Events

How Dark is Space?
Tod R. Lauer
Astronomer, NOIRLab

We used NASA’s New Horizons spacecraft to measure the cosmic optical background (COB) intensity integrated over 0.4 ≲ λ ≲ 0.9 μm. The survey comprises 16 high Galactic-latitude fields. Images were obtained with the LORRI camera when New Horizons was 57 AU distant from the Sun. As such, the sky intensity measurements were unaffected by zodiacal light, which strongly interferes with COB measurements attempted from the inner solar system. T he survey yields a highly significant detection (6.8σ) of the COB at 11.16 ± 1.65 (1.47 sys, 0.75 ran) nW m−2 sr−1 at the LORRI pivot wavelength of 0.608 μm. The estimated integrated intensity from background galaxies, 8.17 ± 1.18 nW m−2 sr−1, can account for the great majority of this signal. The rest of the COB signal is formally classified as anomalous intensity but is not significantly different from zero. The simplest interpretation is that the COB is completely due to galaxies.

Better Together: Combining the Strengths of Rubin, Euclid, and Roman for Time-domain Science and Cosmology
Charlotte Ward
Assistant Professor, Department of Astronomy and Astrophysics in the Eberly College of Sciences at Penn State

We have entered an exciting decade for survey science, with space-based surveys such as Euclid and Roman and ground-based surveys such as Rubin Observatory's Legacy Survey of Space and Time (LSST) providing overlapping imaging datasets across the optical and IR. LSST will identify thousands of tidal disruption events (TDEs) and millions of AGN and supernovae – including hundreds of gravitationally lensed supernovae (gLSNe) from which we can measure the Hubble Constant.

Bringing XFEL Science to the Laboratory: Commissioning the Compact X-ray Light Source at Arizona State University
Sabine Botha, Research Assistant Professor, Department of Physics
Arizona State University

Compact accelerator-driven X-ray sources are emerging as a new class of laboratory-scale facilities capable of delivering capabilities traditionally available only at large national user facilities. At Arizona State University, the Compact X-ray Light Source (CXLS) is currently undergoing commissioning, while its successor, the Compact X-ray Free Electron Laser (CXFEL), is under construction. Together, these instruments aim to bring ultrashort, high-brightness X-ray pulses into the university laboratory, enabling new opportunities in structural biology, medical imaging, atomic, molecular and optical physics, and the study of condensed matter and quantum materials.

Uncovering Extreme Matter When Gravity Waves
Nicolas Yunes, Bob Uyetani Professor in Physics
University of Illinois Urbana-Champaign

Neutron stars contain matter at extreme densities and low temperatures that cannot be reproduced together in terrestrial experiments. Their collisions offer a way to study this matter through gravitational waves. In this colloquium, I will discuss how tidal deformation connects gravitational-wave measurements to stellar structure, and how approximate universal relations help overcome degeneracies in these measurements. I will then explore the connections between microscopic nuclear interactions and macroscopic stellar properties, asking what observations can tell us about matter deep inside neutron stars. A neutron star’s response does not just depend on its equilibrium structure, but also on how rapidly it is driven, how its constituents relax toward equilibrium, and how phase boundaries respond to perturbations. These effects connect dynamical tides and dissipation to the underlying matter physics. I will distinguish what observations already constrain from the signatures that remain difficult to measure, and discuss the prospects for learning more about dense matter when gravity waves.

Light-driven Molecular Transformations Captured by Ultrafast Spectroscopy
Dr. Chavdar Slavov, Assistant Professor, Department of Chemistry
University of South Florida

Femtosecond time-resolved spectroscopy reveals the excited-state pathways and chromophore dynamics that transform light absorption into photochemical and biological function. Using phytochromes, I will illustrate how the protein environment controls chromophore isomerization, which in turn initiates structural changes that regulate biological signaling.