From University of Arizona (US) : “This is What it Looks Like When a Black Hole Snacks on a Star” 

From University of Arizona (US)

9.16.21

Media contact
Daniel Stolte
Science Writer, University Communications
stolte@arizona.edu
520-626-4402

Researcher contact
Ann Zabludoff
Steward Observatory
aiz@arizona.edu

Analyzing observations of an X-ray flare and fitting the data with theoretical models, UArizona astronomers documented a fatal encounter between an unlucky star and an intermediate-mass black hole.

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This illustration shows a glowing stream of material from a star, torn to shreds as it was being devoured by a supermassive black hole. The feeding black hole is surrounded by a ring of dust, not unlike the plate of a toddler is surrounded by crumbs after a meal. Credit: NASA/JPL-Caltech (US).

While black holes and toddlers don’t seem to have much in common, they are remarkably similar in one aspect: Both are messy eaters, generating ample evidence that a meal has taken place.

But whereas one might leave behind droppings of pasta or splatters of yogurt, the other creates an aftermath of mind-boggling proportions. When a black hole gobbles up a star, it produces what astronomers call a “tidal disruption event.” The shredding of the hapless star is accompanied by an outburst of radiation that can outshine the combined light of every star in the black hole’s host galaxy for months, even years.

In a paper published in The Astrophysical Journal, a team of astronomers led by Sixiang Wen, a postdoctoral research associate at the University of Arizona Steward Observatory, use the X-rays emitted by a tidal disruption event known as J2150 to make the first measurements of both the black hole’s mass and spin.

This black hole is of a particular type – an intermediate-mass black hole – which has long eluded observation.

“The fact that we were able to catch this black hole while it was devouring a star offers a remarkable opportunity to observe what otherwise would be invisible,” said Ann Zabludoff, UArizona professor of astronomy and co-author on the paper. “Not only that, by analyzing the flare we were able to better understand this elusive category of black holes, which may well account for the majority of black holes in the centers of galaxies.”

By re-analyzing the X-ray data used to observe the J2150 flare, and comparing it with sophisticated theoretical models, the authors showed that this flare did indeed originate from an encounter between an unlucky star and an intermediate-mass black hole. The intermediate black hole in question is of particularly low mass – for a black hole, that is – weighing in at roughly 10,000 times the mass of the sun.

“The X-ray emissions from the inner disk formed by the debris of the dead star made it possible for us to infer the mass and spin of this black hole and classify it as an intermediate black hole,” Wen said.

Dozens of tidal disruption events have been seen in the centers of large galaxies hosting supermassive black holes, and a handful have also been observed in the centers of small galaxies that might contain intermediate black holes. However, past data has never been detailed enough to prove that an individual tidal disruption flare was powered by an intermediate black hole.

“Thanks to modern astronomical observations, we know that the centers of almost all galaxies that are similar to or larger in size than our Milky Way host central supermassive black holes,” said study co-author Nicholas Stone, a senior lecturer at Hebrew University in Jerusalem (IL). “These behemoths range in size from 1 million to 10 billion times the mass of our sun, and they become powerful sources of electromagnetic radiation when too much interstellar gas falls into their vicinity.”

The mass of these black holes correlates closely with the total mass of their host galaxies; the largest galaxies host the largest supermassive black holes.

“We still know very little about the existence of black holes in the centers of galaxies smaller than the Milky Way,” said co-author Peter Jonker of Radboud University Nijmegen [Radboud Universiteit](NL) and Netherlands Institute for Space Research [Nederlands Instituut voor Ruimteonderzoek](SRON)(NL), both in the Netherlands. “Due to observational limitations, it is challenging to discover central black holes much smaller than 1 million solar masses.”

Despite their presumed abundance, the origins of supermassive black holes remain unknown, and many different theories currently vie to explain them, according to Jonker. Intermediate-mass black holes could be the seeds from which supermassive black holes grow.

“Therefore, if we get a better handle of how many bona fide intermediate black holes are out there, it can help determine which theories of supermassive black hole formation are correct,” he said.

Even more exciting, according to Zabludoff, is the measurement of J2150’s spin that the group was able to obtain. The spin measurement holds clues as to how black holes grow, and possibly to particle physics.

