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We report results of a spectral and timing analysis of the X-ray pulsar XTE J1829−098 using data obtained with the NuSTAR observatory during an outburst in 2018 August. A strong absorption feature was detected at the energy of E cyc ≃ 15 keV in the source spectrum. This feature was interpreted as a cyclotron resonance scattering line corresponding to the magnetic field strength of the neutron star surface B ≃ 1.7 × 1012 G. The pulse phase-resolved spectroscopy shows that the cyclotron line is significantly detected at all phases of the pulse and its energy and other parameters are variable over the pulse period. The timing analysis of the source emission revealed strong pulsations with a period of P = 7.84480(2) s. The pulsed fraction is changed with the energy, including its local increase in the vicinity of the cyclotron line. Using the archival data of the RXTE observatory the presence of the cyclotron line in the spectrum of XTE J1829−098 was independently confirmed and tentative hint for the possible anticorrelation of the line energy with the source flux was revealed. [ABSTRACT FROM AUTHOR]

The analysis of hard X-ray INTEGRAL observations (2003–2008) of superaccreting Galactic microquasar SS433 at precessional phases of the source with the maximum disc opening angle is carried out. It is found that the shape and width of the primary X-ray eclipse are strongly variable, suggesting additional absorption in dense stellar wind and gas outflows from the optical A7I component and the wind–wind collision region. The independence of the observed hard X-ray spectrum on the accretion disc precessional phase suggests that hard X-ray emission (20–100 keV) is formed in an extended, hot, quasi-isothermal corona, probably heated by interaction of relativistic jet with inhomogeneous wind outflow from the precessing supercritical accretion disc. A joint modelling of X-ray eclipsing and precessional hard X-ray variability of SS433 revealed by INTEGRAL by a geometrical model suggests the binary mass ratio 0.25–0.5. The absolute minimum of joint orbital and precessional residuals is reached at . The found binary mass ratio range allows us to explain the substantial precessional variability of the minimum brightness at the middle of the primary optical eclipse. For the mass function of the optical star as derived from Hillwig & Gies data, the obtained value of yields the masses of the components , confirming the black hole nature of the compact object in SS433. [ABSTRACT FROM AUTHOR]