cool? There’s a black hole at the center of the Milky Way. And not just any black hole, it’s a supermassive black hole with more than 4.1 million times the mass of the Sun.

It’s right over there, in the direction of the Sagittarius constellation. Located just 26,000 light-years away. And as we speak, it’s in the process of tearing apart entire stars and star systems, occasionally consuming them, adding to its mass like a voracious shark.

Wait, that doesn’t sound cool, that sort of sounds a little scary. Right?

Don’t worry, you have absolutely nothing to worry about, unless you plan to live for quadrillions of years, which I do, thanks to my future robot body. I’m ready for my singularity, Dr. Kurzweil.

Is the supermassive black hole going to consume the Milky Way? If not, why not? If so, why so?

The discovery of a supermassive black hole at the heart of the Milky Way, and really almost all galaxies, is one of my favorite discoveries in the field of astronomy. It’s one of those insights that simultaneously answered some questions, and opened up even more.

Back in the 1970s, the astronomers Bruce Balick and Robert Brown realized that there was an intense source of radio emissions coming from the very center of the Milky Way, in the constellation Sagittarius.

They designated it Sgr A*. The asterisk stands for exciting. You think I’m joking, but I’m not. For once, I’m not joking.

An illustration of Saggitarius A*. Credit: NASA/CXC/M.Weiss

In 2002, astronomers observed that there were stars zipping past this object, like comets on elliptical paths going around the Sun. Imagine the mass of our Sun, and the tremendous power it would take to wrench a star like that around.

The only objects with that much density and gravity are black holes, but in this case, a black hole with millions of times the mass of our own Sun: a supermassive black hole.

With the discovery of the Milky Way’s supermassive black hole, astronomers found evidence that there are black holes at the heart of every galaxy.

At the same time, the discovery of supermassive black holes helped answer one of the big questions in astronomy: what are quasars? We did a whole article on them, but they’re intensely bright objects, generating enough light they can be seen billions of light-years away. Giving off more energy than the rest of their own galaxy combined.

The quasar SDSS J1106+1939 has the most energetic outflows ever seen, at least five times more powerful than any that have been observed to date. Credit: ESO/L. Calçada

It turns out that quasars and supermassive black holes are the same thing. Quasars are just black holes in the process of actively feeding; gobbling up so much material it piles up in an accretion disk around it. Once again, these do sound terrifying. But are we in any danger?

In the short term, no. The black hole at the center of the Milky Way is 26,000 light-years away. Even if it turned into a quasar and started eating stars, you wouldn’t even be able to notice it from this distance.

A black hole is just a concentration of mass in a very small region, which things orbit around. To give you an example, you could replace the Sun with a black hole with the exact same mass, and nothing would change. I mean, we’d all freeze because there wasn’t a Sun in the sky anymore, but the Earth would continue to orbit this black hole in exactly the same orbit, for billions of years.

Same goes with the black hole at the center of the Milky Way. It’s not pulling material in like a vacuum cleaner, it serves as a gravitational anchor for a group of stars to orbit around, for billions of years.

In order for a black hole to actually consume a star, it needs to make a direct hit. To get within the event horizon, which is only about 17 times bigger than the Sun. If a star gets close, without hitting, it’ll get torn apart, but still, it doesn’t happen very often.

A black hole, with an accretion disk, consuming a star. Credit: ESO/L. Calçada

The problem happens when these stars interact with one another through their own gravity, and mess with each other’s orbits. A star that would have been orbiting happily for billions of years might get deflected into a collision course with the black hole. But this happens very rarely.

Over the short term, that supermassive black hole is totally harmless. Especially from out here in the galactic suburbs.

But there are a few situations that might cause some problems over vast periods of time.

The first panic will happen when the Milky Way collides with Andromeda in about 4 billion years – let’s call this mess Milkdromeda. Suddenly, you’ll have two whole clouds of stars interacting in all kinds of ways, like an unstable blended family. Stars that would have been safe will careen past other stars and be deflected down into the maw of either of the two supermassive black holes on hand. Andromeda’s black hole could be 100 million times the mass of the Sun, so it’s a bigger target for stars with a death wish.

View of Milkdromeda from Earth "shortly" after the merger, around 3.85-3.9 billion years from now Credit: NASA, ESA, Z. Levay and R. van der Marel (STScI), T. Hallas, and A. Mellinger — View of Milkdromeda from Earth “shortly” after the merger, around 3.85-3.9 billion years from now Credit: NASA, ESA, Z. Levay and R. van der Marel (STScI), T. Hallas, and A. Mellinger

Over the coming billions, trillions and quadrillions of years, more and more galaxies will collide with Milkdromeda, bringing new supermassive black holes and more stars to the chaos.

So many opportunities for mayhem.

Of course, the Sun will die in about 5 billion years, so this future won’t be our problem. Well, fine, with my eternal robot body, it might still be my problem.

