Andrea Ghez

Andrea Ghez
Born	16 6, 1965
Birthplace	New York City, New York, U.S.
Nationality	American
Occupation	Astrophysicist, professor
Title	Lauren B. Leichtman and Arthur E. Levine Professor of Astrophysics
Employer	University of California, Los Angeles
Known for	Discovery of a supermassive black hole at the center of the Milky Way
Education	Ph.D. in physics (California Institute of Technology)
Awards	Nobel Prize in Physics (2020), MacArthur Fellowship, Crafoord Prize

Andrea Mia Ghez (born June 16, 1965) is an American astrophysicist and professor at the University of California, Los Angeles (UCLA), where she holds the title of Lauren B. Leichtman and Arthur E. Levine Professor of Astrophysics and serves as director of the UCLA Galactic Center Group. In 2020, she was awarded the Nobel Prize in Physics, shared with Roger Penrose and Reinhard Genzel, for discoveries relating to black holes — specifically, for "the discovery of a supermassive compact object at the centre of our galaxy." Ghez became the fourth woman in history to receive the Nobel Prize in Physics, following Marie Curie (1903), Maria Goeppert Mayer (1963), and Donna Strickland (2018). Her career-defining work involved using the W. M. Keck Observatory in Hawaii to track the orbits of stars at the center of the Milky Way, providing the strongest evidence to date that a supermassive black hole — now known as Sagittarius A* — resides at the galactic center. Her research has fundamentally advanced the understanding of galactic nuclei and the role of supermassive black holes in the structure and evolution of galaxies.

Early Life

Andrea Mia Ghez was born on June 16, 1965, in New York City, New York. She grew up during the era of the Apollo space program, and the Moon landings of the late 1960s had a formative influence on her early ambitions. As a child, Ghez expressed a desire to become an astronaut, and her mother supported this interest by purchasing a telescope for her. This early exposure to astronomy set the stage for what would become a lifelong engagement with the study of the cosmos.

Ghez's path into astrophysics was not without obstacles. Throughout her career, she encountered skepticism from critics who questioned whether her research goals — particularly the effort to observe and characterize the environment at the center of the Milky Way — were feasible. Nevertheless, her early curiosity and determination propelled her forward into an academic career that would eventually yield one of the most significant discoveries in modern astrophysics.

Education

Ghez pursued her undergraduate studies at the Massachusetts Institute of Technology (MIT), where she earned a Bachelor of Science degree in physics. She then continued her graduate education at the California Institute of Technology (Caltech), where she completed her Ph.D. in physics. Her doctoral research introduced her to the techniques of high-resolution imaging and infrared astronomy that would prove central to her later groundbreaking work on the galactic center. At Caltech, she developed expertise in speckle imaging, a technique that allows ground-based telescopes to overcome the blurring effects of Earth's atmosphere and achieve near-diffraction-limited resolution — a capability that would become a cornerstone of her observational methodology.

Career

UCLA and the Galactic Center Group

Following the completion of her doctoral studies, Ghez joined the faculty of the University of California, Los Angeles, where she rose through the academic ranks to become the Lauren B. Leichtman and Arthur E. Levine Professor of Astrophysics. At UCLA, she founded and became director of the Galactic Center Group, a research team dedicated to studying the environment at the center of the Milky Way galaxy.

The central question driving Ghez's research program was whether a supermassive black hole existed at the center of the Milky Way. While theoretical predictions and indirect observations had long suggested the presence of an extremely massive, compact object in the region known as Sagittarius A* (Sgr A*), direct observational proof remained elusive due to the enormous quantities of interstellar dust between Earth and the galactic center, which block visible light. Ghez's approach was to observe in the near-infrared portion of the electromagnetic spectrum, which can penetrate the dust, and to use the most powerful telescopes available combined with cutting-edge imaging techniques to resolve individual stars orbiting close to the galactic center.

Observations at the W. M. Keck Observatory

A critical element of Ghez's research was her use of the W. M. Keck Observatory, located atop Mauna Kea in Hawaii. The Keck Observatory houses twin 10-meter telescopes, which at the time of Ghez's early observations were the largest optical and infrared telescopes in the world. Ghez and her team used these instruments, equipped with adaptive optics systems that correct for atmospheric distortion in real time, to achieve extraordinarily sharp images of stars near the galactic center.

Beginning in the mid-1990s, Ghez and her collaborators embarked on a long-term monitoring campaign, tracking the positions and motions of stars in the immediate vicinity of Sagittarius A*. Over years of painstaking observation, they were able to map the orbits of these stars with increasing precision. One star in particular, known as S0-2 (also designated S2), proved especially informative. S0-2 follows a highly elliptical orbit around the galactic center with a period of approximately 16 years, bringing it to within a few light-hours of the central object at its closest approach.

By tracking S0-2 and other stars through significant portions of their orbits, Ghez's team was able to calculate the mass of the central object using Kepler's laws of orbital mechanics. The results were striking: the stars' motions indicated the presence of an object with a mass of approximately four million times that of the Sun, confined to a region of space too small to be anything other than a supermassive black hole according to the prevailing understanding of physics.

This work, conducted independently of and in parallel with a similar research program led by Reinhard Genzel at the Max Planck Institute for Extraterrestrial Physics in Germany, provided the most compelling empirical evidence that supermassive black holes exist — not merely as theoretical constructs predicted by general relativity, but as real astrophysical objects occupying the centers of galaxies.

Advancing Adaptive Optics and Infrared Techniques

A significant component of Ghez's contribution to astrophysics lies in her development and application of advanced observational techniques. Early in her career, she used speckle imaging — a method that involves taking many short-exposure images and combining them computationally to remove atmospheric blurring — to achieve high-resolution views of the galactic center from ground-based telescopes. As technology advanced, she became a leading proponent and user of adaptive optics, a technique in which a deformable mirror is adjusted in real time, hundreds of times per second, to counteract the turbulence of Earth's atmosphere.

