Black Holes

Looking at the Team Behind the Science

Image of sgra
Sagittarius A*: The Black Hole at the Center of the Milky Way Galaxy
Credit: X-ray: NASA/CXC/SAO; IR: NASA/HST/STScI. Inset: Radio (EHT Collaboration)

Many projects in astrophysics involve huge numbers of scientists and other collaborators — often ranging from senior professors to graduate students and undergraduates. A project like the EHT often requires smaller groups within these large collaborations to concentrate on different problems and questions.

The latest result about the Milky Way's central black using many different telescopes in concert with the Event Horizon Telescope (EHT) is an excellent example of such a successful web of groups working together with others in the project to make the sum even greater than its parts.

To learn more about the group behind the "multiwavelength" (MWL) observations that included Chandra and other telescopes, we asked Sera Markoff and Daryl Haggard, two of the coordinators of the EHT's MWL Working Group, a series of questions.

New NASA Black Hole Sonifications with a Remix

Credit: X-ray: NASA/CXC/Univ. of Cambridge/C. Reynolds et al.; Sonification: NASA/CXC/SAO/K.Arcand, SYSTEM Sounds (M. Russo, A. Santaguida)

Black Hole at the Center of the Perseus Galaxy Cluster (above)

Since 2003, the black hole at the center of the Perseus galaxy cluster has been associated with sound. This is because astronomers discovered that pressure waves sent out by the black hole caused ripples in the cluster's hot gas that could be translated into a note — one that humans cannot hear some 57 octaves below middle C. Now a new sonification brings more notes to this black hole sound machine. This new sonification — that is, the translation of astronomical data into sound — is being released for NASA's Black Hole Week this year.

In some ways, this sonification is unlike any other done before (1, 2, 3, 4) because it revisits the actual sound waves discovered in data from NASA's Chandra X-ray Observatory. The popular misconception that there is no sound in space originates with the fact that most of space is essentially a vacuum, providing no medium for sound waves to propagate through. A galaxy cluster, on the other hand, has copious amounts of gas that envelop the hundreds or even thousands of galaxies within it, providing a medium for the sound waves to travel.

Exploring New Pathways for Massive Black Hole Formation with Chandra

Image of Vivienne Baldassare
Vivienne Baldassare

We are happy to welcome Vivienne Baldassare as our guest blogger. Vivienne is an Assistant Professor of Physics and Astronomy at Washington State University, and led the paper that is the subject of our latest press release. Her work is mainly focused on searching for the smallest supermassive black holes in order to learn more about black hole formation and growth. Prior to her current position, she was a NASA Einstein fellow at Yale University. She earned her PhD in Astronomy & Astrophysics from the University of Michigan in 2017, and a bachelor's degree in Physics from CUNY Hunter College in 2012.

One of the biggest open questions in astrophysics is “how do massive black holes form?” Our recent research with NASA’s Chandra X-ray Observatory provides support for the theory that massive black holes can form in what astronomers call nuclear star clusters.

While big galaxies have supermassive black holes at their centers, small galaxies often have a nuclear star cluster. Nuclear star clusters are extremely dense, with millions of stars packed into a region that is tens of light years across. It was once suggested that supermassive black holes and nuclear star clusters may be mutually exclusive, with the former residing in big galaxies and the latter occurring in small galaxies. However, some galaxies (like our Milky Way!) have been found to contain both. And excitingly, some theories suggest that nuclear star clusters might be able to form massive black holes.

In my first year of graduate school, I carried out a project studying the properties of nuclear star clusters. After that, I transitioned to studying massive black holes in dwarf galaxies, but have always had a soft spot for these fascinating objects. Our new study brought these two areas together.

Feasting Black Holes Caught in Galactic Spiderweb

Image of the Spiderweb Galaxy Field
Spiderweb Galaxy Field
Credit: X-ray: NASA/CXC/INAF/P. Tozzi et al; Optical (Subaru): NAOJ/NINS; Optical (HST): NASA/STScI

Often, a spiderweb conjures the idea of captured prey soon to be consumed by a waiting predator. In the case of the "Spiderweb" protocluster, however, objects that lie within a giant cosmic web are feasting and growing, according to data from NASA's Chandra X-ray Observatory.

The Spiderweb galaxy, officially known as J1140-2629, gets its nickname from its web-like appearance in some optical light images. This likeness can be seen in the inset box where data from NASA's Hubble Space Telescope shows galaxies in orange, white, and blue, and data from Chandra is in purple. Located about 10.6 billion light years from Earth, the Spiderweb galaxy is at the center of a protocluster, a growing collection of galaxies and gas that will eventually evolve into a galaxy cluster.

"Mini" Monster Black Hole Could Hold Clues to Giant's Growth

Image of mrk462
Mrk 462
Credit: X-ray: NASA/CXC/Dartmouth Coll./J. Parker & R. Hickox; Optical/IR: Pan-STARRS

The graphic shows X-rays that NASA's Chandra X-ray Observatory detected from the dwarf galaxy Mrk 462. This X-ray emission (inset) is important because it reveals the presence of a growing supermassive black hole within this relatively small galaxy, as described in our latest press release. The mass contained in this black hole — about 200,000 times the mass of the Sun — provides information to astronomers about how some of the earliest black holes in the Universe may have formed and grown billions of years ago.

The background panel is an optical image from the Pan-STARRS telescope in Hawaii. There are several galaxies that are part of the HCG068 galaxy group on the left-hand side of the image. The galaxy that is emitting copious amounts of X-rays, however, is the much smaller galaxy located to the lower right of the image (marked by the arrow). Mrk 462 is a dwarf galaxy because it contains only a few hundred million stars, which means it holds about a hundred times fewer stars than a galaxy like the Milky Way. Black holes are notoriously hard to find in dwarf galaxies because they are usually too small and dim for optical light telescopes to track the rapid motions of stars in the centers.

