About

Professor Abigail Vieregg is the David N. Schramm Director of the Kavli Institute for Cosmological Physics at the University of Chicago, where she has been a faculty member since 2014. She holds appointments in the Department of Physics, the Enrico Fermi Institute, and the Kavli Institute for Cosmological Physics. Her academic background includes an A.B. from Dartmouth College in 2004 and a Ph.D. from UCLA in 2010. Following her doctoral studies, she was an NSF Office of Polar Programs Postdoctoral Fellow at the Harvard-Smithsonian Center for Astrophysics from 2010 to 2013. Her research focuses on building radio and millimeter wave experiments for neutrino astrophysics and cosmology, utilizing these techniques to study the cosmic microwave background. She is the principal investigator of projects such as PUEO and RNO-G, which are balloon-borne and ground-based radio detectors for ultra-high energy neutrinos. Additionally, she is involved in observational efforts like BICEP and the South Pole Telescope, which observe the CMB from the South Pole, as well as the future ground-based CMB-S4 experiment. Professor Vieregg has received numerous awards for her research, including the Shakti Duggal Award, Sloan Research Fellowship, NASA’s Nancy Grace Roman Technology Fellowship, Cottrell Scholar Award, PECASE award, and the Moore Foundation Experimental Physics Investigators Award. She is also recognized for her excellence in teaching and mentoring, having received the 'spherical cow award' from UChicago physics graduate students for Best Teaching and Mentoring.

Research topics

• Optics
• Physics
• Computer Science
• Astronomy
• Astrophysics
• Acoustics
• Remote sensing
• Telecommunications
• Particle physics
• Electronic engineering
• Geology

Selected publications

• Probing the firn refractive index profile using antenna response

  Journal of Glaciology · 2026-01-01

  articleOpen access

  Abstract The Radio Neutrino Observatory-Greenland (RNO-G, at Summit Station) experiment comprises an extensive fat-dipole antenna array deployed into ice boreholes over an eventual area of approximately 35 km 2 . Since the RNO-G experimental sensitivity depends on the radio-frequency properties of the firn, which are known to vary laterally on sub-km distance scales and vertically on sub-meter distance scales, a technique for quickly extracting information on firn ice properties with depth ( $n(z)$ ) during drilling and deployment is desirable. Given that a dipole’s resonant wavelength is fixed by geometry, the resonant frequency $f_{res}$ (measured as an S-parameter reflection coefficient [‘ $S_{11}$ ’] minimum) scales inversely with the local refractive index, allowing a translation of a depth-dependent $S_{11}$ (z) profile into $n(z)$ . $S_{11}$ (z) data were initially taken in August 2024 using a dipole lowered into a newly drilled 98 ± 1 mm diameter, 350 m deep borehole at Summit Station, Greenland, approximately 1 km from the site of the original GISP-2 core; improved measurements were subsequently made in May 2025. We conclude that $S_{11}$ (z) data can be used to estimate $n(z)$ , on 50 cm vertical scales, at the per cent level of accuracy required by experiments such as RN0-G.

  PublisherDOI

• Constraints on Inflationary Gravitational Waves with Two Years of SPT-3G Data

  ArXiv.org · 2025-05-05

  preprintOpen access

  We present a measurement of the $B$-mode polarization power spectrum of the cosmic microwave background anisotropies at 32 $\le$ $\ell$ $<$ 502 for three bands centered at 95, 150, and 220 GHz using data from the SPT-3G receiver on the South Pole Telescope. This work uses SPT-3G observations from the 2019 and 2020 winter observing seasons of a $\sim$1500 deg$^2$ patch of sky that directly overlaps with fields observed with the BICEP/Keck family of telescopes, and covers part of the proposed Simons Observatory and CMB-S4 deep fields. Employing new techniques for mitigating polarized atmospheric noise, the SPT-3G data demonstrates a white noise level of 9.3 (6.7) $μ$K-arcmin at $\ell \sim 500$ for the 95 GHz (150 GHz) data, with a $1/\ell$ noise knee at $\ell$=128 (182). We fit the observed six auto- and cross-frequency $B$-mode power spectra to a model including lensed $Λ$CDM $B$-modes and a combination of Galactic and extragalactic foregrounds. This work characterizes foregrounds in the vicinity of the BICEP/Keck survey area, finding foreground power consistent with that reported by the BICEP/Keck collaboration within the same region, and a factor of $\sim$ 3 higher power over the full SPT-3G survey area. Using SPT-3G data over the BICEP/Keck survey area, we place a 95% upper limit on the tensor-to-scalar ratio of $r < 0.25$ and find the statistical uncertainty on $r$ to be $σ(r) = 0.067$.

