Daily Archives: June 26, 2022

This article was originally published atThe Conversation (opens in new tab).The publication contributed the article to Space.com'sExpert Voices: Op-Ed & Insights.

Kshitij Aggarwal (opens in new tab), Affiliate Researcher in Astronomy and Astrophysics, West Virginia University

A newly discovered fast radio burst has some unique properties that are simultaneously giving astronomers important clues into what may cause these mysterious astronomical phenomena while also calling into question one of the few things scientists thought they knew about these powerful flares, as my colleagues and I describe in anew study (opens in new tab)in Nature on June 8, 2022.

Fast radio bursts, or FRBs, are extremely bright pulses of radio waves that come from faraway galaxies. They release as much energy in a millisecond asthe sun does over many days (opens in new tab). Researchers here at West Virginia Universitydetected the first FRB back in 2007 (opens in new tab). In the past 15 years, astronomers have detected around 800 FRBs, withmore being discovered every day (opens in new tab).

Related: 'Weird signal' hails from the Milky Way. What's causing it?

When a telescope captures an FRB, one of the most important features researchers look at is something called dispersion. Dispersion is basically a measure of how stretched out an FRB is when it reaches Earth.

The plasma that lies between stars and galaxies causes all light including radio waves to slow down, but lower frequencies feel this effect more strongly and slow down more than higher frequencies. FRBs contain a range of frequencies, so the higher frequency light in the burst hits Earth before the lower frequencies, causing the dispersion. This allows researchers touse dispersion to estimate how far from Earth an FRB originated (opens in new tab). The more stretched out an FRB is, the more plasma the signal must have passed through, the farther away the source must be.

The new FRB my colleagues and I discoveredis named FRB190520 (opens in new tab). We found it using theFive-hundred-meter Aperture Spherical Telescope (opens in new tab)in China. An immediately apparent interesting thing about FRB190520 was that it is one of the only 24 repeating FRBs and repeats much more frequently than others producing 75 bursts over a span of six months in 2020.

Our team then used theVery Large Array (opens in new tab), a radio telescope in New Mexico, to further study this FRB and successfully pinpointed the location of its source a dwarf galaxy roughly 3 billion light years from Earth. It was then that we started to realize how truly unique and important this FRB is.

First, we found thatthere is a persistent, though much fainter, radio signal being emitted (opens in new tab)by something from the same place that FRB190520 came from. Of the more than800 FRBs discovered to date (opens in new tab), only one other has a similar persistent radio signal.

Second, since we were able to pinpoint that the FRB came from a dwarf galaxy, we were able to determine exactly how far away that galaxy is from Earth. But this result didn't make sense. Much to our surprise, the distance estimate we made using the dispersion of the FRB was 30 billion light years from Earth,a distance 10 times larger than the actual 3 billion light years to the galaxy (opens in new tab).

Astronomers have only been able to pinpoint the exact location and therefore distance from Earth of 19 other FRB sources (opens in new tab). For the rest of the roughly 800 known FRBs, astronomers have to rely on dispersion alone to estimate their distance from Earth. For the other 19 FRBs with known locations, the distances estimated from dispersion are very similar to the real distances to their source galaxies. But this new FRB shows that estimates using dispersion can sometimes be incorrect and throws many assumptions out the window.

Astronomers in thisnew field (opens in new tab)still don't knowwhat exactly produces FRBs (opens in new tab), so every new discovery or piece of information is important.

Our new discovery raises specific questions, including whether persistent radio signals are common, what conditions produce them and whether the same phenomenon that produces FRBs is responsible for emitting the persistent radio signal.

And a huge mystery is why the dispersion of FRB190520 was so much greater than it should be. Was it due to something near the FRB? Was it related to the persistent radio source? Does it have to do with the matter in the galaxy where this FRB comes from? All of these questions are unanswered.

My colleagues are going to focus in on studying FRB190520 using a host of different telescopes around the world. By studying the FRB, its galaxy and the space environment surrounding its source, we are hoping to find answers to many of the mysteries it revealed.

More answers will come from other FRB discoveries in the coming years, too. The more FRBs astronomers catalog, the greater the chances of discovering FRBs with interesting properties that can help complete the puzzle of these fascinating astronomical phenomena.

