Astronomers detect the closest example yet of a black hole devouring a star
The event was spotted in infrared data — also a first — suggesting further searches in this band could turn up more such bursts.
Peer-Reviewed PublicationIMAGE: ASTRONOMERS AT MIT AND ELSEWHERE HAVE OBSERVED INFRARED SIGNS OF THE CLOSEST TIDAL DISRUPTION EVENT (TDE) TO DATE. A BRIGHT FLARE WAS DETECTED FROM THE GALAXY NGC 7392 IN 2015 (TOP LEFT PANEL). OBSERVATIONS OF THE SAME GALAXY WERE TAKEN IN 2010-2011 (TOP RIGHT), PRIOR TO THE TDE. THE BOTTOM LEFT SHOWS THE DIFFERENCE BETWEEN THE FIRST TWO IMAGES, REPRESENTING THE ACTUAL, DETECTED TDE. FOR COMPARISON, THE BOTTOM RIGHT PANEL SHOWS THE SAME GALAXY IN THE OPTICAL WAVEBAND. view more
CREDIT: COURTESY OF CHRISTOS PANAGIOTOU, ET AL
Once every 10,000 years or so, the center of a galaxy lights up as its supermassive black hole rips apart a passing star. This “tidal disruption event” happens in a literal flash, as the central black hole pulls in stellar material and blasts out huge amounts of radiation in the process.
Astronomers know of around 100 tidal disruption events (TDE) in distant galaxies, based on the burst of light that arrives at telescopes on Earth and in space. Most of this light comes from X-rays and optical radiation.
MIT astronomers, tuning past the conventional X-ray and UV/optical bands, have discovered a new tidal disruption event, shining brightly in infrared. It is one of the first times scientists have directly identified a TDE at infrared wavelengths.
What’s more, the new outburst happens to be the closest tidal disruption event observed to date: The flare was found in NGC 7392, a galaxy that is about 137 million light-years from Earth, which corresponds to a region in our cosmic backyard that is one-fourth the size of the next-closest TDE.
This new flare, labeled WTP14adbjsh, did not stand out in standard X-ray and optical data. The scientists suspect that these traditional surveys missed the nearby TDE, not because it did not emit X-rays and UV light, but because that light was obscured by an enormous amount of dust that absorbed the radiation and gave off heat in the form of infrared energy.
The researchers determined that WTP14adbjsh occurred in a young, star-forming galaxy, in contrast to the majority of TDEs that have been found in quieter galaxies. Scientists expected that star-forming galaxies should host TDEs, as the stars they churn out would provide plenty of fuel for a galaxy’s central black hole to devour. But observations of TDEs in star-forming galaxies were rare until now.
The new study suggests that conventional X-ray and optical surveys may have missed TDEs in star-forming galaxies because these galaxies naturally produce more dust that could obscure any light coming from their core. Searching in the infrared band could reveal many more, previously hidden TDEs in active, star-forming galaxies.
“Finding this nearby TDE means that, statistically, there must be a large population of these events that traditional methods were blind to,” says Christos Panagiotou, a postdoc in MIT’s Kavli Institute for Astrophysics and Space Research. “So, we should try to find these in infrared if we want a complete picture of black holes and their host galaxies.”
A paper detailing the team’s discovery appears today in Astrophysical Journal Letters. Panagiotou’s MIT co-authors are Kishalay De, Megan Masterson, Erin Kara, Michael Calzadilla, Anna-Christina Eilers, Danielle Frostig, Nathan Lourie, and Rob Simcoe, along with Viraj Karambelkar, Mansi Kasliwal, Robert Stein, and Jeffry Zolkower of Caltech, and Aaron Meisner at the National Science Foundation’s National Optical-Infrared Astronomy Research Laboratory.
A flash of possibility
Panagiotou did not intend to search for tidal disruption events. He and his colleagues were looking for signs of general transient sources in observational data, using a search tool developed by De. The team used De’s method to look for potential transient events in archival data taken by NASA’s NEOWISE mission, a space telescope that has made regular scans of the entire sky since 2010, at infrared wavelengths.
The team discovered a bright flash that appeared in the sky near the end of 2014.
