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Astronomers Discover an Intermediate-Mass Black Hole as it Destroys a Star – Universe Today

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Supermassive black holes (SMBH) reside in the center of galaxies like the Milky Way. They are mind-bogglingly massive, ranging from 1 million to 10 billion solar masses. Their smaller brethren, intermediate-mass black holes (IMBH), ranging between 100 and 100,000 solar masses, are harder to find.

Astronomers have spotted an intermediate-mass black hole destroying a star that got too close. They’ve learned a lot from their observations and hope to find even more of these black holes. Observing more of them may lead to understanding how SMBHs got so massive.

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When a star gets too close to a powerful black hole, a tidal disruption event (TDE) occurs. The star is torn apart and its constituent matter is drawn to the black hole, where it gets caught in the hole’s accretion disk. The event releases an enormous amount of energy, outshining all the stars in the galaxy for months, even years.

That’s what happened with TDE 3XMM J215022.4-055108, which is more readily known as TDE J2150. Astronomers were only able to spot the elusive IMBH because of the burst of x-rays emitted by the hot gas from the star as it was torn apart. J2150 is about 740 million light-years from Earth in the direction of the Aquarius constellation. Now a team of researchers has used observations of the distant J2150 and existing scientific models to learn more about the IMBH.

They’ve published their results in a paper titled “Mass, Spin, and Ultralight Boson Constraints from the Intermediate Mass Black Hole in the Tidal Disruption Event 3XMM J215022.4?055108.” The lead author is Sixiang Wen from the University of Arizona. The paper is published in The Astrophysical Journal.

“The fact that we were able to catch this invisible black hole while it was devouring a star offers a remarkable opportunity to observe what otherwise would be invisible.”

Ann Zabludoff, co-author University of Arizona.

IMBHs are elusive and difficult to study. Astronomers have found several of them in the Milky Way and in nearby galaxies. Mostly they’ve been spotted because of their low-luminosity active galactic nuclei. In 2019 the LIGO and Virgo gravitational wave observatories spotted a gravitational wave from the merger of two IMBHs. As it stands now, there’s a catalogue of only 305 IMBH candidates, even though scientists think they could be common in galactic centers.

One of the problems in seeing them is their low mass itself. While SMBHs can be found by observing how their mass affects the stellar dynamics of nearby stars, IMBHs are typically too small to do the same. Their gravity isn’t powerful enough to change the orbits of nearby stars.

“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.”

This is a Hubble image of J2150 in the white circle. It’s situated inside a dense cluster of stars about 740 million light-years away. X-ray emissions from the TDE were used to spot the IMBH, but Hubble’s visible-light capabilities were needed to pinpoint its location. Image Credit: NASA, ESA, and D. Lin (University of New Hampshire)

It was the eruption of x-rays that made the event visible. The team compared the observed x-rays with models and was able to confirm the presence of an IMBH. “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,” lead author Wen said.

This is the first time that observations have been detailed enough to be able to use a TDE flare to confirm the presence of an IMBH. It’s a big deal, because though we know that SMBHs lie in the center of galaxies like the Milky Way and larger, our understanding of smaller galaxies and their IMBHs is much more limited. They’re just really hard to see.

“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 and SRON Netherlands Institute for Space Research, both in the Netherlands. “Due to observational limitations, it is challenging to discover central black holes much smaller than 1 million solar masses.”

The mystery surrounding IMBHs feeds into the mystery surrounding SMBHs. We can see SMBHs at the heart of large galaxies, but we don’t know exactly how they got that massive. Did they go through mergers? Maybe. Through the accretion of matter? Maybe. Astrophysicists mostly agree that both mechanisms may play a role.

Another question surrounds SMBH “seeds.” The seeds could be IMBHs of tens or hundreds of solar masses. The IMBHs themselves could’ve grown from stellar-mass black holes that grew into IMBHs through the accretion of matter. Another possibility is that long before there were actual stars, there were large gas clouds that collapsed into quasi-stars, that then collapsed into black holes. These strange entities would collapse directly from quasi-star to black hole without ever becoming a star, and are known as direct collapse black holes. But these are all hypotheses and models. Astrophysicists need more actual observations, like in the case of TDE J2150, to confirm or rule anything out.

“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,” Jonker said.

