The South Pole Telescope AGN Monitoring Campaign: First Release of SPTpol Bright AGN Light Curves
Year: 2026
Type: preprint
Abstract: The South Pole Telescope (SPT) collaboration has recently embarked upon a campaign to monitor the brightness of a sample of active galactic nuclei (AGN), both in real time and in archival SPT data. The original design of the SPT was optimized for observations of the cosmic microwave background (CMB) at arc-minute and larger angular scales, and it has been used for this purpose for nearly twenty years, using three generations of CMB cameras. Recently it has been recognized that data from CMB experiments have the potential to be used for AGN monitoring. In this paper, we present the first public release of data from a full sample of SPT-monitored AGN, comprising 158 AGN light curves and associated data from the SPTpol camera, which was operational from 2012-2016. These light curves were created using observations from the SPTpol 500 deg$^{2}$ survey, in which the instrument was used to scan a 500 deg$^2$ patch of the sky several times per day with detectors sensitive to radiation in bands centered at 90 and 150 GHz. We provide a comprehensive description of the observations, the data processing methods, and the resulting light curve catalog. As an example of analyses that these data enable, we searched for a correlation between variability and spectral index, and we looked for ``bluer-when-brighter'' trends in the sample. Our analysis finds $> 10 σ$ correlation between fractional intrinsic variance and mean spectral index in the sample, but no significant evidence for bluer-when-brighter trends. The datasets from this study can be accessed through the SPT Treasury Record of AGN With Historical Activity and Time-Series or STRAWHAT catalog. This initial data release includes SPTpol light curves at 90 and 150 GHz, focusing on total intensity. In later updates, SPTpol polarization data and new observations from the SPT-3G instrument at 90, 150, and 220 GHz will be included.
Source: arXiv (Cornell University)
Authors: Hood, J. C., Ade, P. A. R., Anderson, A. J., Archipley, M., Austermann, J. E., Beall, J. A., Bender, A. N., Benson, B. A., Bianchini, F., Bleem, L. E., Carlstrom, J. E., Chang, C. L., Chaubal, P., Chiang, H. C., Chou, T-L., Citron, R., Moran, C. Corbett, Crawford, T. M., Crites, A. T., de Haan, T., Dobbs, M. A., Everett, W., Foster, A., Gallicchio, J., George, E. M., Gupta, N., Halverson, N. W., Hilton, G. C., Holder, G. P., Holzapfel, W. L., Hrubes, J. D., Huang, N., Hubmayr, J., Irwin, K. D., Jarvela, E., Knox, L., Lee, A. T., Li, D., Lowitz, A., Maccarone, T. J., Malkan, M., McMahon, J. J., Meyer, S. S., Montgomery, J., Natoli, T., Nibarger, J. P., Noble, G., Novosad, V., Padin, S., Patil, S., Phadke, K. A., Pryke, C., Reichardt, C. L., Ruhl, J. E., Saliwanchik, B. R., Schaffer, K. K., Sievers, C., Simpson, A., Smecher, G., Stark, A. A., Tandoi, C., Tucker, C., Veach, T., Vieira, J. D., Wang, G., Whitehorn, N., Wu, W. L. K., Yefremenko, V., Zebrowski, J. A.
Institutions: University of Chicago, Cardiff University, National Institute of Standards and Technology, University of Colorado Boulder, Argonne National Laboratory, The University of Melbourne, California Institute of Technology, High Energy Accelerator Research Organization, International Center for Quantum-field Measurement Systems for Studies of the Universe and Particles, Institute of Particle and Nuclear Studies, Canadian Institute for Advanced Research, McGill University, Harvey Mudd College, European Southern Observatory, University of California, Berkeley, Commonwealth Scientific and Industrial Research Organisation, SLAC National Accelerator Laboratory, Stanford University, Texas Tech University, University of California System, University of California, Davis, Lawrence Berkeley National Laboratory, University of Minnesota, Case Western Reserve University, Three-Speed Logic (Canada), Center for Astrophysics Harvard & Smithsonian, University of Illinois Urbana-Champaign, Southwest Research Institute, Michigan State University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funder: National Science Foundation
OpenAlex ID: W7150838522