Canadian Institute for Theoretical Astrophysics

Since watching Star Trek as a young boy in his parents’ living room, ��߲ݴ�ý alumnus Jamil Shariff has dreamed of exploring strange new worlds – and boldly going where no one has gone before.

"Science fiction definitely sparked my interest in what the future of humanity would look like, the exploration of space and the development of amazing new technologies,” says Shariff, who earned his PhD in astrophysics in 2015.

Jamil Shariff (supplied image)

Formerly a postdoctoral fellow at U of T's Canadian Institute for Theoretical Astrophysics, Shariff is now engineering technology for one of the most ambitious projects in the history of crewed space exploration.

A senior leader in systems design at MDA (the Canadian company famous for building the robotic Canadarm on NASA’s space shuttle and Canadarm2 aboard the International Space Station), Shariff has been working on Canadarm3, the latest iteration of the iconic space hardware.

The new robotic arm is for Lunar Gateway, a space station planned for lunar orbit by the end of the 2020s. It will serve as a research outpost and cosmic pit stop for future missions to the surfaces of the moon, Mars and beyond.

MDA recruited Shariff several years ago, impressed by his PhD research under Professor Barth Netterfield at the David A. Dunlap department of astronomy and astrophysics in the Faculty of Arts & Science. Netterfield is one of the world’s foremost experts in developing systems for high-altitude balloon-borne telescopes.

Watching Star Trek as a kid sparked Shariff's interest in space and astrophysics (supplied image)

“I wouldn't be where I am now if it weren't for professors like Netterfield,” Shariff says. “He’s a mentor, and it really matters to him if the people in his lab succeed.”

Part of an international team of researchers, Shariff and Netterfield designed, built, installed and operated two balloon-borne telescopes and analyzed their data. One of the projects, BLASTPol, examined the role played by magnetic fields in star formation. The other, Spider, was focused on understanding what happened in the very first moments after the Big Bang.

“The fact that I helped work on instrumentation that detected those microwave photons – which are like our baby picture of the universe, the oldest signal we can ever detect – that still amazes me,” Shariff says. “It's stayed with me all this time.”

During his PhD, Shariff spent several months working along other scientists at Antarctica’s McMurdo Station, maintaining and flying Spider in the skies over one of Earth’s most desolate locations. The experience – and learning how to explain his work to a wider audience – prepared Shariff for life after U of T.

“It's important to be able to tell your story – especially if you have a PhD in something like astrophysics – because a recruiter may not exactly understand what you do,” he says. “That really helped me.”

Nearly a decade after graduating, Shariff remains a champion of astrophysics research and U of T's team of experts.

“You’ve got some of the best theorists in the world coming to us," Shariff says. “You have theory, observation and experimentation all happening at U of T. I think that should be a compelling case for donors who are passionate about furthering our understanding of the universe."

For a billion years, Earth's day lasted just 19.5 hours – a new study reveals why

siddiq22 — Thu, 13 Jul 2023 16:54:12 +0000

For a billion years, Earth's day lasted just 19.5 hours – a new study reveals why

siddiq22 Thu, 07/13/2023 - 12:54

Cutline

Without the sun’s pull on the Earth’s atmosphere, our day would be 60 hours long (photo by dima_zel/Getty images)

Chris Sasaki

Topic

Breaking Research

Physical and Environmental Sciences

Astronomy

Astrophysics

Canadian Institute for Theoretical Astrophysics

Climate Change

Faculty of Arts & Science

Physics

Research & Innovation

U of T Scarborough

Subheadline

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

A team of astrophysicists from the ��߲ݴ�ý 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 U of T 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.”

'A very big deal': Astrophysicist Ue-Li Pen on the first image of the Milky Way's supermassive black hole

Christopher.Sorensen — Fri, 13 May 2022 14:03:34 +0000

'A very big deal': Astrophysicist Ue-Li Pen on the first image of the Milky Way's supermassive black hole

Christopher.Sorensen Fri, 05/13/2022 - 10:03

Cutline

The first image of Sagittarius A*, or Sgr A*, the supermassive black hole at the centre of our Milky Way galaxy (Image by Event Horizon Telescope Collaboration)

Josslyn Johnstone

Topic

Our Community

Canadian Institute for Theoretical Astrophysics

Dunlap Institute for Astronomy & Astrophysics

Faculty of Arts & Science

Global

Milky Way

Space

Astronomers this week revealed the first image of the supermassive black hole at the heart of a galaxy not so far, far away – our home galaxy, the Milky Way.

Scientists had previously observed stars orbiting around something invisible, compact and very massive at the centre of the Milky Way. Known as Sagittarius A*, or Sgr A*, the object was strongly believed to be a black hole.

The Event Horizon Telescope (EHT) collaboration is the international research team behind this groundbreaking achievement, involving over 300 scientists from 80 institutions around the globe. The EHT team linked together eight existing radio observatories across the planet to form a single Earth-sized virtual telescope to provide the first direct visual evidence of Sgr A*. The telescope is named after the event horizon, the boundary of the black hole beyond which no light can escape.

It is just the second image of a black hole to be captured after EHT revealed the first-ever image of M87* in the distant Messier 87 galaxy in 2019.

Canadian Institute for Theoretical Astrophysics (CITA) Professor Ue-Li Pen is a collaborating scientist on the EHT project. Currently based in Taipei, Taiwan, Pen is also the director of the Academia Sinica Institute for Astronomy and Astrophysics, one of the key institutes leading the experiment, and an associate faculty member at the Dunlap Institute for Astronomy & Astrophysics in the ��߲ݴ�ý’s Faculty of Arts & Science.

