Explore the vast range of titles available.

The implementation of utilizing superconducting quantum interference device (SQUID) readout for constant voltage biased transition edge sensors (TES) has enabled the detection of the infinitesimal fluctuation in cosmic microwave background (CMB). The properties of the fluctuations will provide us the information of the universe at the time that this light was first emitted. In short, by measuring the CMB today, we learn about the distant, ancient universe—how the universe began, what it is made of, and how it evolved to its current state. Over the past 20 years, we have achieved many successful CMB measurements with Josephson junctions. Brian, I offer my congratulations on your eight decades of life—Happy 80th birthday!

The implementation of utilizing superconducting quantum interference device (SQUID) readout for constant voltage biased transition edge sensors (TES) has enabled the detection of the infinitesimal fluctuation in cosmic microwave background (CMB). The properties of the fluctuations will provide us the information of the universe at the time that this light was first emitted. In short, by measuring the CMB today, we learn about the distant, ancient universe—how the universe began, what it is made of, and how it evolved to its current state. Over the past 20 years, we have achieved many successful CMB measurements with Josephson junctions. Brian, I extend my congratulations on your eight decades of life—Happy 80th birthday!

We present cosmological constraints from a gravitational lensing mass map covering 9400 deg2 reconstructed from measurements of the cosmic microwave background (CMB) made by the Atacama Cosmology Telescope (ACT) from 2017 to 2021. In combination with measurements of baryon acoustic oscillations and big bang nucleosynthesis, we obtain the clustering amplitude σ 8 = 0.819 ± 0.015 at 1.8% precision, S8≡σ8(Ωm/0.3)0.5=0.840±0.028 , and the Hubble constant H 0 = (68.3 ± 1.1) km s−1 Mpc−1 at 1.6% precision. A joint constraint with Planck CMB lensing yields σ 8 = 0.812 ± 0.013, S8≡σ8(Ωm/0.3)0.5=0.831±0.023 , and H 0 = (68.1 ± 1.0) km s−1 Mpc−1. These measurements agree with ΛCDM extrapolations from the CMB anisotropies measured by Planck. We revisit constraints from the KiDS, DES, and HSC galaxy surveys with a uniform set of assumptions and find that S 8 from all three are lower than that from ACT+Planck lensing by levels ranging from 1.7σ to 2.1σ. This motivates further measurements and comparison, not just between the CMB anisotropies and galaxy lensing but also between CMB lensing probing z ∼ 0.5–5 on mostly linear scales and galaxy lensing at z ∼ 0.5 on smaller scales. We combine with CMB anisotropies to constrain extensions of ΛCDM, limiting neutrino masses to ∑m ν < 0.13 eV (95% c.l.), for example. We describe the mass map and related data products that will enable a wide array of cross-correlation science. Our results provide independent confirmation that the universe is spatially flat, conforms with general relativity, and is described remarkably well by the ΛCDM model, while paving a promising path for neutrino physics with lensing from upcoming ground-based CMB surveys.

We present new measurements of cosmic microwave background (CMB) lensing over 9400 deg2 of the sky. These lensing measurements are derived from the Atacama Cosmology Telescope (ACT) Data Release 6 (DR6) CMB data set, which consists of five seasons of ACT CMB temperature and polarization observations. We determine the amplitude of the CMB lensing power spectrum at 2.3% precision (43σ significance) using a novel pipeline that minimizes sensitivity to foregrounds and to noise properties. To ensure that our results are robust, we analyze an extensive set of null tests, consistency tests, and systematic error estimates and employ a blinded analysis framework. Our CMB lensing power spectrum measurement provides constraints on the amplitude of cosmic structure that do not depend on Planck or galaxy survey data, thus giving independent information about large-scale structure growth and potential tensions in structure measurements. The baseline spectrum is well fit by a lensing amplitude of A lens = 1.013 ± 0.023 relative to the Planck 2018 CMB power spectra best-fit ΛCDM model and A lens = 1.005 ± 0.023 relative to the ACT DR4 + WMAP best-fit model. From our lensing power spectrum measurement, we derive constraints on the parameter combination S8CMBL≡σ8Ωm/0.30.25 of S8CMBL=0.818±0.022 from ACT DR6 CMB lensing alone and S8CMBL=0.813±0.018 when combining ACT DR6 and Planck NPIPE CMB lensing power spectra. These results are in excellent agreement with ΛCDM model constraints from Planck or ACT DR4 + WMAP CMB power spectrum measurements. Our lensing measurements from redshifts z ∼ 0.5–5 are thus fully consistent with ΛCDM structure growth predictions based on CMB anisotropies probing primarily z ∼ 1100. We find no evidence for a suppression of the amplitude of cosmic structure at low redshifts.