“We could see there was nothing at first,” Panagiotou recalls. “Then suddenly, in late 2014, the source got brighter and by 2015 reached a high luminosity, then started going back to its previous quiescence.”
They traced the flash to a galaxy 42 megarparsecs from Earth. The question then was, what set it off? To answer this, the team considered the brightness and timing of the flash, comparing the actual observations with models of various astrophysical processes that could produce a similar flash.
“For instance, supernovae are sources that explode and brighten suddenly, then come back down, on similar timescales to tidal disruption events,” Panagiotou notes. “But supernovae are not as luminous and energetic as what we observed.”
Working through different possibilities of what the burst could be, the scientists were finally able to exclude all but one: The flash was most likely a TDE, and the closest one observed so far.
“It’s a very clean light curve and really follows what we expect the temporal evolution of a TDE should be,” Panagiotou says.
Red or green
From there, the researchers took a closer look at the galaxy where the TDE arose. They gathered data from multiple ground- and space-based telescopes which happened to observe the part of the sky where the galaxy resides, across various wavelengths, including infrared, optical, and X-ray bands. With this accumulated data, the team estimated that the supermassive black hole at the center of the galaxy was about 30 million times as massive as the sun.
“This is almost 10 times larger than the black hole we have at our galactic center, so it’s quite massive, though black holes can get up to 10 billion solar masses,” Panagiotou says.
The team also found that the galaxy itself is actively producing new stars. Star-forming galaxies are a class of “blue” galaxies, in contrast to quieter “red” galaxies that have stopped producing new stars. Star-forming blue galaxies are the most common type of galaxy in the universe.
“Green” galaxies lie somewhere between red and blue, in that, every so often they produce a few stars. Green is the least common galaxy type, but curiously, most TDEs detected to date have been traced to these rarer galaxies. Scientists had struggled to explain these detections, since theory predicts that blue star-forming galaxies should exhibit TDEs, as they would present more stars for black holes to disrupt.
But star-forming galaxies also produce a lot of dust from the interactions between and among stars near a galaxy’s core. This dust is detectable at infrared wavelengths, but it can obscure any X-ray or UV radiation that would otherwise be picked up by optical telescopes. This could explain why astronomers have not detected TDEs in star-forming galaxies using conventional optical methods.
“The fact that optical and X-ray surveys missed this luminous TDE in our own backyard is very illuminating, and demonstrates that these surveys are only giving us a partial census of the total population of TDEs,” says Suvi Gezari, associate astronomer and chair of the Science Staff at the Space Telescope Science Institute in Maryland, who was not involved in the study. “Using infrared surveys to catch the dust echo of obscured TDEs…has already shown us that there is a population of TDEs in dusty, star-forming galaxies that we have been missing.”
This research was supported, in part, by NASA.
###
Written by Jennifer Chu, MIT News Office
JOURNAL
The Astrophysical Journal Letters
ARTICLE TITLE
“A luminous dust-obscured Tidal Disruption Event candidate in a star forming galaxy at 42 Mpc”
Ground wide angle camera array detects prompt optical emission of gamma-ray burst
IMAGE: SUCCESSIVE GWAC OBSERVATIONS OF GRB 201223A BEFORE, DURING AND AFTER THE SWIFT TRIGGER TIME. THE TEMPORAL RESOLUTION IS 15 SECONDS. THE MIDDLE YELLOW ARROW POINTS TO THE OPTICAL COUNTERPART. THE IMAGE IN THE THIRD COLUMN OF THE FIRST ROW COVERS THE TRIGGER TIME. view more
CREDIT: NAOC
Researchers led by Dr. XIN Liping from the Space-based Multi-band Astronomical Variable Objects Monitor (SVOM) research team, National Astronomical Observatories of the Chinese Academy of Sciences (NAOC), have detected the prompt optical emission and its transition to the early afterglow of a gamma-ray burst (GRB 201223A), using the Ground Wide Angle Camera Array (GWAC) located at Xinglong Observatory of NAOC.
The study was published in Nature Astronomy on April 10.
Gamma-ray bursts (GRBs) are produced by the collapse of massive stars or the merger of binary neutron stars. They are accompanied by extreme relativistic jets emitting enormous amounts of energy within a few seconds of the bursts. This phenomenon includes the prompt emission caused by the shock in the jet and the afterglow produced by interaction between the jet and external medium.