He recently shared his insights with writer Josslyn Johnstone on the discovery, the results of which were published May 12 in a special issue of The Astrophysical Journal Letters and showcased at simultaneous press conferences held around the world.

What makes this new, second image of a black hole so important?

Scientifically, this discovery is a very big deal because Sgr A* is more than a thousand times closer than M87* – about 27,000 light-years away versus 53 million. We can study it in much finer detail and can do so much more with it than with an object that’s very far away and barely measurable.

This black hole being in our home galaxy – as close to home as you can get when talking about outer space, anyway – makes it that much more fascinating and immediate. I liken it to this: It’s one thing to discover an ancient dinosaur bone, and another entirely to see a live dinosaur right in your backyard.

It is an astounding collective achievement where researchers collaborated across continents, countries, cultures and time zones to make it happen. It shows what amazing things can happen when people work together.

If this black hole is so much closer, why did researchers first capture an image of M87*?

When seen from Earth, the angular size of both black holes is similar. However, M87* is not only much further away, but it is more than a thousand times bigger and more massive than Sgr A*. It's like the moon and the sun – they appear roughly the same size from Earth, but the sun is much larger.

It is hard to make an image instantly because we don't have all the information – the missing pixels, so to speak. Ideally, you would cover the whole Earth with telescopes but, of course, we don't have that many. We had eight telescopes capturing data at any given time. So, to fill in the gaps on the planet where there are no telescopes, where there is no data, we wait for the Earth to rotate.

Because the black hole that is farther away is much bigger, it rotates more slowly. That makes is easier to scan across the black hole and make one image. The black hole in the centre of our own galaxy is much smaller and varying intrinsically – meaning, instead of scanning a static snapshot of an object, you are trying to reconstruct something that is constantly changing as you look at it. It's tricky to disentangle what is due to the earth rotating or the black hole rotating, because they are both changing. That's why it took so many years longer to image Sgr A*, even though the data for both black holes was collected in the same 2017 period.

Is this why there is such a visual difference between the Sgr A* and M87* images?

Right – unlike the 2019 M87* image, which was one clear picture of a black hole, in this case it is a series of images that are reconstructions of what Sgr A* might look like. It is not as distinct, where you can say, “This is it.” Instead, it is a Platonic master image with variations of what it could look like: “It may look like this, or it may look like that.”

It’s like taking a picture of a fast-moving object, like a baseball, on an SLR camera – the ball is moving at the same time as the exposure, so you end up with a distorted image.

What questions are we hoping to answer with this new image?

In a sense, by capturing that first image of the black hole that was farther away, we still had the same questions … then had even more. I think the image of Sgr A* holds all the answers, or at least a lot of them, because we’re able to get that much closer to see what’s going on. We already knew the black hole was there. Now we have a hope of understanding why black holes exist and how they form by studying the surrounding environment. My primary research interests are the compact objects near the black hole called pulsars, so I am looking to measure pulsars in the same dataset.

Now that we have the image, what are the researchers working on next?

The next analysis will be incredibly scientifically valuable, as it will measure the polarization of the emission. Think of polarized sunglasses, where light comes in two polarizations that you can study: reflected sunlight and the resulting glare. By rotating your polarization filter, you can understand what is reflected and what is not. This is similar for the black hole. With polarization, you can study the nature of the radiation emission. Whereas right now, it's a bit unclear what we're looking at. With polarization I think it will be much clearer.

Astronomers focus robotic eyes on the Milky Way, our cosmic home

Christopher.Sorensen — Fri, 21 Jan 2022 00:22:28 +0000

Astronomers focus robotic eyes on the Milky Way, our cosmic home

Christopher.Sorensen Thu, 01/20/2022 - 19:22

Cutline

The Sloan Foundation 2.5-metre telescope at Apache Point Observatory in New Mexico is one of two sites to use a new Focal Plane System to study the Milky Way (photo courtesy of Fermilab Visual Media Services)

Chris Sasaki

Sean Bettam

Topic

Global Lens

Astronomy & Astrophysics

Canadian Institute for Theoretical Astrophysics

Dunlap Institute for Astronomy & Astrophysics

Faculty of Arts & Science

Milky Way

Space

Thanks to a breakthrough robotic innovation, an international collaboration that includes the ��߲ݴ�ý has advanced the Sloan Digital Sky Survey (SDSS), a 20-year-long research project that has been investigating the structure and evolution of our cosmic home, the Milky Way galaxy.

A new Focal Plane System (FPS) is at the heart of the fifth phase of the project, dubbed SDSS-V. The system replaces a time-consuming, hands-on approach to making simultaneous observations of hundreds of stars that required astronomers to manually plug hundreds of optical fibres into holes drilled into a metal plate in the focal plane of a telescope.

With this new innovation, the system’s 500 robotic positioner units replace human hands and precisely maneuver optical fibres into position in the telescope’s focal plane so that each can gather the light of a specific star within the target area.

“We are going from collecting a few thousand spectra per night to nearly 15 thousand,” says Juna Kollmeier, director of SDSS-V, the fifth phase of SDSS, and director of U of T’s Canadian Institute for Theoretical Astrophysics (CITA).

“It's a fantastic change in how we operate that will not only allow us to survey more objects, but to probe these systems over time, on timescales we couldn't access previously. This opens up a tremendous wealth of new science.”