  PublisherOA PDFDOI

• A Multi-Stage Machine Learning Approach to Cosmic Ray Detection in the RNO-G Experiment

  2025-09-23

  articleOpen access

  The Radio Neutrino Observatory-Greenland (RNO-G), deployed at Summit Station, Greenland, aims to detect ultra-high-energy (UHE) neutrinos. To maximize sensitivity, RNO-G operates with low trigger thresholds, leading to data dominated by background noise, including thermal and anthropogenic sources. A potential additional background source is associated with cosmic ray signals coming from cosmic ray-induced air-showers and further sub-showers produced in the ice, which can mimic neutrino signals. Understanding these events is crucial for improving event classification in future neutrino searches. To address this, two parallel approaches are being developed within the collaboration. The primary method employs a linear discriminant analysis, while an exploratory approach, which this presentation is focused on, utilizes a three-stage event filtering scheme. This scheme sequentially applies a cut-based thermal noise filter, followed by machine learning classifiers—a boosted decision tree (BDT) and a convolutional neural network (CNN)—trained on both simulated cosmic-ray candidates and real background-dominated data. The method effectively rejects background while preserving high signal efficiency. The presentation showcases this powerful machine learning based analysis, highlighting its performance in distinguishing deep cosmic-ray candidates from other types of impulsive background. These results will inform future RNO-G neutrino searches, enhancing its capability to isolate astrophysical neutrino events.

  PublisherOA PDFDOI

• Techniques for Continuous Wave Identification and Filtering in the Askaryan Radio Array

  2025-09-24

  articleOpen access

  The Askaryan Radio Array (ARA), located near the geographical South Pole, is among the first experiments at the South Pole designed to detect ultra-high energy neutrinos through the Askaryan effect. When such neutrinos interact within dense media such as ice, they initiate particle cascades that, as they evolve, generate coherent radio pulses. Operating in the 150–850 MHz frequency band, ARA is deployed 80–200 meters deep in Antarctic ice, where the radio frequency background is exceptionally low. Despite the low background, experiments such as ARA must still account for continuous wave (CW) signals, which can originate from anthropogenic sources, instrumental noise, and other environmental factors. These CW signals can potentially obscure the faint neutrino-induced radio pulses, complicating data analysis and event identification. Over the years, ARA has developed and refined a number of techniques for CW filtering and identification, including spectral analysis, notch filtering, and phase-variance methods. These approaches exploit the unique characteristics of CW signals, such as their narrowband nature and temporal persistence, to effectively separate CW contamination from genuine impulsive events. We review the main CW identification and filtering techniques developed within the ARA collaboration and present recent improvements in their adaptive, multi-stage filtering pipelines. These advances have led to faster processing, easier operation, and more accurate CW identification and suppression, improving the consistency and quality of data analysis. The efficacy of these methods is demonstrated through CW identification and filtering for all ARA stations, showcasing their critical role in reducing event misclassification and improving the experiment's overall performance. By refining these techniques, this work not only improves the sensitivity and data analysis performance of ARA, but also underscores the importance of robust CW identification and filtering for current and future neutrino radio detection experiments.

