Sciences and Exploration Directorate



ERIC R SWITZER's Contact Card & Information.
Phone: 301.614.5174
Org Code: 665
Mail Code 665
Greenbelt, MD 20771

Missions & Projects

Brief Bio

Dr. Eric Switzer is a cosmologist with expertise in large-scale structure and cosmic background radiation observations. He has led or participated in project phases through concept, design, integration and test, analysis, and data archival. He is interested in redshifted line intensity mapping, cosmic microwave background anisotropies, and systems engineering for next-generation missions. Dr. Switzer leads the EXCLAIM mission and contributed to the PIPER mission’s cryogenic receiver and flight software development. He is the Roman Space Telescope Wide Field Instrument Integration and Test Project Scientist. Before NASA, he analyzed 21 cm intensity mapping data from the Green Bank Telescope, was part of the team that developed the Atacama Cosmology Telescope, and refined the theory of cosmological helium recombination.

Research Interests

EXCLAIM and Intensity mapping

Astrophysics: Cosmology

The light emitted by atomic transitions in the distant universe will be redshifted by the time it reaches us today. By measuring the spectrum over a region of the sky, a survey can infer the three-dimensional distribution of emission from galaxies in a large volume of the universe.

The EXperiment for Cryogenic Large-Aperture Intensity Mapping (EXCLAIM) is a cryogenic balloon-borne instrument to survey galaxy and star formation history over cosmological time scales. Rather than identifying individual objects, EXCLAIM will be a pathfinder to demonstrate an intensity mapping approach. EXCLAIM will operate at 420-540 GHz with a spectral resolution R=512 to measure the integrated CO and [CII] in redshift windows spanning 0 < z < 3.5. CO and [CII] line emissions are valuable tracers of the gas phases in the interstellar medium involved in star-formation processes. Thus, EXCLAIM will shed light on why the star formation rate declines at z < 2, despite continued clustering of the dark matter. The instrument will employ an array of six superconducting integrated grating-analog spectrometers (micro-spec) coupled to microwave kinetic inductance detectors (MKIDs).

Through a previous collaboration at CITA, Eric analyzed the statistical distribution of matter when the universe was half its present size, using the 21 cm transition of neutral hydrogen and data acquired with the Green Bank Telescope. 

Measurements of the Cosmic Microwave Background

Astrophysics: Cosmology

High-resolution measurements of the CMB intensity have achieved great precision through the Planck Satellite, the Atacama Cosmology Telescope (ACT), and the South Pole Telescope (SPT). Eric was part of the team that developed ACT and its successor ACTPol. In addition to supporting a standard cosmological model of the universe dominated by dark energy and matter, these experiments have measured the gravitational lensing of the CMB by intervening matter and the perturbations to the CMB spectrum from the most massive clusters of galaxies in the universe. Galaxy clusters and high redshift galaxies detected in large high-resolution CMB surveys have guided fields for deeper observations by HST and JWST.

Cosmological inflation is our current leading theory of the early universe, and processes at that time are thought to produce a unique "B-mode" signature in the polarization of the CMB. The Primordial Inflation Polarization Explorer (PIPER) balloon mission is designed to measure this signature across a broad region of the sky and range of wavelengths. Switzer led the PIPER receiver development, implementing and testing a system to operate 2560 Transition Edge Sensors cooled to 100 mK using a Continuous Adiabatic Demagnetization refrigerator.

Atoms in the cosmos

Astrophysics: Cosmology

The early universe was a hot, ionized, and highly uniform gas. As it cooled through expansion, the gas could become neutral and transparent, liberating the thermal photons that are observed today as the cosmic microwave background (CMB). A detailed understanding of this cosmological recombination is required to interpret precise CMB anisotropy measurements of WMAP/Planck/ACT/SPT. Eric refined the calculation of helium recombination and was part of the community that brought the previous generation of analyses to a higher level of precision for modern CMB experiments. Following recombination, the first luminous objects are fueled by gas and reionize the universe -- atoms provide a diagnostic of this rich evolution up to the present.

Current Projects

Roman Space Telescope - Wide Field Instrument Integration and Test Project Scientist

PI - The Experiment for Cryogenic Large-aperture Intensity Mapping (EXCLAIM)



Goddard Space Flight Center - Greenbelt, Maryland

August 2013 - Present

Senior Research Associate

Canadian Institute for Theoretical Astrophysics (CITA) - Toronto, Ontario

September 2011 - August 2013


Kavli Fellow

Kavli Institute for Cosmological Physics (KICP) - Chicago, Illinois

October 2008 - September 2011



  • Ph.D., physics -- Princeton University (Advisors: Lyman Page and Chris Hirata)
  • B.A., physics with specialization in astrophysics -- University of Chicago

