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Free, publiclyaccessible full text available February 9, 2025

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. 
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 Modern cosmic microwave background (CMB) analysis pipelines regularly employ complex timedomain filters, beam models, masking, and other techniques during the production of sky maps and their corresponding angular power spectra. However, these processes can generate couplings between multipoles from the same spectrum and from different spectra, in addition to the typical power attenuation. Within the context of pseudo
C _{ℓ}based,MASTER style analyses, the net effect of the timedomain filtering is commonly approximated by a multiplicative transfer function,F _{ℓ}, that can fail to capture mode mixing and is dependent on the spectrum of the signal. To address these shortcomings, we have developed a simulationbased spectral correction approach that constructs a twodimensional transfer matrix, , which contains information about mode mixing in addition to mode attenuation. We demonstrate the application of this approach on data from the first flight of the ${J}_{\mathit{\ell}\mathit{\ell}\prime}$Spider balloonborne CMB experiment. 
Abstract We present the first linear polarization measurements from the 2015 longduration balloon flight of
Spider , which is an experiment that is designed to map the polarization of the cosmic microwave background (CMB) on degree angular scales. The results from these measurements include maps and angular power spectra from observations of 4.8% of the sky at 95 and 150 GHz, along with the results of internal consistency tests on these data. While the polarized CMB anisotropy from primordial density perturbations is the dominant signal in this region of sky, Galactic dust emission is also detected with high significance. Galactic synchrotron emission is found to be negligible in theSpider bands. We employ two independent foregroundremoval techniques to explore the sensitivity of the cosmological result to the assumptions made by each. The primary method uses a dust template derived fromPlanck data to subtract the Galactic dust signal. A second approach, which constitutes a joint analysis ofSpider andPlanck data in the harmonic domain, assumes a modifiedblackbody model for the spectral energy distribution of the dust with no constraint on its spatial morphology. Using a likelihood that jointly samples the template amplitude andr parameter space, we derive 95% upper limits on the primordial tensortoscalar ratio from Feldman–Cousins and Bayesian constructions, findingr < 0.11 andr < 0.19, respectively. Roughly half the uncertainty inr derives from noise associated with the template subtraction. New data at 280 GHz fromSpider ’s second flight will complement thePlanck polarization maps, providing powerful measurements of the polarized Galactic dust emission. 
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.