Mass ratio in SS433 revisited

We revisit the determination of binary mass ratio in the Galactic microquasar SS433 based on recent GRAVITY VLTI measurements of mass and angular momentum outflow through a circumbinary disc. The new observations combined with the constancy of the binary orbital period over $\sim 30$ yrs confirm that the mass ratio in SS433 is $q=M_\mathrm{x}/M_\mathrm{v}\gtrsim 0.6$. For the assumed optical star mass $M_\mathrm{v}$ ranging from $\sim 8$ to 15 $M_\odot$ such a mass ratio suggests a low limit of the compact object mass of $M_\mathrm{x}\sim 5-9 M_\odot$, placing the compact object in SS433 as a stellar-mass black hole.Comment: 4 pages, 3 figures, accepted in MNRAS, Main Journa

INTEGRAL observations of SS433, a supercritically accreting microquasar with hard spectrum

Observations of SS433 by INTEGRAL carried out in March -- May 2003 are presented. SS433 is evidently detected on the INTEGRAL images of the corresponding sky region in the energy bands 25-50 and 50-100 keV. The precessional variability of the hard X-ray flux is clearly seen. The X-ray eclipse caused by the binary orbital motion is also detected. A possible origin of the hard continuum is briefly discussed.Comment: 5 pages, 6 figures. Accepted to A&A INTEGRAL special volum