Typical high-energy emission lasts only a few milliseconds to tens of seconds, and it is difficult to follow up in real time when ground-based optical telescopes receive alerts triggered by space-based high-energy instruments. Up till now, only a few cases of optical emission have been detected before the end of prompt high-energy emission. These GRBs have longer duration of high-energy emission (>30 seconds). Furthermore, all these measurements were contaminated with reverse shock, making it difficult to clearly review the transition from prompt emission to afterglow.
GWAC, proposed and led by Prof. WEI Jianyan, principal investigator of the SVOM mission, is one of the key ground-based telescopes for the SVOM project. It can cover an ultra-large sky area with a temporal resolution of 15 seconds and a detection capability of magnitude 16. Its scientific purpose is to conduct systematic research on the prompt optical emission of GRBs discovered by the SVOM mission.
In this study, GWAC recorded the entire process—before, during and after the trigger time of the burst. The duration of the high-energy emission was 29 seconds. The emergence of optical and gamma-ray emissions was detected simultaneously.
"The prompt optical emission is far brighter than expected by about four orders of magnitude, if only gamma-ray emission is analyzed, which requires a special physical interpretation for these measurements," said by Dr. XIN.
According to joint analysis using the follow-up observations by F60A, an optical telescope jointly operated by NAOC and Guangxi University, the complete transition from prompt optical emission to afterglow was clearly achieved without any contamination from reverse shock.
The extremely early unique data provided by GWAC place a fine constraint on the characteristics of the progenitor. Scientists expect strong stellar winds around a massive star, which is thought to be the ideal progenitor of a gamma-ray burst. However, the stellar wind is quite small for this event, even at a very close distance from the burst, thus suggesting the progenitor has a small stellar mass.
After the launch of SVOM, simultaneous observations by GWAC and SVOM space-based instruments will have the potential to provide essential data for GRB studies, and finally a large sample with prompt optical observations will be built during SVOM mission.
JOURNAL
Nature Astronomy
ARTICLE TITLE
Prompt-to-afterglow transition of optical emission in a long gamma-ray burst consistent with a fireball
Superflare with massive, high-velocity prominence eruption
IMAGE: ARTIST’S IMPRESSION OF THE SUPERFLARE OBSERVED ON ONE OF THE STARS IN THE V1355 ORIONIS BINARY STAR SYSTEM. THE BINARY COMPANION STAR IS VISIBLE IN THE BACKGROUND ON THE RIGHT. view more
CREDIT: NAOJ
A team of Japanese astronomers used simultaneous ground-based and space-based observations to capture a more complete picture of a superflare on a star. The observed flare started with a very massive, high-velocity prominence eruption. These results give us a better idea of how superflares and stellar prominence eruptions occur.
Some stars have been seen releasing superflares over 10 times larger than the largest solar flare ever seen on the Sun. The hot ionized gas released by solar flares can influence the environment around the Earth, referred to as space weather. More powerful superflares must have an even greater impact on the evolution of any planets forming around the star, or the evolution of any life forming on those planets. But the details of how superflares and prominence eruptions on stars occur have been unclear.
A team led by Shun Inoue at Kyoto University used the 3.8-m Seimei Telescope in Japan and the Transiting Exoplanet Survey Satellite (TESS) to monitor the binary star system V1355 Orionis which is known to frequently release large-scale superflares. V1355 Orionis is located 400 light years away in the constellation Orion.
The team succeeded in capturing a superflare with continuous, high temporal resolution observations. Data analysis shows that the superflare originated with a phenomenon known as a prominence eruption. Calculating the velocity of the eruption requires making some assumptions about aspects that aren’t directly observably, but even the most conservative estimates far exceed the escape velocity of the star (347 km/s), indicating that the prominence eruption was capable of breaking free of the star’s gravity and developing into Coronal Mass Ejections (CMEs). The prominence eruption was also one of the most massive ever observed, carrying trillions of tons of material.
These results appeared as Inoue et al. “Detection of a high-velocity prominence eruption leading to a CME associated with a superflare on the RS CVn-type star V1355 Orionis” in The Astrophysical Journal on April 27, 2023.
