In this special session the Simonyi-NSF Scholars will present their LSST research projects. These scholars are the recipients of NSF grants co-funded as part of the Simonyi-NSF Scholarship Program, a partnership between Charles Simonyi and NSF to support early career scientists in their contribution to Rubin's LSST.

Contributed talks:

• Gautham Narayan on behalf of The Young Supernova Experiment (YSE), The Scalable Cyberinfrastructure for Multi-Messenger Astrophysics (SCIMMA) team, The NSF-Simons SkAI Institute, and The LSST Dark Energy Science Collaboration (DESC)
  Early Rubin science in the time domain
  The Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST)  will discover millions of transient and variable sources at an unprecedented rate. This rich dataset will allow us to answer long-standing open questions on supernova progenitors and the nature of the most exotic transients, feedback and galaxy evolution, and cosmology. I will present an overview of four aspects of the analysis my group is involved in to enable early Rubin science 1) using AI to discover, classify and  quickly follow-up young transients with Rubin and a network of ground- and space- based telescopes, 2) building the Rubin target-of-opportunity (ToO) system with the Scalable Cyberinfrastructure for Multi-Messenger Astrophysics (SCiMMA) group 3) finding and modeling gravitationally-lensed type Ia supernovae to study the Hubble tension and 4) studying the nature of dark energy with type Ia supernovae with the Dark Energy Science Collaboration (DESC).

• Igor Andreoni, Eric Burns, Michael Coughlin, Ashley Villar
  Establishing Multi-wavelength Time-domain Communities in the Rubin Era
  Rubin will revolutionize our observations of the sky over time in optical, producing ~10 million alerts per night. Population studies using data from the LSST will have orders of magnitude more events to learn from. However, we can learn more about what explodes in the night by observing the same transient events at other wavelengths as well. Thus, we require the capability to identify needles in the haystack, and to get rapid follow-up observations performed before the transients fade out of detectability. This problem requires time-domain communities to adapt to the new era including ever more clever classification schemes, adaptation to what is learned in the first years of the LSST, and deeper collaboration than existed in previous surveys. We'll discuss these issues and one particular group which is approaching the problem in a new way.

• Colin Burke, Priya Natarajan, Marla Geha, Vivienne Baldassare
  Constraining supermassive black hole seeding and growth with AGN variability in the Rubin Era
  Active galactic nuclei (AGNs) in dwarf galaxies (dwarf AGNs) are believed to host accreting intermediate-mass
  black holes (IMBHs). The demographics of dwarf AGNs are an important tracer of supermassive black hole (SMBH) growth, because their relic IMBHs act as a fossil record of SMBH seeding pathways at high redshift. Being ubiquitous across wavelengths and timescales, variability is useful for AGN identification and is an important probe of black hole accretion. I will present a new Bayesian hierarchical method and subsequent results constraining the local black hole occupation fraction, mass function, and accretion rate distribution with optical variability. Using simulation-based inference techniques, our observed results can be directly coupled to semi-analytic models of black hole growth to map-out the degeneracies between the initial mass function of high-redshift black hole seeds and their accretion and merger histories. This will provide useful predictions for the Vera C. Rubin Observatory and the Laser Interferometer Space Antenna (LISA).

• Darryl Z. Seligman
  Discovery and preliminary characterization of a third interstellar object: 3I/ATLAS
  We report initial observations aimed at the characterization of a third interstellar object candidate. This object, 3I/ATLAS or C/2025 N1 (ATLAS), was discovered on 2025 July 1 UT and has an orbital eccentricity of e~6.1, perihelion of q~1.36 au, inclination of ~175 deg, and hyperbolic velocity of v_infty~58 km/s. We report deep stacked images obtained using the Canada-France-Hawaii Telescope and the Very Large Telescope that resolve a compact coma. Using images obtained from several smaller ground-based telescopes, we find minimal light curve variation for the object over a ~4 day time span. The visible/near-infrared spectral slope of the object is 17.1+/-0.2 % 100 nm, comparable to other interstellar objects and primitive solar system small bodies (comets and D-type asteroids), although this result is likely affected by some coma contamination. 3I/ATLAS will be observable through early September 2025, then unobservable by Earth-based observatories near perihelion due to low solar elongation. It will be observable again from the ground in late November 2025. Although this limitation unfortunately prohibits detailed Earth-based observations at perihelion when the activity of 3I/ATLAS is likely to peak, spacecraft at Mars could be used to make valuable observations at this time. Additional photometric, spectroscopic, and polarimetric monitoring of 3I/ATLAS by ground- and space-based telescopes, and possibly spacecraft based at Mars, are highly encouraged for characterizing 3I/ATLAS's rotational light curve, activity evolution, nongravitational acceleration, and compositional indicators of formation conditions.

