X-ray Astronomy in Living Color: St. Louis Astronomical Society August 2026 Meeting
Observational astronomy is mostly a story about measuring photons with precision — how many are there, what direction are they coming from, when do they arrive, and what are their energies? The better we can make those measurements the better our understanding of the astrophysical systems that send those photons across the Cosmos to our sky. A key tool in astrophysical studies is spectroscopy — deciphering photon energies by exploring the rainbow of colors in the light that we detect. Most of us are familiar with rainbows created either naturally in a misty sky or intentionally with prisms and diffraction gratings. But how do we do this when we are talking about X-rays? It turns out, this is much more difficult, but extremely important for our understanding of the most exotic phenomena in our Universe, such as black holes and neutron stars! In this talk I will discuss our currently most precise instruments for measuring “X-ray Rainbows”: the Chandra-High Energy Transmission Gratings and the XRISM satellite, which uses “quantum detectors” to open up a new frontier in X-ray spectroscopy. I will also discuss possible future instruments that could be used to make precise measurements of "X-ray rainbows" from distant, supermassive black holes to reveal the “missing matter” in the Universe (that you probably didn’t even realize was missing!)
Michael Nowak is a Research Professor in the Physics Department as well as the Associate Director of the McDonnell Center for the Space Sciences at Washington University in St. Louis. Nowak’s work encompasses both observation and theory of astrophysical compact object (black hole and neutron star) systems. His early theoretical work focused on the hydrodynamics of accretion flows in these systems, and later evolved into theories describing the implications of X-ray spectra and variability for models of astrophysical jets relativistically speeding away from and hot (billions of degrees) coronae surrounding compact object systems. He performs observational studies with a variety of High Energy Astrophysics observatories, including the Chandra, Swift, NICER, and NuSTAR (NASA), and XMM-Newton (ESA) satellites. He currently is a science collaborator, assisting with coordinated X-ray and gamma-ray observations, with the Event Horizon Telescope team who have used radio interferometry to image accretion flows around the supermassive black holes Sgr A* and M87*.
The St. Louis Astronomical Society is an organization for individuals interested in astronomy and telescopes. The public is invited to attend its meetings, telescope observing sessions, and special events. For more information about Astronomical Society events, please visit www.slasonline.org.
Free parking will be available.
Header image: Halley's comet (Credit: NASA Jet Propulsion Laboratory, California Institute of Technology)