This article is republished fromThe Conversation (opens in new tab)under a Creative Commons license. Read theoriginal article (opens in new tab).

Follow all of the Expert Voices issues and debates and become part of the discussion on Facebook and Twitter. The views expressed are those of the author and do not necessarily reflect the views of the publisher.

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Newly discovered fast radio burst challenges what astronomers know - Space.com

Canadian astrophysicist Louise Edwards is used to answering some of the universe's toughest questions. Butat the momentshe's trying to answer this one: How many Canadian Black astronomers does she know?

Edwards, an associate professor inCalifornia Polytechnic State University's physics department, is on a Zoom call with CBCwhile sitting in a friend's brightly lit shed near her home inBerkeley, Calif.

Mulling the question, sheturns her headto the right, facing white wood-panelled walls. She's thinking hard.

"Ummm," she says, looking off into the distance. "There are definitely a few new grad students that I know of."

She pauses and smiles. "I know some physicists. And some education astronomy folks."

It's clear she's struggling.

"Yeah, there's very few," Edwards finally says. "I don't know if there's any other folks who are currently working not as students [but] as astronomers who are Canadian. I don't know. I would imagine I would know them."

Canada hassome of the world's most talented astronomers, astrophysicists and physicists. There's Victoria Kaspi, whose work on pulsars and neutron stars earned her the Gerhard Herzberg Canada gold medal for science and engineering; Sara Seager, a world-renowned astronomer and planetary scientist at MIT who earned a MacArthur "genius" grant in 2013 and is a leader in exoplanet research; and James Peebles, who won the 2019 Nobel Prize in physics.

One thing they have in common? They're all white.

Black astronomers are few and far between in North America,but especially in Canada.Inside the community, members sharestories of discrimination, micro-aggressionsand feelings of isolation, which can ultimately dissuade others from pursuing careers in the sciences.

Monday marked the beginning of Black in Astro Week, which was created in June 2020 by Ashley Walker, a Black astrochemist from Chicago. Its goal? To use social media and hashtags to elevate the voices of Black scientists working in various astronomical fields.

The annual event was bornfrom an incident in May 2020 in New York's Central Park. Christian Cooper, a Black birdwatcher, asked a woman who was white to leash her dog. Instead, she called police, falsely accusing Cooperof harassing her. It was the same day George Floyd was killed by police in Minneapolis.

Soon after the Central Park incident, a social media movement started on Twitter with #Blackbirders. The goal wasto increase recognition of Black people who like birding and to call attention to the harassment they often receive. Soon, a broader movement began with #BlackinX, where Black scientists from other fields were similarly elevated.

Last week, Walker co-authored an article in the journal Nature Astronomy entitled, "The representation of Blackness in astronomy."

A similar article was published in Wired magazine on June 7 entitled, "The unwritten laws of physics for Black women," which examined the experience of Black womenin physics academia.

The thread that weaves through these scientists' stories is one of isolation. They struggle with being the only Black person in a given program or classroom; their ideas aren't valued; and there are no or few Black mentors.

According to the American Physical Society, Black people make up roughly 15 per cent of the U.S. population aged 20-24,but only about three per cent of those who receive a bachelor's degree in physics. When it comes to PhDs, that number falls to little more than two per cent.

In Canada, the ratio is similar.

Kevin Hewitt, a professor in the department of physics and atmospheric science at Dalhousie University in Halifax,led a survey for the Canadian Association of Physicists (which includes those in the fields of astronomy and astrophysics)in 2020. Itfound only one per cent of respondents aged 18-34 identified as Black.In the broader Canadian population, six per cent of people 18-34 identify as Black.

"Black Canadian physicists, we're quite a small number," said Hewitt. "I know personallyabout 10 others, including students and faculty."

Hewitt is activein bringing STEM to Black youth.Heco-foundedImhotep's Legacy Academy, a STEM outreach program in Nova Scotia for Black students. His programs include the Young, Gifted and Black Future Physicists Initiative, a summer camp at Dalhousie.

Why are there so few Black Canadian scientists in general, but in particular, those who seek out a career in astronomical science?

