2018/03/29 by S. Carpano, Stefania Carpano, Chichuan Jin · 13 citations
Physics and Astronomy · #Active galactic nucleus #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Black hole (networking) #Galaxy #Light curve #Physics #Pulsars and Gravitational Waves Research #Spectral energy distribution #Supermassive black hole #astro-ph.HE
paper · pdf · doi:10.1093/mnras/sty841
published in Monthly Notices of the Royal Astronomical Society 477(3), 3178-3184 (Oxford University Press) · 7 pages, 4 figures
arxiv created 2018/03/29 · openalex publication_date 2018/03/29 · arxiv updated 2018/04/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
XMMU J134736.6+173403 is an X-ray source discovered serendipitously by XMM–Newton, which was found to be spatially coincident with a pair of galaxies, including a Seyfert 2 galaxy, but presented in 2003 a very sharp persistent flux drop of a factor of 6.5 within 1 h. From the analysis of a set of 29 Swift observations conducted from 2008 February 6 to 2008 May 23, we discovered twin-peak quasi-periodic oscillations (QPOs) with periods of 23.82 ± 0.07 h and 71.44 ± 0.57 h. Using a Chandra observation of 2008, we evaluate more accurately the position of the X-ray source and show that the new source coordinates coincide with the position of the Seyfert 2 galaxy. We provide a detailed spectral energy distribution (SED) of the active galactic nucleus (AGN) counterpart using multiwavelength observations. The AGN is radio-loud and the broad-band SED modelling indicates a black hole with a mass of 9.8 × 106 M⊙, which accretes at an Eddington ratio of 0.047. QPOs for active galaxies have been reported so far in only few cases, the most reliable one being from RE J1034+396 for which a 1 h periodicity has been discovered analysing a 91 ks XMM–Newton observation. Twin-peak QPOs with an observed frequency ratio of 3:1 have not been reported so far for any AGN. From resonance models of the epicyclic frequencies, we evaluate the different possible mass–spin relations. It’s still not clear what could have been the origin of the high flux and sharp drop only observed in 2003.