Finding our galactic centre
By Elizabeth Kleisath. This article was originally published on Waterloo News.
Three years ago, history was made when the first image of a black hole inspired wonder and awe around the world as we glimpsed the shadow of light escaping from the supermassive black hole M87*. Today, history is being made again as the Event Horizon Telescope (EHT) Collaboration releases the image of a second black hole — Sagittarius A* (Sgr A*) — the one at the centre of our own Milky Way galaxy.
Among the international group of astronomers behind these images is Professor Avery Broderick from the University of Waterloo. Broderick is a founding member of the EHT and has built theoretical models for the EHT’s most promising targets and demonstrated the capacity of the EHT to transform black hole science. As part of the EHT, Broderick’s research group has developed powerful new computational tools that analyzed and interpreted the unique data generated by the global array of radio telescopes. With these tools, the EHT has revealed in greater detail than ever before the astrophysical dramas that play out in the vicinity of a black hole’s event horizon.
“Our image of the first black hole, M87*, was a huge success in science, and has grown into not just a science story, but a human story,” says Broderick, also the Delaney Family John Archibald Wheeler Chair of Theoretical Physics at the Perimeter Institute for Theoretical Physics. “It’s estimated that within three months one in two people on Earth had seen our image.”
Despite both being black holes, M87* and Sgr A* are very different objects. Located at the center of the Milky Way, Sgr A* is 2,000 times closer than M87*. Due to its location, the radio waves must pass through the galaxy’s stars and gas, which causes scattering and blurring before they are ultimately detected by the EHT, much like viewing Sgr A* through frosted glass. Additionally, unlike M87*, Sgr A* does not exhibit light-speed outflows — powerful “jets” that can extend the influence of black holes to well beyond their host galaxies.
Most importantly, Sgr A* is 1,500 times less massive and smaller than M87* — and thus matter and light orbit Sgr A* 1,500 times faster than in M87*.
“Imaging Sgr A* was like trying to take a clear photograph of a energetic puppy chasing its tail. By comparison, in this analogy, M87* would be like a stately old lion, asleep and still,” Broderick says.
“The faster motions in the gas results in significant variability in the data for Sgr A* and required new methods to make sense of the data we collected,” said Boris Georgiev, a PhD student at Waterloo and Perimeter Institute who led a study of what super-computer simulations could tell us about the expected variable emission from Sgr A*. But one astronomer’s noise is another’s music. “By carefully studying the variations, we determined if they are caused by a handful of large moving features or many small ones, testing our ideas about how 100-billion degree plasmas behave near black hole event horizons.”
The EHT isn’t a single telescope, but a world-spanning network of telescopes located at the farthest reaches of the globe that all must observe simultaneously. When combined, together they effectively form the Earth-sized instrument necessary to generate the highest-resolution images ever produced in astronomy. But, with only eight stations, the EHT must wait for the Earth to rotate to fill in the image, collecting radio waves throughout an entire night. Therefore, the rapid changes in the radio emission from Sgr A* presented a significant challenge for the research team — what is the “correct” image of a black hole that is changing even as it is being measured?
To address these challenges and obtain today’s image of Sgr A*, new algorithms were required to overcome its variable nature. In addition to the imaging and analysis tools used with M87* three years ago, two new powerful methods developed by Broderick and his team proved critical.
The first method addressed the problem of Sgr A*’s variable nature. To reconstruct time-averaged images, similar to a long exposure photograph of a sporting event, the EHT simultaneously estimated the range of variations about it. The recovered statistical description of Sgr A*’s variability matched that anticipated by some super-computer simulations, providing new evidence for the existence of the turbulent motions that are believed to be key to driving the plasma toward the black hole.
The second, called THEMIS Bayesian imaging, is a new imaging algorithm, which has also been used to generate some of the first polarized images of M87*. Where other imaging schemes attempt to identify the image that best fits the EHT data, Bayesian imaging instead explores all of the images that are consistent with the data, assigning a probability to each. In this way, THEMIS provides an “error bar” on the image, identifying which aspects can be trusted and which are uncertain. Based on these probabilities, the EHT team confirmed the presence of an event horizon silhouetted against the bright surrounding plasma, the shadow of the black hole at the center of the galaxy.
“We are witnessing an evolution of radio imaging,” Broderick says. “Sgr A* has forced us to contend with image variability, unlocking a new era in radio astronomy in which image dynamics is no longer an obstacle but a new way to learn about the physics of the source.”
There is great scientific advancement in confirming a second black hole. “Where one black hole might be a chance occurrence, two is confirmation and contrast. With two black hole horizons laid bare, the EHT has thrown open a window onto the most extreme gravitational objects in the universe,” Broderick says.
What is unique about Sgr A* is that it is our black hole — the centre of our spiral galaxy. Today’s image opens the door for scientists to learn more about our galaxy’s centre and learn more about black holes. Like M87* previously, this image will cement in the human imagination the terrible and awesome nature of black holes.
Fixing the Internet
By Brian Caldwell. This article was originally published on Waterloo News.
A growing startup company that was co-founded by two Waterloo Engineering graduates is in unicorn territory after securing US $100 million in new funding.
Tailscale Inc., which was launched just three years ago and currently has 35 employees, was founded by alumni Avery Pennarun (BASc ’01, computer engineering) and David Carney (BASc ’01, computer engineering) along with David Crawshaw.
