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Astronomers detect three supermassive black holes at the center of three colliding galaxies

Astronomers detect three supermassive black holes at the center of three colliding galaxies

Three supermassive black holes (SMBHs) glowing in x-ray emissions have been identified by astronomers at the center of three colliding galaxies a billion light-years away from Earth. All three black holes are active galactic nuclei(AGN), consuming material. This finding may clarify a long-standing issue in astrophysics and black hole mergers known as “final parsec problem”. The study appears in The Astrophysical Journal.

Researchers detected the three SMBHs with the data from several telescopes, Sloan Digital Sky Survey (SDSS,) the Chandra X-ray Observatory, and the Wide-field Infrared Survey Explorer (WISE)A nearly unbelievably astronomical event, the fusion of three galaxies may play a crucial role in how the most massive black holes expand over time.

Ryan Pfeifle from George Mason University in Fairfax, Virginia, the paper’s first author said that they found this incredible system through their selection technique while they were only looking for black hole pairs. He also added that this is the most powerful evidence found for such a triple system of active supermassive black holes. It is very challenging to locate triple black hole systems since they are wrapped in gas and dust. It took several telescopes functioning in different parts of the electromagnetic spectrum and also the work with researchers to detect these black holes.

Co-author Shobita Satyapal, also belonging to George Mason said that dual and triple black holes are extremely rare but such systems are actually a natural outcome of galaxy mergers, through which galaxies grow. This triple-merger was first spotted in visible light by the SDSS and only through a citizen science project named Galaxy Zoo the system of colliding galaxies was detected. The system was in a state of galaxy merger glowing in the infrared as seen by the WISE when more than one black holes were expected to be feeding.

Researchers shifted to the Chandra Observatory and the Large Binocular Telescope (LBT) for confirmation as Sloan and WISE data were fascinating clues. Chandra observations revealed bright x-ray sources in the galactic centers where SMBHs are expected to detect. Chandra and Nuclear Spectroscopic Telescope Array (NuSTAR) satellite of NASA discovered more shreds of evidence showing the presence of SMBHs and the existence of large amounts of gas and dust near one of them. It was expected in merging of black holes. Spectral evidence received by optical light data from SDSS and  LBT shows that these are characteristics of the feeding SMBHs.

Christina Manzano-King, co-author from the University of California, Riverside said that optical spectra include plenty of information about a galaxy which is frequently used to detect active accreting supermassive black holes and can tell about their influence on the inhabitant galaxies. Pfeifle said that they have found a new method of identifying triple supermassive black holes using these major observatories as each telescope gives them a distinct idea about these systems. They expect to extend their work to find more triples using the same method.

The final parsec problem is a theoretical problem that is fundamental to our understanding of binary black hole mergers that states that the enormous orbital energy of two approaching black holes stops them from merging. They can get separated by a few light-years, then the merging process stables.

The hyperbolic trajectories of two initially approaching black hole carry them right past each other. The two holes catapult the stars as they interact with them in their proximity transferring a fraction of their orbital energy to a star every time. The energy of the black holes gets reduced by the emission of gravitational waves. The two black holes finally slow down and approach each other more closely shedding enough orbital energy finally getting within just a few parsecs of each other. More matter is discharged via sling-shotting as they come closer. As a result, for the black holes, no more matter is left to interact with and shed more orbital energy. The merging process halts.

Astronomers know that strong gravitational waves are responsible for black hole mergers.LIGO (Laser Interferometry Gravitational-Wave Observatory) discovers a black hole merger almost every week. The final parsec problem is about how they merge with each other finally. Researchers think that a third black hole like seen in this system could give the push needed for the black holes to get merged. Nearly 16% of supermassive black hole pairs in colliding galaxies are expected to interact with a third supermassive black hole before they merge.