One of the problems may be found in the education system.

Take the province of Ontario, for example. Until recently, high schools there had a "streaming" program, which directed students into different post-secondary routes."Academic" courses were more challenging and required for university;"applied" courses prepared students for college and trades;and "essentials" provided support for students in meeting the requirements to graduate.

In 2017, a reportled by Carl James, a professor in the faculty of education at York University in Toronto, found that only 53 per cent of Black students in the Toronto District School Board were put in academic programs, compared to 81 per cent of white students and 80 per cent of other racialized students.

Conversely, 39 per cent of Black students were enrolled in applied programs, compared to 16 per cent of white students and 18 per cent of other racialized students.

"What we found in that study was many of the [Black]parents were talking about how their children were streamed into vocational or essential or low-level courses," James said. Some parents would try to "intervene," he said, but their concerns fell on deaf ears.

James says another aspect is that some cultural groups tend to want their children to go into particular high-end professions, such as law or medicine. If a child expresses a desire to pursue a program of study outside of what their parentswant or know, they may not be supported.

"[Parents]might know a teacher,they might know lawyers, but they might not know much about engineers. They might not know much about science," James said. "The question for some parents might be, how do I support my child in those areas if [I'm not familiar] with it?"

Hakeem Oluseyi, an astrophysicist and STEM educator in the U.S. who is prolific in the astronomical community, believes that science literacy and an interest in science begins at home.

"The point I always make is you can't educate the kids without educating the adults," he said. And parents who go so far as to teach their children math and science at home have an even greater advantage.

But James doesn't think that's enough.

"We just can't look atthe why, and what we should be doing as only the parents because I, as a parent, could do everything possible," he said. Even so, he acknowledged many Black kids don't make it in sciencebecause "somebody ... did not enable and support them."

That's a big part of the problem.Areport by the U.S. Education Advisory Board (EAS) found that 40 per cent of Black students drop out of STEM-related programs across the country. While there's no definitive reason, the study suggested it could be related to discrimination within academiaand that recurring sense of isolation. (Although there issome data on race in Canadian universities, there is noequivalent data on those who leave STEM-related studies.)

This doesn't surprise James.

"You can have the skills and ability. But at the same time, once you're in that position, you're undermined in every way possible," James said. "How long are you going to live in thatsituation?"

Margaret Ikape,a PhD candidate at the University of Toronto's Dunlap Institute for Astronomy and Astrophysics, says she's largely had a positive experience in her field. But, she too, has a sense of being alone in her community.

"You feel that you're breaking new ground," said Ikape, who originally hails from Nigeria."You don't see anybody like you that has done it before you, and so it's really scary."

Shewishes there were more mentors."Sometimes I feel like I would rather speak to someone that would probably understand where I'm coming from."

The fact that there is discrimination implicit or explicit or even a feeling of alienationshouldn't come as a surprise, says Oluseyi.

"You know, there's this standard framing of, 'Oh, [astrophysics is]so racist,' and yadda, yadda, yadda. And I'm gonna make the claim that of course it is, because we're embedded in a society," he said."And that bigger society definitely comes into our field, and who we are in our field is a subset of society."

Back in sunny California, Edwards reflects on her own experience, saying she was fortunatein some ways. Growing up inVictoria, B.C.,a very white city,she had already dealt with asense of isolation, so it wasn't anything new to her once shegotinto astrophysics.But she admits it took her some time to meet another Black astrophysicist.

Edwards says Black in Astro Week is a good way to elevate Black voices and show Black childrenthat not only are there Black astronomers and physicists, there is a place for themin science.

Edwards expressed gratitude to Black in Astro Week founder Ashley Walker, as well as the Vanguard STEM, a similar initiative. "[It] gives wonderful space to a variety of physicists and scientists and astronomers so that different folks can see that, you know, they don't have to fit one particular mould in order to do it."

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Where are all the Black astronomers and physicists? Racism, isolation keeping many away - CBC News

Image: ESA/Hubble and NASA/J. Dalcanton.

