BICEP/Keck

BICEP/Keck

BICEP/Keck is a series of cosmology experiments that measured polarization of the cosmic microwave background using telescopes at the Amundsen–Scott South Pole Station and instruments coordinated by institutions including Caltech, Harvard University, University of Chicago, Princeton University, and Stanford University. The program built on heritage from experiments such as COBE, WMAP, and Planck and interfaced with facilities like the South Pole Telescope and projects supported by agencies including National Science Foundation, NASA, and foundations associated with Simons Foundation. The collaboration included researchers affiliated with universities and laboratories such as University of Minnesota, Yale University, Columbia University, University of California, Berkeley, Jet Propulsion Laboratory, and Fermi National Accelerator Laboratory.

Overview

The project aimed to detect primordial B-mode polarization predicted by inflationary models formulated by theorists such as Alan Guth, Andrei Linde, Paul Steinhardt, Alexei Starobinsky, and Vasily Mukhanov. BICEP/Keck targeted signals related to tensor perturbations described in literature by Martin Rees and Subrahmanyan Chandrasekhar and compared results with temperature and E-mode maps from Planck Collaboration, WMAP Collaboration, and ground campaigns like ACT and SPTpol. The collaboration coordinated analysis methods developed in contexts including LIGO Scientific Collaboration, Baryon Oscillation Spectroscopic Survey, Dark Energy Survey, and theoretical frameworks advanced by Steven Weinberg and John Preskill.

Instrumentation and Observatories

Instrument development drew on technology produced at centers such as Caltech Optical Observatories, Jet Propulsion Laboratory, National Institute of Standards and Technology, Brookhaven National Laboratory, Lawrence Berkeley National Laboratory, and Argonne National Laboratory. Detectors used transition-edge sensors similar to those in experiments by Planck-HFI, POLARBEAR, and SPIDER (suborbital) with readout electronics informed by work at NASA Goddard Space Flight Center and Massachusetts Institute of Technology. Cryogenic and optical designs referenced expertise at University of Chicago and Princeton Plasma Physics Laboratory, while site logistics relied on the United States Antarctic Program and infrastructure at McMurdo Station. The Keck Array expanded on the original BICEP1 and BICEP2 instruments, with optics and polarization modulation techniques analogous to developments at Max Planck Institute for Astrophysics, European Southern Observatory, and Kavli Institute for Cosmological Physics.

Observations and Data Analysis

Observations concentrated on a low-foreground patch overlapping surveys by Planck Collaboration, Herschel Space Observatory, and IRAS, enabling joint component separation using methodologies from Markov Chain Monte Carlo groups at Harvard-Smithsonian Center for Astrophysics and statistical techniques championed by Richard Bond and Uros Seljak. Time-ordered data processing incorporated map-making algorithms similar to those employed by WMAP, and foreground modeling used templates informed by studies from James Webb Space Telescope teams and datasets from Submillimeter Array. Systematics control referenced calibration standards from NIST and beam characterization approaches developed at European Space Agency centers. Cross-correlation analyses linked BICEP/Keck maps with lensing reconstructions from Planck Collaboration and South Pole Telescope teams and applied delensing methods advanced by researchers at Perimeter Institute and Institute for Advanced Study.

Scientific Results and Constraints

Results produced upper limits on the tensor-to-scalar ratio r, constraining inflationary scenarios proposed by Alan Guth, Andrei Linde, A. R. Liddle, and David Wands and informing potentials discussed by Alexander Vilenkin and Edward Witten. Combined analyses with Planck Collaboration and WMAP tightened bounds relative to earlier claims involving polarized foreground interpretation debated in the literature including critiques by groups at University of Cambridge, University of Oxford, and Imperial College London. Measurements also characterized polarized dust emission studied by teams from Max Planck Institute for Radio Astronomy, CITA, and Leiden Observatory, and contributed to cosmological parameter estimation alongside datasets from Baryon Oscillation Spectroscopic Survey, Supernova Legacy Survey, and Sloan Digital Sky Survey. The collaboration’s constraints affected theoretical work on reheating by Kolb and Turner-style frameworks and influenced model selection procedures used by researchers at Perimeter Institute and Kavli Institute.

Collaboration and Timeline

The program evolved from BICEP1 (mid-2000s) to BICEP2 (2010s) and the Keck Array, with project management involving institutions such as Caltech, Harvard University, University of Chicago, Stanford University, and Princeton University. Key milestones aligned with community efforts including data combinations with Planck releases and conference presentations at venues like American Astronomical Society, COSMO, and International Conference on Particle Physics and Cosmology. Funding and oversight involved agencies and organizations such as National Science Foundation, NASA, Simons Foundation, DOE Office of Science, and collaborations with Antarctic logistics from United States Antarctic Program. Personnel associated with milestones included principal investigators and contributors from John Kovac (astrophysicist), teams mentored by faculty at Caltech and Harvard, and students from University of Minnesota, Yale University, and Columbia University who presented results at meetings held at CERN and SLAC National Accelerator Laboratory.

Category:Cosmic microwave background experiments