This artist's illustration depicts what astronomers call a "tidal disruption event," or TDE, when an object such as a star wanders too close to a black hole and is destroyed by tidal forces generated from the black hole's intense gravitational forces. (Credit: NASA/CXC/M.Weiss.
This artist’s illustration depicts what astronomers call a “tidal disruption event,” or TDE, when an object such as a star wanders too close to a black hole and is destroyed by tidal forces generated from the black hole’s intense gravitational forces. (Credit: NASA/CXC/M.Weiss.

The team of researchers was also able to measure the black hole’s spin, which has implications for black hole growth, and maybe for particle physics, too. The black hole is spinning quickly, but it’s not spinning as fast as possible. It begs the question, how did the IMBH attain a speed in this range? The spin opens up some possibilities and eliminates others.

“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,” Zabludoff 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.”

The spin rate may shed some light on potential particle candidates for dark matter, too. One of the hypotheses says that dark matter is made up of particles never seen in a laboratory, called ultralight bosons. These exotic particles, if they exist, would have less than one-billionth the mass of an electron. The IMBHs spin rate may preclude the existence of these candidate particles.

“If those particles exist and have masses in a certain range, they will prevent an intermediate-mass black hole from having a fast spin,” co-author Nicholas Stone 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.”

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This discovery will build toward a better understanding of dwarf galaxies and their black holes, too. But for that to happen, astrophysicists need to observe more of these IMBH tidal disruption events.

“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.

As is often the case in astronomy, astrophysics, and cosmology, future telescopes and observatories should advance our knowledge considerably. In this, the Vera C. Rubin Observatory could play a role. The Rubin could discover thousands of TDEs each year.

Then we may finally be able to piece together the story of not only IMBHs but also SMBHs.

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SpaceX launch marks 300th successful booster landing – Phys.org

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Credit: Unsplash/CC0 Public Domain

SpaceX sent up the 30th launch from the Space Coast for the year on the evening of April 23, a mission that also featured the company’s 300th successful booster recovery.

A Falcon 9 rocket carrying 23 of SpaceX’s Starlink internet satellites blasted off at 6:17 p.m. Eastern time from Cape Canaveral Space Force Station’s Space Launch Complex 40.

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The first-stage booster set a milestone of the 300th time a Falcon 9 or Falcon Heavy booster made a successful recovery landing, and the 270th time SpaceX has reflown a booster.

This particular booster made its ninth trip to space, a resume that includes one human spaceflight, Crew-6. It made its latest recovery landing downrange on the droneship Just Read the Instructions in the Atlantic Ocean.

The company’s first successful booster recovery came in December 2015, and it has not had a failed booster landing since February 2021.

The current record holder for flights flew 11 days ago making its 20th trip off the .

SpaceX has been responsible for all but two of the launches this year from either Kennedy Space Center or Cape Canaveral with United Launch Alliance having launched the other two.

SpaceX could knock out more launches before the end of the month, putting the Space Coast on pace to hit more than 90 by the end of the year, but the rate of launches by SpaceX is also set to pick up for the remainder of the year with some turnaround times at the Cape’s SLC-40 coming in less than three days.

That could amp up frequency so the Space Coast could surpass 100 launches before the end of the year, with the majority coming from SpaceX. It hosted 72 launches in 2023.

More launches from ULA are on tap as well, though, including the May 6 launch atop an Atlas V rocket of the Boeing CST-100 Starliner with a pair of NASA astronauts to the International Space Station.

ULA is also preparing for the second launch ever of its new Vulcan Centaur rocket, which recently received its second Blue Origin BE-4 engine and is just waiting on the payload, Sierra Space’s Dream Chaser spacecraft, to make its way to the Space Coast.

Blue Origin has its own it wants to launch this year as well, with New Glenn making its debut as early as September, according to SLD 45’s range manifest.

2024 Orlando Sentinel. Distributed by Tribune Content Agency, LLC.

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SpaceX launch marks 300th successful booster landing (2024, April 24)
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from https://phys.org/news/2024-04-spacex-300th-successful-booster.html

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Wildlife Wednesday: loons are suffering as water clarity diminishes – Canadian Geographic

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The common loon, that icon of northern wilderness, is under threat from climate change due to declining water clarity. Published earlier this month in the journal Ecology, a study conducted by biologists from Chapman University and Rensselaer Polytechnic Institute in the U.S. has demonstrated the first clear evidence of an effect of climate change on this species whose distinct call is so tied to the soundscape of Canada’s lakes and wetlands.

