Astronomy

Physical and Environmental Sciences

Canadian Institute for Theoretical Astrophysics

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Climate Change

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��˾��ֱ�� Scarborough

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An atmospheric tide driven by the sun countered the effect of the moon, astrophysicists say

A team of astrophysicists from the University of Toronto has revealed how the slow and steady lengthening of Earth’s day caused by the tidal pull of the moon was halted for over a billion years.

They show that from approximately two billion years ago until 600 million years ago, an atmospheric tide driven by the sun countered the effect of the moon, keeping Earth’s rotational rate steady and the length of day at a constant 19.5 hours.

Without this billion-year pause in the slowing of our planet’s rotation, our current 24-hour day would stretch to over 60 hours.

Drawing on geological evidence and using atmospheric research tools, the scientists show that the tidal stalemate between the sun and moon resulted from the incidental but consequential link between the atmosphere’s temperature and Earth’s rotational rate.

The study was published in the journal Science Advances.

The paper’s authors include Professor Norman Murray, a theoretical astrophysicist with the Faculty of Arts & Science’s Canadian Institute for Theoretical Astrophysics (CITA); graduate student Hanbo Wu, with CITA and the department of physics; Kristen Menou, associate professor in the David A. Dunlap department of astronomy and astrophysics and the department of physical and environmental sciences at ��˾��ֱ�� Scarborough; Jeremy Leconte, a CNRS researcher at the Laboratoire d’astrophysique de Bordeaux and a former CITA postdoctoral fellow; and Christopher Lee, assistant professor in the department of physics.

Murray and his collaborators relied on geologic evidence in their study, like these samples from a tidal estuary that reveal the cycle of spring and neap tides. Thick bands correspond to spring tides, and thin bands to neap tides (image by G.E. Williams)

When the moon first formed some 4.5 billion years ago, the day was less than 10 hours long. But since then, the moon’s gravitational pull on the Earth has been slowing our planet’s rotation, resulting in an increasingly longer day. Today, it continues to lengthen at a rate of some 1.7 milliseconds every century.

The moon slows the planet’s rotation by pulling on Earth’s oceans, creating tidal bulges on opposite sides of the planet that we experience as high and low tides. The gravitational pull of the moon on those bulges, plus the friction between the tides and the ocean floor, acts like a brake on our spinning planet.

“Sunlight also produces an atmospheric tide with the same type of bulges,” says Murray. “The sun's gravity pulls on these atmospheric bulges, producing a torque on the Earth. But instead of slowing down Earth’s rotation like the moon, it speeds it up.”

For most of Earth’s geological history, the lunar tides have overpowered the solar tides by about a factor of ten – hence the Earth’s slowing rotational speed and lengthening days.

But some two billion years ago, the atmospheric bulges were larger because the atmosphere was warmer and because its natural resonance – the frequency at which waves move through it – matched the length of day.

The atmosphere, like a bell, resonates at a frequency determined by various factors, including temperature. In other words, waves – like those generated by the enormous eruption of the volcano Krakatoa in Indonesia in 1883 – travel through it at a velocity determined by its temperature. The same principle explains why a bell always produces the same note if its temperature is constant.

Throughout most of Earth’s history that atmospheric resonance has been out of sync with the planet’s rotational rate. Today, each of the two atmospheric “high tides” take 22.8 hours to travel around the world. Since that resonance and Earth’s 24-hour rotational period are out of sync, the atmospheric tide is relatively small.

But during the billion-year period under study, the atmosphere was warmer and resonated with a period of about 10 hours. Also, at the advent of that epoch, Earth’s rotation – slowed by the moon – reached 20 hours.

When the atmospheric resonance and length of day became even factors (ten and 20), the atmospheric tide was reinforced, the bulges became larger and the sun’s tidal pull became strong enough to counter the lunar tide.

“It’s like pushing a child on a swing,” Murray says.

“If your push and the period of the swing are out of sync, it’s not going to go very high. But, if they’re in sync and you’re pushing just as the swing stops at one end of its travel, the push will add to the momentum of the swing and it will go further and higher. That’s what happened with the atmospheric resonance and tide.”

Along with geological evidence, Murray and his colleagues achieved their result using global atmospheric circulation models (GCMs) to predict the atmosphere’s temperature during this period. The GCMs are the same models used by climatologists to study global warming. Murray says the fact they worked so well in the team’s research is a timely lesson.

“I've talked to people who are climate-change skeptics who don't believe in the global circulation models that are telling us we’re in a climate crisis,” he says. “And I tell them: We used these global circulation models in our research, and they got it right. They work.”

Despite its remoteness in geological history, the result adds additional perspective to the climate crisis. Because the atmospheric resonance changes with temperature, Murray points out that our current warming atmosphere could have consequences in this tidal imbalance.

“As we increase Earth's temperature with global warming, we’re also making the resonant frequency move higher – we’re moving our atmosphere farther away from resonance. As a result, there's less torque from the sun and therefore the length the day is going to get longer – sooner than it would otherwise.”