In addition to Kollmeier, other U of T astronomers involved in SDSS-V include Associate Professor Jo Bovy, Assistant Professor Maria Drout and Assistant Professor Ting Li – all of the David A. Dunlap department of astronomy and astrophysics in the Faculty of Arts & Science – and Ted Mackereth, a Banting-Dunlap-CITA post-doctoral fellow.

“I run massive calculations about the Milky Way galaxy,” says Mackereth. “At the end of the day, I want to test these ideas and SDSS-V will be a key way to do that.”

“SDSS has been an important testbed for some of the most exciting advances in machine learning,” adds Bovy, whose early work in previous phases of SDSS pioneered techniques for age-dating in the galaxy. “Using these techniques, we are able to get ages for millions of stars – something we didn't think was possible when SDSS began."

Drout, meanwhile, is one of the leaders of the Time Domain effort in SDSS-V. She and her collaborators will use the spectra statistically to probe the ways in which astrophysical objects change in time.

The Focal Plane System replaces a time-consuming, hands-on approach to making simultaneous observations of hundreds of stars (photo courtesy of SDSS-V)

The development of the new robotic FPS was a five-year effort by an international team, including Ohio State University’s Imaging Sciences Laboratory, the University of Washington, École Polytechnique Fédérale de Lausanne (EPFL) and the Carnegie Observatories in Pasadena.

The design teams overcame numerous challenges posed by the global pandemic by developing and constructing components wherever they were – some in their own garages and backyards – and shipping them elsewhere for further assembly. The robots were built in Switzerland and integrated into the main mechanical units in Columbus, Ohio.

Previous phases of SDSS observed nearly a million stars in our home galaxy using spectrographs – instruments capable of measuring a star’s light at different wavelengths. The resulting spectra reveal a remarkable amount of information about stars: their age, temperature, chemical composition, motion and more. SDSS-V will observe over five million stars.

There are two FPS units. One is in operation on the Sloan Foundation 2.5-metre telescope at Apache Point Observatory (APO) in New Mexico. A second unit is under construction and when complete, will operate on a telescope at the Las Campanas Observatory in northern Chile. (At the Las Campanas Observatory in 1987, U of T astronomer Ian Shelton was one of the two observers to first see Supernova 1987A, an exploding star in the Milky Way galaxy’s companion galaxy, the Large Magellanic Cloud.)

The FPS will enable two of the three core science programs in SDSS-V: the Milky Way Mapper (MWM) and the Black Hole Mapper (BHM). Together, these projects will collect data from millions of objects spread across the sky, from stars in our own galactic backyard to unimaginably distant supermassive black holes.

The MWM will study our home galaxy in unprecedented detail. It will take advantage of our unique perspective within the Milky Way to create a high-resolution map of the galaxy’s stars and how they are moving.

The MWM will also measure masses, ages, chemical compositions, the presence of companions and a slew of other properties for vast samples of stars of all types – including hot massive stars, stars that are just forming and the white dwarfs that are dead remnants of stars like our Sun. It will also target tens of thousands of multi-star and planetary systems in order to understand how often multi-companion systems form and what determines how they are structured.

Looking farther afield, the BHM will study quasars, which are among the most luminous objects in the universe. Powered by material flowing into supermassive black holes at the centres of galaxies, quasars can be used as beacons to trace the growth of these titans over cosmic time. SDSS-V will collect data on more than 300,000 quasars to measure the masses of their black holes, understand the physics of how they gobble up matter and trace their growth over many billions of years.

These vast samples of strikingly different types of targets – millions of Milky Way Galaxy stars, hundreds of thousands of distant quasars – are among the key aspects that set SDSS-V apart from other surveys and are enabled by the new FPS system.

“This project has been truly collaborative, involving the contributions of scientists at more than 50 institutions from around the world,” says Kollmeier.

“We are thrilled to have reached this technological milestone despite being in the midst of a global pandemic and are excited to witness how this shift will enhance the work of the project.”

With files from SDSS

Renowned scholar Juna Kollmeier named director of U of T’s Canadian Institute for Theoretical Astrophysics

Christopher.Sorensen — Wed, 31 Mar 2021 14:25:48 +0000

Renowned scholar Juna Kollmeier named director of U of T’s Canadian Institute for Theoretical Astrophysics

Christopher.Sorensen Wed, 03/31/2021 - 10:25

Cutline

Juna Kollmeier, who will become the new director of CITA on July 1, is an observationally oriented astrophysicist whose research focuses on supermassive black holes, the Milky Way and the intergalactic medium (photo by Bret Harman/TED)

Lucianna Ciccocioppo

Topic

Global Lens

Alumni

Astronomy & Astrophysics

Canadian Institute for Theoretical Astrophysics

Faculty of Arts & Science

Ted Sargent

United States

Renowned astrophysicist Juna Kollmeier, on faculty at the Observatories of the Carnegie Institution for Science, has been named the new director of the ��߲ݴ�ý’s Canadian Institute for Theoretical Astrophysics (CITA), a research centre focused on the origin and evolution of the universe and other phenomena discovered by modern astronomy.

An observationally oriented theorist – uncommon in astrophysics – Kollmeier is the founding director of the Carnegie Theoretical Astrophysics Center and director of the Sloan Digital Sky Surveys (SDSS-V). A scientist committed to public outreach and the “inalienable right to physics” for everyone, she studies how structures grow and evolve in the universe, and focuses on supermassive black holes, the Milky Way and the intergalactic medium. Her 2019 TED Talk has attracted more than 2.6 million views and, among other documentaries, she was in an episode of the series Genius by Stephen Hawking.