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When a star ventures too close to a black hole, gravitational forces create intense tides that break the star apart into a stream of gas, resulting in a cataclysmic phenomenon known as a tidal disruption event. Tremendous amounts of energy are released, causing a tidal disruption to outshine its galaxy in some cases. Credit: Chris Smith (Universities Space Research Association (US)/Goddard Earth Science Technology and Research/ NASA’s Goddard Space Flight Center.

This black hole has a fast spin, but not the fastest possible spin, Zabludoff explained, begging the question of how the black hole ends up with a spin in this range.

“It’s possible that the black hole formed that way and hasn’t changed much since, or that two intermediate-mass black holes merged recently to form this one,” she said. “We do know that the spin we measured excludes scenarios where the black hole grows over a long time from steadily eating gas or from many quick gas snacks that arrive from random directions.”

In addition, the spin measurement allows astrophysicists to test hypotheses about the nature of dark matter, which is thought to make up most of the matter in the universe. Dark matter may consist of unknown elementary particles not yet seen in laboratory experiments. Among the candidates are hypothetical particles known as ultralight bosons, Stone explained.

“If those particles exist and have masses in a certain range, they will prevent an intermediate-mass black hole from having a fast spin,” he said. “Yet J2150’s black hole is spinning fast. So, our spin measurement rules out a broad class of ultralight boson theories, showcasing the value of black holes as extraterrestrial laboratories for particle physics.”

In the future, new observations of tidal disruption flares might let astronomers fill in the gaps in the black hole mass distribution, the authors hope.

“If it turns out that most dwarf galaxies contain intermediate-mass black holes, then they will dominate the rate of stellar tidal disruption,” Stone said. “By fitting the X-ray emission from these flares to theoretical models, we can conduct a census of the intermediate-mass black hole population in the universe,” Wen added.

To do that, however, more tidal disruption events have to be observed. That’s why astronomers hold high hopes for new telescopes coming online soon, both on Earth and in space, including the Vera C. Rubin Observatory, also known as the Legacy Survey of Space and Time, or LSST, which is expected to discover thousands of tidal disruption events per year.

This research was supported by grants from NASA and the U.S.-Israel Binational Science Foundation.

See the full article here .


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As of 2019, the University of Arizona (US) enrolled 45,918 students in 19 separate colleges/schools, including the UArizona College of Medicine in Tucson and Phoenix and the James E. Rogers College of Law, and is affiliated with two academic medical centers (Banner – University Medical Center Tucson and Banner – University Medical Center Phoenix). UArizona is one of three universities governed by the Arizona Board of Regents. The university is part of the Association of American Universities and is the only member from Arizona, and also part of the Universities Research Association(US). The university is classified among “R1: Doctoral Universities – Very High Research Activity”.

Known as the Arizona Wildcats (often shortened to “Cats”), the UArizona’s intercollegiate athletic teams are members of the Pac-12 Conference of the NCAA. UArizona athletes have won national titles in several sports, most notably men’s basketball, baseball, and softball. The official colors of the university and its athletic teams are cardinal red and navy blue.

After the passage of the Morrill Land-Grant Act of 1862, the push for a university in Arizona grew. The Arizona Territory’s “Thieving Thirteenth” Legislature approved the UArizona in 1885 and selected the city of Tucson to receive the appropriation to build the university. Tucson hoped to receive the appropriation for the territory’s mental hospital, which carried a $100,000 allocation instead of the $25,000 allotted to the territory’s only university (Arizona State University(US) was also chartered in 1885, but it was created as Arizona’s normal school, and not a university). Flooding on the Salt River delayed Tucson’s legislators, and by they time they reached Prescott, back-room deals allocating the most desirable territorial institutions had been made. Tucson was largely disappointed with receiving what was viewed as an inferior prize.

With no parties willing to provide land for the new institution, the citizens of Tucson prepared to return the money to the Territorial Legislature until two gamblers and a saloon keeper decided to donate the land to build the school. Construction of Old Main, the first building on campus, began on October 27, 1887, and classes met for the first time in 1891 with 32 students in Old Main, which is still in use today. Because there were no high schools in Arizona Territory, the university maintained separate preparatory classes for the first 23 years of operation.

Research

UArizona is classified among “R1: Doctoral Universities – Very high research activity”. UArizona is the fourth most awarded public university by National Aeronautics and Space Administration(US) for research. UArizona was awarded over $325 million for its Lunar and Planetary Laboratory (LPL) to lead NASA’s 2007–08 mission to Mars to explore the Martian Arctic, and $800 million for its OSIRIS-REx mission, the first in U.S. history to sample an asteroid.

