CRISM Observes Multi-Speed Ultra-Fast Outflows in a Star-Forming Galaxy Merger

CRISM has captured a waking supermassive black hole in a dust-enshrouded galaxy merger IRS 05189-2524, detecting three ultra-fast outflows that travel a significant fraction of light speed. This observation provides a detailed view of how black holes influence their host galaxies during intense star formation and the transition toward elliptical galaxies.

• Three discrete outflow speeds detected: 0.075c, 0.10c, and 0.14c
• Iron line signatures at 6.7 keV and 7 keV reveal ultra-fast winds
• The winds carry more energy than slower molecular winds, potentially quenching star formation
• Supports the role of black hole feedback in shaping galaxy evolution during mergers

Introduction

The video reports on the X ray imaging and spectroscopy mission CRISM and its first six months of observations during which CRISM targeted a galaxy merger, IRS 05189-2524, located about 603 million light years from Earth. The system is a dusty ultraluminous infrared galaxy undergoing a starburst as two smaller galaxies interact and merge. The central question is how the central supermassive black hole, long thought to be dormant for billions of years, influences its host galaxy when accretion resumes.

The Target Galaxy and CRISM’s Capabilities

IRS 05189-2524 is an ultraluminous infrared galaxy that showcases intense star formation hidden by thick dust. CRISM carries a wide angle X ray camera and RESOLVE, a high resolution spectrometer capable of resolving fine X ray spectral features. Together they enable detailed study of the sleep wake cycles of supermassive black holes and the energetic winds they produce.

Observational Breakthrough

In August 2024 CRISM observed the active galactic nucleus in the galaxy merger and identified ultra fast outflows moving toward Earth. Previous X ray studies had detected a single peak corresponding to one velocity, but CRISM’s enhanced resolving power revealed three distinct speeds. The spectra show blue shifted lines corresponding to iron ions at rest frame energies near 6.7 and 7 keV, indicating winds moving at significant fractions of the speed of light. This multi peak structure points to the black hole ejecting several bullets of gas at different velocities, a phenomenon not previously mapped in such detail in a starbursting merger.

Energetics and Implications for Star Formation

The measurements show that the kinetic energy carried by these ultra fast outflows is vastly greater than that of the slower winds in the surrounding galaxy. The implications are profound: the outflows are capable of dispersing cold gas clouds that fuel star formation, effectively quenching the starburst and steering the system toward an elliptical, low star formation state. This observational evidence strengthens the feedback paradigm in which black hole activity regulates galaxy growth and evolution during dramatic mergers.

Connections to Galaxy Evolution Scenarios

CRISM’s findings illuminate a transitional phase in galaxy evolution where a starburst galaxy is evolving into a quasar like state. The intense accretion onto the central black hole drives winds that can halt star formation and lead to the formation of a mature elliptical galaxy. The study also provides context for how massive black holes interact with their galactic environments over the timescales of tens to hundreds of millions of years.

Future Directions

Researchers plan to monitor the system over time to determine if the outflow properties vary and to search for additional ultra fast winds. Looking ahead, future X ray observatories such as the European Space Agency’s Athena mission will offer even more advanced spectrometers, enabling detailed investigations of each evolutionary stage from initial collisions to peak quasar activity across multiple systems. The broader aim is to assemble a comprehensive picture of how black holes sculpt their galaxies in the universe, including our own Milky Way.

Conclusion

The CRISM observations of IRS 05189-2524 provide a rare and valuable natural laboratory for studying black hole feedback in the context of galaxy mergers. By revealing multi speed ultra fast outflows and tying them to vigorous accretion, the study offers crucial clues about how galaxies grow, quench star formation, and eventually become giant ellipticals, a narrative that extends to our own galactic neighborhood.