EXPERTS ADVISORY

The National Academies of Sciences, Engineering, and Medicine recently released its Astro2020 Decadal Survey, a report that identifies key scientific and foundational challenges, opportunities and funding recommendations.

Delayed a year because of the COVID-19 pandemic, the report provides a road map for the upcoming decade of American research in astronomy and astrophysics.

University of Michigan scientists are available to comment.

Oleg Gnedin is a professor of astronomy and an expert on theoretical modeling of galaxy formation. He investigates how massive compact clusters of stars form at high redshift and evolve into globular clusters. These clusters will likely constitute main sources of light from the first galaxies detectable by the James Webb Space Telescope space observatory and proposed ground-based Extremely Large Telescopes. The NAS Decadal Survey emphasized that theoretical modeling is necessary to realize the full potential of these facilities for understanding the drivers of galaxy growth.

Contact: ognedin@umich.edu

Kayhan Gultekin is a member of the NASA’s Laser Interferometer Space Antenna Study Team, charged with developing and articulating a compelling science case supporting the NASA participation in the European Space Agency-led LISA mission as well as providing analysis on scientific and technical issues related to LISA.

The LISA instrument will consist of three spacecraft in a triangular formation with 1.5 million mile arms, moving in an Earth-like orbit around the sun. Gravitational waves from sources throughout the universe will produce slight oscillations in the arm lengths, smaller than the diameter of an atom. LISA will capture these motions—and thus measure the gravitational waves—using laser links to monitor the movement of gold-platinum test masses floating inside the spacecraft.

The unifying theme of Gultekin’s research is black holes and in particular the interface between galaxies and supermassive black holes. He is especially excited about gravitational wave astrophysics and synergies with electromagnetic astrophysics.

“Astronomy is humanity’s oldest science. For almost all of their history, astronomers have used only light as information. Now we are in the age of multi-messenger astronomy, which adds gravitational waves as a new cosmic source of information,” he said. “Gravitational waves give us scientific information that is otherwise unattainable. With gravitational waves, we learn about black holes, compact binary stars, the beginning of the universe and about gravity itself.

“The future of gravitational wave observations is LISA, the Laser Interferometer Space Antenna, a gravitational wave observatory in space. I am very pleased that the National Academy of Sciences recommended that NASA ensure the full scope of LISA’s capabilities. With NASA and U.S. involvement in LISA, this brand new regime of gravitational waves will change our understanding of how supermassive black holes form, grow, evolve and merge.”

Contact: kayhan@umich.edu

Dragan Huterer, professor of physics, works in the field of cosmology and astrophysics, at the interface of cosmology theory and data. His chief expertise is in trying to better understand dark matter and dark energy, two dominant components of mass/energy in the universe whose physical nature remains a mystery.

“The Decadal Survey charts out priorities in astronomy and astrophysics for the next few decades,” he said. “If you are a young practicing astronomer, especially an observer, you will likely be working on, or using data from, one of the telescopes highlighted in the survey in the years to come.”

“I am especially pleased that some fundamental physics questions were highlighted in the Decadal Survey. This includes probing physics of the very early universe (fractions of a second after the Big Bang) by better mapping the cosmic microwave background radiation pattern on the sky, as well as investigating the nature of black holes and neutron stars by measuring gravitational waves emitted when they collide and merge.”

Contact: huterer@umich.edu

Sean Johnson, assistant professor of astronomy, works on observational studies of galaxy evolution. He focuses on the gas flows in and out of galaxies that regulate their star formation and supermassive black hole growth on timescales of billions of years. He also spends time working toward a more inclusive and just scientific environment with active recognition and reflection on the role that our humanity—good and bad—plays in the practice of science.

“The Decadal Survey survey highlights galaxy evolution, and the study of the gaseous galactic ecosystems is a key priority,” he said. “My current research makes extensive use of ultraviolet, optical and infrared observations made with the Hubble Space Telescope. The Decadal survey’s prioritization of a next-generation, much larger, space-based telescope for observing infrared, optical and ultraviolet light will revolutionize our ability to study galactic outflows and inflows. I am also thrilled to see a focus on the state of astronomy as a profession and specific recommendations to increase access and inclusivity in the field.”

