Credit: David Sella
Lina Necib
Credit: David Sella

Astroparticle Physicist Wins 2023 Valley Prize for Work on Dark Matter

As a child in Tunisia, Lina Necib PhD ’17 watched the 1997 film “Contact” and decided to become an astrophysicist. Now at MIT, she studies dark matter’s shadowy clues.

Lina Necib is on the hunt for something invisible.

“It’s a little bit like detective work,” she says. “We have a lot of observational types of evidence, and we’re trying to put all of it together into one picture.”

Necib, an assistant professor of physics at the Massachusetts Institute of Technology, studies dark matter, the elusive stuff that makes up most of the universe’s mass but doesn’t reflect, emit, or absorb light. For her work, Necib has won the 2023 APS Valley Prize, which recognizes early-career physicists for research expected to have a dramatic impact in the field.

In 2020, Necib and her colleagues reported their discovery of a massive stellar stream, a ribbon of stars left over when a galaxy is torn and stretched, orbiting on the outskirts of the Milky Way. Dark matter tugs at these streams, leaving behind fingerprints — evidence of its existence.

Necib believes the stream, dubbed “Nyx” after the Greek goddess of night, might be the remnant of a dwarf galaxy that collided with the much larger Milky Way billions of years ago. To study the stream, her team merged particle physics with cosmological simulations, data from star catalogs, and machine learning — a groundbreaking combination of tools. They published their results in Nature Astronomy.

Necib credits a few other physicists for her successes — “in particular, several women,” including Anna Frebel and Tracy Slatyer at MIT and Mariangela Lisanti at Princeton University.

Mentors as much as colleagues, these women helped Necib adjust to her new faculty role at MIT, which she started during the pandemic and with a newborn baby, she says.

Necib grew up in Tunisia, a small country on Africa’s northern coast, where she says she regularly faced sexist expectations for girls’ behavior and ambitions. One night, when Necib was 8 years old, her family settled in for a movie. The selection? “Contact,” starring Jodie Foster, who plays a scientist searching for aliens. The film opened Necib’s eyes not only to the field of astrophysics, but to a world in which a woman could do astrophysics.

By the end of the movie, Necib had made up her mind: “I’m going to do that!”

She set her sights on college in the U.S. As an undergraduate at Boston University, she leapt into diverse research opportunities, conducting resonance testing of graphene and even joining the search for the Higgs boson at CERN. Her interest in dark matter grew.

During her senior year, at an open house hosted by MIT’s physics doctoral program, Necib struck up a conversation with Jesse Thaler, a theoretical particle physicist. By the end of the chat, Necib knew she wanted to be at MIT.

Necib ultimately asked Thaler to be her dissertation advisor. “He was so enthusiastic about the work that he did. He loved it so much — it was kind of contagious,” she says. “Having an advisor who really put in the time and effort to help me become the physicist that I am changed my life.” Necib earned her doctorate in 2017.

Now in her second year as an assistant professor at MIT, Necib hopes to change cultural attitudes about science careers in Tunisia, where certain professions are given more weight. She wryly summarizes this ranking, starting with the best: “Doctor, engineer, lawyer, failure.”

To topple these perceptions, Necib recently teamed up with Rostom Mbarek, another Tunisian physicist and the Neil Gehrels Prize Postdoctoral Fellow at the Joint Space-Science Institute. The duo just launched an astrophysics podcast entirely in Tunisian Arabic.

In her MIT classroom, Necib strives to debunk outdated perspectives on who does physics.

“I did this experiment last year in one of my first-year physics classes where I asked my students to name physicists,” she recalls. “And all the names they came up with were Nobel Prize winners, but they were also all the same old, Albert Einstein-like examples.”

After that session, Necib had her class learn about more recent work, including the contributions of women and scientists of color to the field.

One of Necib’s “students” is particularly young. Her 17-month-old son can’t yet say “dark matter,” but he has the children’s book “Astrophysics for Babies,” and they go on excursions to Boston’s Museum of Science. He’s a bit young for the exhibits — “he’s just impressed with the escalator,” she says — but she hopes that early exposure will instill in him a love for science.

Meanwhile, her search for dark matter continues. She says that, if someone else solves the mystery of dark matter before she does, it won’t phase her. For her, being a physicist is “really about the people,” like her colleagues, mentors, and students.

“I know amazing people that are doing incredible work,” she says. “Feeling that my work is recognized fills me with so much joy. I hope to pay it forward.”

Liz Boatman is a staff writer for APS News.

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Editor: Taryn MacKinney