  PublisherOA PDFDOI

• Construction, commissioning and operation of the Radio Neutrino Observatory in Greenland (RNO-G)

  2025-09-24

  articleOpen access

  The Radio Neutrino Observatory Greenland (RNO-G) is searching for Askaryan radio signals from ultra-high-energy neutrinos ($E \ge 100\,$PeV) interacting in ice. RNO-G is currently under construction near the apex of the Greenland ice sheet with 8 stations already operational and collecting science data. The constructed observatory will consist of 35 autonomously operating stations deployed over an area of about 50$\,$km$^2$. Its projected sensitivity will allow to test several models of astrophysical and cosmogenic neutrinos with the potential to detect neutrinos above 100$\,$PeV. Each RNO-G station features 24 radio antennas installed in three 100$\,$m-deep-boreholes with a diameter of 30$\,$cm and shallow trenches beneath the surface. The stations are powered by solar and wind energy and are each equipped with low-power electronics for data readout and wireless communication to a central server at the nearby NFS-operated Summit Station. RNO-G is the first experiment probing the large-scale in-ice radio detection with tens of stations and hundreds of channels over a large area. It is designed to withstand the harsh conditions of an Arctic environment, with scalability in mind. As such, its construction and operation provides invaluable insights for the development and construction of the planned 500$\,$km$^2$ radio detector of the IceCube-Gen2 facility. In this contribution, I will give an overview of recent deployment activities, the operation of the 8 deployed stations and discuss the hardware performance.

  PublisherOA PDFDOI

• Sensitivity of BEACON to ultra-high energy diffuse and transient neutrinos

  Journal of Cosmology and Astroparticle Physics · 2025-09-01 · 2 citations

  articleOpen accessCorresponding

  Abstract Ultra-high energy neutrinos ( E > 10 17 eV) can provide insight into the most powerful accelerators in the universe, however their flux is extremely low. The Beamforming Elevated Array for COsmic Neutrinos (BEACON) is a detector concept which efficiently achieves sensitivity to this flux by employing phased radio arrays on mountains, which search for the radio emission of up-going extensive air showers created by Earth-skimming tau neutrinos. Here, we calculate the point-source effective area of BEACON and characterize its sensitivity to transient neutrino fluences with both short (< 15 min) and long (> 1 day) durations. Additionally, by integrating the effective area, we provide an updated estimate of the diffuse flux sensitivity. With just 100 stations, BEACON achieves sensitivity to short-duration transients such as nearby short gamma-ray bursts. With 1000 stations, BEACON achieves a sensitivity to long-duration transients, as well as the cosmogenic flux, ten times greater than existing experiments at 1 EeV. With an efficient design optimized for ultrahigh energy neutrinos, BEACON is capable of discovering the sources of neutrinos at the highest energies.

  PublisherDOI

• The Radio Neutrino Observatory Greenland (RNO-G)

  2025-09-24

  articleOpen access

  The Radio Neutrino Observatory Greenland (RNO-G) is being constructed at Summit Station in Greenland. It seeks to detect the radio emission of neutrinos interacting in the 3~km thick ice. Radio detection of neutrinos is sensitive to neutrinos above 10 PeV and therefore complements existing optical detectors. RNO-G currently consists of 8 out of planned 35 stations, each combining the signals of 24 antennas distributed in shallow trenches and three holes of 100~m depths. This contribution will provide an overview of ongoing activities at RNO-G, with a focus on recent scientific results and plans for future seasons.

  PublisherOA PDFDOI

• SPT-3G D1: Constraints on inflationary gravitational waves with two years of SPT-3G data

