This image, taken by NASA’s James Webb Space Telescope, shows an ancient quasar (circled in red) with fewer than expected neighboring galaxies (bright spheres), challenging physicists’ understanding of how the first quasars and supermassive black holes formed. Credits:Credit: Christina Eilers/EIGER team
At the centre of most galaxies are supermassive black holes. When they are ‘feeding’ they blast out jets of material with associated radiation that can outshine the rest of the galaxy. These are known as quasars and they are usually found in regions where huge quantities of gas exist. However, a recent study found a higher than expected number of quasars that are alone in the Universe. These loners are not surrounded by galaxies nor a supply of gas. The question therefore remains, how are they shining so brightly.
Dyson Spheres have been a tantalising digression in the hunt for alien intelligence. Just recently seven stars have been identified as potential candidates with most of their radiation given off in the infrared wavelengths. Potentially this is the signature of heat from a matrix of spacecraft around the star but alas, a new paper has another slightly less exciting explanation; dust obscured galaxies.
Quasars are fascinating objects; supermassive black holes that are actively feasting on material from their accretion disks. The result is a jet that can outshine the combined light from the entire galaxy! There are smaller blackholes too that are the result of the death of stars and these also sometimes seem to host accretion disks and jets just like their larger cousins. We call these microquasars and, whilst there are similarities between them, there are differences too.
Illustration of an active quasar. New research shows that SMBHs eat rapidly enough to trigger them. Credit: ESO/M. Kornmesser
In the 1970s, astronomers deduced that the persistent radio source coming from the center of our galaxy was actually a supermassive black hole (SMBH). This black hole, known today as Sagittarius A*, is over 4 million solar masses and is detectable by the radiation it emits in multiple wavelengths. Since then, astronomers have found that SMBHs reside at the center of most massive galaxies, some of which are far more massive than our own! Over time, astronomers observed relationships between the properties of galaxies and the mass of their SMBHs, suggesting that the two co-evolve.
Using the GRAVITY+ instrument at the Very Large Telescope Interferometer (VLTI), a team from the Max Planck Institute for Extraterrestrial Physics (MPE) recently measured the mass of an SMBH in SDSS J092034.17+065718.0. At a distance of about 11 billion light-years from our Solar System, this galaxy existed when the Universe was just two billion years old. To their surprise, they found that the SMBH weighs in at a modest 320 million solar masses, which is significantly under-massive compared to the mass of its host galaxy. These findings could revolutionize our understanding of the relationship between galaxies and the black holes residing at their centers.
Artist's impression of blue quasar in the early universe. Credit: S. Munro / CC BY 4.0
Within almost every galaxy is a supermassive black hole. Millions, sometimes billions of solar masses locked within an event horizon of space and time. They can power luminous quasars, drive star formation, and change the evolution of a galaxy. Because of their size and abundance, supermassive black holes must have formed early in cosmic history. But how early is still an unanswered question. It’s a focus of a recent study on the arXiv.
This artist’s impression shows how the distant quasar P172+18 and its radio jets may have looked. To date (early 2021), this is the most distant quasar with radio jets ever found and it was studied with the help of ESO’s Very Large Telescope. It is so distant that light from it has travelled for about 13 billion years to reach us: we see it as it was when the Universe was only about 780 million years old.
A new study shows a way to use quasars to gauge distance in the early Universe.
The simple question of ‘how far?’ gets at the heart of the history of modern astronomy. Looking out across our galactic backyard into the primordial Universe, different yardsticks—often referred to as ‘standard candles’ —are used to gauge various distances, from near to far.
Computer Simulation of a Quasar, a Supermassive Black Hole that is actively feeding and creating tremendous energy - created in "SpaceEngine" pro by author
A monster lurks at the heart of many galaxies – even our own Milky Way. This monster possesses the mass of millions or billions of Suns. Immense gravity shrouds it within a dark cocoon of space and time – a supermassive black hole. But while hidden in darkness and difficult to observe, black holes can also shine brighter than an entire galaxy. When feeding, these sleeping monsters awaken transforming into a quasar – one of the Universe’s most luminous objects. The energy a quasar radiates into space is so powerful, it can interfere with star formation for thousands of light years across their host galaxies. But one galaxy appears to be winning a struggle against its awoken blazing monster and in a recent paper published in the Astrophysical Journal, astronomers are trying to determine how this galaxy survives.
