Fast infrared variability from the black hole candidate MAXI J1535−571 and tight constraints on the modelling

Abstract

We present the results regarding the analysis of the fast X-ray/infrared (IR) variability of the black hole transient MAXI J1535−571. The data studied in this work consist of two strictly simultaneous observations performed with XMM-Newton (X-rays: 0.7−10 keV), VLT/HAWK-I (Ks band, 2.2 μm) and VLT/VISIR (M and PAH2_2 bands, 4.85 and 11.88 μm respectively). The cross-correlation function between the X-ray and near-IR light curves shows a strong asymmetric anti-correlation dip at positive lags. We detect a near-IR QPO (2.5 σ) at 2.07 ± 0.09 Hz simultaneously with an X-ray QPO at approximately the same frequency (f0 = 2.25 ± 0.05). From the cross-spectral analysis a lag consistent with zero was measured between the two oscillations. We also measure a significant correlation between the average near-IR and mid-IR fluxes during the second night, but find no correlation on short timescales. We discuss these results in terms of the two main scenarios for fast IR variability (hot inflow and jet powered by internal shocks). In both cases, our preliminary modelling suggests the presence of a misalignment between disk and jet.

Are Low-Frequency Quasi-Periodic Oscillations seen in accretion flows the disk response to a jet instability?

“…There is therefore no obvious reason why ∆t X should always be shorter than ∆t IR , so we do not expect any clear trend for the time lag between X and OIR QPOs (see also Veledina et al 2013Veledina et al , 2015. This is consistent with OIR QPOs lagging behind X-ray QPOs with ∼ 0.1 sec in several XrBs (Gandhi et al 2010;Kalamkar et al 2016;Gandhi et al 2017), but also with the non detection of any lag in MAXI J1535-571 (Vincentelli et al 2021) or even X-rays possibly lagging behind the optical QPO in MAXI J1820+070 (Paice et al 2021). Moreover, there are evidences of different properties between the two QPOs, like the rms-flux relation (Vincentelli et al 2018) or the time evolution of the power spectral density (Vincentelli et al 2019).…”

Black holes: Timing and spectral properties and evolution

“…This model can also explain the observed lag on a timescale of ∼minutes between radio and sub-mm bands, as the propagation front moves outwards in the jet. In addition to these lags, other tantalizing broadband timing properties are observed in several sources, but their origins remain a topic of debate, including: an anti-correlation of the X-ray and optical/IR at zero-lag (e.g., [175,128]) and quasi periodic oscillations (QPOs) at same temporal frequency in both X-ray and optical/IR [178]. Simultaneous, fast photometry observations in X-rays and longer wavelengths are challenging to coordinate, and the field is relatively young.…”

The Evolution of Rapid Optical/X-ray Timing Correlations in the Initial Hard State of MAXI J1820+070

“…The transition to this anti-correlation in the phase lags occurs at around 0.2 Hz, where there is a sudden discontinuity; analyses of epochs 4 and 5 are inconclusive in showing whether phase lags increase from −π, or decrease from +π at this discontinuity. It is perhaps worth noting that negative phase lags, sometimes approaching ±π, are seen at lower frequencies in multiple other sources (see Gandhi et al 2010;Veledina et al 2017;Malzac et al 2018;Vincentelli et al 2021).…”

“…Therefore, there appears to be a connection with this QPO and the features, including a negative lag in the CCF, in our data. Indeed, QPOs have been associated with changes in the lags in other LMXB sources previously Malzac et al 2018;Vincentelli et al 2021).…”