The LPL’s work in the Cassini spacecraft orbit around Saturn is larger than any other university globally. The UArizona laboratory designed and operated the atmospheric radiation investigations and imaging on the probe. UArizona operates the HiRISE camera, a part of the Mars Reconnaissance Orbiter. While using the HiRISE camera in 2011, UArizona alumnus Lujendra Ojha and his team discovered proof of liquid water on the surface of Mars—a discovery confirmed by NASA in 2015. UArizona receives more NASA grants annually than the next nine top NASA/JPL-Caltech(US)-funded universities combined. As of March 2016, the UArizona’s Lunar and Planetary Laboratory is actively involved in ten spacecraft missions: Cassini VIMS; Grail; the HiRISE camera orbiting Mars; the Juno mission orbiting Jupiter; Lunar Reconnaissance Orbiter (LRO); Maven, which will explore Mars’ upper atmosphere and interactions with the sun; Solar Probe Plus, a historic mission into the Sun’s atmosphere for the first time; Rosetta’s VIRTIS; WISE; and OSIRIS-REx, the first U.S. sample-return mission to a near-earth asteroid, which launched on September 8, 2016.

UArizona students have been selected as Truman, Rhodes, Goldwater, and Fulbright Scholars. According to The Chronicle of Higher Education, UArizona is among the top 25 producers of Fulbright awards in the U.S.

UArizona is a member of the Association of Universities for Research in Astronomy(US), a consortium of institutions pursuing research in astronomy. The association operates observatories and telescopes, notably Kitt Peak National Observatory(US) just outside Tucson. Led by Roger Angel, researchers in the Steward Observatory Mirror Lab at UArizona are working in concert to build the world’s most advanced telescope. Known as the Giant Magellan Telescope(CL), it will produce images 10 times sharper than those from the Earth-orbiting Hubble Telescope.

Giant Magellan Telescope, 21 meters, to be at the NOIRLab(US) National Optical Astronomy Observatory(US) Carnegie Institution for Science’s(US) Las Campanas Observatory(CL), some 115 km (71 mi) north-northeast of La Serena, Chile, over 2,500 m (8,200 ft) high.


The telescope is set to be completed in 2021. GMT will ultimately cost $1 billion. Researchers from at least nine institutions are working to secure the funding for the project. The telescope will include seven 18-ton mirrors capable of providing clear images of volcanoes and riverbeds on Mars and mountains on the moon at a rate 40 times faster than the world’s current large telescopes. The mirrors of the Giant Magellan Telescope will be built at UArizona and transported to a permanent mountaintop site in the Chilean Andes where the telescope will be constructed.

Reaching Mars in March 2006, the Mars Reconnaissance Orbiter contained the HiRISE camera, with Principal Investigator Alfred McEwen as the lead on the project. This National Aeronautics and Space Administration(US) mission to Mars carrying the UArizona-designed camera is capturing the highest-resolution images of the planet ever seen. The journey of the orbiter was 300 million miles. In August 2007, the UArizona, under the charge of Scientist Peter Smith, led the Phoenix Mars Mission, the first mission completely controlled by a university. Reaching the planet’s surface in May 2008, the mission’s purpose was to improve knowledge of the Martian Arctic. The Arizona Radio Observatory(US), a part of UArizona Department of Astronomy Steward Observatory(US), operates the Submillimeter Telescope on Mount Graham.

The National Science Foundation(US) funded the iPlant Collaborative in 2008 with a $50 million grant. In 2013, iPlant Collaborative received a $50 million renewal grant. Rebranded in late 2015 as “CyVerse”, the collaborative cloud-based data management platform is moving beyond life sciences to provide cloud-computing access across all scientific disciplines.
In June 2011, the university announced it would assume full ownership of the Biosphere 2 scientific research facility in Oracle, Arizona, north of Tucson, effective July 1. Biosphere 2 was constructed by private developers (funded mainly by Texas businessman and philanthropist Ed Bass) with its first closed system experiment commencing in 1991. The university had been the official management partner of the facility for research purposes since 2007.

U Arizona mirror lab-Where else in the world can you find an astronomical observatory mirror lab under a football stadium?

University of Arizona’s Biosphere 2, located in the Sonoran desert. An entire ecosystem under a glass dome? Visit our campus, just once, and you’ll quickly understand why the UA is a university unlike any other.