JOURNAL
The Astrophysical Journal
METHOD OF RESEARCH
Observational study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Detection of a High-velocity Prominence Eruption Leading to a CME Associated with a Superflare on the RS CVn-type Star V1355 Orionis
ARTICLE PUBLICATION DATE
27-Apr-2023
Most massive touching stars ever found will eventually collide as black holes
Two massive touching stars in a neighbouring galaxy are on course to become black holes that will eventually crash together, generating waves in the fabric of space-time, according to a new study by researchers at UCL and the University of Potsdam.
Peer-Reviewed PublicationIMAGE: THE SMALLER, BRIGHTER, HOTTER STAR (LEFT), WHICH IS 32 TIMES THE MASS OF OUR SUN, IS CURRENTLY LOSING MASS TO ITS BIGGER COMPANION (RIGHT), WHICH HAS 55 TIMES THE MASS OF OUR SUN. THE STARS ARE WHITE AND BLUE AS THEY ARE SO HOT: 43,000 AND 38,000 DEGREES KELVIN RESPECTIVELY. view more
CREDIT: CREDIT: UCL / J. DASILVA
Two massive touching stars in a neighbouring galaxy are on course to become black holes that will eventually crash together, generating waves in the fabric of space-time, according to a new study by researchers at UCL (University College London) and the University of Potsdam.
The study, accepted for publication in the journal Astronomy & Astrophysics, looked at a known binary star (two stars orbiting around a mutual centre of gravity), analysing starlight obtained from a range of ground- and space-based telescopes.
The researchers found that the stars, located in a neighbouring dwarf galaxy called the Small Magellanic Cloud, are in partial contact and swapping material with each other, with one star currently “feeding” off the other. They orbit each other every three days and are the most massive touching stars (known as contact binaries) yet observed.
Comparing the results of their observations with theoretical models of binary stars’ evolution, they found that, in the best-fit model, the star that is currently being fed on will become a black hole and will feed on its companion star. The surviving star will become a black hole shortly after.
These black holes will form in only a couple of million years, but will then orbit each other for billions of years before colliding with such force that they will generate gravitational waves – ripples in the fabric of space-time – that could theoretically be detected with instruments on Earth.
PhD student Matthew Rickard (UCL Physics & Astronomy), lead author of the study, said: “Thanks to gravitational wave detectors Virgo and LIGO, dozens of black hole mergers have been detected in the last few years. But so far we have yet to observe stars that are predicted to collapse into black holes of this size and merge in a time scale shorter than or even broadly comparable to the age of the universe.
“Our best-fit model suggests these stars will merge as black holes in 18 billion years. Finding stars on this evolutionary pathway so close to our Milky Way galaxy presents us with an excellent opportunity learn even more about how these black hole binaries form.”
Co-author Daniel Pauli, a PhD student at the University of Potsdam, said: “This binary star is the most massive contact binary observed so far. The smaller, brighter, hotter star, 32 times the mass of the Sun, is currently losing mass to its bigger companion, which has 55 times our Sun’s mass.”
The black holes that astronomers see merge today formed billions of years ago, when the universe had lower levels of iron and other heavier elements. The proportion of these heavy elements has increased as the universe has aged and this makes black hole mergers less likely. This is because stars with a higher proportion of heavier elements have stronger winds and they blow themselves apart sooner.
The well-studied Small Magellanic Cloud, about 210,000 light years from Earth, has by a quirk of nature about a seventh of the iron and other heavy metal abundances of our own Milky Way galaxy. In this respect it mimics conditions in the universe’s distant past. But unlike older, more distant galaxies, it is close enough for astronomers to measure the properties of individual and binary stars.
In their study, the researchers measured different bands of light coming from the binary star (spectroscopic analysis), using data obtained over multiple periods of time by instruments on NASA’s Hubble Space Telescope (HST) and the Multi Unit Spectroscopic Explorer (MUSE) on ESO’s Very Large Telescope in Chile, among other telescopes, in wavelengths ranging from ultraviolet to optical to near infrared.
With this data, the team were able to calculate the radial velocity of the stars – that is, the movement they made towards or away from us – as well as their masses, brightness, temperature and orbits. They then matched these parameters with the best-fit evolutionary model.