Astronomers discover new link between dark matter and 'clumpiness' of the universe

Christopher.Sorensen — Wed, 28 Jun 2023 17:30:06 +0000

Astronomers discover new link between dark matter and 'clumpiness' of the universe

Christopher.Sorensen Wed, 06/28/2023 - 13:30

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(image by Volker Springel (Max Planck Institute for Astrophysics) et al)

Chris Sasaki

Topic

Astronomy & Astrophysics

Research

Researchers at the University of Toronto have revealed a theoretical breakthrough that may explain both the nature of invisible dark matter and the large-scale structure of the universe known as the cosmic web.

Their study, published in the Journal of Cosmology and Astroparticle Physics, establishes a new link between these two longstanding problems in astronomy, opening new possibilities for understanding the cosmos.

Keir Rogers (supplied image)

The research suggests that the “clumpiness problem,” which centres on the unexpectedly even distribution of matter on large scales throughout the cosmos, may be a sign that dark matter is composed of hypothetical, ultra-light particles called axions.

The implications of proving the existence of hard-to-detect axions extend beyond understanding dark matter and could address fundamental questions about the nature of the universe itself.

“If confirmed with future telescope observations and lab experiments, finding axion dark matter would be one of the most significant discoveries of this century,” says lead author Keir Rogers, Dunlap Fellow at the Dunlap Institute for Astronomy & Astrophysics in the Faculty of Arts & Science .

“At the same time, our results suggest an explanation for why the universe is less clumpy than we thought – an observation that has become increasingly clear over the last decade or so, and currently leaves our theory of the universe uncertain.”

Dark matter, comprising 85 percent of the universe’s mass, is invisible because it does not interact with light. Scientists study its gravitational effects on visible matter to understand how it is distributed in the universe.

A leading theory proposes that dark matter is made of axions, described in quantum mechanics as “fuzzy” due to their wave-like behaviour. Unlike discrete point-like particles, axions can have wavelengths larger than entire galaxies. This fuzziness influences the formation and distribution of dark matter, potentially explaining why the universe is less clumpy than predicted in a universe without axions.

A computer simulation of a section of the universe with and without axions, showing how the dark matter cosmic web structure is less clumpy if containing axions. For scale, the Milky Way galaxy would sit inside one of the small green dots that are called halos (image by Alexander Spencer London/Alex Laguë)

This lack of clumpiness has been observed in large galaxy surveys, challenging the other prevailing theory that dark matter consists only of heavy, weakly interacting sub-atomic particles called WIMPs. Despite experiments like the Large Hadron Collider, no evidence supporting the existence of WIMPs has been found.

“In science, it’s when ideas break down that new discoveries are made and age-old problems are solved,” Rogers says.

For the study, the research team – led by Rogers and including members of associate professor Renée Hložek’s research group at the Dunlap Institute, as well as from the University of Pennsylvania, the Institute for Advanced Study, Columbia University and King’s College London – analyzed observations of relic light from the Big Bang, known as the Cosmic Microwave Background (CMB), obtained from prior telescope surveys.

The researchers compared these CMB data with galaxy clustering data from the Baryon Oscillation Spectroscopic Survey (BOSS), which maps the positions of approximately a million galaxies in the nearby universe. By studying the distribution of galaxies, which mirrors the behaviour of dark matter under gravitational forces, they measured fluctuations in the amount of matter throughout the universe and confirmed its reduced clumpiness compared to predictions.

A map of galaxies in the local universe as seen by the Sloan Digital Sky Survey, which the researchers used to test the axion theory. Each dot is the position of a galaxy and the Earth sits in the middle of the map
(image courtesy Sloan Digital Sky Survey)

The researchers then conducted computer simulations to predict the appearance of relic light and the distribution of galaxies in a universe with long dark matter waves. These calculations aligned with CMB data from the Big Bang and galaxy clustering data, supporting the notion that fuzzy axions could account for the clumpiness problem.

Future research will involve large-scale surveys to map millions of galaxies and provide precise measurements of clumpiness, including observations over the next decade with the Rubin Observatory. The researchers hope to compare their theory to direct observations of dark matter through gravitational lensing – an effect where dark matter clumpiness is measured by how much it bends the light from distant galaxies, akin to a giant magnifying glass. They also plan to investigate how galaxies expel gas into space and how this affects the dark matter distribution to further confirm their results.

Understanding the nature of dark matter is one of the most pressing fundamental questions and key to understanding the origin and future of the universe.

Presently, scientists do not have a single theory that simultaneously explains gravity and quantum mechanics – a theory of everything. The most popular theory of everything over the last few decades is string theory, which posits another level below the quantum level, where everything is made of string-like excitations of energy. According to Rogers, detecting a fuzzy axion particle could be a hint that the string theory of everything is correct.

“We have the tools now that could enable us to finally understand something experimentally about the century-old mystery of dark matter, even in the next decade or so – and that could give us hints to answers about even bigger theoretical questions,” Rogers says.

“The hope is that the puzzling elements of the universe are solvable.”