“I am thrilled to welcome Juna Kollmeier to the ��߲ݴ�ý to take on this important leadership role,” says Melanie Woodin, dean of the Faculty of Arts & Science, which is home to CITA. “This appointment is truly an outstanding ‘brain gain’ for Canada. An impressive scholar, passionate scientist and mentor, she is also brilliant at engaging the public in understanding our universe. She will undoubtedly advance CITA’s remarkable research and novel discoveries in astrophysics and cosmology to new frontiers.”

Kollmeier’s appointment is the result of a comprehensive, global recruitment process and underscores the university’s commitment to diversifying leadership across disciplines. When she begins on July 1, 2021, Kollmeier will be the first woman to lead CITA.

“CITA is Canada’s hub for research and discovery in theoretical astrophysics,” says Kollmeier. “It's been a tremendous global force, has contributed to cosmology, to our understanding of black hole growth and evolution, to star formation and to high energy astrophysics. I think U of T shines brightly as a place where excellence thrives and grows. This is an incredible opportunity to lead an incredible organization.”

Kollmeier holds a bachelor of science in physics with honours from the California Institute of Technology, and a master of science and PhD in astronomy – both from The Ohio State University, where, in addition to her thesis work, she designed, built and deployed instrumentation parts for two telescopes as part of the Ohio State Astronomy Instrumentation Lab team. She was an Institute for Advanced Study Visiting Professor in 2015-16 and a Fulbright Scholar, and received Hubble and Carnegie-Princeton Fellowships. She is a CIFAR Fellow and, most recently, has been selected the 2022 International Solvay Chair in Physics.

“She is an exceptional scientist, mentor and collaborator,” says Norman Murray, current director of CITA. “I'm excited that she will help advance our mission to expand Canada’s capacity in theoretical astrophysics and grow our national and international networks, as our post-doctoral fellows go on to teach and innovate at many other leading universities.”

Kollmeier replaces Murray, who is completing his third term as director. She says she is looking forward to joining an extraordinary community of scholars at U of T this summer.

“We are arriving at an incredibly exciting point in the overall history of astrophysics, where we have these rich datasets. And they allow us to explore a variety of deep questions, all open questions that are on the verge of breaking apart,” she says. “Joining this community will take my own research to the next level, and that's tremendously exciting.”

Ted Sargent, U of T’s vice-president, research and innovation, and strategic initiatives, says Kollmeier is a globally celebrated scholar.

“Her appointment exemplifies the outstanding calibre of researcher U of T continues to attract,” Sargent says. “Under Professor Kollmeier’s leadership, CITA will continue to achieve transformative discoveries, build national and global networks, and will continue to advance as one of the world’s leading theoretical astrophysics research hubs.”

U of T alumna Wendy Freedman, an astrophysicist at the University of Chicago, hired Kollmeier as the first theorist at the Observatories of the Carnegie Institution for Science, when Freedman was its director.

“Juna is remarkably bright and enthusiastic about whatever she does, and it's hard not to get caught up in her infectious enthusiasm for whatever problem she’s working on,” says Freedman. “She's unusual in that she has a real interest in observations, not just the theory. And she chooses projects that interface very well with what observers are doing, and what you can learn from the observations. It's a great niche area where she can bring together groups of theorists and observers to initiate new projects that can benefit from that kind of analysis. I was delighted when I heard the news. It struck me as a really good match.”

“Juna is very knowledgeable and knows lots of people,” says colleague Matias Zaldarriaga, a cosmologist at the Institute for Advanced Study. “And I think that's a very good combination for someone leading CITA, to recruit and attract people with a wider range of research topics, and to create an atmosphere where people can collaborate and learn new things. She will bring this breadth of interest and expertise that I think will be very noticeable and very attractive to a lot of people.”

Hans-Walter Rix, director at the Max Planck Institute for Astronomy in Heidelberg, Germany, has known Kollmeier since her time at graduate school. “Even back then it was very obvious she just was in a different category than most grad students,” says Rix. “This is a fantastic appointment for CITA because I think it is a role that fits her ambitious capabilities. She brings a vision and an energy that will be a tremendous boost for the place.”

As the first woman to lead CITA, Kollmeier will have a formidable impact, says McGill University’s Victoria Kaspi, physics professor and director of the McGill Space Institute.

“I think she'll be a tremendous role model and a mentor to the next generation of women in astrophysics and in STEM in general,” says Kaspi. “In addition, she also is an incredibly creative, versatile person, and she has tremendous energy and drive. I think she is going to shake the place up and bring CITA to new heights.”

Meg Urry, director of the Yale Center for Astronomy and Astrophysics, and a former president of the American Astronomical Society, says she has seen “Juna’s impressive leadership up close.” Urry serves on the executive committee of the advisory council of the SDSS-V project. “That she is a distinguished theorist selected to lead this important institute – well, it shows Juna is a star on all fronts.”