Their spectroscopic analysis indicated that much of the outer envelope of the smaller star had been stripped away by its larger companion. They also observed the radius of both stars exceeded their Roche lobe – that is, the region around a star where material is gravitationally bound to that star – confirming that some of the smaller star’s material is overflowing and transferring to the companion star.
Talking through the future evolution of the stars, Rickard explained: “The smaller star will become a black hole first, in as little as 700,000 years, either through a spectacular explosion called a supernova or it may be so massive as to collapse into a black hole with no outward explosion.
“They will be uneasy neighbours for around three million years before the first black hole starts accreting mass from its companion, taking revenge on its companion.”
Pauli, who conducted the modelling work, added: “After only 200,000 years, an instant in astronomical terms, the companion star will collapse into a black hole as well. These two massive stars will continue to orbit each other, going round and round every few days for billions of years.
“Slowly they will lose this orbital energy through the emission of gravitational waves until they orbit each other every few seconds, finally merging together in 18 billion years with a huge release of energy through gravitational waves.”
JOURNAL
Astronomy and Astrophysics
METHOD OF RESEARCH
Observational study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
A low-metallicity massive contact binary undergoing slow Case A mass transfer: A detailed spectroscopic and orbital analysis of SSN 7 in NGC 346 in the SMC
ARTICLE PUBLICATION DATE
27-Apr-2023
Casting a safety net: A reliable machine
learning approach for analyzing
coalescing black holes
Self-checking algorithm interprets gravitational-wave data
Peer-Reviewed PublicationIMAGE: A MACHINE LEARNING METHOD WITH ROBUSTNESS GUARANTEES: BY COMPARING TO SIMULATED WAVEFORMS, THE DINGO NEURAL NETWORK VERIFIES ITS OWN RESULTS. DINGO FIRST CALCULATES THE PROPERTIES OF THE BLACK HOLES FROM THE MEASURED GRAVITATIONAL-WAVE SIGNAL. BASED ON THESE CALCULATED PARAMETERS, A GRAVITATIONAL WAVE IS MODELED, AND THEN COMPARED TO THE ORIGINALLY OBSERVED SIGNAL. view more
CREDIT: © M. DAX (MAX PLANCK INSTITUTE FOR INTELLIGENT SYSTEMS)
Tübingen, Potsdam – When two black holes merge, they emit gravitational waves that race through space and time at the speed of light. When these reach Earth, large detectors in the United States (LIGO), Italy (Virgo) and Japan (KAGRA) can detect the signals. By comparing against theoretical predictions, scientists can then determine the black holes' properties: masses, spins, orientation, position in the sky and distance from Earth.
A team of researchers from the Empirical Inference Department at the Max Planck Institute for Intelligent Systems (MPI-IS) in Tübingen and the Department of Astrophysical and Cosmological Relativity at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute/AEI) in Potsdam has now developed a self-checking deep learning system that very accurately extracts information from gravitational-wave data. In the process, the system checks its own predictions about the parameters of merging black holes – a deep neural network with a safety net. A set of 42 detected gravitational waves from merging black holes were successfully analyzed by the algorithm: When cross-checked against computationally expensive standard algorithms, the results were indistinguishable. The study was published on April 26, 2023 in the journal Physical Review Letters.
DINGO: a deep neural network for gravitational-wave analysis
The researchers have developed a deep neural network called DINGO (Deep INference for Gravitational-wave Observations) to analyze the data. DINGO has been trained to extract – or infer – the gravitational-wave source parameters from the detector data. There was a press release on this in December 2021. The network learned to interpret real (observed) gravitational-wave data after training with many millions of simulated signals in different configurations.
Trust, but verify
However, at first glance, it is not possible to tell whether the deep neural network is reading the information correctly. Indeed, one disadvantage of common deep learning systems is that their results sound plausible even when they are wrong. That's why the researchers at MPI-IS and AEI have added a control feature to the algorithm. Maximilian Dax, doctoral student in the Department of Empirical Inference at MPI-IS and first author of the publication explains: “We have developed a network with a safety net. First, the algorithm calculates the properties of the black holes from the measured gravitational-wave signal. Based on these calculated parameters, a gravitational wave is modeled, and then compared to the originally observed signal. The deep neural network can thus cross-check its own results and correct them in case of doubt.”
