SERAFINELLI, ROBERTOROBERTOSERAFINELLISEVERGNINI, PaolaPaolaSEVERGNINIBRAITO, ValentinaValentinaBRAITODELLA CECA, RobertoRobertoDELLA CECAVignali, CCVignaliAMBROSINO, FilippoFilippoAMBROSINOCICONE, CLAUDIACLAUDIACICONEZaino, AAZainoDotti, MMDottiSesana, AASesanaGianolli, VEVEGianolliBallo, LLBalloLA PAROLA, VALENTINAVALENTINALA PAROLAMatzeu, GAGAMatzeu2022-01-212022-01-2120200004-637Xhttp://hdl.handle.net/20.500.12386/31338The elusive supermassive black hole binaries (SMBHBs) are thought to be the penultimate stage of galaxy mergers, preceding a final coalescence phase. SMBHBs are sources of continuous gravitational waves, possibly detectable by pulsar timing arrays; the identification of candidates could help in performing targeted gravitational wave searches. Due to SMBHBs’ origin in the innermost parts of active galactic nuclei (AGN), X-rays are a promising tool for unveiling their presence, by means of either double Fe Kα emission lines or periodicity in their light curve. Here we report on a new method for selecting SMBHBs by means of the presence of a periodic signal in their Swift Burst Alert Telescope (BAT) 105 month light curves. Our technique is based on Fisher’s exact g-test and takes into account the possible presence of colored noise. Among the 553 AGN selected for our investigation, only the Seyfert 1.5 galaxy Mrk 915 emerges as a candidate SMBHB; from subsequent analysis of its light curve we find a period P0 = 35 ± 2 months, and the null hypothesis is rejected at the 3.7σ confidence level. We also present a detailed analysis of the BAT light curve of the only previously X-ray-selected binary candidate source in the literature, the Seyfert 2 galaxy MCG+11-11-032. We find P0 = 26.3 ± 0.6 months, consistent with the one inferred from previously reported double Fe Kα emission lines.STAMPAenArticle10.3847/1538-4357/abb3c32-s2.0-85092643873WOS:000576071100001https://iopscience.iop.org/article/10.3847/1538-4357/abb3c3https://api.elsevier.com/content/abstract/scopus_id/850926438732020ApJ...902...10SFIS/05 - ASTRONOMIA E ASTROFISICA