  Physical review. D/Physical review. D. · 2025-12-08 · 6 citations

  article

  We present a measurement of the $B$-mode polarization power spectrum of the cosmic microwave background anisotropies at $32\ensuremath{\le}\ensuremath{\ell}<502$ for three bands centered at 95, 150, and 220 GHz using data from the SPT-3G receiver on the South Pole Telescope. This work uses SPT-3G observations from the 2019 and 2020 winter observing seasons of a $\ensuremath{\sim}1500\text{ }\text{ }{\mathrm{deg}}^{2}$ patch of sky that directly overlaps with fields observed with the BICEP/Keck family of telescopes and covers part of the proposed Simons Observatory and CMB-S4 deep fields. Employing new techniques for mitigating polarized atmospheric noise, the SPT-3G data demonstrates a white noise level of 9.3 $(6.7)\text{ }\text{ }\mathrm{\ensuremath{\mu}}\mathrm{K}\text{\ensuremath{-}}\mathrm{arcmin}$ at $\ensuremath{\ell}\ensuremath{\sim}500$ for the 95 GHz (150 GHz) data, with a $1/\ensuremath{\ell}$ noise knee at $\ensuremath{\ell}=128$ (182). We fit the observed six auto- and cross-frequency $B$-mode power spectra to a model including lensed $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ $B$-modes and a combination of Galactic and extragalactic foregrounds. This work characterizes foregrounds in the vicinity of the BICEP/Keck survey area, finding foreground power consistent with that reported by the BICEP/Keck collaboration within the same region and a factor of $\ensuremath{\sim}3$ higher power over the full SPT-3G survey area. Using SPT-3G data over the BICEP/Keck survey area, we place a 95% upper limit on the tensor-to-scalar ratio of $r<0.25$ and find the statistical uncertainty on $r$ to be $\ensuremath{\sigma}(r)=0.067$.

  PublisherDOI

• High-Fidelity Simulations of the Full Askaryan Radio Array and its Sensitivity to Ultra-High Energy Neutrinos

  2025-09-24

  articleOpen access

  The Askaryan Radio Array (ARA) is a five-station, in-ice radio detector located at the South Pole searching for particle cascades from cosmogenic and astrophysical neutrinos with ≥ 1e17 eV of energy. Cascades in this energy regime emit radio-wavelength Askaryan radiation that can be observed by one or more ARA stations. With the recent KM3Net observation of an approximately 220 PeV neutrino, there is renewed, urgent interest in further unlocking the ultra-high energy neutrino sky. We present updated calculations of ARA’s array-wide effective volume, sensitivity, and expected event rates for ultra-high energy neutrino-induced cascades. Notably, results now account for the contributions of secondary particles from neutrino interactions (such as muon tracks) and multi-station detections within a detailed detector simulation framework. Previous work has shown these secondary interactions and multi-station coincidences compose 25% and 8% of the detector’s effective area, respectively. We intend to extend these results towards a novel analysis that estimates the degree to which secondary cascades and multi-station observations are detectable in a real neutrino search. This will inform future UHE neutrino searches as it will characterize the feasibility of detecting such events.

  PublisherOA PDFDOI

• Towards the First Neutrino Search with RNO-G

  2025-09-24

  articleOpen access

  The Radio Neutrino Observatory in Greenland (RNO-G) is located at Summit Station and is designed to detect Askaryan emission from ultra-high energy (UHE) neutrinos above 100 PeV. The detector is proposed to have 35 stations of which 8 have been deployed so far. Each station is made up of 9 antennas at the surface and 18 antennas that are buried in the ice down to a depth of 100 meters with the purpose of triggering on and reconstructing neutrino-like signals. The partially completed detector has been collecting data since 2021 and this data is being used for RNO-G’s first neutrino search. This talk will outline progress towards this search, such as the data processing pipeline, analysis variables, initial reconstructions, and background/signal separation.

  PublisherOA PDFDOI

Recent grants

• Radio Detection of the Highest Energy Neutrinos with a Ground-Based Interferometric Phased Array

  NSF · $481k · 2016–2019

• RAPID: Time-Critical Enhancements for the Radio Neutrino Observatory in Greenland (RNO-G)

  NSF · $112k · 2021–2022

Frequent coauthors

• Stephanie Wissel

  419 shared

• C. Deaconu

  350 shared

• K. Hughes

  335 shared

• E. Oberla

  332 shared

• Kwok Lung Fan

  308 shared

• Andrew Ludwig

  University of California, Los Angeles

  261 shared

• K. D. Irwin

  258 shared

• D. Seckel

  252 shared

Education

• B.A.

  Dartmouth College

  2004

• Ph.D.

  UCLA

  2010

Awards & honors

• Shakti Duggal Award
• Sloan Research Fellowship
• NASA’s Nancy Grace Roman Technology Fellowship
• Cottrell Scholar Award
• PECASE award