The challenge is that gravitational waves produced during merging would be too low-frequency for LIGO or the VIRGO observatory to detect. Researchers may have to depend on future observatories like LISA, ESA/NASA’s Laser Interferometer Space Antenna to detect those waves. LISA is better-equipped than LIGO or VIRGO to detect merging of giant and massive black holes as it can detect lower frequency gravitational waves.

Reference: The Astrophysical Journal.

The all-new Event Horizon Telescope is being designed

The all-new Event Horizon Telescope is being designed

Radio telescopes around the globe were used in April 2017 to conduct a fantastic feat: two supermassive black holes were observed all together. This was the Horizon Telescope event and the first outcomes, released back in April, gave us the very first image of one of these new artifacts.

The National Science Foundation has granted a $12.7 million grant to the cooperation to schedule the next-generation Horizon Telescope (ngEHT) event. It will use the funds to improve the current design. The telescope is currently being produced by linking current installations worldwide. This technique, which is known as interferometry, allows astronomers to have a radio telescope that is effectively the size of the Earth.

Led by Principal Investigator Shep Doeleman at the Center for Astrophysics at Harvard, and Smithsonian (CfA), the new ngEHT award will fund design and prototyping efforts by researchers at several US institutes. These include Dr. Gopal Narayanan at the University of Massachusetts, Amherst, Dr. Vincent Fish at the MIT Haystack Observatory, and Drs. Katherine L. (Katie) Bouman and Gregg Hallinan at Caltech. At the CfA, Drs. Michael Johnson, Jonathan Weintroub, and Lindy Blackburn are co-Principal Investigators of the ngEHT program.

On April 10th, 2019, the International Event Horizon Telescope Collaboration released the first image of a supermassive black hole. A bright ring of emission at the heart of the Virgo A galaxy revealed a black hole, known as M87, that has a mass of 6.5 billion Suns. Einstein’s theory of gravity spectacularly passed this new test in this extreme cosmic laboratory. For this work, the EHT Collaboration will receive the Breakthrough Prize in Fundamental Physics this November.

Black holes are now accessible for direct imaging, objects with gravity so sharp that light can not escape. More precise gravity tests can now be considered, and it is possible to study in detail the processes by which supermassive black holes energize the brightness and dynamics of most galaxy cores. The next-generation EHT (ngEHT) will sharpen the focus on black holes and allow researchers to move on to the event horizon from still-imagery to real-time space-time videos.

Announcement of the Next Generation Event Horizon Telescope

(Credits: Harvard CFA)

New telescopes and technology will allow scientists to study the black holes in more frequencies, significantly improve our understanding. Each observatory will have to be equipped with ways to record and transfer an incredible amount of data.

The team observed the supermassive black hole in the Milky Way two years ago, but its mercurial character has made the analysis quite tricky. Doeleman confirms that they are working hard on it, so we might soon see an equally breathtaking image. As he said, the best is truly yet to come.

 

Researchers plan to release black hole movie soon

Researchers plan to release black hole movie soon

Before releasing the first-ever image of a black hole, an international team of researchers were already scheduling a movie sequel depicting how huge clouds of gas are permanently absorbed into the void. The required observations have already been recorded by the Event Horizon Telescope Collaboration and scientists are currently processing the data for the release of the first video in 2020.

Shep Doeleman, the project director is hopeful that by the end of the next decade, it would be possible to make real-time movies of black holes that depict their action at a cosmic stage beside their appearance.

The complete group of 347 scientists from around the world won $3 million and were awarded the Breakthrough Prize in Fundamental Physics for the so-called “Oscar of science” image. Doeleman, a 52-year-old cosmologist at the Harvard-Smithsonian Centre for Astrophysics and the father of two joked that his wife might be finally convinced that he was doing something worthwhile as he worked on this for more than 20 years.

Astronomers did not have the sharpness in their images to detect the shape of the light which was being swallowed by the black holes. After the team linked multiple radio telescopes together, creating an Earth-sized massive telescope the barrier was finally overcome and thus objects that appear microscopic in the night sky could now be observed with high resolution.

