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Free, publiclyaccessible full text available August 1, 2024

Abstract The Summertime Line Intensity Mapper (SLIM) is a mmwave lineintensity mapping (mmLIM) experiment for the South Pole Telescope (SPT). The goal of SPTSLIM is to serve as a technical and scientific pathfinder for the demonstration of the suitability and infield performance of multipixel superconducting filterbank spectrometers for future mmLIM experiments. Scheduled to deploy in the 202324 austral summer, the SPTSLIM focal plane will include 18 dualpolarisation pixels, each coupled to an
thinfilm microstrip filterbank spectrometer that spans the 2 mm atmospheric window (120–180 GHz). Each individual spectral channel feeds a microstripcoupled lumpedelement kinetic inductance detector, which provides the highly multiplexed readout for the 10k detectors needed for SPTSLIM. Here, we present an overview of the preliminary design of key aspects of the SPTSLIM focal plane array, a description of the detector architecture and predicted performance, and initial test results that will be used to inform the final design of the SPTSLIM spectrometer array.$$R = \lambda / \Delta \lambda = 300$$ $R=\lambda /\Delta \lambda =300$ 
Abstract Including millimeterwave data in multiwavelength studies of the variability of active galactic nuclei (AGN) can provide insights into AGN physics that are not easily accessible at other wavelengths. We demonstrate in this work the potential of cosmic microwave background (CMB) telescopes to provide longterm, highcadence millimeterwave AGN monitoring over large fractions of sky. We report on a pilot study using data from the SPTpol instrument on the South Pole Telescope (SPT), which was designed to observe the CMB at arcminute and larger angular scales. Between 2013 and 2016, SPTpol was used primarily to observe a single 500 deg^{2}field, covering the entire field several times per day with detectors sensitive to radiation in bands centered at 95 and 150 GHz. We use SPT 150 GHz observations to create AGN light curves, and we compare these millimeterwave light curves to those at other wavelengths, in particular
γ ray and optical. In this Letter, we focus on a single source, PKS 2326502, which has extensive, daytimescale monitoring data in gammaray, optical, and now millimeterwave between 2013 and 2016. We find PKS 2326502 to be in a flaring state in the first 2 yr of this monitoring, and we present a search for evidence of correlated variability between millimeterwave, opticalR band, andγ ray observations. This pilot study is paving the way for AGN monitoring with current and upcoming CMB experiments such as SPT3G, Simons Observatory, and CMBS4, including multiwavelength studies with facilities such as Vera C. Rubin Observatories Large Synoptic Survey Telescope. 
Free, publiclyaccessible full text available February 1, 2024

Optimal Cosmic Microwave Background Lensing Reconstruction and Parameter Estimation with SPTpol DataAbstract We perform the first simultaneous Bayesian parameter inference and optimal reconstruction of the gravitational lensing of the cosmic microwave background (CMB), using 100 deg 2 of polarization observations from the SPTpol receiver on the South Pole Telescope. These data reach noise levels as low as 5.8 μ K arcmin in polarization, which are low enough that the typically used quadratic estimator (QE) technique for analyzing CMB lensing is significantly suboptimal. Conversely, the Bayesian procedure extracts all lensing information from the data and is optimal at any noise level. We infer the amplitude of the gravitational lensing potential to be A ϕ = 0.949 ± 0.122 using the Bayesian pipeline, consistent with our QE pipeline result, but with 17% smaller error bars. The Bayesian analysis also provides a simple way to account for systematic uncertainties, performing a similar job as frequentist “bias hardening” or linear bias correction, and reducing the systematic uncertainty on A ϕ due to polarization calibration from almost half of the statistical error to effectively zero. Finally, we jointly constrain A ϕ along with A L , the amplitude of lensinglike effects on the CMB power spectra, demonstrating that the Bayesian method can be used to easily infer parameters both from an optimal lensing reconstruction and from the delensed CMB, while exactly accounting for the correlation between the two. These results demonstrate the feasibility of the Bayesian approach on real data, and pave the way for future analysis of deep CMB polarization measurements with SPT3G, Simons Observatory, and CMBS4, where improvements relative to the QE can reach 1.5 times tighter constraints on A ϕ and seven times lower effective lensing reconstruction noise.more » « less

Abstract We present the first measurements of asteroids in millimeter wavelength data from the South Pole Telescope (SPT), which is used primarily to study the cosmic microwave background (CMB). We analyze maps of two ∼270 deg^{2}sky regions near the ecliptic plane, each observed with the SPTpol camera ∼100 times over 1 month. We subtract the mean of all maps of a given field, removing static sky signal, and then average the meansubtracted maps at known asteroid locations. We detect three asteroids—(324) Bamberga, (13) Egeria, and (22) Kalliope—with signaltonoise ratios (S/N) of 11.2, 10.4, and 6.1, respectively, at 2.0 mm (150 GHz); we also detect (324) Bamberga with an S/N of 4.1 at 3.2 mm (95 GHz). We place constraints on these asteroids’ effective emissivities, brightness temperatures, and lightcurve modulation amplitude. Our flux density measurements of (324) Bamberga and (13) Egeria roughly agree with predictions, while our measurements of (22) Kalliope suggest lower flux, corresponding to effective emissivities of 0.64 ± 0.11 at 2.0 and < 0.47 at 3.2 mm. We predict the asteroids detectable in other SPT data sets and find good agreement with detections of (772) Tanete and (1093) Freda in recent data from the SPT3G camera, which has ∼10× the mapping speed of SPTpol. This work is the first focused analysis of asteroids in data from CMB surveys, and it demonstrates we can repurpose historic and future data sets for asteroid studies. Future SPT measurements can help constrain the distribution of surface properties over a larger asteroid population.