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Jacqueline Antwi-Danso …NSERC Banting Postdoctoral Fellow at the David A. Dunlap Department for Astronomy & Astrophysics
In the 1990s, astronomers discovered two distant, massive galaxies that had completely stopped, or quenched their star formation. The discovery marked a complete shift in everything astronomers thought they knew about how galaxies formed.
Massive galaxies like the Milky Way took several billion years to form. But those newly discovered galaxies did so in just a fraction of that time.
“The discovery meant that these galaxies were older than the age of the universe, which is physically impossible,” says Jacqueline Antwi-Danso, the NSERC Banting Postdoctoral Fellow at the David A. Dunlap Department for Astronomy & Astrophysics.
“When we look at the formation histories of these distant quenched galaxies, the observations suggest that they formed too quickly and too early compared to what we see in cosmological simulations.”
Antwi-Danso is tackling one of astronomy’s biggest challenges in her search to find the earliest distant quenched galaxies in the universe. She is particularly interested in how these galaxies formed and when they stopped forming stars.
Astronomers have discovered several more distant, quenched galaxies at increasingly earlier periods in the universe’s history. These galaxies are more massive than the Milky Way and yet formed within a billion years of the Big Bang (which happened nearly 14 billion years ago). In other words, they formed their stars extremely rapidly, unlike any galaxy observed in the present-day.
So, what does this all mean for astronomers? The extreme star formation processes implied by these observations of distant quenched galaxies are uncomfortably close to the limits permitted by galaxy formation physics. Therefore, trying to understand these objects in more detail is a high priority research area for astronomers.
Massive galaxies like the Milky Way have up to a trillion stars and are characterised by luminous, spiral-like arms of active star formation. Meanwhile, distant, quenched galaxies are composed of old stars and look like relics: small orange-red blobs. This is because their light has been “stretched out” to infrared wavelengths due to the expansion of the universe, which also makes them fainter and harder to spot.
At U of T, Antwi-Danso is building on significant findings from a study she participated in as a PhD student at Texas A&M University. Using the 8-metre telescope at the Gemini South Observatory based in Chile, the FENIKS collaboration surveyed large areas of the sky to increase the chances of finding these rare massive galaxies. They designed and installed two new imaging filters on the telescope to push the boundary of what was possible with ground-based infrared telescopes. The survey led to two critical discoveries.
The first was the identification of two new distant quenched galaxies. The discovery confirmed existing knowledge about the formation histories of distant galaxies, “namely, that these galaxies form too early and too quickly based on what theory predicts,” Antwi-Danso explains.
The study also highlighted that astronomers can reliably use ground-based telescopes to observe distant quenched galaxies as far back as 12.5 billion years into history of the universe. To detect them at earlier times than this, space-based data is required.
Additionally, astronomers are rethinking long-standing models of galaxy formation as they observe distant quenched galaxies with supermassive black holes at their centers emitting energetic radiation.
This is important, Antwi-Danso says, because the differing models for light emission from stars and supermassive black holes can affect estimates of the physical properties of these distant galaxies.
As more questions arise, there is an increasing need to ensure the accuracy of the physical properties of distant quenched galaxies derived from modeling their observations. Fortunately, there have been significant technological advancements to address this need.
Harnessing the power of space-based technology
The next stages of Antwi-Danso’s research involve further exploration of those two distant galaxies she discovered from Chile. To do so, she’s leveraging the power of the James Webb Space Telescope (JWST).
Distant galaxies are hard to detect because their emitted light is shifted to infrared wavelengths, where the earth’s atmosphere blocks most of the light. The sky in the infrared is about 10,000 times brighter than the typical distant massive galaxy. This makes it extremely difficult to detect the most distant quenched galaxies using ground-based telescopes.
The JWST – which launched in December 2021 – is about 100 times more sensitive than the largest ground-based infrared telescopes and can observe galaxies in a fraction of the time of its predecessors.