NGC 2217, in the constellation of Canis Major and located about 65 million light years away, is a galaxy in transition. It appears as a ring galaxy, with a central bar inside an oval-shaped ring, enclosed further out by two tightly wound spiral arms. There appears to be clear space between the inner oval and the outer ring, though in reality that space will contain faint stars and gas. Galactic structures such as these often form following a head on collision with another, smaller galaxy.

The outer ring is still forming stars, but the inner oval is red and dusty. Star formation there appears to have ceased, and the light is increasingly dominated by interstellar dust reflecting starlight. Galaxies with this smeared-out, dusty appearance are known as lenticular galaxies, which NGC 2217 seems to be turning into. Look closely, however, and youll notice two things about the galaxys core. One is that the galaxy has not one, but two bars, with the second, inner, bar hidden at the centre of the outer bar. These are so-called nested bars, with one nestled inside the other. The longer outer bar formed first and funnelled gas from the outer regions of the galaxy into the centre, where that gas formed stars and, in this case, those stars and the funnelled gas became the basis of an inner bar. And the second thing to notice about NGC 2217s core is that the inner bar has a blue tint, indicative of hot, young stars that are still being born there.

Nested-bar galaxies could be hugely important in the overall evolution of galaxies and the intergalactic medium. Double bars are thought to be more efficient at funnelling gas into the centre of a galaxy than just a single bar. This gas, besides forming stars, also feeds the supermassive black hole that lurks at the centre of a galaxy. When one of these black holes is overfed, it can spew some of its meal back out into space, in the form of radiation called feedback. This feedback can forever alter a galaxy, blowing all its star-forming material away into the intergalactic medium.

Galaxies with double bars have only really been known about since the late 1990s, when the likes of the Hubble Space Telescope, which took this image, were finally able to resolve the smaller inner bars. Today, about 50 nearby spiral galaxies are known to have nested bars, and its estimated that up to 30 per cent of all barred spirals have double bars. Image: ESA/Hubble and NASA/J. Dalcanton.

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NGC 2217, is a galaxy in transition Astronomy Now - Astronomy Now Online

Stars are born when clouds of dust and gas form into clumps, and these clumps attract more material because of their gravity. Eventually, when enough material has fused together, the knot collapses under its own gravity and gets hot, becoming a protostar. This becomes the core of a star, which evolves from it (via NASA).

That's why nebulae, which are clouds of dust and gas, are often hotbeds of star formation. But it's not only the case that nebulae create stars the stars which are born can affect the structure of a nebula in turn as well.

In the case of the Tarantula Nebula, the researchers mapped the cold gas of the nebula to see how it was affected by star formation. According to ESO, the images, which combine the ALMA radio data overlaid over previous infrared observations from the European Southern Observatory's Very Large Telescope and ESO's Visible and Infrared Survey Telescope for Astronomy, show wisps of gas which are likely the remnants of star formation.

The spidery shape of the Tarantula Nebula's gas clouds show cold, dense gas that has the potential to collapse and form new stars, according to the data collected by ALMA (via ESO).

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How Astronomers Are Investigating This Nebula Where Stars Are Being Born - SlashGear

They don't call Jupiter "King of Planets" for nothing. It's massive, really heavy, andnow scientists think it ate chunks of other planets to get as big as it is.

That's right, the gas giant named after Greek and Roman gods is thought to have absorbed a series of small "planetesimals" en route to claiming its place as the biggest planet in the solar system.

The theory comes from an international team of astronomers led by Yamila Miguel from the SRON Netherlands Institute for Space Research and is set out in an article in Astronomy & Astrophysics.

It follows news last year that NASA scientists are baffled by the discovery that the planet's Great Red Spot is accelerating.

When NASA's Juno space mission arrived at Jupiter in 2016, scientists caught a glimpse of the remarkable beauty of the fifth planet from the sun.

Besides the famous Great Red Spot, Jupiter turns out to be littered with hurricanes, almost giving it the appearance and mystique of a Van Gogh painting.

But what lay underneath the outer layer was not immediately clear.

Juno was however able to measure variations in gravitational pull above different locations on the planet's surface, giving the astronomers information about what lay below.

What they found was not a homogenous and well-mixed composition, but instead a higher concentration of "metals" - elements heavier than hydrogen and helium - towards the centre of the planet.

