Black Holes Archives

August 9, 2023August 9, 2023 by Brian Koberlein

Could This Supermassive Black Hole Only Have Formed by Direct Collapse?

Artist's impression of an active supermassive black hole in the early universe. Credit: NOIRLab/NSF/AURA/J. da Silva

Nearly every galaxy in the universe contains a supermassive black hole. Even galaxies that are billions of light years away. This means supermassive black holes form early in the development of a galaxy. They are possibly even the gravitational seeds around which a galaxy forms. But astronomers are still unclear about just how these massive gravitational beasts first appeared.

August 3, 2023August 3, 2023 by Brian Koberlein

Does the Milky Way's Supermassive Black Hole Have a Companion?

Sag A* compared to M87* and the orbit of Mercury. Credit: EHT collaboration

At the heart of our galaxy, there is a monster black hole. Known as Sagittarius A*, it has a mass of 4.2 million Suns, and it’s only about 27,000 light-years from Earth. Sag A* is the closest supermassive black hole, and one of only two that we’ve observed directly. It is so close that we can even see stars closely orbiting it. Some of those stars we’ve been observing for more than 20 years, which means we have a very good handle on their orbits. We’ve used those orbits to determine the mass of Sag A*, but a new study looks at a different question: does our galaxy’s black hole have a companion?

July 28, 2023July 28, 2023 by Carolyn Collins Petersen

How Did Supermassive Black Holes Grow So Quickly, So Early?

An international team of astronomers using archival data from the NASA/ESA Hubble Space Telescope and other space- and ground-based observatories have discovered a unique object in the distant, early Universe that is a crucial link between young star-forming galaxies and the earliest supermassive black holes. Current theories predict that supermassive black holes begin their lives in the dust-shrouded cores of vigorously star-forming “starburst” galaxies.

Supermassive black holes haunt the cores of many galaxies. Yet for all we know about black holes (not nearly enough!), the big ones remain a mystery, particularly when they began forming. Interestingly, astronomers see them in the early epochs of cosmic history. That raises the question: how did they get so big when the Universe was still just a baby?

June 21, 2023June 21, 2023 by Carolyn Collins Petersen

The Milky Way’s Supermassive Black Hole had a Burst of Activity 200 Years Ago. We Just Saw the Echo.

Imagery from NASA’s Imaging X-ray Polarimetry Explorer and Chandra X-ray Observatory have been combined to show X-ray data of the area around Sagittarius A*, the supermassive black hole at the core of the Milky Way galaxy. The lower panel combines IXPE data, in orange, with Chandra data in blue. The upper panel depicts a much wider field-of-view of the center of the Milky Way, courtesy of Chandra. The thin white lines layered onto the top panel frame the highlighted area, and indicate that the perspective in the bottom panel has been rotated approximately 45 degrees to the right. The combination of IXPE and Chandra data helped researchers determine that the X-ray light identified in the molecular clouds originated from Sagittarius A* during an outburst approximately 200 years ago. Credits: IXPE: NASA/MSFC/F. Marin et al; Chandra: NASA/CXC/SAO; Image Processing: L.Frattare, J.Major & K.Arcand

We in the Milky Way Galaxy are pretty lucky to have a fairly quiet central supermassive black hole in Sgr A*. It’s not loud and bright like an active galactic nucleus. It appears to be active for brief periods before going to sleep. Two hundred years ago, it “woke up” for about a year and a half and had a bite to eat.

June 19, 2023June 19, 2023 by Brian Koberlein

Astronomers Have Never Detected Merging Supermassive Black Holes. That Might Be About to Change

Simulation of merging supermassive black holes. Credit: NASA's Goddard Space Flight Center/Scott Noble

Gravitational wave astronomy currently can only detect powerful rapid events, such as the mergers of neutron stars or stellar mass black holes. We’ve been very successful in detecting the mergers of stellar mass black holes, but a long-term goal is to detect the mergers of supermassive black holes.

June 15, 2023June 15, 2023 by Matt Williams

Pulsars Could Help Map the Black Hole at the Center of the Milky Way

The Atacama Large Millimeter/submillimeter Array (ALMA) looked at Sagittarius A*, (image of Sag A* by the EHT Collaboration) to study something bright in the region around Sag A*. Credit: ESO/José Francisco Salgado.

The Theory of General Relativity (GR), proposed by Einstein over a century ago, remains one of the most well-known scientific postulates of all time. This theory, which explains how spacetime curvature is altered in the presence of massive objects, remains the cornerstone of our most widely-accepted cosmological models. This should come as no surprise since GR has been verified nine ways from Sunday and under the most extreme conditions imaginable. In particular, scientists have mounted several observation campaigns to test GR using Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way.

Last year, the Event Horizon Telescope (EHT) – an international consortium of astronomers and observatories – announced they had taken the first images of Sag A*, which came just two years after the release of the first-ever images of an SMBH (M87). In 2014, the European members of the EHT launched another initiative known as BlackHoleCam to gain a better understanding of SMBHs using a combination of radio imaging, pulsar observations, astrometry, and GR. In a recent paper, the BHC initiative described how they tested GR by observing pulsars orbiting Sgr A*.

June 9, 2023June 9, 2023 by Brian Koberlein

If Black Holes Evaporate, Everything Evaporates

How virtual particles radiate away from any mass. Credit: Wondrak, et al

Hawking radiation is one of the most famous physical processes in astronomy. Through Hawking radiation, the mass, and energy of a black hole escape over time. It’s a brilliant theory, and it means that black holes have a finite lifetime. If Hawking radiation is true. Because as famous as it is, Hawking radiation is unproven. The theory is not even theoretically proven.

May 26, 2023May 26, 2023 by Brian Koberlein

When Black Holes Merge, They'll Ring Like a Bell

Artist view of a black hole ringing down into a stable state. Credit: Yasmine Steele at University of Illinois – Urbana Champaign

When two black holes collide, they don’t smash into each other the way two stars might. A black hole is an intensely curved region of space that can be described by only its mass, rotation, and electric charge, so two black holes release violent gravitational ripples as merge into a single black hole. The new black hole continues to emit gravitational waves until it settles down into a simple rotating black hole. That settling down period is known as the ring down, and its pattern holds clues to some of the deepest mysteries of gravitational physics.

May 23, 2023May 23, 2023 by Evan Gough

Where Are the Missing Black Holes? The Hubble May Have Helped Find One

This Hubble Space Telescope image shows the globular cluster Messier 4. It contains several hundre thousand stars, and its center might host an elusive intermediate-mass black hole. The black hole could have 800 solar masses. Image Credit: ESA/Hubble & NASA

Most black holes are stellar mass black holes. They’re created when a star several times more massive than our Sun reaches the end and collapses in on itself. There are also supermassive black holes (SMBH,) the behemoths at the center of galaxies that can boast billions of times more mass than the Sun.

But where are the intermediate-mass black holes?

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.