Astronomers double number of known 'repeating fast radio bursts' using new data tools

Christopher.Sorensen — Mon, 01 May 2023 15:35:57 +0000

Astronomers double number of known 'repeating fast radio bursts' using new data tools

Christopher.Sorensen Mon, 05/01/2023 - 11:35

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An artist’s impression of the CHIME telescope, used by researchers from the CHIME/FRB Collaboration in detecting flashes of radio waves known as 'fast radio bursts' (illustration by CHIME/FRB Collaboration, with artistic additions by Luka Vlajić)

Meaghan MacSween

Topic

Astronomy & Astrophysics

Research

Space

Astronomers in the Canadian-led CHIME/FRB Collaboration – including researchers from the University of Toronto – have doubled the number of known repeating sources of mysterious flashes of radio waves, known as fast radio bursts (FRBs). Through the discovery of 25 new repeating sources (for a total of 50), the team has also solidified the idea that all FRBs may eventually repeat.

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 of our Milky Way, and are likely produced by the cinders left behind after stars die. Most of the thousands of FRBs that astronomers have discovered to date have only ever been seen to burst once, but there is a small subset that have been seen to burst multiple times.

One of the big questions is whether the repeating FRBs, and those that don’t repeat, have similar origins. One key clue is that the two populations seem to have different characteristics – such as the durations of the bursts they produce and the range of frequencies emitted. This has led to the consensus that there are possibly two distinct categories of FRBs: repeaters and one-offs, with different origins.

Finding more repeating sources is key to answering this question – and in new research published in the Astrophysical Journal, the CHIME/FRB Collaboration presents 25 new sources. While the team had previously established repeating FRBs as a class of sources, this is the first time they have combed through the data to find every repeating source detected so far, including the less obvious ones. To make this happen, the group developed a new set of statistics tools.

The CHIME telescope in Penticton, B.C. (photo by Andre Renard/CHIME/FRB Collaboration)

“We can now accurately calculate the probability that two or more bursts coming from similar locations are not just a coincidence,” explains Ziggy Pleunis, a Dunlap postdoctoral fellow at the Dunlap Institute for Astronomy & Astrophysics and corresponding author of the publication. “These new tools were essential for this study, and will also be very useful for similar research going forward.”

Thanks to radio telescopes like the Canadian Hydrogen Intensity Mapping Experiment (CHIME), the number of detected FRBs has grown from less than a hundred to thousands in recent years due to CHIME’s capacity to scan the entire northern sky every day.

“That’s how CHIME has an edge over other telescopes when it comes to discovering FRBs,” Pleunis says.

In their new research, the CHIME/FRB Collaboration has demonstrated that many repeating FRBs are surprisingly inactive, producing less than one burst per week of observing time.

“Many apparently one-off FRBs have simply not yet been observed long enough for a second burst from the source to be detected,” Pleunis explains.

Repeating sources of FRBs are uniquely valuable to astronomers. First, knowing that a source is a repeater creates an opportunity to observe that same source with other telescopes in more detail. Secondly, more bursts offer more information on the diversity of emission that a source can produce.

“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 of astronomy and astrophysics in the Faculty of Arts & Science.

Ibik has led the search for the galaxies in which some of the newly identified repeating FRBs are embedded, as reported in an accompanying research publication currently under review. “We were able to hone in on some of these repeating sources and have already identified likely associated galaxies for two of them.”

Pleunis notes that this new discovery brings astronomers closer to understanding what FRBs are – leading to even further-reaching implications.

“FRBs are likely produced by the leftovers from explosive stellar deaths.” Pleunis says. “By studying repeating FRB sources in detail, we can study the environments that these explosions occur in and better understand 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 CHIME project is co-led by the University of British Columbia, McGill University, University of Toronto and the Dominion Radio Astrophysical Observatory, with collaborating institutions across North America.

CHIME’s research is funded by the Canadian Foundation for Innovation’s Leading Edge Fund, by contributions from the province of British Columbia and Quebec, and by ��˾��ֱ��’s Dunlap Institute for Astronomy and Astrophysics, among other sources.

First space images captured by balloon-borne telescope

siddiq22 — Fri, 21 Apr 2023 13:34:16 +0000

First space images captured by balloon-borne telescope

siddiq22 Fri, 04/21/2023 - 09:34

Cutline

A false-colour image of the “Tarantula Nebula” taken in visible and ultraviolet light by the SuperBIT telescope shortly after launch (image courtesy of SuperBIT)

Topic

Astronomy & Astrophysics

Astrophysics

Faculty & Staff

Graduate Students

Research

Astronomers have successfully launched a balloon-borne telescope that has begun capturing images of the universe on its first flight above the Earth’s atmosphere.

The Super Pressure Balloon-Borne Imaging Telescope (SuperBIT) was flown to the edge of space by a helium-filled NASA scientific balloon the size of a football stadium. There, it will help researchers investigate the mystery of dark matter.

SuperBIT has already taken its first images on this flight, showing the “Tarantula Nebula” – a bright cluster of gas and dust in a galaxy neighbourhood near our Milky Way – and the collision between the two galaxies NGC 4038 and NGC 4039, known as “the Antennae.”

SuperBIT is a collaboration between the University of Toronto, Princeton University, Durham University and NASA.