• Sarah Greenstreet, Siegfried Eggl, Samuel Cornwall, Dmitrii Vavilov
  Rubin Rocks: A web service for statistics on NEO dynamical histories
  As current NEO surveys steadily increase the number of known objects, and with the expectation of significant contributions from the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST), our ability to understand the history of these objects correspondingly increases. Fitting numerical integrations to the observed population provides rich datasets from which the history of these objects can be inferred. Because such comprehensive integrations are computationally expensive, it is impractical to perform for the purposes of many smaller scale studies, such as the examination of a single NEO. We present here a web service for querying the statistical information on the dynamical histories of NEOs, including, but not limited to, source region probabilities, residence times, and time to initial entry, as functions of orbital elements. The service leverages comprehensive integrations of NEO orbits to provide a look up table of these statistics, which we provide access to through a publicly available API.

• Jonathan Blazek
  Simulation-based modeling with neural networks for galaxy IA and bias
  Taking full advantage of high-precision cosmological data from Rubin LSST and other upcoming surveys will require both improved understanding of systematic effects and new statistical approaches. Two main systematics are intrinsic alignments (IA) and galaxy bias, which impact measurements of weak lensing and galaxy clustering. Current modeling often utilizes perturbation theory to extract information beyond the linear regime. However, future analyses will likely require fully nonlinear descriptions, especially for weak lensing measurements that rely on small-scale information. I will present recent and ongoing work to develop a simulation-based modeling framework for IA and bias, based on gravity-only simulations and semi-analytic models for galaxy occupation and IA. We are able to produce large, simulated volumes with realistic galaxy statistics, including flexible parameterizations for IA and the galaxy-halo connection. Using these simulations as training data, we have constructed neural network-based emulators to allow direct, simulation-based modeling of IA, lensing, and galaxy clustering. This approach will provide an accurate, nonlinear model for both standard lensing statistics (e.g. the two-point lensing and clustering correlation functions) as well as any beyond two-point statistic that can be measured from simulated data.

• Alex Drlica-Wagner, Gary Bernstein, Robert Gruendl, Monika Adamow, Daniel Gomes, Chin Yi Tan, Vernon Wetzel
  Jump Starting LSST Proper Motion Science with DECam Observations
  The Rubin Observatory’s Legacy Survey of Space and Time (LSST) will provide exceptional observations of the positions and fluxes of faint stars. Precise measurements of stellar proper motions are critical for understanding the formation and content of the Milky Way galaxy. However, these measurements require observations distributed over a long time baseline in order to detect the extremely small angular motions of stars. Early LSST observations can be combined with more than a decade of existing observations from the Dark Energy Camera (DECam) on the 4m Blanco Telescope to rapidly accelerate our ability to measure stellar proper motions. Furthermore, advanced techniques for improving the astrometric accuracy of ground-based observations developed for the Dark Energy Survey can be extended to the entire DECam data set and to future observations from LSST. We will present an overview of our efforts to use DECam to jump start proper motion science with LSST and projections for the potential reach of combined observations.

• Mansi Kasliwal
  Babamul on BOOM: A multi-stream open-source event broker developed by the Zwicky Transient Facility
  I will present BOOM - Burst and Outburst Observations Monitor - an open-source analysis framework focused on real-time joint brokering of multiple alert streams. Harnessing a Rust-based software stack, a NoSQL MongoDB database, a Redis/Valkey in-memory processing queue and a Kafka cluster, we are already achieving feature parity with 5x higher throughput than the current ZTF solution. Babamul - our public interface - will serve multiple jointly filtered streams over kafka.  Our stream will have the results of joint queries of the Rubin and Zwicky Transient Facility alert streams,  enriched with new multi-modal machine learning models (Apple CiDeR) and cross-matches with many static catalogs.   Skyportal - our open source marshal interface for visualization, analysis and follow-up coordination - can easily plug into the babamul streams and communicate effectively between different instances.   We are grateful to the Simonyi-NSF program for supporting this software infrastructure development effort.
   

Go to the list of all contributed abstracts.