Work by 91亚色 astronomer and research colleagues in U.S. may provide clues into development of surrounding galaxies

TORONTO, June 11 2024 - Clouds of gas in a distant galaxy are being pushed faster and faster out among neighbouring stars by blasts of radiation from the supermassive black hole at the galaxy鈥檚 centre, a discovery that helps illuminate the way active black holes can continuously shape their galaxies by spurring on or snuffing out the development of new stars.

A team of researchers, including 91亚色 Faculty of Science Professor and Physics and Astronomy Chair , revealed the accelerating gas through years of observations of a quasar 鈥� a black hole surrounded by a hot and bright disk of matter 鈥� some 30 billion light years away in the constellation Bo枚tes.

Hall says that while this quasar acceleration has been seen before, including by researchers involved in this study, the level of detail here is unprecedented.

鈥淲e were able to make 130 observations over the course of eight years, so our confidence in this acceleration is quite high,鈥� says Hall. 鈥淭he difference in information could be compared to looking at two photographs at different points in time versus a movie.鈥�

Black holes are believed to be situated at the centre of most galaxies. Quasars are supermassive black holes surrounded by disks of matter being pulled in by the black hole鈥檚 enormous gravitational power.

The research was led by University of Wisconsin鈥揗adison astronomy professor Catherine Grier and recent graduate Robert Wheatley, and also included researchers from Pennsylvania State University, the University of Arizona, and others. and the findings are also being presented today at the 244th meeting of the American Astronomical Society.

鈥淭he material in that disk is always falling into the black hole, and the friction it feels heats up the disk and makes it very, very hot and very, very bright,鈥� says Grier. 鈥淭hese quasars are really luminous and 鈥� because there鈥檚 a large range of temperatures from the interior to the far parts of the disk 鈥� their emission covers almost all of the electromagnetic spectrum.鈥�

The bright light makes visible quasars nearly as old as the universe (and as many as 13 billion light years away when their light was emitted), and the broad range of their radiation makes them particularly useful for astronomers to probe the early universe.

Researchers used more than eight years of observations of a quasar called SBS 1408+544, collected by a quasar monitoring program carried out by the now known as the Black Hole Mapper Reverberation Mapping Project. They tracked winds composed of gaseous carbon by spotting light from the quasar that was missing 鈥� light that was being absorbed by the gas. But instead of being absorbed at exactly the right spot in the spectrum that would indicate carbon, the shadow shifted farther from home with every new look.

鈥淭hat shift tells us the gas is moving fast, and faster all the time,鈥� says Wheatley. 鈥淲e think the wind is accelerating because it鈥檚 being pushed by radiation that is blasted off of the accretion disk.鈥�

The winds pushing gas out from the quasar are of interest to astronomers because they are a way in which the supermassive black holes might influence the evolution of the galaxies that surround them.

Depending on the circumstances, a quasar鈥檚 winds could supply pressure that squeezes gas together and speeds the birth of stars in its host galaxy. Or it could scour away that fuel and keep potential stars from forming.

To study quasars, astronomers look at their spectra, which is a measure of how much light the quasar gives off at each wavelength 鈥� from ultraviolet through the full visible spectrum from blue to red, and into infrared. A spectrum can reveal far more about a quasar than a simple telescope image 鈥� so by repeatedly measuring spectra over many years, astronomers can watch quasar light fluctuations and learn about the motion of the gas in the accretion disk, which can be used to determine the mass.

鈥淟ight has a force, so if you shine enough light on an object it can move,鈥� says Hall. 鈥淲e think that may be what's going on here, but it's not clear because I don't think we see enough of an increase in light to explain the acceleration we see. It's possible that wavelengths of ultraviolet light that we can鈥檛 observe directly are responsible, but right now it鈥檚 not clear. I look forward to seeing what this quasar does in the future.鈥�

About 91亚色

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TORONTO, Nov. 2, 2020 鈥� The Sloan Digital Sky Survey鈥檚 (SDSS) fifth generation collected its very first observations of the cosmos at 1:47 a.m. on Oct. 24. As the world's first all-sky time-domain spectroscopic survey, SDSS-V will provide groundbreaking insight into the formation and evolution of galaxies 鈥� like our own Milky Way 鈥� and the supermassive black holes that lurk at their centers.

The SDSS, an international consortium that includes 91亚色 as an associate member, just-launched a fifth generation survey to continue the path-breaking tradition set by previous surveys with a focus on the ever-changing night sky and the physical processes that drive these changes, from flickers and flares of supermassive black holes to the back-and-forth shifts of stars being orbited by distant worlds.聽SDSS-V will provide the spectroscopic backbone needed to achieve the full science potential of聽satellites like NASA鈥檚 TESS, ESA鈥檚 Gaia, and the latest all-sky X-ray mission, eROSITA.

"My colleagues and I on the Black Hole Mapper team seek to understand how the matter swirling around supermassive black holes is organized,鈥� says 91亚色 Professor of the Faculty of Science who is part of the SDSS-V team. 鈥淭hese black holes can have dramatic effects on their surrounding galaxies, so they are part of the puzzle of understanding how our current Universe of galaxies came to be."

The SDSS has always relied heavily on phone and digital communication. But adapting to exclusively virtual communication tactics was a challenge, as was tracking global supply chains and laboratory availability at various university partners while they shifted in and out of lockdown during the final ramp-up to the survey鈥檚 start. Particularly inspiring were the project's expert observing staff, who worked in even-greater-than-usual isolation to shut down, and then reopen, the survey's mountain-top observatories.