We present the outline of the optical design of a TeraHertz (THz) imager for the detection of shrapnel-loaded improvised explosive devices (IED) devices at “stand-off” distances of 14–26 meters. The system will use 4 antenna-coupled TES detector arrays of 16 by 16 pixels cooled in a cryogen-free system with microwave readout to see beneath clothing at non-lethal detonation distances. A spatial resolution of ∼10 mm and close to video frame rates is anticipated.

We present cosmological constraints from a gravitational lensing mass map covering 9400 sq. deg. reconstructed from CMB measurements made by the Atacama Cosmology Telescope (ACT) from 2017 to 2021. In combination with BAO measurements (from SDSS and 6dF), we obtain the amplitude of matter fluctuations \\(_8 = 0.819 0.015\\) at 1.8% precision, \\(S_8_8(_ m/0.3)^0.5=0.8400.028\\) and the Hubble constant \\(H_0= (68.3 1.1)\\, km\\,s^-1\\,Mpc^-1\\) at 1.6% precision. A joint constraint with CMB lensing measured by the Planck satellite yields even more precise values: \\(_8 = 0.812 0.013\\), \\(S_8_8(_ m/0.3)^0.5=0.8310.023\\) and \\(H_0= (68.1 1.0)\\, km\\,s^-1\\,Mpc^-1\\). These measurements agree well with \\(\\)CDM-model extrapolations from the CMB anisotropies measured by Planck. To compare these constraints to those from the KiDS, DES, and HSC galaxy surveys, we revisit those data sets with a uniform set of assumptions, and find \\(S_8\\) from all three surveys are lower than that from ACT+Planck lensing by varying levels ranging from 1.7-2.1\\(\\). These results motivate further measurements and comparison, not just between the CMB anisotropies and galaxy lensing, but also between CMB lensing probing \\(z 0.5-5\\) on mostly-linear scales and galaxy lensing at \\(z 0.5\\) on smaller scales. We combine our CMB lensing measurements with CMB anisotropies to constrain extensions of \\(\\)CDM, limiting the sum of the neutrino masses to \\( m_ < 0.13\\) eV (95% c.l.), for example. Our results provide independent confirmation that the universe is spatially flat, conforms with general relativity, and is described remarkably well by the \\(\\)CDM model, while paving a promising path for neutrino physics with gravitational lensing from upcoming ground-based CMB surveys.

CMB-S4—the next-generation ground-based cosmic microwave background (CMB) experiment—is set to significantly advance the sensitivity of CMB measurements and enhance our understanding of the origin and evolution of the universe. Among the science cases pursued with CMB-S4, the quest for detecting primordial gravitational waves is a central driver of the experimental design. This work details the development of a forecasting framework that includes a power-spectrum-based semianalytic projection tool, targeted explicitly toward optimizing constraints on the tensor-to-scalar ratio, r, in the presence of Galactic foregrounds and gravitational lensing of the CMB. This framework is unique in its direct use of information from the achieved performance of current Stage 2–3 CMB experiments to robustly forecast the science reach of upcoming CMB-polarization endeavors. The methodology allows for rapid iteration over experimental configurations and offers a flexible way to optimize the design of future experiments, given a desired scientific goal. To form a closed-loop process, we couple this semianalytic tool with map-based validation studies, which allow for the injection of additional complexity and verification of our forecasts with several independent analysis methods. We document multiple rounds of forecasts for CMB-S4 using this process and the resulting establishment of the current reference design of the primordial gravitational-wave component of the Stage-4 experiment, optimized to achieve our science goals of detecting primordial gravitational waves for r > 0.003 at greater than 5σ, or in the absence of a detection, of reaching an upper limit of r < 0.001 at 95% CL.

