SS433: a massive X-ray binary at advanced evolutionary stage

Abstract

INTEGRAL IBIS/ISGRI 18-60 keV observations of SS433 performed in 2003-2011 enabled the hard X-ray phase-resolved orbital and precessional light curves and spectra to be constructed. The spectra can be fitted by a power-law with photon index $\simeq 3.8$ and remain almost constant while the X-ray flux varies by a factor of a few. This suggests that the hard X-ray emission is produced in an extended quasi-isothermal hot 'corona' surrounding central parts of a supercritical accretion disc. A joint analysis of the broadband 18-60 keV orbital and precessional light curves was performed in the model assuming a significant Roche lobe overfilling by the optical star, up to its filling the outer Lagrangian surface enabling mass loss through the outer Lagrangian L${}_2$ point. From this modeling, the relativistic-to-optical component mass ratio $q=M_x/M_v\gtrsim 0.4÷0.8$ is estimated. An analysis of the observed long-term stability of the orbital period of SS433 with an account of the recent observations of SS433 by the VLTI GRAVITY interferometer enabled an independent mass ratio estimate $q>0.6$. This estimate in combination with the radial velocity semi-amplitude for stationary He II emission, $K_x=168\pm 18$ km/s (Hillwig et al 2004) suggests the optical component mass in SS433 $M_v>12M_{\odot }$. Thus, the mass of the relativistic component in SS433 is $M_x>7M_{\odot }$, which is close to the mean mass of black holes in X-ray binaries ($\sim 8M_{\odot }$). The large binary mass ratio in SS433 allows us to understand why there is no common envelope in this binary at the secondary mass transfer evolutionary stage and the system remains semi-detached (van den Heuvel et al. 2017). We also discuss unsolved issues and outline prospects for further study of SS433.

20 pages, 16 figures, to be submitted to New Astronomy

References in corpus (11)

• The Nature of SS433 and the Ultraluminous X-ray Sources
• Very high energy particle acceleration powered by the jets of the microquasar SS 433
• Mass Transfer from Giant Donors
• Spectroscopic Observations of the Mass Donor Star in SS 433
• Fluctuations and symmetry in the speed and direction of the jets of SS433 on different timescales
• Diagnostics of the black hole candidate SS433 with the RXTE
• Monte-Carlo simulations of the broadband X-ray continuum of SS433
• Mass ratio in SS433 revisited
• Super-Keplerian Equatorial Outflows in SS 433. Centrifugal Ejection of the Circumbinary Disk
• Gamma-rays from SS433: evidence for periodicity
• FERMI observation of the jets of the microquasar SS433

Cited by in corpus (12)

• The Pair-Instability Mass Gap for Black Holes
• No peaks without valleys: The stable mass transfer channel for gravitational-wave sources in light of the neutron star-black hole mass gap
• Transient Double-beam Spectrograph for the 2.5-m Telescope of the Caucasus Mountain Observatory of SAI MSU
• NuSTAR reveals the hidden nature of SS433
• The INTEGRAL view on Black Hole X-ray Binaries
• Discovery of orbital Eccentricity and Evidence for orbital Period Increase of SS433
• Phase-resolved spectroscopic analysis of the eclipsing black hole X-ray binary M33 X-7: System properties, accretion, and evolution
• Hypercritical Accretion for Black Hole High Spin in Cygnus X-1
• Population synthesis of ultraluminous X-ray sources with magnetised neutron stars
• Evolutionary Increase of the orbital Separation and Change of the Roche Lobe Size in SS433
• Black holes at cosmic dawn in the redshifted 21cm signal of HI
• Arcsecond-Scale X-ray Imaging and Spectroscopy of SS 433 with Chandra HETG