Astronomers Spy Quartet of Cavities From Giant Black Holes

Optical & X-ray Images of  RBS 797, side-by-side
Galaxy Cluster RBS 797
Credit: X-ray: NASA/CXC/Univ. of Bologna/F. Ubertosi; Optical: NASA/STScl/M.Calzadilla

Four enormous cavities, or bubbles, have been found at the center of a galaxy cluster using NASA's Chandra X-ray Observatory, as described in our latest press release. The left panel of this graphic shows an optical image of the galaxy cluster called RBS 797, from NASA's Hubble Space Telescope. Hot gas that envelopes the individual galaxies is invisible in optical light, but it is detected in X-rays by Chandra (right). One pair of cavities can be seen towards the left and right of center in the Chandra image as black oval-shaped regions. The other pair is less distinct, but can be found above and below the center of the image.

"X-ray Magnifying Glass" Enhances View of Distant Black Holes

X-ray image and illustration of MG B2016+112
Gravitationally-Lensed System MG B2016+112
Credit: Illustration: NASA/CXC/M. Weiss; X-ray (inset): NASA/CXC/SAO/D. Schwartz et al.

A new technique using NASA's Chandra X-ray Observatory has allowed astronomers to obtain an unprecedented look at a black hole system in the early Universe, as reported in our latest press release. This is providing a way for astronomers to look at faint and distant X-ray objects in more detail than had previously been possible.

Astronomers used an alignment in space that shows "gravitational lensing" of light from two objects that are nearly 12 billion light years away. An artist's illustration in the main part of this graphic shows how the paths of light from these distant objects are bent and amplified by a galaxy along the line of sight between Earth and the objects.

Huge Rings Around a Black Hole

Image of V404 Cygni
V404 Cygni
Credit: X-ray: NASA/CXC/U.Wisc-Madison/S. Heinz et al.; Optical/IR: Pan-STARRS

This image features a spectacular set of rings around a black hole, captured using NASA's Chandra X-ray Observatory and Neil Gehrels Swift Observatory. The X-ray images of the giant rings reveal information about dust located in our galaxy, using a similar principle to the X-rays performed in doctor's offices and airports.

The black hole is part of a binary system called V404 Cygni, located about 7,800 light years away from Earth. The black hole is actively pulling material away from a companion star — with about half the mass of the Sun — into a disk around the invisible object. This material glows in X-rays, so astronomers refer to these systems as "X-ray binaries."

Telescopes Unite in Unprecedented Observations of Famous Black Hole


More Information
Video compilation: NASA/GSFC/SVS/M.Subbarao & NASA/CXC/SAO/A.Jubett


In April 2019, scientists released the first image of a black hole in the galaxy M87 using the Event Horizon Telescope (EHT). This supermassive black hole weighs 6.5 billion times the mass of the sun and is located at the center of M87, about 55 million light-years from Earth.

The supermassive black hole is powering jets of particles that travel at almost the speed of light, as described in our latest press release. These jets produce light spanning the entire electromagnetic spectrum, from radio waves to visible light to gamma rays.

To gain crucial insight into the black hole's properties and help interpret the EHT image, scientists coordinated observations with 19 of the world's most powerful telescopes on the ground and in space, collecting light from across the spectrum. This is the largest simultaneous observing campaign ever undertaken on a supermassive black hole with jets.

M87 in Multiple Wavelengths
M87 in Multiple Wavelengths

The NASA telescopes involved in this observing campaign included the Chandra X-ray Observatory, Hubble Space Telescope, Neil Gehrels Swift Observatory, the Nuclear Spectroscopic Telescope Array (NuSTAR), and the Fermi Gamma-ray Space Telescope.

From NASA’s Jet Propulsion Laboratory to the Universe's Earliest Jet propulsion Laboratory

Thomas Connor with Mars Rover in background in a large, white room
Thomas Connor

We are happy to welcome Thomas Connor as a guest blogger today. Thomas is a NASA Postdoctoral Fellow at NASA Jet Propulsion Laboratory (JPL) in Pasadena, California and the author of a paper that is the subject of our most recent press release. He completed his undergraduate degree at Case Western Reserve University and earned his doctorate from Michigan State University. Prior to starting at JPL, Dr. Connor was a postdoctoral fellow at the Observatories of the Carnegie Institution for Science. His scientific interests include black holes in the dawn of the Universe, the evolution of galaxies in dense environments, and the structure of the Cosmic Web.

Most of the fundamental questions of astronomy relate to how the universe as we observe it was assembled. From stars and planets to nebulae and galaxies, many of the investigations of astronomy come down to crafting a coherent narrative of formation and evolution. Currently, that narrative is struggling to be built in the early universe, where supermassive black holes with masses a billion times that of the Sun are seen only a few hundred million years after the Big Bang. The challenge here is that, while we can model ways for such massive objects to form and grow, compressing that growth into such a short time scale is much more difficult. As an analogy, it is not surprising that an author can write a novel, but it would be astounding if she could do so in only one day.

Black holes grow by eating their surroundings, but, contrary to the typical depiction of these objects, they do not suck. Rather, they slowly nibble their way through an "accretion disk," an orbiting disk of gas that acts as a buffet for the black hole. As more gas makes its way inward, this disk will get hot from all of the friction of particles rubbing together, and it will start glowing like a hot coal. This bright light will act like a strong wind, pushing away further gas from replenishing the disk. Thus, the black hole's feeding is self-limiting — if it eats too fast, it won't be able to restock the buffet, and so it will have to slow down. This fundamental limit is why we are puzzled at how such massive black holes can exist so early.

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