The team used three telescopes to establish the evidence of concept and the first measurements of the black hole were published in 2008. They had combined eight radio telescopes in Chile, Spain, Mexico, the US, and the South Pole by April 2017. The astronomers were able to observe the boundaries of the black holes by using these massive instruments which observe high-frequency radio waves.

The group also observed the center of our own Milky Way: Sagittarius-A* in addition to its observations of the black hole in the Messier 87 (M87) galaxy. Doeleman explained that while orbits of matter around Sagittarius-A* takes only half an hour and can change during one night of observation, it takes about a month to orbit around M87. He also added that the first cut of the movie could be made by 2020 and researchers would need more telescopes on Earth as well as in orbit, to strengthen the resolution.

Doeleman is optimistic about the possibility of future funding from governments as well as possibly from private donors after the first image of M87 captured people’s imagination. He also said that the EHT has added more value than any other scientific project in history. As explorers, they are reporting what they have observed at the edges of the black hole with their instruments.

black hole winds

Astronomers discover a super-fast star thrown out of the Milky Way

Many stars orbit near the Sagittarius A*, which is the super-massive black hole at the centre of the Milky Way galaxy. Some stars have been ripped apart when they got too close to the super-massive black hole. Other stars have changed colour due to the extremely high gravitational effects and in a few cases, the stars just slingshot into the intergalactic space like the S5-HVS1 star.

As reported in a paper available on the pre-print server arXiv, yet to be peer-reviewed, an international group of scientists have spotted a hypervelocity star as they were studying interesting objects for the Southern Stellar Stream Spectroscopic Survey(S5). The speed of hyper-velocity refers to a staggering 1,107 kilometres per second which is equivalent to 2.275 million miles per hour and could cover the distance between New York and Sydney in just 15.7 seconds.

There must be something that has accelerated to move the star at such high speed and a team of researchers are trying to estimate from where the star could most possibly come from. The most likely explanation based on their analysis is the core of the milky way which easily refers to the Sagittarius A*.

If the super-massive black hole is the real reason, then the star was probably kicked away with a velocity of more than 1800 kilometres per second and has been slowing down on its travel for about 4.8 million years. The star is a standard hydrogen fusing star or the main sequence object and is located close to 30,000 light-years from the Earth.

It is the fastest main sequence star which was ever discovered and it is not unique as astronomers have discovered dozens of stars like these and although many of such stars appear to have accelerated out of the galaxy by events other than the interactions with Sagittarius A*. Researchers are suggesting that if one of the two stars in a binary system goes supernova, it could be enough to push its companion beyond the disk of the Milky Way.

However, the stars are not only being kicked out as scientists have detected stars entering the galaxy from the smaller companions of Milky Way. They could have been also accelerated by a supernova or a supermassive black hole yet to be observed.

Journal Reference: arXiv

 

Artists impression of ASKAP antennas at Murchison Radioastronomy Observatory

Researchers discover the origin of single fast radio burst for the first time

This universe has always been a box full of mystical discoveries. Such a recent discovery was of radio waves that are emitted from an unknown source for a momentary period,  termed as Fast Radio Bursts. The study has been published in the Science journal.

The very first FRB was discovered in the year 2007. Since then the scientists have been successful in detecting 86 FRB’s. On the other hand, there are almost 2000 FRB’s which show up in the sky but because of their fleeting nature, it becomes very difficult to detect them.

Generally, these fast radio bursts are of two types where either there will be one-off FRB and the other can be repeating FRB. This recent discovery of FRB suggested that it is a one-off FRB which lasted for 1.3 milliseconds. It was named FRB-180924 and this name helps in knowing the date on which it was detected i.e. 24th September 2018.

There is a consensus amongst all the scientists where they know that they cannot track the origin of any one-off FRB but on the contrary, FRB-180924 was tracked by a team from Australia Commonwealth Science and Industrial Research Organization. The results of this unprecedented feat reveal that this one-off FRB was originated from the outskirts of a milky way sized galaxy nearly 3.6 billion light years far away from earth.