Astronomers at U of T, other universities propose measures to reduce their carbon footprint

Christopher.Sorensen — Wed, 24 Jun 2020 13:42:20 +0000

Astronomers at U of T, other universities propose measures to reduce their carbon footprint

Christopher.Sorensen Wed, 06/24/2020 - 09:42

Cutline

U of T's Chris Matzner is the lead author of a white paper that proposes, among other things, prioritizing international travel for early-career astronomers and adopting carbon offsets (photo by Mujahid Safodien/AFP via Getty Images)

Chris Sasaki

Topic

Our Community

Canadian Institute for Theoretical Astrophysics

Climate Change

Dunlap Institute for Astronomy & Astrophysics

Faculty of Arts & Science

Global

Sustainability

In 1960, long before his acclaimed book and television series Cosmos, the astronomer Carl Sagan determined that the inferno-like temperatures on Venus were the result of an atmosphere composed almost entirely of carbon dioxide. The gas had turned Venus into a greenhouse, trapping the sun’s energy and raising the planet’s surface temperature to above the melting point of lead.

Carbon dioxide is also having a significant effect on our planet. Since the industrial revolution, the level of carbon dioxide in our atmosphere has risen drastically and is driving a greenhouse effect.

“Like Sagan, astronomers today study planetary atmospheres and think about whether planets have the right conditions for life,” says Chris Matzner, a professor in the Faculty of Arts & Science’s David A. Dunlap department of astronomy and astrophysics. “We understand the physics of global warming and our current climate crisis.”

It should come as no surprise, then, that Matzner – along with astronomers from U of T’s Faculty of Arts & Science and other Canadian institutions – has recently published a white paper that examines the carbon footprint of astronomical research and recommends ways of reducing it.

“Climate change has become an unparalleled crisis,” says Matzner, lead author of the paper. “It poses serious consequences for life on our planet. Our oceans are acidifying, extreme weather events are becoming more frequent, food and water insecurity is increasingly threatening the most vulnerable. The only responsible thing to do is to enact, in one’s professional life, the changes that we as a society have committed to.”

The paper, titled “Astronomy in a Low-Carbon Future,” was written for inclusion in the Canadian astronomical community’s long-range plan that identifies its priorities for the next 10 years. U of T authors include astronomers from the David A. Dunlap department of astronomy and astrophysics, the Dunlap Institute for Astronomy & Astrophysics and the Canadian Institute for Theoretical Astrophysics (CITA). Other authors are from McGill University, Université de Montreal, St. Mary’s University, the National Research Council’s Herzberg Astronomy and Astrophysics Research Centre and the Universities of Alberta, New Brunswick and Waterloo.

Among many issues discussed in the white paper is the impact of air travel, which is a major contributor to the global climate crisis. Astronomers fly frequently to observatories around the globe, including remote locations like Antarctica. They also fly to give talks and work with collaborators and to attend conferences, workshops and meetings.

What’s more, professional expectations for hiring, tenure, and promotions often reward extensive international travel.

Matzner and his co-authors propose multiple strategies to reduce astronomy’s travel-generated carbon footprint. They recommend replacing non-essential air travel with remote participation, ground travel or extended stays that encompass multiple events. They recommend prioritizing air travel for early-career astronomers over scientists with established careers because networking and in-person collaboration can be critical for young researchers. And when air travel is unavoidable, the resulting carbon produced should be offset 100 per cent. For example, Matzner and his Dunlap Institute colleagues have instituted a carbon offset pilot program in their own departments.

They argue that when hiring and promoting, institutions should put less emphasis on the overall number of presentations an individual may have given at international institutions – a practice that entails an abundance of travel – and more value on a smaller number of high-impact presentations, as well as written research contributions. Similarly, the authors urge agencies and governments to treat climate-mitigation costs as legitimate research expenses, allowing grants to cover the potentially higher costs of ground transportation or carbon offsets.

The authors also examine how the infrastructure of astronomical research comes with an environmental price tag, writing that “telescopes, buildings and computing facilities must also be counted toward our climate impact.”

For example, when it is completed, the Square Kilometre Array (SKA) will be the largest radio telescope array ever built, comprising thousands of radio antennas and dishes in South Africa and Australia. The authors point out that the supercomputer built to collect and process the enormous amounts of data generated will require as much electricity as 1,080 average homes.

Matzner and his co-authors also recognize the role that astronomers as scientists, educators and communicators have to play in informing the public about the climate crisis. Not only do they understand the physics, they have the opportunity to reach the public through outreach events, the media and even introductory astronomy courses which, the authors point out, are often the only science course that many undergraduate students take.

It’s a role not unlike the one Sagan played throughout his life by educating the public about our unique place in the cosmos and the fragility of the planet.

“Our lovely blue planet, the Earth, is the only home we know,” Sagan wrote in Cosmos. “Venus is too hot. Mars is too cold. But the Earth is just right, a heaven for humans.”

U of T department of astronomy and astrophysics celebrates new name in honour of long-time supporters, the Dunlap family

Christopher.Sorensen — Fri, 20 Dec 2019 15:40:01 +0000

U of T department of astronomy and astrophysics celebrates new name in honour of long-time supporters, the Dunlap family

Christopher.Sorensen Fri, 12/20/2019 - 10:40

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(photo by Shutterstock)

Sarah MacFarlane

Topic

Our Community

Alumni

Astronomy & Astrophysics

Canadian Institute for Theoretical Astrophysics

Dunlap Institute for Astronomy & Astrophysics

Faculty of Arts & Science

Meric Gertler

It is a historic time for the ��߲ݴ�ý’s department of astronomy and astrophysics – not only as it approaches its centenary next year, but also as it embraces a new name: the David A. Dunlap Department of Astronomy & Astrophysics. The new name was announced officially Dec. 19 at a reception to honour the Dunlap family, hosted by U of T President Meric Gertler and Professor Melanie Woodin, dean of the Faculty of Arts & Science.

