Extraordinary Black Hole

A Different Kind of Black Hole


Astronomers discovered a black hole unlike any other. At one hundred thousand solar masses, it is smaller than the black holes we have found at the centers of galaxies but bigger than the black holes that are born when stars explode. This makes it one of the only confirmed intermediate-mass black holes, an object that has long been sought by astronomers.

Anil Seth

“We have very good detections of the biggest, stellar-mass black holes up to 100 times the size of our sun, and supermassive black holes at the centers of galaxies that are millions of times the size of our sun, but there aren’t any measurements of black between these. That’s a large gap,” said senior author Anil Seth, associate professor of astronomy at the University of Utah and co-author of the study. “This discovery fills the gap.”

The black hole was hidden within B023-G078, an enormous star cluster in our closest neighboring galaxy Andromeda. Long thought to be a globular star cluster, the researchers argue that B023-G078 is instead a stripped nucleus. Stripped nuclei are remnants of small galaxies that fell into bigger ones and had their outer stars stripped away by gravitational forces. What’s left behind is a tiny, dense nucleus orbiting the bigger galaxy and at the center of that nucleus, a black hole.

“Previously, we’ve found big black holes within massive, stripped nuclei that are much bigger than B023-G078. We knew that there must be smaller black holes in lower mass stripped nuclei, but there’s never been direct evidence,” said lead author Renuka Pechetti of Liverpool John Moores University, who started the research while at the U. “I think this is a pretty clear case that we have finally found one of these objects.”

The study published on Jan. 11, 2022, in The Astrophysical Journal.

A decades-long hunch

B023-G078 was known as a massive globular star cluster—a spherical collection of stars bound tightly by gravity. However, there had only been a single observation of the object that determined its overall mass, about 6.2 million solar masses. For years, Seth had a feeling it was something else.

“I knew that the B023-G078 object was one of the most massive objects in Andromeda and thought it could be a candidate for a stripped nucleus. But we needed data to prove it. We’d been applying to various telescopes to get more observations for many, many years and my proposals always failed,” said Seth. “When we discovered a supermassive black hole within a stripped nucleus in 2014, the Gemini Observatory gave us the chance to explore the idea.”

A wide-field image of M31 with the red box and inset showing the location and image of B023-G78 where the black hole was found.

With their new observational data from the Gemini Observatory and images from the Hubble Space Telescope, Pechetti, Seth and their team calculated how mass was distributed within the object by modeling its light profile. A globular cluster has a signature light profile that has the same shape near the center as it does in the outer regions. B023-G078 is different. The light at the center is round and then gets flatter moving outwards. The chemical makeup of the stars changes too, with more heavy elements in the stars at the center than those near the object’s edge.

“Globular star clusters basically form at the same time. In contrast, these stripped nuclei can have repeated formation episodes, where gas falls into the center of the galaxy, and forms stars. And other star clusters can get dragged into the center by the gravitational forces of the galaxy,” said Seth. “It’s kind of the dumping ground for a bunch of different stuff. So, stars in stripped nuclei will be more complicated than in globular clusters. And that’s what we saw in B023-G078.”

The researchers used the object’s mass distribution to predict how fast the stars should be moving at any given location within the cluster and compared it to their data. The highest velocity stars were orbiting around the center. When they built a model without including a black hole, the stars at the center were too slow compared their observations. When they added the black hole, they got speeds that matched the data. The black hole adds to the evidence that this object is a stripped nucleus.

“The stellar velocities we are getting gives us direct evidence that there’s some kind of dark mass right at the center,” said Pechetti. “It’s very hard for globular clusters to form big black holes. But if it’s in a stripped nucleus, then there must already be a black hole present, left as a remnant from the smaller galaxy that fell into the bigger one.”

The researchers are hoping to observe more stripped nuclei that may hold more intermediate-mass black holes. These are an opportunity to learn more about the black hole population at the centers of low-mass galaxies, and to learn about how galaxies are built up from smaller building blocks.

“We know big galaxies form generally from the merging of smaller galaxies, but these stripped nuclei allow us to decipher the details of those past interactions,” said Seth.

Other authors include Sebastian Kamann of the Liverpool John Moores University; Nelson Caldwell, Harvard-Smithsonian Center for Astrophysics; Jay Strader, Michigan State University; Mark den Brok, Leibniz-Institut für Astrophysik Potsdam; Nora Luetzgendorf, European Space Agency; Nadine Neumayer, Max Planck Institüt für Astronomie; and Karina Voggel, Observatoire astronomique de Strasbourg.