The international team was able to do this task through the help of an advanced array of antennas a.k.a Australian Square Kilometer Array Pathfinder (ASKAP). The ASKAP takes almost 10 trillion raw measurements per second for an entire patch of sky.

Before the tracking of FRB-180924, scientists have been able to track one FRB which belongs to the repeater FRB category and thus its tracking was comparatively very easy. Its name is FRB-121102 discovered in a star-forming region of a dwarf galaxy almost 3-billion light years away from our Universe.

Therefore, to track FRB-180924 the ASKAP which comprises of 36 telescopes was arranged in such a manner that all these telescopes were concentrated to a small part of the sky which helped researchers to get observations, just like getting 36 separate instant replays of the incidence.

Keith Bannister who led this research project claims that this discovery will help in understanding the Universe.

Even after gathering all of this information, the reason behind the occurrence of such FRB’s is still unknown. But with time it is assured that this discovery will prove to be a milestone for many more mind-blowing discoveries which will help in revealing the hidden truths of this universe.

 

Accretion disk

Researchers announce discovery that can change the concept of death of galaxies

At American Astronomical Society‘s annual meeting in St. Louis, Missouri, Allison Kirkpatrick, assistant professor in physics and astronomy at the University of Kansas, will present the discovery of “cold quasars“. These are the galaxies with a huge amount of cold gas but can still produce new stars in spite of a quasar located at the centre. This breakthrough finding turns down many assumptions regarding the maturation of galaxies and it represents a phase in the life cycle of the galaxy which was not yet known.

A quasar which stands for quasi-stellar radio source can be described as a supermassive black hole on steroids. When gas falls toward a quasar at the galaxy’s centre it forms an accretion disk which has the potential to generate a huge amount of electromagnetic energy that has luminosity, hundred times more than a normal galaxy. It has been thought till now, that when a quasar forms, it signals the end of the galaxy’s ability to form new stars.

Kirkpatrick remarked that the gas which is accreting on the black hole gets heated and it forms X-rays. The light wavelength is a direct correspondence of the amount of heat. When something generates X-rays, then it is one of the hottest things in the universe. Humans, on the other hand, produce infrared light. After the accretion of the gas on the black hole, it moves at relativistic speeds and thus forms a magnetic field around gas. Similar to solar flares, there can be materials shooting off from the black hole. This essentially cuts off the gas supply in the galaxy, as a result, it loses the ability to form stars.

However, in the survey conducted by Kirkpatrick, nearly 10 percent of the galaxies with accreting black holes had a supply of cold gas remaining even after this phase and formed new stars. This is highly surprising and these are very unique objects. Out of this, a further 10 percent is even more unexpected. These are blue sources which resemble the end stages of a supermassive black hole. They are evolving to passive elliptical galaxy yet have a huge amount of cold gas in them. These are called cold quasars.

Kirkpatrick said that these galaxies are very rare and they have been observed in the transition period right before the star formation in the galaxy is over. These objects were first identified in the Sloan Digital Sky  – the detailed map of the universe. They were surveyed with the help of XMM Newton Telescope and Herschel Space Telescope. Next up, Kirkpatrick wants to determine if this occurs to every galaxy or a specific group of galaxies.

NGC 1052 DF2 ghostly galaxy lacking dark matter

Researchers solve the mystery of galaxy which is void of dark matter

An earlier discovery that a galaxy without dark matter existed was indeed a mystery and was incompatible according to current theories however it has now been resolved. According to a new analysis the NGC1052-DF2 galaxy which was found last year is closer to us than expected and previously calculated, which means it is likely to contain dark matter. The study has been published in the Monthly Notices of the Royal Astronomical Society.