Artist's impression of a shroud of dust cloaking a supermassive black hole, alongside the X-ray view of where black holes should be. Image credit: X-ray: NASA/CXC/Penn State/B.Luo et al; Illustration: NASA/CXC/M. Weiss
Quasars are the most powerful sources of light in the universe, but sometimes they’re hard to find. A team of astronomers used the Chandra X-ray Space Telescope to find some diamonds in the rough.
We puny humans think we can accelerate particles? Look how proud we are of the Large Hadron Collider. But any particle accelerator we build will pale in comparison to Quasars, nature’s champion accelerators.
Using the microlensing metthod, a team of astrophysicists have found the first extra-galactic planets! Credit: NASA/Tim Pyle
The first confirmed discovery of a planet beyond our Solar System (aka. an Extrasolar Planet) was a groundbreaking event. And while the initial discoveries were made using only ground-based observatories, and were therefore few and far between, the study of exoplanets has grown considerably with the deployment of space-based telescopes like the Kepler space telescope.
As of February 1st, 2018, 3,728 planets have been confirmed in 2,794 systems, with 622 systems having more than one planet. But now, thanks to a new study by a team of astrophysicists from the University of Oklahoma, the first planets beyond our galaxy have been discovered! Using a technique predicting by Einstein’s Theory of General Relativity, this team found evidence of planets in a galaxy roughly 3.8 billion light years away.
For the sake of their study, the pair used the Gravitational Microlensing technique, which relies on the gravitational force of distant objects to bend and focus light coming from a star. As a planet passes in front of the star relative to the observer (i.e. makes a transit), the light dips measurably, which can then be used to determine the presence of a planet.
In this respect, Gravitational Microlensing is a scaled-down version of Gravitational Lensing, where an intervening object (like a galaxy cluster) is used to focus light coming from a galaxy or other large object located beyond it. It also incorporates a key element of the highly-effective Transit Method, where stars are monitored for dips in brightness to indicate the presence of an exoplanet.
In addition to this method, which is the only one capable of detecting extra-solar planets at truly great distances (on the order of billions of light years), the team also used data from NASA’s Chandra X-ray Observatory to study a distant quasar known as RX J1131–1231. Specifically, the team relied on the microlensing properties of the supermassive black hole (SMBH) located at the center of RX J1131–1231.
They also relied on the OU Supercomputing Center for Education and Research to calculate the microlensing models they employed. From this, they observed line energy shifts that could only be explained by the presence of of about 2000 unbound planets between the quasar’s stars – which ranged from being as massive as the Moon to Jupiter – per main-sequence star.
Image of the gravitational lens RX J1131-1231 galaxy with the lens galaxy at the center and four lensed background quasars. It is estimated that there are trillions of planets in the center elliptical galaxy in this image. Credit: University of Oklahoma
As Xinyu Dai explained in a recent University of Oklahoma press release:
“We are very excited about this discovery. This is the first time anyone has discovered planets outside our galaxy. These small planets are the best candidate for the signature we observed in this study using the microlensing technique. We analyzed the high frequency of the signature by modeling the data to determine the mass.”
While 53 planets have been discovered within the Milky Way galaxy using the Microlensing technique, this is the first time that planets have been observed in other galaxies. Much like the first confirmed discovery of an extra-solar planet, scientists were not even certain planets existed in other galaxies prior to this study. This discovery has therefore brought the study of planets beyond our Solar System to a whole new level!
And as Eduardo Guerras indicated, the discovery was possible thanks to improvements made in both modelling and instrumentation in recent years:
“This is an example of how powerful the techniques of analysis of extragalactic microlensing can be. This galaxy is located 3.8 billion light years away, and there is not the slightest chance of observing these planets directly, not even with the best telescope one can imagine in a science fiction scenario. However, we are able to study them, unveil their presence and even have an idea of their masses. This is very cool science.”
In the future, exoplanet discoveries are likely to be made within and beyond the Milky Way Galaxy. Credit: NASA
At this juncture, the odds are good that some of these discoveries will be in neighboring galaxies. Perhaps then we can begin to determine just how common planets are in our Universe. At present, it is estimated that could be as many as 100 billion planets in the Milky Way Galaxy alone! But with an estimated 1 to 2 trillion galaxies in the Universe… well, you do the math!