Through the course of their research, the scientists found that July rainfall results in reduced July water clarify in loon territories in Northern Wisconsin. In turn, this makes it difficult for adult loons to find and capture their prey — mainly small fish — underwater, meaning they are unable to meet their chicks’ metabolic needs. Undernourished, the chicks face higher mortality rates. The consistent foraging techniques used by loons across their range means this impact is likely echoed wherever they are found — from Alaska to Canada to Iceland.

The researchers used Landsat imagery to find that there has been a 25-year consistent decline in water clarity, and during this period, body weights of adult loon and chicks alike have also declined. With July being the month of most rapid growth in young loons, the study also pinpointed water clarity in July as being the greatest predictor of loon body weight. 

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One explanation for why heavier rainfall leads to reduced water clarity is the rain might carry dissolved organic matter into lakes from adjacent streams and shoreline areas. Lawn fertilizers, pet waste and septic system leaks may also be to blame.

The researchers, led by Chapman University professor Walter Piper, hope to use these insights to further conservation efforts for this bird Piper describes as both “so beloved and so poorly understood.”

Return of the king

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Giant prehistoric salmon had tusk-like teeth for defence, building nests

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The artwork and publicity materials showcasing a giant salmon that lived five million years ago were ready to go to promote a new exhibit, when the discovery of two fossilized skulls immediately changed what researchers knew about the fish.

Initial fossil discoveries of the 2.7-metre-long salmon in Oregon in the 1970s were incomplete and had led researchers to mistakenly suggest the fish had fang-like teeth.

It was dubbed the “sabre-toothed salmon” and became a kind of mascot for the Museum of Natural and Cultural History at the University of Oregon, says researcher Edward Davis.

But then came discovery of two skulls in 2014.

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Davis, a member of the team that found the skulls, says it wasn’t until they got back to the lab that he realized the significance of the discovery that has led to the renaming of the fish in a new, peer-reviewed study.

“There were these two skulls staring at me with sideways teeth,” says Davis, an associate professor in the department of earth sciences at the university.

In that position, the tusk-like teeth could not have been used for biting, he says.

“That was definitely a surprising moment,” says Davis, who serves as director of the Condon Fossil Collection at the university’s Museum of Natural and Cultural History.

“I realized that all of the artwork and all of the publicity materials and bumper stickers and buttons and T-shirts we had just made two months prior, for the new exhibit, were all out of date,” he says with a laugh.

Davis is co-author of the new study in the journal PLOS One, which renames the giant fish the “spike-toothed salmon.”

It says the salmon used the tusk-like spikes for building nests to spawn, and as defence mechanisms against predators and other salmon.

The salmon lived about five million years ago at a time when Earth was transitioning from warmer to relatively cooler conditions, Davis says.

It’s hard to know exactly why the relatives of today’s sockeye went extinct, but Davis says the cooler conditions would have affected the productivity of the Pacific Ocean and the amount of rain feeding rivers that served as their spawning areas.

Another co-author, Brian Sidlauskas, says a fish the size of the spike-toothed salmon must have been targeted by predators such as killer whales or sharks.

“I like to think … it’s almost like a sledgehammer, these salmon swinging their head back and forth in order to fend off things that might want to feast on them,” he says.

Sidlauskas says analysis by the lead author of the paper, Kerin Claeson, found both male and female salmon had the “multi-functional” spike-tooth feature.

“That’s part of our reason for hypothesizing that this tooth is multi-functional … It could easily be for digging out nests,” he says.

“Think about how big the (nest) would have to be for an animal of this size, and then carving it out in what’s probably pretty shallow water; and so having an extra digging tool attached to your head could be really useful.”

Sidlauskas says the giant salmon help researchers understand the boundaries of what’s possible with the evolution of salmon, but they also capture the human imagination and a sense of wonder about what’s possible on Earth.

“I think it helps us value a little more what we do still have, or I hope that it does. That animal is no longer with us, but it is a product of the same biosphere that sustains us.”

This report by The Canadian Press was first published April 24, 2024.

Brenna Owen, The Canadian Press

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