Dark matter is indeed a big mystery in itself as we cannot detect that it exists and even we do not know it exists but we know it is present which creates the effect of mass in the universe. Objects in the galaxies move faster than they should be moving because of this undetectable force due to the extra mass of dark matter which in turn generates more gravitational force than normal.

Dark matter is fundamental to our understanding of the universe. It has helped in the formation of stars and galaxies from the primaeval soup that existed after big bang and dark matter is what prevents bodies in the galaxy from just flying off into the unknown.

After reading and seeing the formation of the NGC1052-DF2 galaxy it changes the way as to how we think galaxies are formed. For decades we have thought that galaxies were formed due to dark matter and later forms stars due to the gases present in the dark matter. It is a critical ingredient in understanding the universe.

An international team of researchers led by the Instituto de Astrofísica de Canarias (IAC) decided to take a closer look at this galaxy and found out that anomalous measurements that were recorded in previous research have pointed out the absence of dark matter was dependant on the distance to the galaxy around 64 million light years away. Researchers used five separate telescopes including Hubble and the Gemini Observatory to recalculate the distance to NGC1052-DF2 galaxy.

The distance obtained was close to 42 million light years away instead of 62 million light years which was recorded earlier and based on this, the mass of galaxy was half as less than it was previously assumed to be and the stars were about a quarter their weight. This galaxy has lesser mass but the existing mass contains more dark matter than traditional matter. The previous theory of absence of dark matter was due to the slow movement of star clusters however now the movement seems normal. It now appears as an ordinary low brightness galaxy with plenty of room for dark matter. More such galaxies exist where absence of dark matter is speculated, the NGC1052-DF4 being a similar case.

star near a supermassive black hole

Researchers plan for improved black hole images with the aid of space telescopes

Scientists are trying to click a better quality picture of a black hole because that’s the way we can learn more about the strange phenomenon. Scientists from Radboud University in Nijmegen, Netherlands along with the European Space Agency have plans to get improved pictures of black holes.

The Event Horizon Telescope’s first picture was a great scientific success which was possible due to the cooperation, engineering as well as the technology but the picture was a bit blurry. The researchers have planned to launch a radio telescope into the space to get a more clear image of a black hole and the plan was published in Astronomy and Astrophysics paper.

EHT works on the principle of interferometry and they are a group of radio telescopes working around the world in coordination with each other. So together they act as a type of virtual telescope as the size of the earth and this is the reason we get a telescope big enough to see a black hole. Astronomers have to face a lot of difficulties due to the earth’s atmosphere and thus the telescopes have to adjust to the atmosphere to collect those images of objects at a far distance and that’s the reason they are designed in special locations that are at high altitude.

These telescopes are in Alps, Sierra Nevada, Atacama, and Hawaii. The atmosphere restricts the highest-frequency radio waves from reaching the scopes. The scope of the linkage is restricted by the size of the planet and thus the link cannot expand more than the width of the planet. The authors of the paper have a solution to both atmospheric problem as well as the problem of the size of the earth and put the radio telescopes in the respective places. The name of their project is Event Horizon Imager and the image is produced clearer than the EHT.

In this project, two or three satellites are put in the orbit which will be acting as radio observations. Freek Roelofs, a lead author of the article and PhD candidate at Radboud University said that using satellites are more advantageous than permanent radio telescopes according to the event of EHT.

Heino Falcke, radio astronomy Professor said that there are many advantages of the moving of satellites around the earth and he also added that with the help of them we can take clearer images of the black hole which shows the original details of it. The EHI would work with the combination of EHT as a kind of hybrid and Falcke said that by implementing this moving images of a black hole can be created and more can be noted.

 

                                                       

Asteroid Apophis Closest Approach To Earth

A 1100 ft wide asteroid to pass by Earth within a decade

According to reports from NASA, a huge asteroid will be visible to the human eyes when it passes the Earth at a very close distance, equal to the heights at which spacecraft orbit the Earth.