- by Lisa Potter, published in @theU and the Deseret News

 

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James Webb Space Telescope

James Webb Space Telescope


In December 2020 the James Webb Space Telescope (JWST) finally launched. The $10 billion observatory is a twenty-year joint effort of NASA, the European Space Agency, and the Canadian Space Agency, and the most powerful telescope ever developed. Its mission—peer 13.5 billion lightyears back in time to the earliest stages of the universe.

Anil Seth

JWST’s launch date was December 25 from Europe’s Spaceport in Kourou, French Guiana. Longtime fans of the telescope are celebrating it as a Christmas miracle. It was the first planned to launch in 2007, but decades of delays and false hope drove the project from its initial budget of $500 million up to its current $10 billion cost.

You can watch recorded launch video and future NASA livestreams at  https://www.nasa.gov/nasalive.

The stakes are high for Anil Seth, associate professor in the Department of Physics & Astronomy. Out of more than 1,000 proposals for observation time on the telescope, Seth’s is one of 266 that were approved. He spoke with AtTheU to talk about this cosmic milestone.

What is the James Webb Space Telescope?

It is the largest and most powerful telescope that we’ve ever sent into space—the primary mirror is about the size of a typical house. It’s really big compared to the Hubble Space Telescope, which has a primary mirror the size of a bedroom. Hubble uses the ultraviolet and visible light to create jaw-dropping images of deep space that fundamentally changed our understanding of the cosmos. JWST will be much, much, much farther away than Hubble, located almost one million miles from Earth. From there, it can detect the faintest traces of infrared light, the wavelength of light emitted by everything that produces heat.

NASA assembly, July 2017

The telescope’s primary power is to detect faint galaxies far, far away. It’ll be able to pick up the infrared light spectrum of planets, newly forming stars, black holes, and other faint objects in ways that we’ve never been able to before. Almost every astronomer is probably going to want to use JWST for something. We saw so much using the Hubble Space Telescope. With JWST, we’ll be able to see more than we can imagine. It’s very exciting.

The launch date has been pushed back several times including once this week. Is the telescope launch tricker then usual?

The size makes it really hard to launch. The telescope has three big segments—a sunshield the size of a tennis court, the house-sized primary mirror, and the secondary mirror, Right now, it’s all packaged up like a Christmas present to fit inside the rocket. After launch, the segments will begin to unfold. It’s a complicated process involving hundreds of steps that have to work perfectly. This has never been done before—one error and the whole project could fail. That’s why people are so stressed out!

Where will JWST orbit in space?

It’s going to orbit the sun almost one million miles away from Earth. It will live at what is called a Lagrange point, a location where gravity from the earth and sun are equal. And will just sit there, orbiting with the Earth around the sun. This ensures that the telescope will always point away from the sun.

Full-scale model, September 2005

Anything warm emits infrared light—stars, humans, every other thing on Earth. To make an infrared-detecting telescope, the equipment needs to be extremely cold, so its heat doesn’t interfere with infrared readings from space. That’s what the sun shield is for. The massive mylar sail will create a shadow that prevents the telescope from absorbing heat. The sunshade will begin to unfurl a week after launch, starting with 107 release mechanisms that have to fire simultaneously. The sun shield will then always be between the telescope and sun, keeping the telescope really cold. If this doesn’t happen right…it’ll be bad.

JWST’s location also provides a wide-open view for observations. The Hubble space telescope orbits the Earth just over 300 miles up, which means the planet sometimes blocks the telescope’s vision as it orbits the earth every 90 minutes. At JWST’s Lagrange position, it’s much easier to keep a single orientation in the sky for a longer time and to make observations constantly. So we’ll end up getting more data each year from JWST than from Hubble.

You will be one of the first astronomers to get observation time on the JWST. Can you tell us about your research?

I study black holes. Every black hole has stuff falling onto it that emits light. It turns out that a lot of that light gets emitted at infrared wavelengths. This telescope is much, much, more sensitive to those wavelengths than any other previous telescope. The problem is that we’ve never seen what a faint black hole looks like at these wavelengths.

The Andromeda Galaxy, approximately 2.5 million light-years from Earth.