The team of astronomers says the most likely explanation is that Jupiter absorbed numbers of "planetesimals", getting bigger and bigger.

Planetesimals are one of a class of bodies that are believed to have coalesced to form Earth and the other planets after condensing from concentrations of diffuse matter early in the history of the solar system.

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How did Jupiter get so big? Astronomers now think it 'ate' chunks of other planets - Sky News

The 500-Meter Aperture Spherical Telescope (FAST), (aka. Tianyan, Eye of Heaven), is the largest radio observatory in the world. Since the observatory became operational in January 2020, this facility has made significant contributions to radio astronomy and the Search for Extraterrestrial Intelligence (SETI). In particular, the observatory has been instrumental in detecting Fast Radio Burts (FRBs) and other cosmic phenomena that could be (but probably arent) possible indications of extraterrestrial communications.

Last week, while sifting through FAST data, the China Extraterrestrial Civilization Research Group (CECRG) from Beijing Normal University revealed that they discovered several signals that might be artificial in origin (a possible indication of an advanced civilization). These signals consisted of narrow-band electromagnetic radio transmission and were considered one of the best candidates for an extraterrestrial signal. Ah, but theres a snag. According to subsequent news releases, those radio transmissions were apparently from Earth!

Since the first SETI experiments began in the early 1960s (with Project Ozma), radio transmissions have remained the primary signature for which researchers have been looking. As the worlds largest and most sensitive radio telescope (even larger than the venerable Arecibo Observatory), FAST is the worlds premier radio facility dedicated to SETI research. One of its six main objectives* is to search the cosmos for possible technosignatures i.e., indications of technological activity.

To this end, Beijing Normal University, the National Astronomical Observatory of the Chinese Academy of Sciences (NAO/CAS), and the Berkeley SETI Research Center at UC Berkeley have partnered to create an international SETI research effort. In 2018, FAST took the first step by installing debugged back-end equipment to screen useful narrow-band candidate signals from background radio noise. By September 2020, the observatory officially began conducting science operations that included synchronous sky surveys and targetted exoplanet observations.

The team discovered two groups of suspicious signals that same year while processing data from the 2019 synchronic sky survey. This year, said CECRG team leader Professor Zhang Tongjie, the team found more possible radio signals while looking through data obtained during an exoplanet observation campaign. The Chinese state-affiliated news source Global Times shared the story on June 13th (since deleted), attesting to this discovery. As Prof. Zhang said in a statement to Chinese media:

The possibility that the suspicious signal is some kind of radio interference is also very high, and it needs to be further confirmed and ruled out. This may be a long process. China Sky Eye will repeat the observation of suspicious signals that have been discovered to further identify and detect new signals.

Berkeleys SETI Research Center, Dan Werthimer, who is part of the international collaboration and was involved in the survey, denied this a few days later. The signals that we found so far are all [radio frequency] interference, he said. Theyre not from extraterrestrials. Theyre from terrestrials. Werthimer has reportedly co-authored a preprint paper that details how the FAST findings were a false positive. Ironically, Prof. Zhang was correct when he suggested this but was incorrect when he said it might take a long time to confirm or deny it.

Such is the nature of SETI research, and the FAST observatory and its researchers should probably get accustomed to failure. It is, after all, the most likely outcome for those dedicated to searching for needles in the cosmic haystack, especially when we arent even sure what these needles will look like. As former NASA scientist and best-selling author David Brin once said about this field of research:

Few important subjects are so data-poor, so subject to unwarranted and biased explanations and so caught up in mankinds ultimate destiny than this one.

Theres plenty of good news for those left feeling disappointed by this retraction. For example, the Japan Aerospace Exploration Agency (JAXA) just announced that their Hayabusa2 sample-return mission found no less than 20 strains of amino acids (the building blocks of DNA) on asteroid Ryugu. Second, the James Webb Space Telescope will be revealing its first images very soon and turning its infrared imaging capability toward several nearby exoplanets. The data it provides on these planets atmospheres could soon lead to a breakthrough in the search for habitable worlds beyond our Solar System!

In the end, all we can do is keep searching, waiting, and refining our methods. If theres anyone out there also looking to answer the big question (Are we alone?), were sure to find them eventually.