“This very fitting development recognizes the historic benefaction made in memory of David A. Dunlap, as well as the tremendous support provided to astronomy and astrophysics at U of T by his grandsons, Dr. David Dunlap and Dr. Moffat Dunlap,” says President Gertler. “It celebrates the crucial contribution of the Dunlap family to Canada’s global leadership in expanding our knowledge of the universe.”

The Dunlap family’s support of U of T spans nearly a century, dating back to 1921 when David A. Dunlap was inspired by a lecture hosted by Professor Clarence Chant, founder of what was then the newly established department of astronomy.

After Dunlap’s death, his widow, Jessie Donalda Dunlap, made a gift in her late husband’s honour, resulting in the establishment of the David Dunlap Observatory in 1935. A 76-hectare property in Richmond Hill and the world’s second-largest telescope at the time provided the foundation for cutting-edge astronomical research, including being the first observatory to prove the existence of black holes.

Over the years, increasing light pollution began to affect visibility from the observatory. In 2008, members of the Dunlap family agreed to the sale of the property. David M. Dunlap and J. Moffat Dunlap’s subsequent endowed gift to U of T resulted in the establishment of the Dunlap Institute for Astronomy & Astrophysics. The institute resides on U of T’s St. George campus, alongside the department of astronomy and astrophysics – which was renamed to encompass astrophysics in 2001– and the Canadian Institute for Theoretical Astrophysics (CITA).

“The Dunlap family’s long-standing support of the ��߲ݴ�ý has been exemplary and transformative,” says Woodin. “It is because of donors like the Dunlap family that U of T is able to continue making leaps forward in scientific research and discovery.”

The reception honoured David and Moffat for their family’s legacy of inspiring generosity and unwavering commitment to the advancement of astronomical research and discovery.

“Our family’s much-loved connection to the ��߲ݴ�ý began with our grandfather’s vision,” says David. “Over the years, we’ve been able to see the impact of our family’s gifts in the form of important and remarkable developments in astronomy at U of T. We are very happy to be able to celebrate his memory in this meaningful way.”

Over the past century, the department has secured its place at the forefront of astronomy and astrophysics, both in Canada and internationally. Students and faculty investigate distant galaxies, dark energy and the origins of the universe – from interdisciplinary strategies for determining the mass of the Milky Way galaxy, to research expeditions to Antarctica to observe light from the universe when it was 380,000 years old through the South Pole Telescope.

Professor Raymond Carlberg, chair of the David A. Dunlap Department of Astronomy and Astrophysics, is looking forward to the future. “The department has made many exciting discoveries and advances in recent years,” says Carlberg, “and thanks to the support of the Dunlap family, this is just the beginning.”

U of T astrophysicist Ue-Li Pen on first-ever image of a black hole and the international collaboration behind it

geoff.vendeville — Wed, 10 Apr 2019 20:36:53 +0000

U of T astrophysicist Ue-Li Pen on first-ever image of a black hole and the international collaboration behind it

geoff.vendeville Wed, 04/10/2019 - 16:36

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The first-ever image of a black hole, at the center of the Messier 87 galaxy, was captured through a broad international collaboration that included U of T researcher Ue-Li Pen (photo courtesy of U.S. National Science Foundation)

Geoffrey Vendeville

Topic

Global Lens

Canadian Institute for Theoretical Astrophysics

Dunlap Institute for Astronomy & Astrophysics

Faculty of Arts & Science

Global

Research & Innovation

The appearance of a black hole has been the stuff of scientists' predictions and sci-fi writers' imaginations – until today.

In press conferences held on three continents, an international team of scientists announced they had taken the first-ever picture of a gargantuan black hole. The Event Horizon Telescope (EHT) collaboration, involving eight ground-based telescopes across the globe, targeted two supermassive black holes: Sagittarius A*, which is 26,000 light-years from Earth at the centre of the Milky Way, and one in Messier 87, a giant elliptical galaxy in the constellation Virgo.

The scientists successfully captured an image of the black hole and its shadow in M87. The black hole is 55 million light-years from Earth and has a mass 6.5 billion times that of our sun.

"If immersed in a bright region, like a disc of glowing gas, we expect a black hole to create a dark region similar to a shadow – something predicted by Einstein’s general relativity that we’ve never seen before,” said Heino Falcke of Radboud University, the chair of the EHT Science Council, in a news release.

"This shadow, caused by the gravitational bending and capture of light by the event horizon, reveals a lot about the nature of these fascinating objects and allowed us to measure the enormous mass of M87’s black hole."

As interim director of the ��߲ݴ�ý’s Canadian Institute for Theoretical Astrophysics, Professor Ue-Li Pen played an administrative role in the global collaboration that brought these black holes into focus.

Pen, who is also an associate faculty member at U of T's Dunlap Institute for Astronomy & Astrophysics, spoke to U of T News about the scientific team effort that generated our first look at a black hole.

(photo by Geoffrey Vendeville)

Who are the scientists working in the Event Horizon Telescope collaboration and what are they doing?

It's a collaboration of hundreds of over 200 scientists from 13 institutions and many countries. It's a global initiative. In order to have such a high-resolution image, which has never been done before, you use the Earth's size as your telescope. You're connecting telescopes across the planet to make one coherent image.

The telescopes involved are in Chile, Spain, the U.S., Mexico and Hawaii. There is another at the South Pole used indirectly for calibration.

How do these telescopes work together?

