Visiting Assoc Scientist, Astronomy

Full-time Science Huntsville, AL, US

3 days ago Requisition

USRA and the Science and Technology Institute are seeking a full-time Associate Scientist (Visiting) to join our team. The associate scientist will study the electromagnetic (EM) observing strategies that best constrain the gravitational-wave (GW) counterparts of Extreme Mass Ratio Inspirals (EMRIs) for LISA. Using quasi-periodic eruptions (QPEs) and quasi-periodic oscillations (QPOs) from active galactic nuclei as periodic EM signatures of EMRIs, the researcher will characterize how sampling cadence, observation duration, and data gaps limit the recovery of phase information, and determine the minimum EM observing investment needed to usefully anchor a gravitational-wave search — providing practical, telescope-time-limited guidance for planning future multi-messenger observing campaigns.

This is a one-year appointment with the potential to extend to three years, contingent on funding and performance.

• Construct synthetic electromagnetic (EM) signals from EMRI trajectories intersecting a precessing accretion disk, modeling quasi-periodic eruptions (QPEs) as disk-crossing events, and calculate expected light curves for known QPE/QPO EMRI candidates
• Design and run mock EM observing campaigns that systematically vary sampling cadence, observation duration, session length, and data gaps, treating each as a hyperparameter of the search
• Apply a trans-dimensional, non-parametric reconstruction (adapted from Bayes Wave Voices ) to recover harmonic phase evolution from each mock light curve, and quantify how well the recovered phase anchors a matched gravitational-wave search
• Use the Eryn trans-dimensional sampler to determine the minimum number of harmonics and spline knots needed to capture the periodic EM signal under realistic, sparse observing conditions
• Perform model selection across observing-schedule hyperparameters to identify the minimum EM observing duration and cadence that yields a usable gravitational-wave phase constraint, given limited telescope time
• Characterize how aliasing, spectral leakage, and irregular sampling bias phase and period recovery for QPE- and QPO-like periodic signals, and propose mitigation strategies informed by prior knowledge of signal morphology
• Translate results into practical recommendations for scheduling EM observing campaigns (e.g., XMM-Newton, Chandra, NICER) in support of LISA multi-messenger EMRI searches
• Contribute to open-source software development, testing, and documentation on Git Hub, in line with the project's Open Science and Data Management Plan
• Prepare results for publication in journals and present findings at national and international conferences, including within the LISA Consortium

PhD in Physics, Astronomy, Astrophysics, or a related field, or equivalent combination of education and experience.

Candidates with at least 5 years of experience performing this type of work are highly preferred. Prior experience with time-domain astronomy and analysis of quasi-periodic or periodic signals (e.g., QPEs, QPOs, or comparable variable/transient phenomena) is strongly preferred. Experience with observation scheduling, survey/cadence optimization, or the design of observing campaigns is a plus. Familiarity with Bayesian inference (e.g., MCMC, nested sampling) and gravitational-wave data analysis or LISA science is a plus but not required.

• Strong understanding of time-domain astronomy, particularly the timing analysis of quasi-periodic and periodic X-ray or optical signals
• Familiarity with sampling theory and its practical limitations: aliasing, spectral leakage, and the effects of…