*Other objectives include a large-scale neutral hydrogen survey, very long baseline interferometry (VLBI), probing the interstellar medium (ISM), pulsar observations, and timing.

Further Reading: Weixin, EarthSky

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Chinese Astronomers Detect an Interesting (But NOT Alien) Signal With the FAST Radio Observatory - Universe Today

South Africas MeerKAT telescope. Credit: South African Radio Astronomy Observatory (SARAO)

An international team of astronomers has combined the power of 64 radio telescope dishes for the first time to detect the faint signatures of neutral hydrogen gas across cosmological scales.

The achievement was accomplished using the South African-based MeerKAT telescope, a precursor to the worlds largest radio observatory, the SKA Observatory (SKAO), which will probe the Universe in unprecedented detail.

A primary aim for the SKAO is to understand the evolution and content of the Universe along with the mechanisms which drive its accelerating expansion. One way to achieve this is by observing the Universes structure on the largest scales. On these scales, entire galaxies can be considered as single points and analysis of their distribution reveals clues about the nature of gravity and mysterious phenomena such as dark matter and dark energy.

Radio telescopes are a fantastic instrument for this since they can detect radiation at wavelengths of 21cm generated by neutral hydrogen, the most abundant element in the Universe. By analyzing 3D maps of hydrogen spanning millions of light-years, we probe the total distribution of matter in the Universe.

The SKAO, which has its headquarters based at Jodrell Bank, Cheshire, is currently under construction. However, there are already pathfinder telescopes, such as the 64-dish array MeerKAT, in place to guide its design. Based in the Karoo Desert and operated by the South African Radio Astronomy Observatory (SARAO), MeerKAT will eventually go on to be a part of the full SKAO.

MeerKAT and the SKAO will primarily operate as interferometers, where the array of dishes are combined as one giant telescope capable of imaging distant objects with high resolution. However, the interferometer will not be sensitive enough to the largest scales most interesting for cosmologists studying the Universe. explained the co-lead author of the new research paper, Steven Cunnington. Therefore, we instead use the array as a collection of 64 individual telescopes which allows them to map the giant volumes of sky required for cosmology.

For many years I have worked towards forecasting the future capability of the SKAO. To now reach a stage where we are developing the tools we will need and demonstrating their success with real data is incredibly exciting. This only marks the beginning of what we hope will be a continuous showcase of results which advances our understanding of the Universe.

Steven Cunnington

The single-dish mode of operation has been driven by a team at the University of the Western Cape, with several observations already conducted with MeerKAT. This ambitious project involves many other institutions spanning four continents. In the new researchsubmitted for publication, a team that includes Manchester-based astronomers Steven Cunnington, Laura Wolz and Keith Grainge, present the first ever cosmological detection using this single-dish technique.

The new detection is of a shared clustering pattern between MeerKATs maps and galaxy positions determined by the optical Anglo-Australian Telescope. Since it is known that these galaxies trace the overall matter of the Universe, the strong statistical correlation between the radio maps and the galaxies shows the MeerKAT telescope is detecting large-scale cosmic structure. This is the first time such detection has been made using a multi-dish array operating as individual telescopes. The full SKAO will rely on this technique and this therefore marks an important milestone in the roadmap for the cosmology science case with the SKAO.

This detection was made with just a small amount of pilot survey data, revealed Steven Cunnington. Its encouraging to imagine what will be achieved as MeerKAT continues to make increasingly larger observations.

For many years I have worked towards forecasting the future capability of the SKAO. To now reach a stage where we are developing the tools we will need and demonstrating their success with real data is incredibly exciting. This only marks the beginning of what we hope will be a continuous showcase of results which advances our understanding of the Universe.