We present new arcminute-resolution maps of the Cosmic Microwave Background temperature and polarization anisotropy from the Atacama Cosmology Telescope, using data taken from 2013-2016 at 98 and 150 GHz. The maps cover more than 17,000 deg\\(^2\\), the deepest 600 deg\\(^2\\) with noise levels below 10 \\(\\)K-arcmin. We use the power spectrum derived from almost 6,000 deg\\(^2\\) of these maps to constrain cosmology. The ACT data enable a measurement of the angular scale of features in both the divergence-like polarization and the temperature anisotropy, tracing both the velocity and density at last-scattering. From these one can derive the distance to the last-scattering surface and thus infer the local expansion rate, \\(H_0\\). By combining ACT data with large-scale information from WMAP we measure \\(H_0 = 67.6 1.1\\) km/s/Mpc, at 68% confidence, in excellent agreement with the independently-measured Planck satellite estimate (from ACT alone we find \\(H_0 = 67.9 1.5\\) km/s/Mpc). The \\(\\)CDM model provides a good fit to the ACT data, and we find no evidence for deviations: both the spatial curvature, and the departure from the standard lensing signal in the spectrum, are zero to within 1\\(\\); the number of relativistic species, the primordial Helium fraction, and the running of the spectral index are consistent with \\(\\)CDM predictions to within \\(1.5 - 2.2\\). We compare ACT, WMAP, and Planck at the parameter level and find good consistency; we investigate how the constraints on the correlated spectral index and baryon density parameters readjust when adding CMB large-scale information that ACT does not measure. The DR4 products presented here will be publicly released on the NASA Legacy Archive for Microwave Background Data Analysis.

We present the temperature and polarization angular power spectra of the CMB measured by the Atacama Cosmology Telescope (ACT) from 5400 deg\\(^2\\) of the 2013-2016 survey, which covers \\(>\\)15000 deg\\(^2\\) at 98 and 150 GHz. For this analysis we adopt a blinding strategy to help avoid confirmation bias and, related to this, show numerous checks for systematic error done before unblinding. Using the likelihood for the cosmological analysis we constrain secondary sources of anisotropy and foreground emission, and derive a \"CMB-only\" spectrum that extends to \\(=4000\\). At large angular scales, foreground emission at 150 GHz is \\(\\)1% of TT and EE within our selected regions and consistent with that found by Planck. Using the same likelihood, we obtain the cosmological parameters for \\(\\)CDM for the ACT data alone with a prior on the optical depth of \\(=0.0650.015\\). \\(\\)CDM is a good fit. The best-fit model has a reduced \\(^2\\) of 1.07 (PTE=0.07) with \\(H_0=67.91.5\\) km/s/Mpc. We show that the lensing BB signal is consistent with \\(\\)CDM and limit the celestial EB polarization angle to \\(_P =-0.07^0.09^\\). We directly cross correlate ACT with Planck and observe generally good agreement but with some discrepancies in TE. All data on which this analysis is based will be publicly released.

The Atacama B-mode Search (ABS) is an experiment designed to measure cosmic microwave background (CMB) polarization at large angular scales (\\(>40\\)). It operated from the ACT site at 5190~m elevation in northern Chile at 145 GHz with a net sensitivity (NEQ) of 41 \\(\\)K\\( s\\). It employed an ambient-temperature sapphire half-wave plate rotating at 2.55 Hz to modulate the incident polarization signal and reduce systematic effects. We report here on the analysis of data from a 2400 deg\\(^2\\) patch of sky centered at declination \\(-42^\\) and right ascension \\(25^\\). We perform a blind analysis. After unblinding, we find agreement with the Planck TE and EE measurements on the same region of sky. We marginally detect polarized dust emission and give an upper limit on the tensor-to-scalar ratio of \\(r<2.3\\) (95% cl) with the equivalent of 100 on-sky days of observation. We also present a new measurement of the polarization of Tau A and introduce new methods associated with HWP-based observations.