They simultaneously observe the object through a technique called VLBI (Very Long Baseline Interferometry). They record the voltages of the light, you ship the disks to one place and you combine the voltages to form an image. At the end of the day, this is the image of a black hole.

The scientists looked at two black holes specifically. One in our galaxy and another in a neighbouring galaxy. Why did they choose these two?

These are the largest black holes as measured in angular size in the sky. So the one in our galaxy, of course, looks large because it's nearby, and the other is intrinsically much bigger but further away, but similar in angular size.

Can you explain what's meant by the event horizon?

It's the boundary around a black hole – the point of no return. Things can only go in and never come out. It's a one-way street.

So how can we take a picture of a black hole, if even light disappears beyond the event horizon?

By picture, we mean a shadow. The black hole is this black thing in the middle where no light is coming from. It is the absence of light that makes you say it's a black hole.

What is the ring we see around it?

It's a lensed image of matter that's falling into the black hole. It is bright on one side because some of the matter is moving toward it as it orbits around the black hole. The matter on one side is moving toward us and the matter on the other side is moving away. The Doppler shift makes this side look brighter.

Black holes often appear in science fiction as a scary phenomenon. Do we have any reason to fear that we will be sucked into a black hole anytime soon?

Unlikely. It's unlikely that there is any black hole nearby. We are searching very hard and these are all very far away.

What were some of the challenges involved in getting pictures of a black hole?

There was a combination of challenges. The two biggest telescopes were not really completed until a few years ago. The two big players are the Large Millimeter Telescope in Mexico – I visited that telescope last spring – that's the world's biggest telescope at that wavelength. The other is the ALMA telescope (Atacama Large Millimeter/submillimeter Array) that was recently finished and only recently has had the ability to take data in the right form.

They also had to overcome technological challenges observing at these high frequencies. The data rate is enormous. Being able to process it wasn't possible until a few years ago.

How did you react when you first saw the pictures of the black hole? Were you surprised?

Surprised is probably the wrong word because this was kind of known since Einstein's days. It confirms the theory that was proposed 100 years ago. In that sense, it's not surprising. It's like the LIGO event a few years ago (the direct observation of gravitational waves) that was also predicted by Einstein.

What I personally find interesting, which may not be the same as what my colleagues think, is that it gives us, for the first time, the ability to use a black hole as a tool.

What do you mean?

What we're seeing is the lensing effect of the black hole, meaning we're seeing the black hole bending and absorbing light. The ring you see is actually stuff on the far side of the black hole that went around the black hole and comes toward you.

That opens the path to use black holes as a new tool. One of the things I'm interested in is thinking of ways of understanding the nature of space-time, quantum gravity. This is the first step. This is not the end – it's the beginning of a way of measuring black holes.

What are the next questions people are going to be asking about black holes?

I think the big question that was even evident in Einstein's days was: What happens with quantum mechanics and gravity?

We don't know how to reconcile the nature of quantum mechanics, which is a probabilistic description of the world, with general relativity, which is a deterministic description. There's a mystery, and the black hole is a place where these two effects come head-to-head.

In other words, we might be able to observe phenomena that explain or offer some clues into quantum mechanics and gravity?

Exactly – how these two interact.

How much time and effort went into this collaboration?

If you look at how science happens, it's often through long-term efforts. It's one of those things that in our society is not that appreciated, and which our political system makes difficult to set up.

Einstein theorized this 100 years ago, and it's been a 100-year path to get here. This is a long-term effort. Even the Event Horizon Telescope collaboration took 10 years to set up this network of telescopes. The telescopes weren't built for the collaboration. It was an international effort, and that's something that requires a lot of positive will from people of different backgrounds, with different ideas and different funding schemes. They had to be committed for the long term.

That's something which I think we need more of. The world would be a better place if we could work together.

A decade of the Dunlap Institute: 'We’re not only celebrating a 10-year anniversary, but a 100-year conversation'

noreen.rasbach — Thu, 17 Jan 2019 20:19:02 +0000

A decade of the Dunlap Institute: 'We’re not only celebrating a 10-year anniversary, but a 100-year conversation'

noreen.rasbach Thu, 01/17/2019 - 15:19

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The Dunlap Institute has sparked a love of astronomy in tens of thousands through events like viewing the last transit of Venus in 2012 (photo by Chris Sasaki)

Chris Sasaki

Topic

Our Community

Alumni

Astronomy & Astrophysics

Canadian Institute for Theoretical Astrophysics

Dunlap Institute for Astronomy & Astrophysics

Faculty of Arts & Science

��߲ݴ�ý President Meric Gertler and Faculty of Arts & Science Dean David Cameron hosted David and Moffat Dunlap and members of the Dunlap family at a gala dinner last month to cap off the 10^thanniversary of the Dunlap Institute for Astronomy & Astrophysics.

The Dunlap Institute, established in 2008, joined the department of astronomy and astrophysics and the Canadian Institute for Theoretical Astrophysics (CITA) at U of T to form the leading centre for astronomical research in Canada.

In the decade that followed, Dunlap grew to increasingly deliver on its mandate to develop innovative astronomical technology, conduct groundbreaking research, train the next generation of astronomers, and share the excitement of astronomy with the public.

Also in attendance was CITA’s Peter Martin, who was instrumental in founding the institute. “The Dunlap Institute is strongly rooted in traditions associated with the Dunlap name,” Martin said. “The institute has touched many, nationally and internationally, through its innovative and ambitious research, training, and education programs. What a wonderful start over the first decade.”