“A dedicated team of students developing one of the world’s great telescopes – it’s inspiring,” says Barth Netterfield, a professor in ��˾��ֱ��'s David A. Dunlap department of astronomy and astrophysics and the department of physics in the Faculty of Arts & Science, and an associate at the Dunlap Institute for Astronomy and Astrophysics.

“After a decade of tremendous effort, we are getting these exquisite images with a wide range of science goals, which will help us to better understand the universe.”

A false-colour image taken by the SuperBIT telescope shows of a pair of galaxies smashing into each other (image courtesy of SuperBIT)

The balloon aunched from Wānaka, New Zealand earlier this week, following a two-year delay due to the COVID pandemic.

Carried by seasonally stable winds for about three months, SuperBIT will circumnavigate the southern hemisphere several times – imaging the sky all night, then using solar panels to recharge its batteries during the day.

SuperBIT flies at an altitude of 33.5 kilometres, above 99.5 per cent of the Earth’s atmosphere. It takes high-resolution images like those from the Hubble Space Telescope, but with a much wider field of view.

The scientific goal for the first flight is to measure the properties of dark matter, a heavy but invisible type of material.

SuperBIT will test whether dark-matter particles can bounce off each other, by mapping the dark matter around clusters of galaxies that are colliding with neighbouring galaxy clusters.

The SuperBIT telescope in New Zealand prior to the launch (photo courtesy of Columbia Scientific Balloon Facility)

Various theories suggest that some dark matter might either slow down, spread out, or get chipped off during a collision.

Although dark matter is invisible, SuperBIT will map where it is by the way it bends passing rays of light – a technique known as gravitational lensing.

While telescopes on the ground must squint through the Earth’s atmosphere – meaning their view can become blurred – space-based telescopes get a clear view of the light that has travelled billions of years from the distant universe.

Members of the SuperBIT team prepare for a flight test (photo courtesy of SuperBIT)

SuperBIT is the first balloon-borne telescope capable of taking wide-field images – its sharpness of vision is not affected by the atmosphere, but only by the laws of optics.

During its final test flight in 2019, SuperBIT demonstrated extraordinary pointing stability.

“Imagine you’re trying to thread a needle that’s 2.5 kilometres away – so roughly 30 city blocks,” explains Emaad Paracha, a PhD candidate in the department of physics.

“SuperBIT has the ability to point to the exact spot you’d need that needle to be thread, while keeping that thread from touching the sides of the needle for up to 60 minutes.”

SuperBIT cost about US$5 million – almost 1,000 times less than an equivalent satellite. Not only is helium cheaper than rocket fuel, but the ability of SuperBIT to return to Earth via parachute meant the team could tweak its design over several test flights.

“A successful SuperBIT launch paves the way to a future in which individual academic institutions are able to design, develop and operate world-class space instruments at a low cost, while also providing the training opportunity for instrument development and data analysis for the students,” says Ajay Gill, a PhD candidate at the David A. Dunlap department of astronomy and astrophysics and the Dunlap Institute.

SuperBIT can also be upgraded on a regular basis. For example, the development team buys a new camera shortly before each launch, because modern detectors are improving so rapidly.

The team already has funding to upgrade SuperBIT’s 0.5-metre telescope to 1.6 metres, which would boost light gathering power tenfold, with a wider-angle lens and more megapixels.

The relatively cheap cost may even make it possible for a fleet of balloon-borne telescopes to offer time to astronomers around the world. Interested members of the public can track SuperBIT's flight status on NASA's website.

The mission was funded by NASA, the Canadian Space Agency, the Royal Society and ��˾��ֱ��'s Dunlap Institute for Astronomy and Astrophysics.

With notes from Meaghan MacSween

Add new author/reporter

Leighton Kitson

International team of astronomers discovers two rare binary star systems

lanthierj — Mon, 11 Jul 2022 20:31:04 +0000

International team of astronomers discovers two rare binary star systems

lanthierj Mon, 07/11/2022 - 16:31

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Original illustration of protoplanetary disc by Sahl Rowther, et al, (https://doi.org/10.3847/1538-4357/ac3975); with binary stars added by Poon, et al. (images by Poon, Zhu, Zanazzi, ��˾��ֱ��; Sahl Rowther, et al, Warwick University)

Chris Sasaki

Topic

Graduate Students

Research & Innovation

Space

An international team of astronomers has identified only the second and third examples of a rare type of star system comprising two central stars orbiting each other, encompassed by a remarkable disk of gas and dust.

“If there were a planet in one of these systems, it would be like the planet Tatooine from Star Wars,” says Michael Poon, a PhD student in the Faculty of Arts & Science’s David A. Dunlap Department of Astronomy & Astrophysics and one of two University of Toronto researchers involved in the discovery.

“You would see two suns in the sky orbiting each other. In addition, there’s a disk around the stars. Picture Saturn's rings but much, much larger – with the stars in the middle.”

Such disks are referred to as protoplanetary disks because they eventually form into families of planets like our solar system. The newly discovered systems are rare because their disks lie at an angle to the orbits of their central stars.

“The discovery of objects like these is important for our understanding of planet formation,” says J.J. Zanazzi, a postdoctoral fellow in the faculty’s Canadian Institute for Theoretical Astrophysics (CITA). “Planets are born from them so the existence of disks around binary stars shows it’s likely we will find more planets orbiting binaries.

“They’ll also help us understand whether life can exist on a planet that orbits a binary star at an angle because of how that orientation affects temperature and other conditions.”

The discovery of the new objects, designated Bernhard-1 and Bernhard–2, is described in a paper being published July 4 in the Astrophysical Journal Letters.

The lead author is Wei Zhu from Tsinghua University, Beijing, formerly a postdoctoral fellow with the Faculty of Arts & Science’s Canadian Institute for Theoretical Astrophysics (CITA). Zanazzi and Poon are ��˾��ֱ�� co-authors.

Bernhard-1 and Bernhard-2 are so distant, we can’t see their two central stars individually (such pairs of stars are known as binary stars). Instead, we only see a single point of light and measure the total brightness of the binary.

The researchers identified the new objects by analyzing the complex and distinctive variations in brightness caused by their unusual geometry. A graph of those variations over time is referred to as a light curve and the light curves of the new systems match that of the first such system ever discovered – an object referred to as Kearns Herbst 15D (KH 15D).

The light curves of Bernhard-1 and Bernhard-2 dip to a fraction of their peak brightness – the former for 112 days every 192 days; the latter for 20 days every 62 days. These dips are the sign that one of the stars in each binary is moving behind the disk as seen from Earth. When the star re-emerges, the brightness of the system returns to normal.

Also, when the co-authors compared recent observations with archival data going back decades, they found that both objects varied in brightness over much longer periods. Previous analysis of KH 15D by Poon, Zhu and Zanazzi, along with the work of other researchers, concluded that this long-term pattern revealed that the disk and stars were at an angle to each other.

Because binary stars and their protoplanetary disks condense from the same vast, spinning cloud of material, the disk typically lies in the same plane as the orbits of the stars – just as the orbits of most of the planets and moons in our solar system lie on the same plane. Imagine two figure skaters, holding hands, twirling around each other while other skaters circle the pair; all are skating on the same plane of the surface of the ice.

But KH 15D, Bernhard-1 and Bernhard-2 are rare in that their circumbinary disks are at an angle to the planes of the orbiting stars. Because of this tilt, the disks wobble like a spinning top, a motion referred to as precession, as they move between us and the stars, causing the light of the central stars to dim. For KH 15D, that cycle of dimming could take anywhere from 60 to 6,000 years.

The two types of variations in brightness combine to create the signature light curve of KH 15D-like objects.

The discovery of Bernhard-1 and Bernhard-2 was made when Klaus Bernhard, an amateur astronomer and member of the Bundesdeutsche Arbeitsgemeinschaft für Veränderliche Sterne, analyzed data from the Zwicky Transient Facility. The ZTF’s instrument surveys the entire northern sky every two days, providing data for countless objects over long stretches of time.

Combing through the data, Bernhard uncovered KH 15D-like candidates. He then shared his findings with Poon, Zanazzi and Zhu whose further analysis revealed Bernhard-1 and Bernhard–2.

Now that the researchers have found two more of these rare celestial objects, they are optimistic more discoveries will follow.

“Just this month, Gaia released its most recent data,” says Zanazzi of the space mission that has been observing a billion stars in the Milky Way Galaxy since its launch in 2013. “And now that we have this model for these objects, we’re hopeful we can use it to find more objects to add to the list.”

“We’re also hopeful more observers will look at Bernhard-1 and Bernhard–2 for longer periods,” says Poon. “We’re lucky that KH 15D has been observed at a special time where its orientation causes the light of the central stars to dim. We’re confident that Bernhard-1 and Bernhard-2 also exist in this favourable orientation, so having more observations will increase our understanding of these rare objects.”

Hubble Space Telescope captures largest near-infrared image to find universe’s rarest galaxies

geoff.vendeville — Mon, 06 Jun 2022 15:02:06 +0000

Hubble Space Telescope captures largest near-infrared image to find universe’s rarest galaxies

geoff.vendeville Mon, 06/06/2022 - 11:02

Cutline

Galaxies from the last 10 billion years witnessed in the 3D-DASH program, created using 3D-DASH/F160W and ACS-COSMOS/F814W imaging (image by Lamiya Mowla)

Josslyn Johnstone

Topic

Faculty of Applied Science & Engineering

Research and Innovation

Space

An international team of scientists recently released the largest near-infrared image ever taken by NASA’s Hubble Space Telescope, enabling astronomers to map the star-forming regions of the universe and learn how the earliest, most distant galaxies originated. Named 3D-DASH, this high-resolution survey will allow researchers to find rare objects and targets for follow-up observations with the recently launched James Webb Space Telescope (JWST) during its decades-long mission.

A preprint of the paper to be published in The Astrophysical Journal is available on arXiv.

Lamiya Mowla

“Since its launch more than 30 years ago, the Hubble Space Telescope has led a renaissance in the study of how galaxies have changed in the last 10 billion years of the universe,” says Lamiya Mowla, Dunlap Fellow at the Faculty of Arts & Science’s Dunlap Institute for Astronomy & Astrophysics at the University of Toronto and lead author of the study.