I’m leading a project that will look at places where we know black holes exist, because we’ve measured them from the motions of the stars around them, but that are very faint. These are so much fainter than something like a quasar, which is where the black hole is devouring as much material as it can. The black holes I’m interested in are just sipping their material, and they’re much more typical of the average black hole in the universe. We’re basically looking unique signatures in this wavelength spectrum that will tip us off to a black hole is present. One of the objects we’ll focus on is the first one ever photographed.

- by Lisa Potter, first published at @theU

 

NASA J.W.S.T. VIDEO


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Hedgehogs and Undergrads

Hedgehogs and Undergrads


The students’ fresh, undaunted determination to scientific inquiry, combined with a lack of preconceived notions and a willingness to learn, were key factors that enabled their groundbreaking discoveries.

Corvin Arveseth, BS’21, can’t remember when he wasn’t fascinated by science and biology. So, when he came to the University of Utah and declared his majors in biology and biochemistry, he knew he wanted hands-on experience in research. “I didn’t know anything [about the] Hedgehog (Hh) signaling [pathway] until I read an advertisement put out by Ben Myers in a biology department newsletter looking for undergraduate researchers,” he says. “After reading some background information and meeting with Ben about the Hh pathway, I became intrigued with the work being done in his lab.”

The Hh pathway he’s referring to is akin to a master set of instructions for animal development and regeneration. It controls the formation of nearly every organ in the human body. Signaling pathway like Hh serve as a molecular “telephone wire” from the cell surface to the nucleus. When cells in our bodies communicate with one another, signals are relayed along these molecular telephone wires, turning on expression of genes involved in growth, differentiation, or in some cases skin and brain cancers.

The Hh pathway got its unusual name from decades-old genetic studies in fruit flies, where mutations in critical developmental genes led the flies to take on a bristly hedgehog-like appearance. However, versions of the Hh pathway operate throughout the animal kingdom, controlling development, stem cell biology, and cancer in many different contexts.

But even after many years of effort by labs all over the world, surprisingly little was known about how the Hh pathway actually works at a molecular level. Scientists knew that the signals conveyed by these molecular telephone wires were fundamental to human development and disease, but they didn’t know what the signals were, or how they were transmitted intracellularly. Consequently, health researchers’ ability to control Hh signaling in many diseases including cancer had been limited.

So, this is a story not just about a seemingly intractable research question, which is de rigeur in scientific circles, but how a team of largely undergraduate students in a four-year-old lab worked together under enormous odds to shake loose that answer. Myers says that that it was because of inexperience, not in spite of it, that the undergraduates in his lab were able to make these discoveries. These students’ fresh, undaunted determination to scientific inquiry, combined with a lack of preconceived notions and a willingness to learn, were key factors that enabled their groundbreaking discoveries.

Two papers, both with U undergraduates as first or co-first authors, were the gratifying result.

Mysterious pathways

When Myers first set up his lab at the U in 2018, the key molecule in the Hh pathway that grabbed his attention was SMOOTHENED (SMO), a so-called “transmembrane protein” that spans across the cell membrane from the outside to the interior. SMO was known to be critical for transmitting signals from the cell surface to the nucleus. But what were the five or six steps between receiving the message and turning on gene expression? There was a “major disconnection about how this worked,” says Myers.

The twenty-five-year-old mystery was indeed tantalizing. It was “this interesting mystery coupled with the importance of Hh function,” says Aveseth, “in developmental and cancer biology [which] hooked me right away,”

Spearheading the project

Arveseth was the point of the spear for this project begun at the beginning of his sophomore year. But there were many others on the team, all of whom are “both incredibly smart, and also very kind and a lot of fun to work with,” according to Myers. This includes Nate Iverson, a third year chemistry major with an interest in cellular signaling. “Having HCI in close connection with the University gave me greater access to research possibilities, and I was able to find an opening in the Myers lab studying Hedgehog signal transduction.”

And then there was biology major Isaac Nelson, who worked tirelessly to produce a freezer full of carefully prepared, purified fragments of SMO for biochemical studies, only to hit a brick wall when he and Myers were unable to formulate a good hypothesis to drive an experiment. “It was only after starting up an international collaboration,” says Myers, “that the critical experiments snapped into view for us.” This led Nelson to send his samples to one of the lab’s new collaborators in Germany, and they used his samples to try an experiment that worked right away. In the midst of a raging pandemic, Nelson’s purified proteins helped to launch a new and entirely unexpected phase of the project, expanding the collaboration to include other scientists around the world.

“It was another scenario,” says Myers, “where everyone worked well together.”