The dinner also acknowledged the long and historic relationship between the Dunlap family and the university, which began in 1921 when David and Moffat’s grandfather, David A. Dunlap, met Clarence Chant, founder of U of T’s department of astronomy, at an astronomy lecture given by Chant.

In 1926, Dunlap’s widow, Jessie Donalda Dunlap donated funds in memory of her late husband that made possible the Dunlap Observatory in Richmond Hill. Then, in 2007, an endowed gift from David and Moffat led to the establishment the Dunlap Institute.

10 years of the Dunlap Institute: A timeline

In the words of the institute’s current director, Bryan Gaensler, “We’re not only celebrating a 10-year anniversary, but a 100-year conversation.”

Today, the research themes of the institute have grown to encompass optical, infrared and radio instrumentation; data analysis; dark energy; large-scale structure in the universe; the Cosmic Microwave Background; the interstellar medium; galaxy evolution; and cosmic magnetism.

Dunlap scientists play leading roles in Canadian and international collaborations destined to make groundbreaking discoveries for decades to come, including the Canadian Hydrogen Intensity Mapping Experiment (CHIME), the Dragonfly Telescope Array, the Square Kilometre Array, the Large Synoptic Survey Telescope, the South Pole Telescope, and many others.

Dunlap’s annual Astronomical Instrumentation Summer School for undergraduate and graduate students from around the world has been the institute’s flagship training initiative since 2012. And the Dunlap Institute has sparked a love of astronomy in tens of thousands through events like Astronomy on Tap T.O., and through opportunities to view the 2012 transit of the Venus, the 2015 Supermoon total lunar eclipse, and the 2017 solar eclipse.

“The first 10 years of the Dunlap Institute were about figuring out what we want to do and then finding the right people to do it,” Gaensler said. “We now have a clear plan for the future and a superb team on board, and we’re ready to put our foot to the floor. Brace yourselves for an upcoming torrent of new discoveries and talented young researchers.”

Look up! Check out U of T’s musical exploration of the night sky and these other Nuit Blanche events

Romi Levine — Fri, 28 Sep 2018 04:00:00 +0000

Look up! Check out U of T’s musical exploration of the night sky and these other Nuit Blanche events

Romi Levine Fri, 09/28/2018 - 00:00

Cutline

U of T's Matt Russo (right) with friend and bandmate Andrew Santaguida in the portable planetarium they built for their Nuit Blanche installation (photo courtesy of Matt Russo)

Romi Levine

Topic

City & Culture

Canadian Institute for Theoretical Astrophysics

Cities

Dunlap Institute for Astronomy & Astrophysics

Faculty of Arts & Science

Faculty of Medicine

U of T Scarborough

Imagine a time in Toronto before city lights and skyscrapers, when you could look up and see the night sky, bright with stars and planets.

Matt Russo wants to give Torontonians a taste of what the city was like before light pollution with his One Sky installation at this year’s Nuit Blanche, the all-night art festival that begins on Saturday evening.

The astrophysicist and planetarium operator at ��߲ݴ�ý’s Dunlap Institute for Astronomy & Astrophysics in the Faculty of Arts & Science has teamed up with the institute and his friend and bandmate Andrew Santaguida to build an outdoor planetarium where you can see – and hear – the night sky.

“The night sky is something that can unite everyone,” says Russo. “Everyone has access to the same sky and every culture realized that early on. They wanted to understand the motions of the night sky and what it means for them.

“With this exhibit, we're trying to bring together all those experiences into a unified whole.”

Not only will people visiting the installation be able to see the twinkling stars, they’ll be able to hear them too. One Sky comes out of the musical venture SYSTEM Sounds, whose members include Russo, Santaguida and Dan Tamayo, a postdoctoral researcher at the Canadian Institute for Theoretical Astrophysics and the Centre for Planetary Sciences at U of T Scarborough. The group creates music out of the movements of the universe.

“The music is out there,” Russo previously told U of T News. “I'm just finding a way to make it audible. It's kind of like there's an electric guitar in space and I'm plugging in the cable.”

Russo is particularly interested in providing people who are partially sighted and blind an opportunity to experience the universe through sound. He’s been working with various groups including the Canadian Council of the Blind over the past year to fine tune that experience.

Earlier this year, Russo made headlines with his planetarium show Our Musical Universe, which gave attendees a multi-sensory experience of the cosmos. One Sky aims to do this on a larger scale.

“This is the main event,” says Russo.

Canadian Institute for Theoretical Astrophysics

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For a billion years, Earth's day lasted just 19.5 hours – a new study reveals why

'A very big deal': Astrophysicist Ue-Li Pen on the first image of the Milky Way's supermassive black hole

Astronomers focus robotic eyes on the Milky Way, our cosmic home

Renowned scholar Juna Kollmeier named director of U of T’s Canadian Institute for Theoretical Astrophysics

Astronomers at U of T, other universities propose measures to reduce their carbon footprint

U of T department of astronomy and astrophysics celebrates new name in honour of long-time supporters, the Dunlap family

U of T astrophysicist Ue-Li Pen on first-ever image of a black hole and the international collaboration behind it

A decade of the Dunlap Institute: 'We’re not only celebrating a 10-year anniversary, but a 100-year conversation'

10 years of the Dunlap Institute: A timeline

Look up! Check out U of T’s musical exploration of the night sky and these other Nuit Blanche events

Read more about Our Musical Universe

There’s more to explore at Nuit Blanche. Grab another cup of coffee and head over to these installations created by U of T community members: