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Please join me in congratulating the recipients of the 2026 Fieldus Award: Simran Nerval and Mairead Heiger!

Simran’s research focuses on inflation and testing physics beyond the standard picture. In ACT Final Data Release 6, Simran took part in the science team producing constraints for the paper on extended models. In her recently-submitted first-author paper, “Constraining primordial oscillations and inflationary particle production with Planck, ACT DR6, and DESI DR2” she used these data sets to limit the oscillatory signals that might arise in non-standard inflationary models. And, working with Erika Hornecker and others, she’s been a leader in the detailed analysis of instrumental time streams to identify and classify `glitches’ and point sources; see Nerval, Hornecker, et al 2025 ,

Simran also has an impressive record of working for the benefit of others in many ways, including science communication and outreach (especially to underrepresented groups), working for equity, diversity, and inclusion, and representing
– Multiple outreach efforts to underrepresented groups, including a pandemic-era online workshop “Age of the Universe” which led to the “Coding the Cosmos” workshops for high school students, focused on low-income groups in the Greater Toronto Area. Simran developed “Coding” from scratch, then used Dunlap seed funding to grow it into a large program, with over 30 volunteers, ten developers and ten executives, that delivers workshops around southern Ontario. In addition to disseminating knowledge, “Coding the Cosmos” provides its graduate and undergraduate participants with significant training in education and outreach.
– Mentorship program coordinator for the GEnder MINorities In Physics (GEMINI-P) program at Queen’s University (during her Master’s degree)
– Director of External Affairs for the Innovation, Diversity, Exploration, & Advancement in STEM (IDEAS) Initiative, also at Queen’s
– Member of the CASCA Graduate Student Committee (2020-2024), including organization of the Graduate Student Workshops and the Canadian Telescope/Theoretical Seminars. She created the rubrics used by the GSC to evaluate talks and posters for prizes at our CASCA annual meetings.
– GSC representative to CASCA’s Equity, Diversity, and Inclusion Committee, contributing especially to the CASCA Climate Survey — defining its questions, getting ethics approval, and leading substantial portions of its analysis and report writing.
– Similar roles on our own Community & Culture Committee.
– Co-director of AstroTours (2021-2023) including a period of entirely online AstroTours. Simran introduced lab tours to the series, and improved how the program is budgeted.
– Mentor of ten undergraduate and high school students.

Mairead’s research bridges multiple areas of astronomy and astrophysics. On the observational end, she led the spectroscopic follow-up and first detailed abundance analyses of the ultra-faint dwarf galaxies Eridanus IV and Centaurus I with Magellan/IMACS and Magellan/MIKE (Heiger et al. 2024, ApJ, 961, 234; Heiger et al. 2025, arXiv:2508.11012).
On the methodological end, she built DLEIY, a novel galactic chemical evolution framework (Heiger et al. 2026, arXiv:2602.22333).

In her recent observational work, Mairead led high-resolution Magellan/MIKE follow-up of the brightest member stars of the ultra-faint dwarf galaxies Eridanus IV and Centaurus I, producing the first detailed chemical abundances for either system. Among other results, she showed that the star in Eridanus IV is a carbon-enhanced, extremely metal-poor (CEMP-no) star, and carried out a careful progenitor analysis, tentatively concluding that despite the tantalizing abundance pattern, it is unlikely to be the descendant of a single Population III supernova.

In the DLEIY paper (YIELD backwards!) Mairead improves on the often poorly-defined models used in chemical enrichment studies. She uses the observed star formation history and metallicity distribution function as inputs rather than forward-modelling them, removing many restrictive parametric assumptions about star formation histories that plague standard models. She jointly models multiple galaxies within a hierarchical Bayesian framework, sharing the parameters that should be universal (yields, the Type Ia delay-time distribution) while keeping environment-specific parameters (outflows) local — allowing her to break the yield-outflow degeneracy. She finds the core-collapse Fe yield agrees well with theoretical yield tables, while the measured Mg yield is 2-4 higher than the major yield sets (discrepant at ~5 sigma with all but one), providing a model-independent confirmation of long-suspected Mg under-production in supernova models. The inferred Type Ia rate is also estimated about 5 times higher than in field galaxies, and the delay-time distribution is much steeper (roughly t^-2) than the canonical t^-1 from transient surveys. Together, these results point toward a metallicity dependence of Type Ia supernova production, with implications reaching from binary evolution to supernova surveys to chemical evolution modelling in general.

Beyond research, Mairead has made significant contributions to her peers’ welfare. While GASA co-chair from 2020-2024, Mairead very effectively represented student interests, coordinated academic programming, and helped lead the Department’s outreach efforts. As a member of the department’s Mediation Committee, she co-wrote a report that has been influential in improving the graduate students’ compensation, and gathered data for a supplemental report to departmental leadership on hidden health care costs, which disproportionately affect disabled students. Mairead has also been a dedicated mentor, leading several undergraduates in projects related to the DOROTHY data-driven metallicity project (and a CASCA Best Undergraduate Talk award) as well as undergraduate and first-year graduate students through the SURP program and the Department’s mentorship program. And, she has been active in leading directed reading groups.

Clearly, both of this year’s recipients exemplify the very high level of research acumen and service that the Fieldus Award is meant to celebrate.

Congratulations, Simran and Mairead!