The algorithm controls itself, making it much more reliable than previous machine learning methods. But not only that. “We were surprised to discover that the algorithm is often able to identify anomalous events, namely real data inconsistent with our theoretical models. This information can be used to quickly ‘flag’ data for additional investigation,” says Stephen Green, co-lead author, and former Senior Scientist at the AEI (now at the University of Nottingham).
“We can guarantee the accuracy of our machine learning method – which almost never happens in the field of deep learning. It therefore becomes compelling for the scientific community to use the algorithm to analyze gravitational-wave data,” says Alessandra Buonanno, author and director of the Department Astrophysical and Cosmological Relativity at the AEI. Scientists from around the world are studying gravitational waves in large collaborations, such as the LIGO Scientific Collaboration (LSC), in which more than 1,500 researchers are organized.
Bernhard Schölkopf, who is a Director at MPI-IS, adds: “Today, DINGO analyzes gravitational-wave data – but such a self-controlling and self-correcting method is also interesting for other scientific applications where it is crucial to be able to corroborate the correctness of ‘black-box’ neural network methods.”
DINGO: a deep neural network for gravitational-wave analysis
CREDIT
© M. Dax (Max Planck Institute for Intelligent Systems)
Membership in the LSC
Maximilian Dax and Jonas Wildberger, the two Ph.D. students at MPI-IS, are also members of the LIGO Scientific Collaboration. Through this membership, they can quickly access the gravitational-wave detector data, and collaborate with the relevant working groups. Their goal is to develop DINGO into a standard method for the analysis of gravitational-wave data.
JOURNAL
Physical Review Letters
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Neural Importance Sampling for Rapid and Reliable Gravitational-Wave Inference
Doubling the number of sources of repeating fast radio bursts
New technique for identifying FRBs offers promise of further discoveries
Peer-Reviewed PublicationAstronomers from McGill University are part of an international team that has discovered 25 new sources of repeating fast radio bursts (FRBs), these explosions in the sky that come from far beyond the Milky Way. This discovery brings the total number of confirmed FRB sources to 50. Based on data gathered by the CHIME/FRB collaboration, the new study, published this week in The Astrophysical Journal, may also bring scientists closer to understanding the origins of these mysterious phenomena.
A new way of identifying FRBs
Thanks to the radio telescopes such as those at CHIME, which scan the entire northern sky every day, the number of detected FRBs has grown exponentially in recent years. The research team used a new set of statistical tools they developed to go over the data gathered by CHIME between September 30, 2019, and May 1, 2021, to confirm whether what they were saying were indeed FRBs.
“We combed through the data to find every repeating source detected so far, including the less obvious ones,” says Ziggy Pleunis, the first author of the paper who started working on the research as a PhD student at McGill University. He is now a Dunlap Postdoctoral Fellow at the Dunlap Institute for Astronomy and Astrophysics. “These new tools were essential for this study because we can now accurately calculate the probability that two or more bursts coming from similar locations are not just a coincidence. It should be very useful for similar research going forward.”
"These new discoveries will allow the scientific community to study more repeating FRBs in fantastic detail across the full electromagnetic spectrum and help answer a major open-question in the field: Do repeating and non-repeating FRBs originate from distinct populations?” Adds Aaron Pearlman, an FRQNT postdoctoral fellow at McGill University’s Trottier Space Institute who also collaborated on the paper. “I'm excited for the new insights that will be unlocked as a result of our study."
"It is exciting that CHIME/FRB saw multiple flashes from the same locations, as this allows for the detailed investigation of their nature,” says Adaeze Ibik, a PhD student in the David A. Dunlap Department for Astronomy and Astrophysics at the University of Toronto, who has led the search for the galaxies in which some of the newly identified repeating FRBs are embedded.
“We were able to hone in on some of these repeating sources and have already identified likely associated galaxies for two of them.”
Shedding light on the mysterious origins of FRBs
FRBs are considered one of the biggest mysteries in astronomy, but their exact origins are unknown. Astronomers do know that they come from far outside our Milky Way and are most likely produced by the cinders left behind after stars die.
One unexpected finding described in the paper is that contrary to what has previously been thought, all FRBs may be repeaters rather than one-offs. It is simply that many repeating FRBs are surprisingly inactive, producing fewer than one burst per week, and that the apparently one-off FRBs have simply not been observed for long enough until now for a second burst to be detected.
