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تسجيل مستخدم جديدNuSTAR monitoring of MAXI J1348-630: evidence of high density disc reflection
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We present the broadband spectral analysis of all the six hard, intermediate and soft state NuSTAR observations of the recently discovered transient black hole X-ray binary MAXI J1348-630 during its first outburst in 2019. We first model the data with a combination of a multi-colour disc and a relativistic blurred reflection, and, whenever needed, a distant reflection. We find that this simple model scheme is inadequate in explaining the spectra, resulting in a very high iron abundance. We, therefore, explore the possibility of reflection from a high-density disc. We use two different sets of models to describe the high-density disc reflection: relxill-based reflection models, and reflionx-based ones. The reflionx-based high-density disc reflection models bring down the iron abundance to around the solar value, while the density is found to be $10^{20.3-21.4} rm cm^{-3}$. We also find evidence of a high-velocity outflow in the form of $sim$7.3 keV absorption lines. The consistency between the best-fit parameters for different epochs and the statistical significance of the corresponding model indicates the existence of high-density disc reflection in MAXI J1348-630.
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We studied the multi-wavelength timing and spectral properties of the high mass X-ray binary MAXI J1348$-$630 during two successive outbursts of April and June 2019 using ALMA, Swift, Chandra, NuSTAR and NICER. The position of the source was measured
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The fast variability observed in the X-ray emission from black-hole binaries has a very complex phenomenology, but offers the possibility to investigate directly the properties of the inner accretion flow. In particular, type-B oscillations in the 2-
8 Hz range, observed in the Soft-Intermediate state, have been associated to the emission from a relativistic jet. We present the results of the timing and spectral analysis of a set of observations of the bright transient MAXI J1348-630 made with the NICER telescope. The observations are in the brightest part of the outburst and all feature a strong type-B QPO at ~4.5 Hz. We compute the energy dependence of the fractional rms and the phase lags at the QPO frequency, obtaining high signal-to-noise data and sampling for the first time at energies below 2 keV. The fractional rms decreases from more than 10% at 9 keV to 0.6% at 1.5 keV, and is constant below that energy. Taking the 2-3 keV band as reference, photons at all energies show a hard lag, increasing with the distance from the reference band. The behaviour below 2 keV has never been observed before, due to the higher energy bandpass of previous timing instruments. The energy spectrum can be fitted with a standard model for this state, consisting of a thin disc component and a harder power law, plus an emission line between 6 and 7 keV. We discuss the results, concentrating on the phase lags, and show that they can be interpreted within a Comptonization model.
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