A black hole X-ray binary at $\sim$ 100 Hz: multiwavelength timing of MAXI J1820+070 with HiPERCAM and NICER

J.A. Paice , P. Gandhi , T. Shahbaz , P. Uttley , Z. Arzoumanian , P.A. Charles , V.S. Dhillon , K.C. Gendreau , S.P. Littlefair , J. Malzac (1) , S. Markoff , T.R. Marsh , R. Misra , D.M. Russell , A. Veledina

1 IRAP - Institut de recherche en astrophysique et planétologie

We report on simultaneous sub-second optical and X-ray timing observations of the low-mass X-ray binary black hole candidate MAXI J1820+070. The bright 2018 outburst rise allowed simultaneous photometry in five optical bands (ugriz_s) with HiPERCAM/GTC (Optical) at frame rates over 100 Hz, together with NICER/ISS observations (X-rays). Intense (factor of 2) red flaring activity in the optical is seen over a broad range of time-scales down to ∼10 ms. Cross-correlating the bands reveals a prominent anticorrelation on time-scales of ∼seconds, and a narrow sub-second correlation at a lag of ≈ +165 ms (optical lagging X-rays). This lag increases with optical wavelength, and is approximately constant over Fourier frequencies of ∼0.3–10 Hz. These features are consistent with an origin in the inner accretion flow and jet base within ∼5000 Gravitational radii. An additional ∼+5 s lag feature may be ascribable to disc reprocessing. MAXI J1820+070 is the third black hole transient to display a clear ∼0.1 s optical lag, which may be common feature in such objects. The sub-second lag variation with wavelength is novel, and may allow constraints on internal shock jet stratification models.

Mots clés: accretion; accretion discs; X-rays: binaries; X-rays: individual: MAXI J1820+070

Domaines: Astrophysique [astro-ph]

J.A. Paice, P. Gandhi, T. Shahbaz, P. Uttley, Z. Arzoumanian, et al.. A black hole X-ray binary at $\sim$ 100 Hz: multiwavelength timing of MAXI J1820+070 with HiPERCAM and NICER. Monthly Notices of the Royal Astronomical Society, 2019, 490 (1), pp.L62-L66. ⟨10.1093/mnrasl/slz148⟩. ⟨hal-02410941⟩