The asteroid is named 99942 Apophis, measuring 1100 ft wide. It will be passing the sky like a bright star-like point of light and will gain in brightness and velocity on Friday, 13 April 2029.

At a distance of 19000 miles from the surface of Earth, it will be visible to the human eyesight. The residents of Southern Hemisphere will be able to observe it first, namely the eastern and western coasts of Australia.

After that, it will be moving across the Indian Ocean and will be crossing the Atlantic Ocean in an hour’s duration, finally passing by the United States in the evening.

It is very rare for an asteroid of this dimension to cross Earth so closely. According to NASA, there have been smaller asteroids of 10-20 metres which have passed the Earth at very similar distances but those of the size of Apophis have been rare.

The observation and scientific opportunities related to this event were discussed by scientists at NASA at the Planetary Defence Conference 2019 which was held in Maryland.

Scientists have calculated that the asteroid will cover a distance which is more than the width of the full moon in the duration of only one minute and its brightness will be comparable to that of the stars in the Little Dipper constellation.

Marina Brozovic, a radar scientist who works at NASA’s Jet Propulsion Laboratory situated in Pasadena, California commented that the close approach of the asteroid Apophis in 2029 will be a very exciting opportunity for the scientific world. She also said that the observations will be made with both optical and radar telescopes.

With the help of radar observations, it might be possible to view the details of the surface which are only of a few metres in size.

The asteroid Apophis was discovered on 19th of June, 2004 by a group of researchers that included Roy A. Tucker, David J. Tholen, and Fabrizio Bernardi. It was detected at the Kitt Peak National Observatory. The name Apophis is the Greek name of Apep, the enemy of Sun God in Egyptian Mythology.

When initially found, researchers detected the chance of the asteroid hitting Earth at a probability of 2.7% in 2029. However, the latest calculations show that the asteroid may hit our planet at a chance of 1 in 100000, several decades later.

intergalactic stars

Researchers successfully recreate the sounds of stars through simulation softwares

It is well known that sound cannot propagate in vacuum as it requires a medium for its transmission. Sounds propagate as longitudinal waves in solids and fluids and also as a tranverse wave in solid structures. But scientists have been able to overcome this limitation as they have developed an innovative way for interpreting the signals which have been emitted by cosmos.

Researchers at University of Wisconsin-Madison have separated a different type of resonance which are caused by stars. These vibrations are actually variations in the temperature and the brightness of stars. Very powerful telescopes can spot these vibrations and then recreate the sounds of the stars with the help of computer simulations.

Jacqueline Goldstein, a graduate student in astronomy at University of Wisconsin-Madison said that a cello’s sound is because of its shape and size, similarly the vibrations of the stars are also dependent on their size and composition. Goldstein studies the connection between the structure of stars and their vibrations with the help of the software which simulates many stars and their frequencies. After comparing the simulations to the real stars, she can improve her model and make necessary changes.

For human beings to hear the sounds, the speed of the vibrations have to be increased by thousand to million times, besides repeating the frequencies from minutes to days. These are known as starquakes after their seismic variants on Earth and the field of study is called as astroseismology.

After the fusion of hydrogen in stars to heavier elements in the star cores, plasmic gas vibrates and hence the stars flicker. Researchers can know about the structure of stars through these fluctuations and also the changes which may occur in the star with the passage of time.

Goldstein studies those stars which are bigger than the sun as these are the ones which explode and lead to the formation of black holes, neutron stars and the heavy objects in the cosmos. Scientists want to study about the functioning of these stars and how they make an impact in the expansion and evolution of the universe.

With the help of professors of astronomy, Rich Townsend and Ellen Zweibel, Goldstein has created a computer software named GYRE which is plugged into the simulation software for stars, MESA. These softwares make it possible to develop models of different kinds of stars and observe their vibrations as they may appear to astronomers.

Since, GYRE and MESA are open source programs, they can be accessed freely by the scientists and modified. Goldstein is currently making a modified version of GYRE to take advantage of the data obtained by TESS.