They are out to “fix the Internet,” according to a blog post by Pennarun, by providing a simpler alternative to virtual private network (VPN) systems that doesn’t require costly hardware or infrastructure.
“So, here’s what we’re doing to do with a hundred million dollars: more of what we’ve been doing, for the people we’ve both doing it for,” wrote Pennarun, the CEO, in the folksy post. “At a healthy pace, at human scale. With a focus on quality and craftsmanship. And trust. And security. And customer service. And … profitability. Like a bunch of weirdos.
“I could show you our fancy Vision Statement and Mission Statement, but I’ve been referring to them less and less lately. Now I just tell people: We’re here to fix the Internet. If we don’t, who will?”
The funding round, which was led by Charles Rivers Ventures (CRV) and Insight Partners, values the Toronto-based company at $1 billion.
Tailscale has benefitted from the move to working from home via remote connections during the COVID-19 pandemic, rapidly increasing its active monthly users. It is aiming to triple its staff by the end of the year.
Main photo by Olia Danilevich from Pexels.
Waterloo alumnus installed as president of Yukon University
University of Waterloo alumnus Dr. Lesley Brown will be officially installed as president and vice chancellor of Yukon University. Brown's official installation ceremony takes place today.
Her appointment was announced last June and she has been in the role since August 2021.
Brown is an accomplished scholar in the field of Kinesiology, with a research specialization in balance and fall prevention in the elderly and people with Parkinson’s disease. Brown has served on numerous organizations at the provincial and national level. These include Social Science & Humanities Research Council of Canada (SSHRC), the research advisory committee and board of the Alberta Rural Development Network, Parkinson Alberta and the Alberta Epigenetics Network. She has also served as the Vice-Chair of the Alliance of Canadian Comprehensive Research Universities (ACCRU), and as a member of the Executive Steering Committee for the Alberta Strategy on Patient Oriented Research.
An accomplished academic and administrative leader, most recently Brown served as Provost and Vice President, Academic, at Mount Royal University (MRU) in Calgary. Before that appointment, Brown was at the University of Lethbridge, serving as a faculty member and an administrator in a number of roles including Vice President Research (interim), Associate Vice President (Research) and Vice Provost (Academic).
Dr. Brown obtained her PhD in Kinesiology from the University of Waterloo in 1996. Brown's PhD supervisor, Professor Emeritus Jim Frank, will be travelling to her installation ceremony today in Whitehorse to participate in the ceremony and bring an official certificate of greeting on behalf of President and Vice-Chancellor Vivek Goel and the University of Waterloo.
“Yukon University’s exceptional potential to broaden its scope of impact through teaching excellence, research and student success, along with its deep commitment to Indigenization, Reconciliation and community education, is what attracted me to this opportunity. As I moved through the interview process it became very evident that Yukon University is poised to influence the future of Canada’s Northern and Arctic regions and its people. I am so honoured to step into this role,” said Brown.
Amanda McKenzie wins academic integrity award
A message from the Office of the Vice-President, Academic.
Congratulations to Amanda McKenzie, who recently received the Tricia Bertram Gallant Award for Outstanding Service from the International Center for Academic Integrity (ICAI), an organization that focuses on advancing academic integrity worldwide. Amanda’s role as the University of Waterloo’s Director of Quality Assurance (Academic Programs), Amanda has oversight of the Office of Academic Integrity. The award recognizes and honours ICAI members who have provided outstanding service to their institution or to the community with respect to academic integrity.
Amanda was the first Canadian to be on ICAI’s Board of Directors. Recently, she played a key role in ICAI’s work consulting with the Ukrainian National Quality Assurance body in support of the country’s efforts to advance its system of academic integrity and quality assurance. As part of this process, she has conducted numerous workshops in addition to supporting coordination behind the scenes. She has also played an active role in developing Canada-specific programming for the ICAI’s annual conference since 2014.
These externally focused activities help position the University of Waterloo as a leader in academic integrity initiatives and allows Amanda to bring best practices from partner institutions home for Waterloo to consider for implementation here.
Remembering Kish Hahn
A message from Systems Design Engineering.
The Department of Systems Design Engineering is saddened to announce the passing of Professor Kish Hahn on April 30, 2022, at the age of 90.
Professor Hahn lived a full life, with 38 years spent at the University of Waterloo. He arrived at the university in 1962 with his wife, Helena, for a role in the Department of Design, a precursor to the Department of Systems Design Engineering (SYDE). His perspective on design education was honed through expertise in human factors engineering and training as a professional photographer. Many of his photos from the 1960s are archived by the University of Waterloo.
Professor Hahn’s impact on the SYDE department cannot be overstated. During his tenure, the SYDE program directed its own admissions process. He saw talent and potential in students that demonstrated their abilities through accomplishments other than required high school grades. He advocated for their admission and enjoyed mentoring them to success. Students appreciated his dynamic teaching methods, noting “he could motivate a rock”. His enthusiasm changed the career trajectory of countless SYDE alumni and inspired many current faculty to pursue the fields of human factors and ergonomics. In recognition of his dedication to teaching and learning, Professor Hahn received the Centre for Teaching Excellence’s Distinguished Teacher Award in 1992.
We extend our deepest sympathies to Professor Hahn’s family, especially his daughters Michele and Francoise. Share online condolences and memories of Professor Hahn on the memorial website.