“The 3D-DASH program extends Hubble’s legacy in wide-area imaging so we can begin to unravel the mysteries of the galaxies beyond our own.”

For the first time, 3D-DASH provides researchers with a complete near-infrared survey of the entire COSMOS field, one of the richest data fields for extragalactic studies beyond the Milky Way. As the longest and reddest wavelength observed with Hubble – just beyond what is visible to the human eye – near-infrared means astronomers are better able to see the earliest galaxies that are the farthest away.

Astronomers also need to search a vast area of the sky to find rare objects in the universe. Until now, such a large image was only available from the ground and suffered from poor resolution, which limited what could be observed. 3D-DASH will help to identify unique phenomena like the universe’s most massive galaxies, highly active black holes, and galaxies on the brink of colliding and merging into one.

The Hubble Space Telescope captured the entire COSMOS field by stitching together multiple images into one master image, a process called mosaicing (animation by Ivelina Momcheva)

“I am curious about monster galaxies, which are the most massive ones in the universe formed by the mergers of other galaxies. How did their structures grow, and what drove the changes in their form?” says Mowla, who began working on the project in 2015 as a graduate student at Yale University. “It was difficult to study these extremely rare events using existing images, which is what motivated the design of this large survey.”

To image such an expansive patch of sky, the researchers employed a new technique with Hubble known as Drift And SHift (DASH). DASH creates an image that is eight times larger than Hubble’s standard field of view by capturing multiple shots that are then stitched together into one master mosaic, similar to taking a panoramic picture on a smartphone.

DASH also takes images faster than the typical technique, snapping eight pictures per Hubble’s orbit instead of one picture, achieving in 250 hours what would previously have taken 2,000 hours.

“3D-DASH adds a new layer of unique observations in the COSMOS field and is also a steppingstone to the space surveys of the next decade,” says Ivelina Momcheva, head of data science at the Max Planck Institute for Astronomy and principal investigator of the study. “It gives us a sneak peek of future scientific discoveries and allows us to develop new techniques to analyze these large datasets.”

A patch of sky imaged by 3D-DASH, showing the brightest and rarest objects of the universe such as monster galaxies (image by Gabe Brammer)

3D-DASH covers a total area almost six times the size of the moon in the sky as seen from Earth. This record is likely to remain unbroken by Hubble’s successor, JWST, which is instead built for sensitive, close-up images to capture fine detail of a small area. It is the largest near-infrared image of the sky available to astronomers until the next generation of telescopes launch in the next decade, such as the Nancy Grace Roman Space Telescope and Euclid.

Until then, professional astronomers and amateur stargazers alike can explore the skies using an interactive, online version of the 3D-DASH image created by Gabriel Brammer, a faculty member at the Cosmic Dawn Center in the Niels Bohr Institute, University of Copenhagen.

The Hubble Space Telescope is a project of international cooperation between NASA and European Space Agency (ESA). NASA's Goddard Space Flight Center manages the telescope in Greenbelt, Maryland. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.

The full image is available at the Mikulski Archive for Space Telescopes.

��˾��ֱ�� students who crushed it in 2018

geoff.vendeville — Tue, 18 Dec 2018 18:15:14 +0000

��˾��ֱ�� students who crushed it in 2018

geoff.vendeville Tue, 12/18/2018 - 13:15

Cutline

The Indigenous Studies Students' Union held a powwow in the Goldring Centre in March. Hundreds of people showed up to celebrate Indigenous communities, cultures and languages (photo by Laura Pedersen)

Topic

Undergraduate Students

Victoria College

It would be difficult to overstate the hard work and achievement of University of Toronto students this year. They literally went to the ends of the Earth.

Matt Young, a PhD student in astronomy, returned from a two-month-long trip to Antarctica, where he helped upgrade a camera on a one-tonne telescope at a research station. The instrument observes the cosmic microwave background – electromagnetic radiation left by the Big Bang – that offers clues about the early universe.

Closer to home, the accomplishments of ��˾��ֱ�� students were equally impressive. They overcame difficulties to succeed in their studies, held events enriching life on campus and inspired others with their dedication to learning.

Here's just a small sample of what they were up to this year:

The ��˾��ֱ�� students who kept up the tradition of Black graduation

Students prepare to make a grand entrance at Black graduation in Hart House's Great Hall (photo by Geoffrey Vendeville)

Black graduations, or commencements, have become a fixture of university calendars south of the border, including at Harvard and Stanford. In 2017, ��˾��ֱ�� students made history by organizing what was believed to be Canada's first Black graduation ceremony.

This year, Ayaan Abdulle, Matthew Campbell-Williams, Anyika Mark and a dedicated team of volunteers carried the torch. They invited Dionne Brand, a past Toronto poet laureate and winner of the Governor General’s Award who received an honorary degree from ��˾��ֱ��, to deliver a guest lecture. And the class of '18 toasted their accomplishments in style, filing into Hart House's Great Hall to the tune of “To Be Young, Gifted and Black.”

From a Tibetan refugee camp to ��˾��ֱ�� Dentistry

The road to ��˾��ֱ�� was a tough one for Khamsum Wangdu. He and his brother grew up in Nepal in a Tibetan refugee camp. They were training to be dentists, but before they could take their licensing exams, the 2015 earthquake struck, killing 9,000 people and injuring 22,000.