鈥淚n a year when humanity has been challenged across the globe, I am so proud of the worldwide SDSS team for demonstrating鈥攅very day鈥攖he very best of human creativity, ingenuity, improvisation, and resilience. It has been a challenging period for the team, but I鈥檓 happy to say that the pandemic may have slowed us, but it has not stopped us,鈥� says SDSS-V Director, Juna Kollmeier.

The Sloan Digital Sky Survey鈥檚 fifth generation made its first observations earlier this month. This image shows a sampling of data from those first SDSS-V data. The central sky image is a single field of SDSS-V observations. The purple circle indicates the telescope鈥檚 field-of-view on the sky, with the full Moon shown as a size comparison. SDSS-V simultaneously observes 500 targets at a time within a circle of this size. The left panel shows the optical-light spectrum of a quasar--a supermassive black hole at the center of a distant galaxy, which is surrounded by a disk of hot, glowing gas. The purple blob is an SDSS image of the light from this disk, which in this dataset spans about 1 arcsecond on the sky, or the width of a human hair as seen from about 21 meters (63 feet) away. The right panel shows the image and spectrum of a white dwarf --the left-behind core of a low-mass star (like the Sun) after the end of its life. Image Credit: Hector Ibarra Medel, Jon Trump, Yue Shen, Gail Zasowski, and the SDSS-V Collaboration. Central background image: unWISE / NASA/JPL-Caltech / D.Lang (Perimeter Institute).

Funded primarily by member institutions, along with grants from the Alfred P. Sloan Foundation, the U.S. National Science Foundation, and the Heising-Simons Foundation, SDSS-V will focus on three primary areas of investigation, each exploring different aspects of the cosmos using different spectroscopic tools. Together these three project pillars 鈥� called 鈥淢appers鈥� 鈥� will observe more than six million objects in the sky, and monitor changes in more than a million of those objects over time.

The survey鈥檚 Local Volume Mapper will enhance our understanding of galaxy formation and evolution by probing the interactions between the stars that make up galaxies and the interstellar gas and dust that is dispersed between them. The Milky Way Mapper will reveal the physics of stars in our Milky Way, the diverse architectures of its star and planetary systems, and the chemical enrichment of our galaxy since the early universe. The Black Hole Mapper will measure masses and growth over cosmic time of the supermassive black holes that reside in the hearts of galaxies as well as the smaller black holes left behind when stars die.

"I've been affiliated with the SDSS since 2000 and my career of studying supermassive black holes began with SDSS data,鈥� says Hall. 鈥淣ow that 91亚色 has secured a full membership for my research group, undergraduate and graduate students at 91亚色 can join me in studying SDSS observations as soon as they arrive from the telescope."

The Black Hole Mapper was one of the first of the three Mappers to gather data.

鈥淭hese early observations are already important for a wide range of science goals,鈥� says SDSS-V Spokesperson Gail Zasowski of the University of Utah. 鈥淓ven these first targets cover goals from mapping the inner regions of supermassive black holes and searching for exotic multiple-black hole systems, to studying nearby stars and their dead cores, to tracing the chemistry of potential planet-hosting stars across the Milky Way.鈥�

SDSS-V will operate out of both Apache Point Observatory in New Mexico, home of the survey鈥檚 original 2.5-meter telescope, and Carnegie鈥檚 Las Campanas Observatory in Chile, where it uses the 2.5-meter du Pont telescope.

SDSS-V's first observations were gathered in New Mexico with existing SDSS instruments, as a necessary change of plans due to the pandemic. As laboratories and workshops around the world navigate safe reopening, SDSS-V's own suite of new innovative hardware is on the horizon---in particular, systems of automated robots to aim the fiber optic cables used to collect the light from the night sky. These will be installed at both observatories over the next year. New spectrographs and telescopes are also being constructed to enable the Local Volume Mapper observations.

"I was only a few years out of graduate school when I began work with the SDSS," says Hall. "Now I'm Chair of the Department of Physics and Astronomy, but I'm just as excited about this survey as I was 20 years ago. I look forward to many more years of learning about our Galaxy and the Universe with the Sloan Digital Sky Survey!"

For more information, see the SDSS-V鈥檚 website at .

(Image can be downloaded here: )

Caption: The Sloan Digital Sky Survey鈥檚 fifth generation made its first observations earlier this month. This image shows a sampling of data from those first SDSS-V data. The central sky image is a single field of SDSS-V observations. The purple circle indicates the telescope鈥檚 field-of-view on the sky, with the full Moon shown as a size comparison. SDSS-V simultaneously observes 500 targets at a time within a circle of this size. The left panel shows the optical-light spectrum of a quasar--a supermassive black hole at the center of a distant galaxy, which is surrounded by a disk of hot, glowing gas. The purple blob is an SDSS image of the light from this disk, which in this dataset spans about 1 arcsecond on the sky, or the width of a human hair as seen from about 21 meters (63 feet) away. The right panel shows the image and spectrum of a white dwarf --the left-behind core of a low-mass star (like the Sun) after the end of its life. Image Credit: Hector Ibarra Medel, Jon Trump, Yue Shen, Gail Zasowski, and the SDSS-V Collaboration. Central background image: unWISE / NASA/JPL-Caltech / D.Lang (Perimeter Institute).

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