Quasars Archives

November 9, 2023November 9, 2023 by Matt Williams

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.

September 20, 2023September 20, 2023 by Evan Gough

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

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.

September 13, 2023September 13, 2023 by Carolyn Collins Petersen

Quasars Have Always Had Dark Matter Halos

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.

July 10, 2023July 10, 2023 by Matt Williams

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.

June 29, 2023June 29, 2023 by Carolyn Collins Petersen

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.

May 23, 2023May 23, 2023 by Matt Williams

eROSITA Sees Changes in the Most Powerful Quasar

Artist’s impression of a quasar. These all have supermassive black holes at their hearts. Credit: NOIRLab/NSF/AURA/J. da Silva

After almost seventy years of study, astronomers are still fascinated by active galactic nuclei (AGN), otherwise known as quasi-stellar objects (or “quasars.”) These are the result of supermassive black holes (SMBHs) at the center of massive galaxies, which cause gas and dust to fall in around them and form accretion disks. The material in these disks is accelerated to close to the speed of light, causing it to release tremendous amounts of radiation in the visible, radio, infrared, ultraviolet, gamma-ray, and X-ray wavelengths. In fact, quasars are so bright that they temporarily outshine every star in their host galaxy’s disk combined.

The brightest quasar observed to date, 100,000 billion times as luminous as our Sun, is known as SMSS J114447.77-430859.3 (J1144). This AGN is hosted by a galaxy located roughly 9.6 billion light years from Earth between the constellations Centaurus and Hydra. Using data from the eROSITA All Sky Survey and other space telescopes, an international team of astronomers conducted the first X-ray observations of J1144. This data allowed the team to investigate prevailing theories about AGNs that could provide new insight into the inner workings of quasars and how they affect their host galaxies.

May 16, 2023May 16, 2023 by Matt Williams

Galactic Black Hole Winds Blow Up to a Third the Speed of Light. The Impact on Their Galaxies is Impressive.

An artist’s impression of what the dust around a quasar might look like from a light year away. Credit Peter Z. Harrington

They are known as ultra-fast outflows (UFOs), powerful space winds emitted by the supermassive black holes (SMBHs) at the center of active galactic nuclei (AGNs) – aka. “quasars.” These winds (with a fun name!) move close to the speed of light (relativistic speeds) and regulate the behavior of SMBHs during their active phase. These gas emissions are believed to fuel the process of star formation in galaxies but are not yet well understood. Astronomers are interested in learning more about them to improve our understanding of what governs galactic evolution.

This is the purpose of the SUper massive Black hole Winds in the x-rAYS (SUBWAYS) project, an international research effort dedicated to studying quasars using the ESA’s XMM-Newton space telescope. The first results of this project were shared by a group of scholars led by the University of Bologna and the National Institute for Astrophysics (INAF) in Italy. In the paper that describes their findings, the team presented X-ray spectroscopic data to characterize the properties of UFOs in 22 luminous galaxies.

March 14, 2023March 14, 2023 by Matt Williams

Warm Carbon Increased Suddenly in the Early Universe. Made by the First Stars?

While previous studies have suggested a rise in warm carbon, much larger samples – the basis of the new study – were needed to provide statistics to accurately measure the rate of this growth.

According to the most widely-accepted model of cosmology, the Universe began roughly 13.8 billion years ago with the Big Bang. As the Universe cooled, the fundamental laws of physics (the electroweak force, the strong nuclear force, and gravity) and the first hydrogen atoms formed. By 370,000 years after the Big Bang, the Universe was permeated by neutral hydrogen and very few photons (the Cosmic Dark Ages). During the “Epoch of Reionization” that followed, the first stars and galaxies formed, reoinizing the neutral hydrogen and causing the Universe to become transparent.

For astronomers, the Epoch of Reionization still holds many mysteries, like when certain heavy elements formed. This includes the element carbon, a key ingredient in the formation of planets, an important element in organic processes, and the basis for life as we know it. According to a new study by the ARC Center of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), it appears that triply-ionized carbon (C iv) existed far sooner than previously thought. Their findings could have drastic implications for our understanding of cosmic evolution.

February 15, 2023February 15, 2023 by Carolyn Collins Petersen

The Event Horizon Telescope Gazes into the Heart of a Distant Quasar

an artistic concept of a quasar — Concept image of a galactic quasar. Astronomers used the Event Horizon Telescope to study details at the heart of one like this called NRAO 530. Credit: ParallelVision, Pixabay

Oftentimes in astronomy, it takes a village of telescopes and people to make an amazing find. In the case of the quasar NRAO 530, it took a planet full of radio dishes ganged together to peer into its heart. Then, it took a major collaboration of scientists to figure out what the instruments were telling them.

January 24, 2023January 24, 2023 by Matt Williams

Dust is Hiding how Powerful Quasars Really are

In the 1970s, astronomers discovered that the persistent radio source at the center of our galaxy was a supermassive black hole (SMBH). Today, this gravitational behemoth is known as Sagittarius A* and has a mass roughly 4 million times that of the Sun. Since then, surveys have shown that SMBHs reside at the center of most massive galaxies and play a vital role in star formation and galactic evolution. In addition, the way these black holes consume gas and dust causes their respective galaxies to emit a tremendous amount of radiation from their Galactic Centers.

These are what astronomers refer to as Active Galactic Nuclei (AGN), or quasars, which can become so bright that they temporarily outshine all the stars in their disks. In fact, AGNs are the most powerful compact steady sources of energy in the Universe, which is why astronomers are always trying to get a closer look at them. For instance, a new study led by the University of California, Santa Cruz (UCSC) indicates that scientists have substantially underestimated the amount of energy emitted by AGN by not recognizing the extent to which their light is dimmed by dust.