After our neighborhood is completely out of galaxies to consume, then there will just be countless eons of time for stars to interact for orbit after orbit. Some will get flung out of Milkdromeda, some will be hurled down into the black hole.

And others will be safe, assuming they can avoid this fate over the Googol years it’ll take for the supermassive black hole to finally evaporate. That’s a 1 followed by 100 zeroes years. That’s a really really long time, so now I don’t like those odds.

For our purposes, the black hole at the heart of the Milky Way is completely and totally safe. In the lifetime of the Sun, it won’t interact with us in any way, or consume more than a handful of stars.

But over the vast eons, it could be a different story. I hope we can be around to find out the answer.

July 11, 2016February 22, 2017 by Fraser Cain

How Fast Can Stars Spin?

Everything in the Universe is spinning. Spinning planets and their spinning moons orbit around spinning stars, which orbit spinning galaxies. It’s spinning all the way down.

Consider that fiery ball in the sky, the Sun. Like all stars, our Sun rotates on its axis. You can’t tell because staring at the Sun long enough will permanently damage your eyeballs. Instead you can use a special purpose solar telescope to observe sunspots and other features on the surface of the Sun. And if you track their movements, you’ll see that the Sun’s equator takes 24.47 days to turn once on its axis. Unlike its slower poles which take 26.24 days to turn.

The Sun isn’t a solid ball of rock, it’s a sphere of hot plasma, so the different regions can complete their rotation at different rates. But it rotates so slowly that it’s an almost perfect sphere.

If you were standing on the surface of the Sun, which you can’t, of course, you would be whipping around at 7,000 km/h. That sounds fast, but just you wait.

How does that compare to other stars, and what’s the fastest that a star can spin?

Achenar is located at the lower right of the constellation Eridanus. — Achenar rotates much faster than our Sun. It is located at the lower right of the constellation Eridanus.

A much faster spinning star is Achenar, the tenth brightest star in the sky, located 139 light-years away in the constellation of Eridanus. It has about 7 times the mass of the Sun, but it spins once on its axis every 2 days. If you could see Achenar up close, it would look like a flattened ball. If you measured it from pole to pole, it would be 7.6 Suns across, but if you measured across the equator, it would be 11.6 Suns across.

If you were standing on the surface of Achenar, you’d be hurtling through space at 900,000 km/h.

The very fastest spinning star we know of is the 25 solar mass VFTS 102, located about 160,000 light-years away in the Large Magellanic Cloud’s Tarantula Nebula – a factory for massive stars.

If you were standing on the surface of VFTS 102, you’d be moving at 2 million km/h.

In fact, VFTS 102 is spinning so quickly, it can just barely keep itself together. Any faster, and the outward centripetal force would overcome the gravity holding its guts in, and it would tear itself apart. Perhaps that’s why we don’t see any spinning faster; because they couldn’t handle the speed. It appears that this is the fastest that stars can spin.

This is an artist's concept of the fastest rotating star found to date. The massive, bright young star, called VFTS 102, rotates at a million miles per hour, or 100 times faster than our Sun does. Centrifugal forces from this dizzying spin rate have flattened the star into an oblate shape and spun off a disk of hot plasma, seen edge on in this view from a hypothetical planet. The star may have "spun up" by accreting material from a binary companion star. The rapidly evolving companion later exploded as a supernova. The whirling star lies 160,000 light-years away in the Large Magellanic Cloud, a satellite galaxy of our Milky Way. Credit: NASA, ESA, and G. Bacon (STScI) — This is an artist’s concept of VFTS 102, the fastest rotating star found to date. Credit: NASA, ESA, and G. Bacon (STScI)

One other interesting note about VFTS 102 is that it’s also hurtling through space much faster than the stars around it. Astronomers think it was once in a binary system with a partner that detonated as a supernova, releasing it into space like a catapult.

Not only stars can spin. Dead stars can spin too, and they take this to a whole other level.

Neutron stars are what you get when a star with much more mass than the Sun detonates as a supernova. Suddenly you’ve got a stellar remnant with twice the mass of the Sun compressed down into a tiny ball about 20 km across. All that angular momentum of the star is retained, and so the neutron star spins at an enormous speed.

The fastest neutron star ever recorded spins around 700 times a second. We know it’s turning this quickly because it’s blasting out beams of radiation that sweep towards us like an insane lighthouse. This, of course, is a pulsar, and we did a whole episode on them.

A regular star would be torn apart, but neutron stars have such intense gravity, they can rotate this quickly. Over time, the radiation streaming from the neutron star strips away its angular momentum, and it slows down.

A black hole with an accretion disk. Credit: (NASA/Dana Berry/SkyWorks Digital)

Black holes can spin even faster than that. In fact, when a black hole is actively feeding from a binary companion, or a supermassive black hole is gobbling up stars, it can rotate at nearly the speed of light. The laws of physics prevent anything in the Universe spinning faster than the speed of light, and black holes go right up to the edge of the law without breaking it.

Astronomers recently found a supermassive black hole spinning up to 87% the maximum speed permitted by relativity.

