Johanna Nagy

Assistant Professor

Rockefeller Building 203 (Office) & 16 (Nagy Lab)

Other Information

Degree: Ph.D., Case Western Reserve University '17 B.S., Stanford '10

Nagy with SPIDER just before the Dec. 2022 Antarctic launch

Nagy Lab


Experimental Cosmology, Astronomical Instrumentation


Nagy’s research group focuses on experimental cosmology, probing the evolution and composition of the Universe by building microwave telescopes and analyzing the resulting data.

Precision measurements of the Cosmic Microwave Background (CMB) radiation are continuing to transform our understanding of the Universe.  Emitted just a few hundred thousand years after the Big Bang, the CMB photons are influenced by the structure and contents of the Universe and even carry a record of events that occurred before they were formed.    Measuring the characteristics of the CMB thus allows us to use the Universe as a laboratory, exploiting the cumulative interactions of the photons over vast distances and cosmic timescales to amplify small effects.

Nagy’s lab designs and builds instruments to enable more precise measurements of the CMB. Her group works on a combination of balloon-borne and ground-based telescopes, including SPIDER, Taurus, and CMB-S4.Together these experiments probe topics including the physics of inflation, the optical depth to reionization, and the properties of fundamental particles.  In the lab, her group works on many different aspects of instrumentation including low temperature detectors, optics, and calibration as well as data analysis.

Publications: Selected from Google Scholar

I Gullett, et al.,  “Sidelobe Modeling and Mitigation for a Three Mirror Anastigmat Cosmic Microwave Background Telescope”. Applied Optics 62 (16), 4334-4341

Shaaban, M. M., et al.,  “Weak Lensing in the Blue: A Counter-intuitive Strategy for Stratospheric Observations”, The Astronomical Journal, vol. 164, no. 6, 2022. doi:10.3847/1538-3881/ac9b1c.

Filippini, J. P., et al.,  “In-Flight Gain Monitoring of SPIDER’s Transition-Edge Sensor Arrays”, Journal of Low Temperature Physics, vol. 209, no. 3–4, pp. 649–657, 2022. doi:10.1007/s10909-022-02729-5.

Gallardo, P. A., et al.,  “Optical Design Concept of the CMB-S4 Large-Aperture Telescopes and Cameras”, in Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI, 2022, vol. 12190. doi:10.1117/12.2626876.

Barron, D. R., “Conceptual Design of the Modular Detector and Readout System for the CMB-S4 Survey Experiment”, in Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI, 2022, vol. 12190. doi:10.1117/12.2630494.

Leung, J. S.-Y., et al., “A Simulation-based Method for Correcting Mode Coupling in CMB Angular Power Spectra”, The Astrophysical Journal, vol. 928, no. 2, 2022. doi:10.3847/1538-4357/ac562f.

Ade, P. A. R., et al., “A Constraint on Primordial B-modes from the First Flight of the SPIDER Balloon-borne Telescope”, The Astrophysical Journal, vol. 927, no. 2, 2022. doi:10.3847/1538-4357/ac20df.

Abazajian, K., et al., “CMB-S4: Forecasting Constraints on Primordial Gravitational Waves”, The Astrophysical Journal, vol. 926, no. 1, 2022. doi:10.3847/1538-4357/ac1596.

Gambrel, A. E., et al., “The XFaster Power Spectrum and Likelihood Estimator for the Analysis of Cosmic Microwave Background Maps”, The Astrophysical Journal, vol. 922, no. 2, 2021. doi:10.3847/1538-4357/ac230b.

Shaw, E. C., et al., “Design and Pre-flight Performance of SPIDER 280 GHz Receivers”, in Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy X, 2020, vol. 11453. doi:10.1117/12.2562941.

O’Dwyer, M., Copi, C. J., Nagy, J. M., Netterfield, C. B., Ruhl, J., and Starkman, G. D., “Hemispherical Variance Anomaly and Reionization Optical Depth”, Monthly Notices of the Royal Astronomical Society, vol. 499, no. 3, pp. 3563–3570, 2020. doi:10.1093/mnras/staa3049.

Gill, A., et al., “Optical Night Sky Brightness Measurements from the Stratosphere”, The Astronomical Journal, vol. 160, no. 6, 2020. doi:10.3847/1538-3881/abbffb.

Sirks, E. L., et al., “Download by Parachute: Retrieval of Assets from High Altitude Balloons”, Journal of Instrumentation, vol. 15, no. 5, p. P05014, 2020. doi:10.1088/1748-0221/15/05/P05014.

Osherson, B., et al., “Particle Response of Antenna-Coupled TES Arrays: Results from SPIDER and the Laboratory”, Journal of Low Temperature Physics, vol. 199, no. 3–4, pp. 1127–1136, 2020. doi:10.1007/s10909-020-02415-4.

Romualdez, L. J., et al., “Robust Diffraction-limited Near-infrared-to-near-ultraviolet Wide-field Imaging from Stratospheric Balloon-borne Platforms—Super-pressure Balloon-borne Imaging Telescope Performance”, Review of Scientific Instruments, vol. 91, no. 3, 2020. doi:10.1063/1.5139711.

Gualtieri, R., et al., “SPIDER: CMB Polarimetry from the Edge of Space”, Journal of Low Temperature Physics, vol. 193, no. 5–6, pp. 1112–1121, 2018. doi:10.1007/s10909-018-2078-x.

Bergman, A. S., et al., “280 GHz Focal Plane Unit Design and Characterization for the SPIDER-2 Suborbital Polarimeter”, Journal of Low Temperature Physics, vol. 193, no. 5–6, pp. 1075–1084, 2018. doi:10.1007/s10909-018-2065-2.

Nagy, J. M., et al., “A New Limit on CMB Circular Polarization from SPIDER”, The Astrophysical Journal, vol. 844, no. 2, 2017. doi:10.3847/1538-4357/aa7cfd.

Hubmayr, J., et al., “Design of 280 GHz Feedhorn-coupled TES Arrays for the Balloon-borne Polarimeter SPIDER”, in Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VIII, 2016, vol. 9914. doi:10.1117/12.2231896

.Bryan, S., et al., “A Cryogenic Rotation Stage with a Large Clear Aperture for the Half-wave Plates in the SPIDER Instrument”, Review of Scientific Instruments, vol. 87, no. 1, 2016. doi:10.1063/1.4939435.