Contact: seanjoh@umich.edu

Keith Riles, professor of physics and charter member of the LIGO Scientific Collaboration since its founding in 1997, iis familiar with the exploding new field of gravitational wave science. He has held a variety of scientific leadership positions within the LSC over the last 24 years and presently co-chairs the LSC editorial board. He is broadly knowledgeable on gravitational wave astrophysics and cosmology, with particular expertise in continuous gravitational wave signals.

“The latest Decadal Survey rightly highlights the growing importance of gravitational wave signals to astronomy and the critical role gravitational waves will play over the next two decades in understanding astrophysics and the early universe,” he said. “Gravitational waves permit us to ‘see’ otherwise invisible processes such as collisions of massive black holes billions of years ago and can also give us an early warning of impending collisions of neutron stars which can then be observed by other astronomers as they happen.

“The Decadal Survey appropriately calls for intense R&D into the technology needed for 3rd-generation gravitational wave detectors that could not only detect virtually every black hole and neutron star collision occurring in the universe, but also peer back far enough in time to detect possible primordial black holes created during the Big Bang.”

Contact: kriles@umich.edu

Mateusz Ruszkowski, associate professor of astronomy, is an expert on numerical magneto-hydrodynamics simulations of plasmas in astrophysical contexts. He is a theoretical astrophysicist whose research focuses on computational modeling of astrophysical feedback processes, such as the impact of gaseous outflows driven by supermassive black holes and supernova explosions on galaxies and galaxy clusters. He is the principal or co-principal investigator on several NASA- and NSF-funded programs examining the profound impact of magnetic fields and cosmic rays on these processes.

“True progress in our understanding of the supermassive black hole feedback can only be made by confronting state-of-the-art theoretical models with new observations,” he said. “The missions envisioned in the NAS Decadal Survey review may enable critical new measurements that are needed to transform our understanding of the physics of supermassive black holes.

“One major challenge in this field is to unravel how the energy released near the supermassive black holes is distributed over many orders of magnitude in distance. This energy is released in the central ‘engine,’ comparable in size to our solar system (where the relativistic jets are launched and the black hole spin energy is extracted), and then deposited on the scales as large as those of central regions of galaxy clusters where it helps to regulate growth of galaxies.

“Understanding these feedback processes will ultimately help answer the profound question of how the supermassive black holes affect galaxy evolution. As envisioned in the NAS decadal review, the very high spatial and spectral resolution of the new instruments capable of detecting X-rays is essential for shedding new light on the impact of these fascinating feedback processes, especially in large gaseous dark matter halos where we can image it directly.”

Contact: 734-255-4249, mateuszr@umich.edu

Marcelle Soares-Santos is a professor of physics. Her research aims to uncover the nature of the accelerated expansion of the cosmos. Her team detected the light from a gravitational wave-emitting collision of two neutron stars, the first ever to be observed. The discovery was heralded as the Science breakthrough of the year 2017 and inaugurated the era of multi-messenger astronomy, one of the central topics featured in the Astro2020 Decadal Survey.

She was also an associate scientist at the Fermi National Accelerator Laboratory and is one of the leaders of the ongoing Snowmass physics community planning process, organized by the Division of Particles and Fields of the American Physical Society.

“Together, Snomass and the Astro decadal survey set the agenda for the future in this field of research,” she said. “It is particularly exciting to see multi-messenger astronomy featured so strongly in the Astro2020 report, as this boosts the case for this emerging field to be at the forefront of new discoveries in the coming decade.”

Contact: mssantos@umich.edu, Twitter: @msoares_santos

Gregory Tarlé is a professor of physics. His research in experimental astrophysics and cosmology focuses on studying the constituents of the dark universe. In the last decade, he has been a leader in developing instrumentation for the Dark Energy Survey and the Dark Energy Spectroscopic Survey (PDF), which attempt to understand the fundamental nature of the mysterious dark energy that currently dominates our universe and is causing its expansion to accelerate.

He is currently involved in MegaMapper, a future generation highly multiplexed spectroscopic survey to study Inflation and Dark Energy that has been highlighted by the Astro2020 Decadal Survey.

“The nature of Dark Energy will likely not be revealed by a single experiment,” Tarlé said. “Rather, an understanding may take a century of research, much like it took a century to develop an understanding of the nature of elementary particles, starting with the Millikan oil drop experiment and extending through the discovery of the Higgs boson.”

Contact: 734-417-0686, gtarle@umich.edu