In fact, it has doubled the number of spectroscopic observations of the most distant, quenched galaxies within only two years of operation. Before its launch, astronomers had spectra of only 35 of these galaxies observed within the first two billion years of the universe’s history.
To further observe those two galaxies, Antwi-Danso will use data from the JWST to examine their spectra – the light emitted by these galaxies over a range of wavelengths – which can reveal information like chemical composition. Insights will help provide a more accurate understanding of their formation histories to compare with updated cosmology simulations, and, hopefully, offer new answers about possible tensions between theory and observations.
Additionally, Antwi-Danso is part of the Canadian NIRISS Unbiased Cluster Survey (CANUCS), a multi-institutional collaboration that uses gravitational lensing — a phenomenon where a massive object acts as a cosmic magnifying glass — to study the building blocks of the earliest galaxies.
Within that collaboration, Antwi-Danso is also a researcher on the Technicolor Survey, which employs multiple filters on the JWST’s Near-Infrared Camera to observe quenched galaxies at wavelengths that are inaccessible from the ground.
“We want to find galaxies that contain the first generations of stars, and then model their observations with galaxy formation models to infer their physical properties and star formation histories,” Antwi-Danso says.
With the technological advantages provided by the JWST to push the boundaries of distant galaxy observations, Antwi-Danso’s research will provide valuable insight into understanding how early galaxies came to be.
“We’re really excited to see where the results lead and to compare those observations with current theoretical predictions for these distant massive galaxies.”
Profile
Prisca Abah: Ghana’s modelling powerhouse
Ghanaian model, philanthropist and advocate, Prisca Abah, who is known for her contributions to the fashion industry, is strutting her stuff on higher levels.
She was recently selected as one of the models for the Big8 Girls Project, an initiative by Clinton Samuel to celebrate influential African models.
The project consisted of three episodes: the Bio Shoot which highlighted Abah’s professionalism through a corporate-themed photoshoot; Afrodeity which focused on showcasing her confidence and artistry, celebrating the African divine feminine and royalty which presented Abah as a symbol of African cultural pride, embodying strength and elegance.
The Big8 concept, produced by Clinton Samuel, intentionally highlights and celebrates the strongest and most influential models on the African continent, congratulating their steadfastness and contributions to the African fashion industry, even as they grind and win in other aspects of life.
The Big8 sets hierarchy and high standards in the African fashion and modelling industry, crowning eight of them with the ‘Top Model’ status as the leading female models in Ghana at the moment.
“Working with these fiery women will surely ignite more creative minds and stir the pot of positive competition,” said Clinton.
Abah’s early life and career
Prisca Abah began her modelling career in 2013, achieving her first notable milestone in 2014 with an editorial shoot for 5-Star International Modelling Agency. In 2015, she made her runway debut at the Ghana Fashion Awards.
From 2016 to 2018, Abah participated in major African fashion events such as Glitz Africa Fashion Week, Mercedes-Benz Fashion Week in Johannesburg, and Rhythms on the Runway.
During this period, she received accolades, including the “Best Female Model of the Year” and spoke as a UN Ambassador for Sustainable Development Goal 12 at the Sustainable Rice Platform Conference.
International recognition and pageantry
In 2022, Abah expanded her reach by entering the pageantry world. She placed as the first runner- up at the Beauty of Africa International Pageant and represented Ghana at the Miss Globe World Finals, where she earned the title of Miss Globe Africa 2022.
Philanthropy
Abah founded the Palins Foundation, a non-profit organisation, aimed at empowering women and youth through initiatives in education, skills training, and personal development.
Awards and collaborations
In 2023, Abah received the Best Model of the Year award at the Time Ghana Arts and Entertainment Awards. She has collaborated with leading designers such as Charlotte Prive and Ejiro Amos Tafiri, further solidifying her influence in African fashion.
Legacy
Prisca Abah is recognised not only for her contributions to the fashion industry but also for her philanthropic efforts. Her journey serves as an inspiration to young Africans, encouraging them to pursue their dreams while giving back to society.