Amid assisting with medical and relief efforts, they learned that Canadian authorities had fast-tracked their family’s sponsorship application. They were both accepted to dentistry schools in Canada – Khamsum at ��˾��ֱ�� and his brother Kunsang at Dalhousie University. Khamsum got into an accelerated program for internationally trained dentists and is due to graduate in 2020.

“Being accepted into the University of Toronto is not simply a dream come true, it is the chance of a lifetime,” he said.

The student who made his voice heard

Behzad Farkhari performed on the big Bollywood stage over the summer (photo via Facebook)

Behzad Farkhari, in neuroscience and psychology at ��˾��ֱ�� Scarborough, overcame his boyhood shyness to perform Bollywood songs. This summer, he got to perform on the biggest stage yet of his career on Dil Hai Hindustani, the Indian equivalent of American Idol. He placed ninth among the 21,000 musicians who auditioned for the reality show.

The undergraduate who made the most of university and inspired others to do the same

Allie Sinclair proved good grades don't have to come at the cost of everything else. She was involved in research from her very first week at ��˾��ֱ��, landing a position in a psychology lab. As an undergraduate, she took the stage as part of the Victoria College Drama Society, went for hikes, mentored other students and even co-wrote a paper that was accepted for publication in a scholarly journal.

She graduated last year at the top of her class with a GPA of 4.0. But before leaving ��˾��ֱ�� for graduate school in the U.S., she and fellow top students from previous years shared some advice.

The student who was the picture of perseverance

Elspeth Arbow during a physiotherapy session at Toronto General Hospital after her double-lung transplant (photo by Geoffrey Vendeville)

There was no stopping Elspeth Arbow, even when she became so short of breath that she struggled to get to class. The cinema studies student at Innis College kept up with her studies and won a student leadership award despite cystic fibrosis, which sapped her energy and required her to undergo a double-lung transplant for the second time in 10 years. She recovered from the operation and began her final semester this fall.

The scholarship winner who was the first in her Kenyan village to study abroad

Emmanuela Alimlim grew up in a rural Kenyan village of about 100 people, in family of 12 kids. She was the first person from her village to study abroad when she came to ��˾��ֱ�� to take economics on a Mastercard Foundation Scholarship.

In Toronto, she overcame the stresses of living thousands of kilometres away from home, in a place with a very different climate and customs, to contribute meaningfully to life on campus. She founded the Eastern African Students' Association and a non-profit that supports the education of girls and women back in Kenya.

��˾��ֱ��'s newest Rhodes Scholar

Edil Ga'al made friends and found supportive staff at ��˾��ֱ��'s Victoria College (photo by Nick Iwanyshyn)

At ��˾��ֱ��, students are encouraged to engage with the world. Edil Ga'al lived up to those expectations and then some.

African studies and political science were the subjects that spoke to her. The Victoria College student explored them in the classroom and beyond, completing an internship at a human-rights NGO in Uganda and making two trips to Rwanda.

In December, she was one of only 11 Canadian students to receive a Rhodes Scholarship to continue their education at Oxford. She hopes to contribute to discussions on peace, stability and justice as an academic or fieldworker. “I know it’s a lofty goal, but you kind of have to dream big,” she said.

The engineering student who had a hand in an Oscar-winning film

There are no small parts in a film. The same could be said for the work behind the scenes. Charlie Katrycz, in mechanical engineering, contributed to Guillermo del Toro's and The Shape of Water's Oscar glory in 2018 by helping to build the tank for the movie's amphibian man.

Outstanding Indigenous students who organized a powwow and gave back to their communities

Dancers at the 2018 powwow at the Goldring Centre organized by the Indigenous Studies Students' Union (photo by Laura Pedersen)

Indigenous students organized the first powwow on campus in 20 years in 2017. This year, the expected attendance was so great that the event was moved to the Goldring Centre for High Performance Sport.

Hundreds of people turned out, some hailing from northern Ontario, to celebrate Indigenous students, language and culture. Students, staff and faculty danced across the gym floor together.

Earlier this year, two Indigenous students with an impressive track record inside the classroom and beyond were recognized with the President's Award for Outstanding Indigenous Student of the Year. Julie Blair returned to school after a 20-year hiatus to earn a 3.9 GPA and lead Indigenous committees and clubs. Meanwhile, PhD student Rebecca Beaulne-Stuebing studied the untold histories of Anishinaabe-led schools in relation to Indigenous activist movements.

The quadruple threat

Abigail Whitney operates with the same 24 hours a day as the rest of us, but she’s found the time to be a student, actor, model and director. Whitney, a University College student, was the face of a national ad campaign for Sephora, she appeared in CoverGirl and Vogue Italia and made her directorial debut with the UC Follies' show, Les Frères (The Brothers) by Sandra A. Daley-Sharif.

