Is SS 433 a misaligned ultraluminous X-ray source? Constraints from its reflected signal in the Galactic plane

Abstract

We evaluate the emission that must arise due to reflection of the putative collimated X-ray radiation of SS 433 by atomic gas and molecular clouds in the Galactic plane and compare the predicted signal with existing RXTE and ASCA data for the region of interest. Assuming that the intrinsic X-ray spectrum of SS 433 is similar to that of ultraluminous X-ray sources (ULXs), we obtain an upper limit of ∼ 2 × 10 39 erg s −1 on its total (angular-integrated) luminosity in the 2-10 keV energy band, which is only weakly dependent on the half-opening angle, Θ r , of the emission cone. In contrast, the upper limit on the apparent luminosity of SS 433 (that would be perceived by an observer looking at its supercritical accretion disk face-on) decreases with increasing Θ r and is ∼ 3 × 10 40 erg s −1 for Θ r Θ p = 21 • , where Θ p is the precession angle of the baryonic jets (assuming that the emission cones precess in the same manner as the jets). This leaves open the possibility that SS 433 is a misaligned ULX. Further investigation of the reflection signal from the molecular clouds using higher angular resolution observations could improve these constraints with the potential to break the degeneracy between Θ r and the apparent luminosity.

NuSTAR reveals the hidden nature of SS433

“…For half--opening angles < 20 degrees (consistent with simulations of the source 28 ), the X--ray luminosity would appear in--excess--of 10 39 erg/s, and SS433 would be classified as a ULX. While this has long been suspected 16,29 , our direct constraint on the intrinsic X--ray luminosity confirms this assertion. The intrinsic radiative luminosity appears around or up to an order of magnitude smaller than the kinetic luminosity of the jet 30 (10 38 --10 39 erg/s).…”

Spectral Changes in the Hyperluminous Pulsar in NGC 5907 as a Function of Super-Orbital Phase

“…This would require an inclination angle of q »  25 during the faint phases (based on the 2012 data) and a half opening angle of the precession of~ 13 . This is lower than the precession seen in SS 433 (Khabibullin & Sazonov 2016), which is often argued to be a Galactic example of super-Eddington accretion analogous to ULXs, but viewed close to edge-on such that the X-ray emitting regions are obscured from view (Fabrika 2004). Under the assumption of a strong magnetic field, we estimated much higher viewing angles (almost edgeon, see Section 4.1), which would require a much smaller variability in θ to obtain similar flux variability.…”

Outbursts of the intermediate-mass black hole HLX-1: a wind-instability scenario

“…The inferred emission region for this extended component is ∼ 10 12 − 10 13 cm (Marshall et al 2012;Kubota et al 2010;Krivosheyev et al 2009;Cherepashchuk et al 2007;Kotani et al 1996), which is as large or larger than the size of the accretion disk (Rout ≈ 2 × 10 12 cm: Gies et al 2002). The observed X-ray luminosity of SS 433 (LX ≈ 10 36 erg s −1 ) is ∼10 −3 -10 −4 times the true luminosity (Khabibullin & Sazonov 2016;Fabrika et al 2015;Medvedev & Fabrika 2010), because only a small fraction of X-rays are scattered at all angles by the outflow while most of the radiation is emitted inside the polar-axis funnel (Atapin et al 2015;Medvedev & Fabrika 2010). If a similar fraction of the X-ray luminosity is scattered by a wind above the disk plane in HLX-1, the pressure exerted by the irradiation flux would satisfy the condition given in Phillips & Podsiadlowski (2002) and cause an intermittent mass transfer.…”