Erin Kara studies supermassive black holes

Black holes remain among the most misunderstood objects in the universe, largely due to common misconceptions fueled by their name. Universe Today reported that rather than being spatial tunnels leading to certain death, black holes are actually the collapsed remnants of stars compressed so densely that gravitational forces at their surfaces reach the speed of light. This extreme condition creates an outer boundary known as the event horizon, preventing anything, including light, from escaping. At the Kavli Institute for Astrophysics and Space Research, Professor Erin Kara leads a research group studying how supermassive black holes grow, evolve, and influence the massive galaxies that house them.

Tracing X-Ray Reverberations at MIT

Kara began her academic path at the Institute of Astronomy at Cambridge University, completing a master’s degree in physics followed by a Ph.D. focused on black hole X-ray reverberation under the supervision of Andy Fabian OBE FRS. In 2009, Fabian and his research team identified strange time delays while reviewing archival X-ray data from the corona, the crown-shaped high-energy region surrounding a black hole. Researchers interpreted these signals as the first evidence of X-ray reverberations, determining that radiation generated in the corona bounces off the accretion disk of swirling gas and dust.

They had only found these echoes in one black hole. But the archive was full of data of these reverberation signals that no one had analyzed in this particular way. So I had my whole PhD to kind of play with this archive, and it felt very discovery-driven. Kara explained regarding the archival data.

Instruments Mapping Supermassive Black Holes

Following her doctoral work, Kara completed postdoctoral research at the University of Maryland and NASA’s Goddard Space Flight Center. During that time, she contributed to the Japanese Hitomi mission, which failed after 40 days in space but successfully validated its microcalorimeter instrument. That technology later influenced the X-ray Imaging and Spectroscopy Mission, known as XRISM, where Kara now leads a science group analyzing X-ray emissions from supermassive black hole coronas.

Kara also collaborated with the MIT team behind the Neutron Star Interior Composition Explorer, or NICER, which is integrated with the International Space Station to measure X-ray timing from astrophysical sources. Today, she and her students leverage data from both XRISM and NICER to map extreme regions around galactic centers. Their investigations extend to tidal disruption events, periodic eruptions, and black hole outbursts, revealing that systems can activate and deactivate much faster than previously assumed.

As Kara noted, scientists can now observe that these systems turn on and off at rates much faster than previously thought possible. Furthermore, researchers are observing that matter is being pulled into black holes faster than expected, potentially because stars are whipping around and becoming trapped in the accretion disks of black holes.

Upcoming Observatories Scanning the Sky

Research efforts will expand with upcoming observatories designed to capture ultraviolet sources and gravitational waves. Kara’s team prepares to analyze data from the Ultraviolet Transient Astronomy Satellite and the Laser Interferometer Space Antenna, missions tasked with continuously scanning for hot ultraviolet sources and detecting low-frequency gravitational waves generated by black hole mergers.

It’s amazing that we as humans can know anything about what’s happening billions of light-years away, Kara said. There’s a lot of new open puzzles about supermassive black holes that I’m excited about.