Candidate periodically variable quasars from the Dark Energy Survey and the Sloan Digital Sky Survey Academic Article uri icon


  • Abstract Periodically variable quasars have been suggested as close binary supermassive black holes. We present a systematic search for periodic light curves in 625 spectroscopically confirmed quasars with a median redshift of 1.8 in a 4.6deg2 overlapping region of the Dark Energy Survey Supernova (DES-SN) fields and the Sloan Digital Sky Survey Stripe 82 (SDSS-S82). Our sample has a unique 20-year long multi-color (griz) light curve enabled by combining DES-SN Y6 observations with archival SDSS-S82 data. The deep imaging allows us to search for periodic light curves in less luminous quasars (down to r 23.5 mag) powered by less massive black holes (with masses 108.5M) at high redshift for the first time. We find five candidates with significant (at <99.74% single-frequency significance in at least two bands with a global p-value of 7 1043 103 accounting for the look-elsewhere effect) periodicity with observed periods of 35years (i.e., 12years in rest frame) having 46 cycles spanned by the observations. If all five candidates are periodically variable quasars, this translates into a detection rate of ${sim }0.8^{+0.5}_{-0.3}$% or ${sim }1.1^{+0.7}_{-0.5}$ quasar per deg2. Our detection rate is 480times larger than those found by previous searches using shallower surveys over larger areas. This discrepancy is likely caused by differences in the quasar populations probed and the survey data qualities. We discuss implications on the future direct detection of low-frequency gravitational waves. Continued photometric monitoring will further assess the robustness and characteristics of these candidate periodic quasars to determine their physical origins.

published proceedings


altmetric score

  • 10.5

author list (cited authors)

  • Chen, Y., Liu, X., Liao, W., Holgado, A. M., Guo, H., Gruendl, R. A., ... Walker, A. R.

citation count

  • 10

complete list of authors

  • Chen, Yu-Ching||Liu, Xin||Liao, Wei-Ting||Holgado, A Miguel||Guo, Hengxiao||Gruendl, Robert A||Morganson, Eric||Shen, Yue||Zhang, Kaiwen||Abbott, Tim MC||Aguena, Michel||Allam, Sahar||Avila, Santiago||Bertin, Emmanuel||Bhargava, Sunayana||Brooks, David||Burke, David L||Rosell, Aurelio Carnero||Carollo, Daniela||Kind, Matias Carrasco||Carretero, Jorge||Costanzi, Matteo||da Costa, Luiz N||Davis, Tamara M||De Vicente, Juan||Desai, Shantanu||Diehl, H Thomas||Doel, Peter||Everett, Spencer||Flaugher, Brenna||Friedel, Douglas||Frieman, Joshua||García-Bellido, Juan||Gaztanaga, Enrique||Glazebrook, Karl||Gruen, Daniel||Gutierrez, Gaston||Hinton, Samuel R||Hollowood, Devon L||James, David J||Kim, Alex G||Kuehn, Kyler||Kuropatkin, Nikolay||Lewis, Geraint F||Lidman, Christopher||Lima, Marcos||Maia, Marcio AG||March, Marisa||Marshall, Jennifer L||Menanteau, Felipe||Miquel, Ramon||Palmese, Antonella||Paz-Chinchón, Francisco||Plazas, Andrés A||Sanchez, Eusebio||Schubnell, Michael||Serrano, Santiago||Sevilla-Noarbe, Ignacio||Smith, Mathew||Suchyta, Eric||Swanson, Molly EC||Tarle, Gregory||Tucker, Brad E||Varga, Tamas Norbert||Walker, Alistair R

publication date

  • September 2020