Recent graduate Madison “Madi” Walker, BS’21, with a cell and molecular emphasis, was also part of the team. She is still working in the Myers lab studying another critical aspect of SMO signaling, namely the interaction between SMO and the enzyme G protein-coupled receptor kinase 2. Earlier, former undergraduate Jacob Capener, BS’20, assisted in the work.

Another critical member of the Myers lab team is Will Steiner, BS’21, who is currently collaborating with Arveseth and Nelson to purify SMO in complex with its binding partners in order to work out their atomic structures. He became interested in this area of research after taking the cell biology and biochemistry course at the U. “Biochemistry was particularly compelling and got me excited about the chemical reactions behind human physiology,” he says.

It starts in the classroom

Rigorous courses were critical in preparing Myers’ undergraduate team for the hands-on research that led to their remarkable findings in the lab. He has nothing but kudos for the U’s curriculum. “Coursework before the lab experience [for undergraduate researchers] was very, very good here. In general, I’ve been lucky to attract motivated and curious students to my lab. They are inspired to push the research forward. They are all up to the challenge. And they have a great esprit de corps. They all work incredibly well together as a team to drive the science forward.”

That kind of correlated teamwork was not necessarily easy to enact under the circumstances. “Fortunately, we were able to finish the last key experiment of the first paper,” says Myers, in March 2020, just before the pandemic started to take hold and shut lab work down. He’s always believed that having undergraduates get a taste of cutting-edge research is important. They “shouldn’t have to work on something trivial… . What’s exciting about science is to push the boundaries.”

And yes, for Myers and the other senior members of his lab, including graduate students Danielle Hedeen and Aram Centeno, lab manager Ju-Fen Zhu, and former lab technician John Happ, “you have to be committed to helping everybody in your lab, even if they’re neophytes.” Clearly it’s been worth it. “And being a little bit of a neophyte is good,” he says, “because you don’t talk yourself out of doing experiments that are simple, unorthodox.”

Asking the right questions

What Myers is trying to say, and seems to have proven over the course of the past three years and now the publication of two discovery-laden papers, is that their remarkable findings stemmed from the initial naïve view that the SMO protein didn’t fit the mold of other proteins as was previously assumed. He and Arveseth took a guess that SMO might be directly coupled to a critical intracellular signaling molecule called PKA. This was a rather wild idea, since there were few if any examples of transmembrane proteins that directly interacted with PKA. “It was a guess, how it might work, and a couple of months later: big discovery. Our initial guess was on the right track. There was a whole new unexpected thing going on but that made sense.”

Though early on the team suspected what they had discovered was important, “we didn’t know if we had a full explanation of how the system worked. We weren’t sure if it was the main event or an auxiliary event.” In the first paper, published in the journal PLOS Biology last year, they explained that: what they thought they knew, and what they weren’t sure about . . . yet.

But it was only after the pandemic was in full force that the team pivoted to the second exciting phase of the project, expanding to include Susan Taylor’s lab at the University of California, San Diego, one of the world’s foremost authorities on the PKA molecule the Myers team had implicated in their research.

Taylor and her colleagues had a critical insight regarding the SMO-PKA interaction which eventually formed the basis of a second manuscript, currently in press in the journal Nature Structural and Molecular Biology. “It is a truly remarkable and inspiring collaboration that continues to this day, and I am so proud of how everybody was able to join forces and overcome so many obstacles created by the COVID-19 pandemic,” says Myers. And his team is anticipating that even more exciting discoveries are on the horizon. Eventually, this work may lead to better drugs to treat some of the diseases that result from aberrant Hh signaling, including various skin and brain cancers.

In all, with the resulting two papers, the project turned out to be a “best case scenario that wasn’t planned,” and a lesson of how important it is to keep an open mind, which often leads to big discoveries. Concludes Myers, “To be honest, it comes down to the willingness to try new things and to have the ability to work together as a team. In reality, this would have been way too much for any individual scientist, even a highly trained one, to do alone.”

Success is never final, however. And Arveseth, recipient of no less than ten scholarships and awards during his sojourn at the U, is now on his way to Washington University in St. Louis. There he will begin an MD/PhD program as a physician-scientist this fall. There he will focus on hematology and oncology. His colleagues are also pursuing their academic and research careers full-steam ahead. They, along with their mentor, Ben Myers are a testament to the notion that persistence in knowledge gathering pays off but that it must be paired and even driven by a relentlessly open mind.

- by David Pace, first published @ biology.utah.edu

 

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