The integration of adaptive optics with the Keck Observatory's large aperture enabled Ghez's team to achieve angular resolution comparable to that of the Hubble Space Telescope, but with far greater light-gathering power in the infrared. This technological capability was essential to resolving the crowded stellar field at the galactic center and tracking the minute positional changes of individual stars over time.

Testing General Relativity

Beyond establishing the existence of the supermassive black hole, Ghez's observations opened new avenues for testing Albert Einstein's general theory of relativity in an extreme gravitational environment. As stars like S0-2 pass close to the black hole at velocities of thousands of kilometers per second, the effects predicted by general relativity — such as gravitational redshift — become measurable. Ghez and her team have used these close encounters to test whether general relativity holds in the strong gravitational field near a supermassive black hole, contributing to a broader effort in fundamental physics to probe the limits of Einstein's theory.

Contributions to Scientific Culture and Creativity

Beyond her research, Ghez has been an active voice in discussions about the role of creativity in scientific inquiry. In 2025, she participated in an interdisciplinary panel discussion at the American Academy of Arts and Sciences on the topic of "Science and Creativity," where panelists explored how creativity and innovative thinking drive scientific discovery. Ghez's participation in such forums reflects her engagement with the broader intellectual community and her interest in how the scientific process intersects with creative and interdisciplinary thinking.

In a 2022 interview during Nobel Week in Stockholm, Ghez reflected on her career and the path that led to her Nobel Prize-winning discovery. She discussed the challenges of pursuing a research program that required decades of sustained observation and the importance of persistence in scientific investigation.

Role at the University of California

Ghez has spoken about the importance of the University of California system as an environment for scientific research. In a 2025 feature by the University of California, she was highlighted as one of several UC Nobel laureates who discussed why the university system served as a fertile ground for their discoveries. Ghez credited the research infrastructure, access to major observatories, and the collaborative culture at UCLA as key factors enabling her work. She emphasized that the kind of long-term, high-risk research that led to the confirmation of the Milky Way's supermassive black hole required institutional support and patience — qualities she found at UCLA.

Personal Life

Ghez has kept much of her personal life outside the public record. She resides in the Los Angeles area, where she continues her research and teaching at UCLA. Public accounts from her Nobel Prize interviews indicate that she has a family and has spoken about the challenge of balancing the demands of an intensive observational research program with personal life.

Ghez has also spoken publicly about her experience as a woman in a field historically dominated by men. As the fourth woman to win the Nobel Prize in Physics, her achievement has been noted for its significance in the context of gender representation in the sciences. In interviews, she has discussed the skepticism she encountered earlier in her career from those who doubted the feasibility of her research approach — criticism she overcame through persistence and the strength of her observational results.

Recognition

Nobel Prize in Physics

On October 6, 2020, the Royal Swedish Academy of Sciences announced that Andrea Ghez would share one half of the Nobel Prize in Physics with Reinhard Genzel "for the discovery of a supermassive compact object at the centre of our galaxy." The other half of the prize was awarded to Roger Penrose "for the discovery that black hole formation is a robust prediction of the general theory of relativity." Ghez and Genzel each received one quarter of the prize.

The Nobel Committee recognized that Ghez's decades-long observational campaign, using the world's largest telescopes with adaptive optics, had provided conclusive evidence that an invisible and extremely heavy object governs the orbits of stars at the center of the Milky Way, with a supermassive black hole being the only currently known explanation.

Other Awards and Honors

Prior to the Nobel Prize, Ghez received numerous accolades for her research. She was awarded the Crafoord Prize in Astronomy by the Royal Swedish Academy of Sciences, one of the most significant honors in fields not covered by the Nobel Prize. She also received a MacArthur Fellowship, often colloquially referred to as the "genius grant," which recognized the exceptional creativity and promise of her research program.

Ghez has been elected to membership in the National Academy of Sciences and the American Academy of Arts and Sciences, both of which recognize outstanding contributions to scientific research. She has also received recognition from the W. M. Keck Observatory for her use of their facilities in making discoveries of fundamental importance to astrophysics.

Legacy

Andrea Ghez's work on the supermassive black hole at the center of the Milky Way represents one of the landmark achievements of observational astrophysics in the late twentieth and early twenty-first centuries. Her research, conducted over more than two decades of sustained observation, transformed what had been a theoretical prediction — the existence of supermassive black holes at galactic centers — into an established empirical fact.

The confirmation of Sagittarius A* as a supermassive black hole with a mass of approximately four million solar masses has had far-reaching implications for the understanding of galaxy formation and evolution. Supermassive black holes are now understood to reside at the centers of most, if not all, large galaxies, and the relationship between these black holes and their host galaxies is a major area of active research in astrophysics. Ghez's work provided a critical piece of the observational foundation for this understanding.

Her pioneering use of adaptive optics and high-resolution infrared imaging techniques advanced the capabilities of ground-based astronomy and demonstrated that Earth-based telescopes could achieve observations previously thought to require space-based instruments. This methodological contribution has had a lasting impact on the field, enabling a wide range of subsequent observational programs beyond the study of the galactic center.

As one of only a small number of women to have received the Nobel Prize in Physics, Ghez's achievement has been recognized for its broader significance in demonstrating the contributions of women to the highest levels of scientific research. Her career has served as a reference point in ongoing discussions about diversity and representation in the physical sciences, and she has used her platform to encourage the next generation of scientists.

The UCLA Galactic Center Group, which Ghez founded and continues to lead, remains one of the premier research teams studying the environment around supermassive black holes, and her ongoing work continues to push the boundaries of what can be observed and understood about these extreme astrophysical objects.