Pleunis notes that this new research brings us closer to understanding what FRBs are.
“FRBs are likely produced by the leftovers from explosive stellar deaths. By studying repeating FRB sources in detail, we can study the environments that these explosions occur in and understand better the end stages of a star's life. We can also learn more about the material that's being expelled before and during the star’s demise, which is then returned to the galaxies that the FRBs live in.”
The study:
“CHIME/FRB Discovery of 25 Repeating Fast Radio Burst Sources” by Bridget Andersen et al published in The Astrophysical Journal
DOI: 10.3847/1538-4357/acc6c1
The Trottier Institute:
The Trottier Space Institute at McGill is an interdisciplinary center that brings together researchers engaged in astrophysics, planetary science, atmospheric science, astrobiology and other space-related research at McGill University. The main goals of the Institute are to:
- Provide an intellectual home for faculty, research staff, and students engaged in astrophysics, planetary science, and other space-related research at McGill University.
- Support the development of technology and instrumentation for space-related research.
- Foster cross-fertilization and interdisciplinary interactions and collaborations among Institute members in Institute-relevant research areas.
- Share with students, educators, and the public an understanding of and an appreciation for the goals, techniques and results of the Institute's research.
JOURNAL
The Astrophysical Journal
ARTICLE TITLE
CHIME/FRB Discovery of 25 Repeating Fast Radio Burst Sources
ARTICLE PUBLICATION DATE
26-Apr-2023
Looking for insights from our nearest star-forming galaxy
Vallia Antoniou, an assistant professor of practice in the Department of Physics and Astronomy at Texas Tech, has been awarded observing time on the powerful Chandra X-Ray Telescope to explore some of the deepest recesses of the universe.
It marks the second major Chandra program led by Antoniou, who is also a research associate with the Smithsonian Astrophysical Observatory.
Each year, astronomers from around the world follow a rigorously competitive process to receive Chandra time. The telescope was launched aboard the space shuttle Columbia in 1999 and orbits Earth, offering previously unavailable views of deep space at wavelengths that are not accessible from ground telescopes. During its more than two decades in space, the telescope has revolutionized the field of X-ray astronomy.
“The main idea is to study nearby star-forming galaxies, the Large Magellanic Cloud,” Antoniou said. “It gives us an opportunity to study analogs of much more distant galaxies, yet obviously outside our Milky Way galaxy.”
The program focuses on the Large Magellanic Cloud, the nearest star-forming galaxy which orbits the Milky Way at approximately 160,000 light-years from Earth.
Antoniou, also the director of the Preston Gott Skyview Observatory about 15 miles north of Lubbock, was awarded one mega-second of Chandra telescope time, which equates to roughly 11.5 days (a mega-second is 1 million seconds).
Her proposal in the Very Large Program (VLP) category was approved for the specific viewing cycle in late June. Since the VLP category was first introduced in 2017, only seven VLPs have been awarded time from among the 64 proposed.
Early findings should be available to the public late this summer, she said.
Her research focuses on understanding the formation and evolution of X-ray binaries in different galactic environments. The sheer distances involved can impede this work, making access to powerful telescopes necessary.
“Chandra’s proposal selection process is highly competitive, and Vallia’s research program was the only VLP approved out of nine submitted in Cycle 24,” said Sung-Won Lee, chair of the physics and astronomy department. “This project is an international collaboration of scientists, and I am very pleased that our very own faculty is recognized internationally and will lead this important scientific mission.”
Antoniou said the awarded telescope time should give the team additional insights into the populations of stellar remnants such as pulsars and black holes and their behavior when they consume the stars orbiting them (so-called X-ray binaries).”
The team has selected 10 regions of the Large Magellanic Cloud, focusing on areas of the galaxy that they expect to have high X-ray binary formation rates, which in turn will provide a deeper understanding of the system and stars. The program completes an effort started by Antoniou studying the smaller sibling of the Large Magellanic Cloud, the Small Magellanic Cloud, which was awarded time as a Chandra X-Ray Visionary Program.
“This is another good example that our department is conducting very competitive research internationally,” Lee said.