By Edem Mensah Tsortorme
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Juventus Duorinaah, Ghana’s first deaf Lawyer
In a landmark moment for Ghana’s legal landscape, Juventus Duorinaah Esq., has etched his name in history as the country’s first lawyer with a hearing impairment.
His journey from a humble background to breaking barriers in the legal profession serves as a powerful inspiration for countless individuals in the disability community, proving that determination and resilience can defy societal expectations and create pathways to success.
For Juventus, the recognition as Ghana’s first deaf lawyer feels surreal.
“It feels like a dream,” he reflects, acknowledging the stereotypes surrounding deafness and the humble background from which he hails.
Juventus’ passion for law sparked in 2008 while seeking admission to the University of Ghana (UG). Although he initially faced challenges due to the nature of the application process, the help of his older brother and his determined spirit led him to pursue a Bachelor of Arts degree in 2012, followed by a Master of Laws at Cardiff University in 2014.
His passion for the study of law became highly intense when he had to study alongside qualified lawyers from several jurisdictions, even though he did not have a legal background. Here, he faced the unique challenge of studying without sign language interpreters, relying instead on a palantypist to transcribe lectures.
Juventus’ role model was his professor and mentor, Professor Luke Clement, who profoundly inspired him in shaping his understanding of law and human rights.
He remembers Prof. Thomas Stephens from the University of Ghana School Of Law, who inspired him with his way of dressing, in-depth knowledge of the law and engagement with students.
He recounts the enormous challenges he encountered during the COVID-19 pandemic in 2020, when lectures moved online, and Dr Stephen’s tremendous support to ensure things moved quickly and smoothly for him.
“I also had the chance to have a few classes with the Dean himself, Prof. Raymond Atuguba. He taught the course such that some of us never felt scared as other lecturers made the course,’ he recalled.
Juventu’s academic journey was fraught with challenges, particularly in communication.
The year 2007 was the last time he studied with deaf peers. He was often the only deaf person in his classes throughout the following years of his education, which made interaction with peers difficult.
Despite these hurdles, he remained high-spirited, studying late into the night and seeking help from kind classmates when necessary.
Reflecting on his academic experience at UG, he connected his affection for the university to his older brother, who is also an alumnus. He felt inspired to be a student of the premier university, saying he would choose the University of Ghana any time, any day, if given the chance to further his studies or work.
The University Of Ghana School Of Law, along with its Dean, Professor Raymond Atuguba, the Director of Legal Education of the Ghana School of Law, Yaw Bramiah Oppong, and his capable team, including the Registrar and Deputy Registrar of the Ghana School of Law and the Office for Students with Special Needs (UG), made significant contributions to his journey.
Prof. Atuguba acknowledged Juventus’ achievement as evidence of the university’s commitment to Diversity, Equity and Inclusion.
Commenting on how the school accommodated his special needs, Prof. Atugugba explained that ‘In the case of Juventus, we worked closely with him to understand and address his special needs, ensuring he had access to the teaching and learning resources in the appropriate formats that would support his academic journey.
Professor Atuguba noted that Juventus’s journey is just beginning, and the future holds promise for him and the many lives he aims to touch along the way.
Juventus’s close friend, Ida Esi McOwusu Esq., described her first encounter with Juventus as ‘intriguing.’ “My first meeting with Juventus was in class, where he sat right in front of me in first year,” Ida reveals. She was intrigued and wanted to find out more about him, especially how Juventus navigated his way to this level. “I got closer and we became friends from there,” she remarked.
Mr Francis Kweku Essel, Juventus’ interpreter, shed light on the primary challenges he faced in carrying out his job, particularly the complex nature of legal terminology and concepts. This validates Ida’s comment on the interpreters’ lack of legal background as a challenge Lawyer Duorinaah encountred.
Juventus dreams of becoming a judge and aims to enhance justice delivery while serving as a role model for young people with disabilities.
He is currently mentoring a group of young deaf students interested in pursuing law, hoping to pave the way for future generations. What’s next for Lawyer Juventus? His next step is to complete his pupilage, after which he can decide further his legal career.