Selected Publications


2023. "Systematic error mitigation for the PIXIE Fourier transform spectrometer." Journal of Cosmology and Astroparticle Physics 2023 (07): 057 [10.1088/1475-7516/2023/07/057] [Journal Article/Letter]

2023. "Extragalactic science with the experiment for cryogenic large-aperture intensity mapping." Monthly Notices of the Royal Astronomical Society 521 (4): 6124-6142 [10.1093/mnras/stad916] [Journal Article/Letter]

2022. "Operational Optimization to Maximize Dynamic Range in EXCLAIM Microwave Kinetic Inductance Detectors." Journal of Low Temperature Physics 209 (5-6): 1038-1046 [10.1007/s10909-022-02760-6] [Journal Article/Letter]

2022. "Constraining low redshift [C II] emission by cross-correlating FIRAS and BOSS data." Monthly Notices of the Royal Astronomical Society 514 (1): 1169-1187 [10.1093/mnras/stac1301] [Journal Article/Letter]

2021. "Experiment for cryogenic large-aperture intensity mapping: instrument design." Journal of Astronomical Telescopes, Instruments, and Systems 7 (04): [10.1117/1.jatis.7.4.044004] [Journal Article/Letter]

2021. "Intensity mapping without cosmic variance." Physical Review D 104 (8): 083501 [10.1103/physrevd.104.083501] [Journal Article/Letter]

2021. "Superfluid liquid helium control for the primordial inflation polarization explorer balloon payload." Review of Scientific Instruments 92 (6): 064501 [10.1063/5.0048800] [Journal Article/Letter]

2021. "Anti-reflection coated vacuum window for the Primordial Inflation Polarization ExploreR (PIPER) balloon-borne instrument." Review of Scientific Instruments 92 (3): 035111 [10.1063/5.0029430] [Journal Article/Letter]

2019. "Evidence for C II diffuse line emission at redshift z ̃ 2.6." Monthly Notices of the Royal Astronomical Society 489 (1): L53-L57 [10.1093/mnrasl/slz126] [Journal Article/Letter]

2019. "Sub-Kelvin cooling for two kilopixel bolometer arrays in the PIPER receiver." Review of Scientific Instruments 90 (9): 095104 [10.1063/1.5108649] [Journal Article/Letter]

2019. "The Atacama Cosmology Telescope: two-season ACTPol extragalactic point sources and their polarization properties." Monthly Notices of the Royal Astronomical Society 486 (4): 5239-5262 [10.1093/mnras/sty2934] [Journal Article/Letter]

2019. "Intensity Mapping in the Presence of Foregrounds and Correlated Continuum Emission." The Astrophysical Journal 872 (1): 82 [10.3847/1538-4357/aaf9ab] [Journal Article/Letter]

2018. "Low-amplitude clustering in low-redshift 21-cm intensity maps cross-correlated with 2dF galaxy densities." Monthly Notices of the Royal Astronomical Society 476 (3): 3382-3392 [10.1093/mnras/sty346] [Journal Article/Letter]

2015. "Interpreting the Unresolved Intensity of Cosmologically Redshifted Line Radiation." The Astrophysical Journal 815 51 [10.1088/0004-637X/815/1/51] [Journal Article/Letter]

2014. "Erasing the Variable: Empirical Foreground Discovery for Global 21 cm Spectrum Experiments." The Astrophysical Journal 793 (2): 102 [Journal Article/Letter]

2013. "The Atacama Cosmology Telescope: cosmological parameters from three seasons of data." Journal of Cosmology and Astroparticle Physics 2013 (10): 060-060 [10.1088/1475-7516/2013/10/060] [Journal Article/Letter]

2013. "The Atacama Cosmology Telescope: Sunyaev-Zel'dovich selected galaxy clusters at 148 GHz from three seasons of data." Journal of Cosmology and Astroparticle Physics 2013 (07): 008-008 [10.1088/1475-7516/2013/07/008] [Journal Article/Letter]

2013. "Measurement of 21 cm Brightness Fluctuations at z ~ 0.8 in Cross-correlation." ApJL 763 L20 [Journal Article/Letter]

2013. "Determination of z ~ 0.8 neutral hydrogen fluctuations using the 21 cm intensity mapping autocorrelation." MNRASL 434 L46 [Journal Article/Letter]

2011. "Overview of the Atacama Cosmology Telescope: Receiver, Instrumentation, and Telescope Systems." ApJS 194 41 [Journal Article/Letter]

2010. "Extragalactic Millimeter-wave Sources in South Pole Telescope Survey Data: Source Counts, Catalog, and Statistics for an 87 Square-degree Field." ApJ 719 763 [Journal Article/Letter]

2008. "Primordial helium recombination. I. Feedback, line transfer, and continuum opacity." PRD 77 83006 [Journal Article/Letter]