If you were hoping there are antimatter lurking out there, hoarding all that precious future energy, I’m sorry to say, but astronomers have looked and they haven’t found it. Just like the socks in your dryer, we may never discover where it all went.

June 25, 2016August 21, 2016 by Matt Williams

A Star Is About To Go 2.5% The Speed Of Light Past A Black Hole

Artist’s impression of the star S2 passing very close to the supermassive black hole at the centre of the Milky Way. Credit: ESO

Since it was first discovered in 1974, astronomers have been dying to get a better look at the Supermassive Black Hole (SBH) at the center of our galaxy. Known as Sagittarius A*, scientists have only been able to gauge the position and mass of this SBH by measuring the effect it has on the stars that orbit it. But so far, more detailed observations have eluded them, thanks in part to all the gas and dust that obscures it.

Luckily, the European Southern Observatory (ESO) recently began work with the GRAVITY interferometer, the latest component in their Very Large Telescope (VLT). Using this instrument, which combines near-infrared imaging, adaptive-optics, and vastly improved resolution and accuracy, they have managed to capture images of the stars orbiting Sagittarius A*. And what they have observed was quite fascinating.

One of the primary purposes of GRAVITY is to study the gravitational field around Sagittarius A* in order to make precise measurements of the stars that orbit it. In so doing, the GRAVITY team – which consists of astronomers from the ESO, the Max Planck Institute, and multiple European research institutes – will be able to test Einstein’s theory of General Relativity like never before.

The core of the Milky Way. Credit: NASA/JPL-Caltech/S. Stolovy (SSC/Caltech) — *Spitzer image of the core of the Milky Way Galaxy. Credit: NASA/JPL-Caltech/S. Stolovy (SSC/Caltech)*

In what was the first observation conducted using the new instrument, the GRAVITY team used its powerful interferometric imaging capabilities to study S2, a faint star which orbits Sagittarius A* with a period of only 16 years. This test demonstrated the effectiveness of the GRAVITY instrument – which is 15 times more sensitive than the individual 8.2-metre Unit Telescopes the VLT currently relies on.

This was an historic accomplishment, as a clear view of the center of our galaxy is something that has eluded astronomers in the past. As GRAVITY’s lead scientist, Frank Eisenhauer – from the Max Planck Institute for Extraterrestrial Physics in Garching, Germany – explained to Universe Today via email:

“First, the Galactic Center is hidden behind a huge amount of interstellar dust, and it is practically invisible at optical wavelengths. The stars are only observable in the infrared, so we first had to develop the necessary technology and instruments for that. Second, there are so many stars concentrated in the Galactic Center that a normal telescope is not sharp enough to resolve them. It was only in the late 1990′ and in the beginning of this century when we learned to sharpen the images with the help of speckle interferometry and adaptive optics to see the stars and observe their dance around the central black hole.”

But more than that, the observation of S2 was very well timed. In 2018, the star will be at the closest point in its orbit to the Sagittarius A* – just 17 light-hours from it. As you can see from the video below, it is at this point that S2 will be moving much faster than at any other point in its orbit (the orbit of S2 is highlighted in red and the position of the central black hole is marked with a red cross).

When it makes its closest approach, S2 will accelerate to speeds of almost 30 million km per hour, which is 2.5% the speed of light. Another opportunity to view this star reach such high speeds will not come again for another 16 years – in 2034. And having shown just how sensitive the instrument is already, the GRAVITY team expects to be able make very precise measurements of the star’s position.

In fact, they anticipate that the level of accuracy will be comparable to that of measuring the positions of objects on the surface of the Moon, right down to the centimeter-scale. As such, they will be able to determine whether the motion of the star as it orbits the black hole are consistent with Einstein’s theories of general relativity.

“[I]t is not the speed itself to cause the general relativistic effects,” explained Eisenhauer, “but the strong gravitation around the black hole. But the very high orbital speed is a direct consequence and measure of the gravitation, so we refer to it in the press release because the comparison with the speed of light and the ISS illustrates so nicely the extreme conditions.

Artist's impression of the influence gravity has on space time. Credit: space.com — *Artist’s impression of the influence gravity has on space-time. Credit: space.com*

As recent simulations of the expansion of galaxies in the Universe have shown, Einstein’s theories are still holding up after many decades. However, these tests will offer hard evidence, obtained through direct observation. A star traveling at a portion of the speed of light around a supermassive black hole at the center of our galaxy will certainly prove to be a fitting test.

And Eisenhauer and his colleagues expect to see some very interesting things. “We hope to see a “kick” in the orbit.” he said. “The general relativistic effects increase very strongly when you approach the black hole, and when the star swings by, these effects will slightly change the direction of the
orbit.”

While those of us here at Earth will not be able to “star gaze” on this occasion and see R2 whipping past Sagittarius A*, we will still be privy to all the results. And then, we just might see if Einstein really was correct when he proposed what is still the predominant theory of gravitation in physics, over a century later.

Further Reading: eso.org