Reference: HI intensity mapping with MeerKAT: power spectrum detection in cross-correlation with WiggleZ galaxies by Steven Cunnington, Yichao Li, Mario G. Santos, Jingying Wang, Isabella P. Carucci, Melis O. Irfan, Alkistis Pourtsidou, Marta Spinelli, Laura Wolz, Paula S. Soares, Chris Blake, Philip Bull, Brandon Engelbrecht, Jos Fonseca, Keith Grainge and Yin-Zhe Ma, 3 June 2022, Astrophysics > Cosmology and Nongalactic Astrophysics.arXiv:2206.01579

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Astronomers Combine the Power of 64 Telescopes To Observe the Structure of the Universe - SciTechDaily

Astronomer Feryal zel is one of the pioneers of black hole photography. With two pictures in the album, she explains what we have learned about these gravitational monsters - and what comes next

By Abigail Beall

Nabil Nezzar

A FEW weeks ago, we got our first look at a portrait of the mysterious behemoth at the centre of the Milky Way, the supermassive black hole known as Sagittarius A*. The image is an amazing feat of astronomical endeavour, made possible thanks to a planet-sized array of telescopes called the Event Horizon Telescope (EHT). It was even harder to capture than the previous black hole picture taken by the EHT, which was the first ever. But it is also special because this black hole is at the heart of our home galaxy.

Feryal zel at the University of Arizona was one of the first people to come up with a way of photographing black holes and she is now a key member of the EHT collaboration. New Scientist caught up with her to find out what we have learned from the latest image, how it puts our understanding of gravity to the test and what to expect next from the nascent field of black hole photography.

Abigail Beall: What first drew you to black holes?

Feryal zel: When I started graduate school, astronomy was having a golden age. Part of that was the age of discovery of how black holes and neutron stars behave. Then I realised these are basically extreme laboratories in space. I can combine what I love about theoretical physics with this amazing data and explore things that we cant with a lab on Earth.

What is so mysterious about black holes?

Black holes were, at first, a mathematical construct from Einsteins theory of gravity, general relativity. When gravity is strong enough, the

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Feryal zel on what the first two pictures of black holes tell us - New Scientist

UC Berkeley

If, as astronomers believe, the death of large stars leave behind black holes, there should be hundreds of millions of them scattered throughout the Milky Way galaxy. The problem is, isolated black holes are invisible.

Now, a team led by University of California, Berkeley, astronomers has for the first time discovered what may be a free-floating black hole by observing the brightening of a more distant star as its light was distorted by the objects strong gravitational fieldso-called gravitational microlensing.

The team, led by graduate student Casey Lam andJessica Lu, a UC Berkeley associate professor of astronomy, estimates that the mass of the invisible compact object is between 1.6 and 4.4 times that of the sun. Because astronomers think that the leftover remnant of a dead star must be heavier than 2.2 solar masses in order to collapse to a black hole, the UC Berkeley researchers caution that the object could be a neutron star instead of a black hole. Neutron stars are also dense, highly compact objects, but their gravity is balanced by internal neutron pressure, which prevents further collapse to a black hole.

Whether a black hole or a neutron star, the object is the first dark stellar remnant a stellar ghostdiscovered wandering through the galaxy unpaired with another star.

This is the first free-floating black hole or neutron star discovered with gravitational microlensing, Lu said. With microlensing, were able to probe these lonely, compact objects and weigh them. I think we have opened a new window onto these dark objects, which cant be seen any other way.

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Determining how many of these compact objects populate the Milky Way galaxy will help astronomers understand the evolution of starsin particular, how they dieand of our galaxy, and perhaps reveal whether any of the unseen black holes are primordial black holes, which some cosmologists think were produced in large quantities during the Big Bang.

The analysis by Lam, Lu and their international team has been accepted for publication inThe Astrophysical Journal Letters.

RELATED: Ice May Be Hiding in Ancient Moon Volcanoes

The analysis includes four other microlensing events that the team concluded were not caused by a black hole, though two were likely caused by a white dwarf or a neutron star. The team also concluded that the likely population of black holes in the galaxy is 200 millionabout what most theorists predicted.

Notably, a competing team from the Space Telescope Science Institute (STScI) in Baltimore analyzed the same microlensing event and claims that the mass of the compact object is closer to 7.1 solar masses and indisputably a black hole. A paper describing the analysis by the STScI team, led byKailash Sahu, has been accepted for publication inThe Astrophysical Journal.

(WATCH the video for this story below.)

Source: University of California, Berkeley

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Astronomers Think They've Detected a 'Dark' Free-Floating Black Hole For the First Time - Good News Network