The scientist who went to the bottom of the Earth

Matt Young took a selfie at the South Pole while on a research trip during his PhD studies at ��˾��ֱ�� (photo courtesy of Matt Young)

A research station at the South Pole bears the names of two legendary early 20^th-century explorers who ventured into the icy unknown. Matt Young's adventure to the South Pole began last winter. He took five flights over two weeks to reach a research station, where he helped upgrade a camera that surveys the sky at microwave frequencies to reveal the cosmic microwave background. The instrument produces a snapshot of the universe as it was less than 400,000 years after the Big Bang.

Young evidently didn't have his fill of fun – he returned to Antarctica this fall.

The serial-killer researcher who connected the dots and made headlines

Sasha Reid has an unusual academic interest: serial killers and their motivations. She has spreadsheets filled with the names of series killers and their modus operandi. After seeing a pattern in missing persons in Toronto, she came to suspect there was a serial killer at large in Toronto and shared her theory with the police. Her suspicions appeared to be confirmed when police later arrested a man in connection with the deaths of eight men with ties to the gay village. Reid made national and international news.

The Nigerian students wh o give African expats a taste of home

(photo courtesy of Paul Borkwood/CBC Licensing)

This was a big year for Stephen Ayeni and Naafiu Mohammed, ��˾��ֱ�� Mississauga students from Nigeria who met in math class in 2015. They missed the cuisine from home and figured that other African students did too. That was the impetus for their e-commerce site, Afrocart, which offers cereals, snacks, flour, spices and other items, including a batter dispenser to make Nigerian puff-puffs and rock buns.

��˾��ֱ�� PhD student in astronomy heads to 'bottom of the world' to upgrade telescope

noreen.rasbach — Tue, 27 Mar 2018 04:00:00 +0000

��˾��ֱ�� PhD student in astronomy heads to 'bottom of the world' to upgrade telescope

noreen.rasbach Tue, 03/27/2018 - 00:00

Cutline

“Most of the problems you come across are unique and often require novel solutions,” says Matt Young about his work at the Amundsen-Scott South Pole Station (photo courtesy of Matt Young)

Eric Geringas

Topic

Global Lens

Graduate Students

When Matt Young was a kid growing up in Perth, Australia, his family would go on camping trips to the southern tip of Western Australia. There was a sign there, on the beach, saying “Next Stop: Antarctica.”

Little did he know that some 20 years later, as a University of Toronto graduate student, he’d be spending two months at the South Pole, helping upgrade the camera on a giant telescope that observes the Cosmic Microwave Background – light from the earliest days of the universe.

Last November, the third-year PhD student made the long trek from Toronto to the “bottom of the world” – the Amundsen-Scott South Pole Station – taking five flights over two weeks to get there. He had just a few weeks of the Antarctic summer – 24-hour sunlight and balmy temperatures of just -30ºC – to work with another graduate student, overhauling and upgrading the telescope’s camera.

The work involved disassembling the one-tonne instrument, replacing its three lenses with ones made with a new anti-reflective coating, and the high-stakes work of assembling and installing 10 new detector wafers, delicate sensors that focus and record the microwaves captured by the camera from the telescope’s 10-metre dish. One false move or dropped screw, and the entire wafer could be rendered useless.

The telescope at the Amundsen-Scott South Pole Station (photo by Keith Vanderlinde)

For Young, this was the reason he had pivoted from his undergraduate engineering degree to graduate work in astronomy.

“The work I’m doing here is exactly what I love – hands-on work with a huge variety of scientific equipment,” he says. “Most of the problems you come across are unique and often require novel solutions.”

The 15-hour days of painstaking labour didn’t faze him at all – they were exactly what he had eagerly signed up for.

“There’s a huge difference between looking at diagrams of the telescope in Toronto, and actually taking things apart myself,” Young says. “Being here puts everything together. The skills I’m learning here are invaluable. I doubt I could pick them up any other way than by being directly involved.”

That’s exactly why ��˾��ֱ��'s department of astronomy and astrophysics strives to give its graduate students as many opportunities as possible to travel to the world’s most important telescopes.

“Giving graduate students the opportunity to go into the field and make these measurements themselves completely changes the experience, from sitting at a desk and having someone email you a data set into a really fully interactive science experiment where you’re running the whole show,” says Assistant Professor Keith Vanderlinde of the Faculty of Arts & Science and ��˾��ֱ��'s Dunlap Institute for Astronomy & Astrophysics.

“It enriches their learning experience enormously. At the end of the day, it makes them better scientists.”

As the austral summer comes to an end, Young is on his way back to warmer climes, and his PhD research with Vanderlinde.

“Seeing as my passion is scientific instrumentation, the most valuable thing you can have is hands-on experience,” he says.

“Even with the long days, I’ve loved every second of it. It just helps confirm that this is what I want to be doing as a career.”

Unlocking the mystery of Fast Radio Bursts: ��˾��ֱ�� astronomers

Romi Levine — Wed, 21 Mar 2018 16:31:15 +0000

Unlocking the mystery of Fast Radio Bursts: ��˾��ֱ�� astronomers

Romi Levine Wed, 03/21/2018 - 12:31

Cutline

A team of researchers from ��˾��ֱ�� are collaborating with Thoth Technology to unlock the mysteries of Fast Radio Bursts (photo by Andre Renard)

Krista Davidson

Topic

Our Community