AstroSat view of MAXI J1535−571: broad-band spectro-temporal features

Sreehari, H.; Ravishankar, B. T.; Iyer, Nirmal; Agrawal, Vivek; Katoch, Tilak; Mandal, Samir; Nandi, Anuj

doi:10.1093/mnras/stz1327

Cited by 79 publications

(67 citation statements)

References 51 publications

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“…2 (bottom panels) shows how the broadband noise can be well fitted by two Lorentzians centered at ≈0.5 Hz and ≈5 Hz, respectively, while a type-C QPO (Casella et al 2005;Motta et al 2015) and its second harmonic are clearly detected at ≈2.25 Hz and 4.5 Hz. These values are consistent with the values measured from quasisimultaneous Astrosat X-ray timing observations (Bhargava et al 2019;Sreehari et al 2019). Results from the fit are reported in Table 2.…”

Section: X-ray and Near-ir Power Spectral Densitiessupporting

confidence: 86%

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

Vincentelli

Casella

Russell³

et al. 2021

Monthly Notices of the Royal Astronomical Society

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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.

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Section: X-ray and Near-ir Power Spectral Densitiessupporting

confidence: 86%

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

Vincentelli

Casella

Russell³

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…where the disc component dominates) and the X-ray variability decreases, reaching fractional rms amplitudes < 5 per cent. It is worth noting that quasi-periodic oscillations (QPOs) were detected during the main outburst of J1535 (Mereminskiy et al 2018;Stevens et al 2018;Huang et al 2018;Stiele & Kong 2018;Shang et al 2019;Sreehari et al 2019), however, we did not detect any significant QPO during the reflares. This result could potentially be related to differences in the physical conditions during the normal bright outburst and the fainter reflares or it could be that QPOs are too weak to be detected at the low count rates we ob-serve.…”

Section: Outburst Reflares Of Maxi J1535-571: the State Transition Identificationcontrasting

confidence: 66%

A NICER look at the state transitions of the black hole candidate MAXI J1535−571 during its reflares

Cúneo

Alabarta

Zhang

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The black hole candidate and X-ray binary MAXI J1535−571 was discovered in 2017 September. During the decay of its discovery outburst, and before returning to quiescence, the source underwent at least four reflaring events, with peak luminosities of ∼1035–36 erg s−1 (d/4.1 kpc)2. To investigate the nature of these flares, we analysed a sample of NICER (Neutron star Interior Composition Explorer) observations taken with almost daily cadence. In this work, we present the detailed spectral and timing analysis of the evolution of the four reflares. The higher sensitivity of NICER at lower energies, in comparison with other X-ray detectors, allowed us to constrain the disc component of the spectrum at ∼0.5 keV. We found that during each reflare the source appears to trace out a q-shaped track in the hardness–intensity diagram similar to those observed in black hole binaries during full outbursts. MAXI J1535−571 transits between the hard state (valleys) and softer states (peaks) during these flares. Moreover, the Comptonized component is undetected at the peak of the first reflare, while the disc component is undetected during the valleys. Assuming the most likely distance of 4.1 kpc, we find that the hard-to-soft transitions take place at the lowest luminosities ever observed in a black hole transient, while the soft-to-hard transitions occur at some of the lowest luminosities ever reported for such systems.

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“…The absorption column density is around 5 × 10 22 cm −2 for all the segments. Sreehari et al (2019) and Sridhar et al (2019) report a slightly lower value for the same observation. The difference in the N H is arising due to a difference in the ancillary response file (ARF) of SXT used by different authors.…”

Section: Spectral Analysismentioning

confidence: 75%

Spectro-timing analysis of MAXI J1535–571 using AstroSat

Bhargava

Belloni

Bhattacharya

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We report the results of the analysis of an AstroSat observation of the Black Hole candidate MAXI J1535−571 during its Hard Intermediate state. We studied the evolution of the spectral and timing parameters of the source during the observation. The observation covered a period of ∼5 days and consisted of 66 continuous segments, corresponding to individual spacecraft orbits. Each segment was analysed independently. The source count rate increased roughly linearly by ∼30%. We modelled the spectra as a combination of radiation from a thermal disk component and a power-law. The timing analysis revealed the presence of strong Quasi Periodic Oscillations with centroid frequency ν QPO fluctuating in the range 1.7-3.0 Hz. We found a tight correlation between the QPO centroid frequency ν QPO and the power-law spectral index Γ, while ν QPO appeared not to be correlated with the linearly-increasing flux itself. We discuss the implications of these results on physical models of accretion.

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AstroSat view of MAXI J1535−571: broad-band spectro-temporal features

Cited by 79 publications

References 51 publications

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

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

A NICER look at the state transitions of the black hole candidate MAXI J1535−571 during its reflares

Spectro-timing analysis of MAXI J1535–571 using AstroSat

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