Sub-second optical/near-infrared quasi-periodic oscillations from the black hole X-ray transient Swift J1727.8-1613
: Vincentelli, F. M.; Shahbaz, T.; Casella, P.; Dhillon, V. S.; Paice, J.; Altamirano, D.; Segura, N. Castro; Fender, R.; Gandhi, P.; Littlefair, S.; Maccarone, T.; Malzac, J.; O'Brien, K.; Russell, D. M.; Tetarenko, A. J.; Uttley, P.; Veledina, A.
Publisher: OXFORD UNIV PRESS
: OXFORD
: 2025
: Monthly Notices of the Royal Astronomical Society
: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
: MON NOT R ASTRON SOC
: 539
: 3
: 2347
: 2361
: 15
: 0035-8711
: 1365-2966
DOI: https://doi.org/10.1093/mnras/staf600
: https://academic.oup.com/mnras/article/539/3/2347/8113289
: https://research.utu.fi/converis/portal/detail/Publication/498696726
We report on the detection of optical/near-infrared (O-IR) quasi-periodic oscillations (QPOs) from the black hole (BH) X-ray transient Swift J1727.8-1613. We obtained three X-ray and O-IR high-time-resolution observations of the source during its intermediate state (2023 September 9, 15, and 17) using NICER, HAWK-I@VLT, HIPERCAM@GTC, and ULTRACAM@NTT. We clearly detected a QPO in the X-ray and O-IR bands during all three epochs. The QPO evolved, drifting from 1.4 Hz in the first epoch, up to 2.2 Hz in the second, and finally reaching 4.2 Hz in the third epoch. These are among the highest O-IR QPO frequencies detected for a BH X-ray transient. During the first two epochs, the X-ray and O-IR emission are correlated, with an optical lag (compared to the X-rays) varying from +70 to 0 ms. Finally, during the third epoch, we measured, for the first time, a lag of the z(s) band with respect to the g(s) band at the QPO frequency (approximate to +10 ms). By estimating the variable O-IR SED we find that the emission is most likely non-thermal. Current state-of-the-art models can explain some of these properties, but neither the jet nor the hot flow model can easily explain the observed evolution of the QPOs. While this allowed us to put tight constraints on these components, more frequent coverage of the state transition with fast multiwavelength observations is still needed to fully understand the evolution of the disc/jet properties in BH low-mass X-ray binaries.
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HiPERCAM was funded by the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013) under ERC-2013-ADG Grant Agreement no. 340040 (HiPERCAM), with additional funding for operations and enhancements provided by the UK Science and Technology Facilities Council (STFC). FMV and TS acknowledge support from the Agencia Estatal de Investigación del Ministerio de Ciencia, Innovación y Universidades (AEI-MCIU) under grant PID2020-114822GB-I00 and PID2023-151588NB-I00. FMV and DA acknowledge support from the Science and Technology Facilities Council grant ST/V001000/1. FMV acknowledges the financial support from the Visitor and Mobility program of the Finnish Centre for Astronomy with ESO (FINCA). VSD is supported by STFC. AJT acknowledges the support of the Natural Sciences and Engineering Research Council of Canada (NSERC; funding reference number RGPIN-2024-04458). PG acknowledges support from a Royal Society Leverhulme Trust Senior Fellowship and support from an STFC Small Award. This research has been supported by the Academy of Finland grant 355672 (AV). Nordita is supported in part by NordForsk.
