This New Map of 1.3 Million Quasars Is A Powerful Tool

This figure from the research shows the sky distribution of the new Quaia quasar catalogue in Galactic coordinates and is displayed using a Mollweide projection. The grey region across the center is the Milky Way, a blind spot in the Quaia catalogue. Image Credit: K. Storey-Fisher et al. 2024

Quasars are the brightest objects in the Universe. The most powerful ones are thousands of times more luminous than entire galaxies. They’re the visible part of a supermassive black hole (SMBH) at the center of a galaxy. The intense light comes from gas drawn toward the black hole, emitting light across several wavelengths as it heats up.

But quasars are more than just bright ancient objects. They have something important to show us about the dark matter.

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The Brightest Object Ever Seen in the Universe

This artist’s impression shows the record-breaking quasar J059-4351, the bright core of a distant galaxy that is powered by a supermassive black hole. The light comes from gas and dust that's heated up before it's drawn into the black hole. Credit: ESO/M. Kornmesser

It’s an exciting time in astronomy today, where records are being broken and reset regularly. We are barely two months into 2024, and already new records have been set for the farthest black hole yet observed, the brightest supernova, and the highest-energy gamma rays from our Sun. Most recently, an international team of astronomers using the ESO’s Very Large Telescope in Chile reportedly saw the brightest object ever observed in the Universe: a quasar (J0529-4351) located about 12 billion light years away that has the fastest-growing supermassive black hole (SMBH) at its center.

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What are the Differences Between Quasars and Microquasars?

Artist's impression of a microquasar

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.

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Astronomers are Getting Really Good at Weighing Baby Supermassive Black Holes

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.

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Vera Rubin Will Find Binary Supermassive Black Holes. Here’s How.

This image is from a simulation of two merging black holes. The upcoming Vera Rubin Observatory should be able to detect binary black holes before they merge. But the vexing problem of false positives needs a solution. Image Credit: Simulating eXtreme Spacetimes (SXS) Project

When galaxies merge, we expect them to produce binary black holes (BBHs.) BBHs orbit one another closely, and when they merge, they produce gravitational waves that have been detected by LIGO-Virgo. The upcoming Vera Rubin Observatory should be able to find them before they merge, which would open a whole new window into the study of galaxy mergers, supermassive black holes, binary black holes, and gravitational waves.

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Sometimes Compact Galaxies Hide Their Black Holes

Illustration of an active quasar. What role does its dark matter halo play in activating the quasar? Credit: ESO/M. Kornmesser
Illustration of an active quasar. New research shows that SMBHs eat rapidly enough to trigger them. Credit: ESO/M. Kornmesser

Quasars, short for quasi-stellar objects, are one of the most powerful and luminous classes of objects in our Universe. A subclass of active galactic nuclei (AGNs), quasars are extremely bright galactic cores that temporarily outshine all the stars in their disks. This is due to the supermassive black holes in the galactic cores that consume material from their accretion disks, a donut-shaped ring of gas and dust that orbit them. This matter is accelerated to close to the speed of light and slowly consumed, releasing energy across the entire electromagnetic spectrum.

Based on past observations, it is well known to astronomers that quasars are obscured by the accretion disk that surrounds them. As powerful radiation is released from the SMBH, it causes the dust and gas to glow brightly in visible light, X-rays, gamma-rays, and other wavelengths. However, according to a new study led by researchers from the Centre for Extragalactic Astronomy (CEA) at Durham University, quasars can also be obscured by the gas and dust of their entire host galaxies. Their findings could help astronomers better understand the link between SMBHs and galactic evolution.

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Gluttonous Black Holes Eat Faster Than Thought. Does That Explain Quasars?

Illustration of an active quasar. What role does its dark matter halo play in activating the quasar? Credit: ESO/M. Kornmesser
Illustration of an active quasar. New research shows that SMBHs eat rapidly enough to trigger them. Credit: ESO/M. Kornmesser

At the heart of large galaxies like our Milky Way, there resides a supermassive black hole (SMBH.) These behemoths draw stars, gas, and dust toward them with their irresistible gravitational pull. When they consume this material, there’s a bright flare of energy, the brightest of which are quasars.

While astrophysicists think that SMBHs eat too slowly to cause a particular type of quasar, new research suggests otherwise.

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Quasars Have Always Had Dark Matter Halos

Illustration of an active quasar. What role does its dark matter halo play in activating the quasar? Credit: ESO/M. Kornmesser
Illustration of an active quasar. New research shows that SMBHs eat rapidly enough to trigger them. Credit: ESO/M. Kornmesser

When you look at most galaxies in the Universe, you’re looking at the homes of supermassive black holes. It now appears that quasars, which are active galaxies spitting out huge amounts of radiation from the region around their black holes, also have massive dark matter halos. It turns out they’ve always had them. And, their black hole activity has a direct connection with those halos.

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A Black Hole Switched On in the Blink of an Eye

This artist’s impression depicts a rapidly spinning supermassive black hole surrounded by an accretion disc. This thin disc of rotating material consists of the leftovers of a Sun-like star which was ripped apart by the tidal forces of the black hole. Shocks in the colliding debris as well as heat generated in accretion led to a burst of light, resembling a supernova explosion. Credit: ESO, ESA/Hubble, M. Kornmesser

In 2019, a team of astronomers led by Dr. Samantha Oates of the University of Birmingham discovered one of the most powerful transients ever seen – where astronomical objects change their brightness over a short period. Oates and her colleagues found this object, known as J221951-484240 (or J221951), using the Ultra-Violet and Optical Telescope (UVOT) on NASA’s Neil Gehrels Swift Observatory while searching for the source of a gravitational wave (GW) that was thought to be caused by two massive objects merging in our galaxy.

Multiple follow-up observations were made using the UVOT and Swift’s other instruments – the Burst Alert Telescope (BAT) and X-Ray Telescope (XRT), the Hubble Space Telescope, the South African Large Telescope (SALT), the Wide-field Infrared Survey Explorer (WISE), the ESO’s Very Large Telescope (VLT), the Australia Telescope Compact Array (ATCA), and more. The combined observations and spectra revealed that the source was a supermassive black hole (SMBH) in a distant galaxy that mysteriously “switched on,” becoming one of the most dramatic bursts of brightness ever seen with a black hole.

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860 Million-Year-Old Quasar Had Already Amassed 1.4 Billion Times the Mass of the Sun

Artist concept of a growing black hole, or quasar, seen at the center of a faraway galaxy. (NASA/JPL-Caltech)
Artist concept of a growing black hole, or quasar, seen at the center of a faraway galaxy. JWST has studied two of them in the very early universe. (NASA/JPL-Caltech)

It wasn’t long after the Big Bang that early galaxies began changing the Universe. Less than a billion years later, they had already put on a lot of weight. In particular, their central supermassive black holes were behemoths. New images from JWST show two massive galaxies as they appeared less than a billion years after the universe began.

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