摘要：Our paper Monceau-Baroux et al. (2015) presented numerical
simulations of the precessing SS433 jet up to parsec scales,
and its main finding was a dynamical recollimation effect: the
jet transits from a winding helix to a more hollow straight
jet. We argued that this transition occurred at 0.068 parsec,
and gave a physical argument based on ram pressure that
balances the pressure of the interstellar medium (ISM). This
writes as ρ 0 γ 2
0 v
2
0 d
2
0 /d
2
1
= P ISM (our Eq. (2)), where the ρ 0 d 2
0 /d
2
1
is intended to estimate the density decrease in the jet beam
at a distance d 1 , while the jet is injected at d 0 . The factor
v 2
0
(and its Lorentz factor γ 0 , relatively small in the case
of SS433) quantifies the squared beam velocity. Given the
constant ISM pressure (7.5 × 10 −6 gcm −1 s −2 ), the distance
d 0 = 0.008 pc, and typical density/velocity values, this can
quantify the distance d 1 where effects caused by the ISM
pressure occur. Unfortunately, the estimate d 1 ≈ 8.5d 0 (i.e.
0.068 pc) we quoted in Eq. (3) used the ISM density for ρ 0
(namely ρ ISM = 8.3×10 −24 gcm −3 ), together with a beam speed
of v b = 0.26c. A corrected estimate with the actual beam density
adopted in our study (ρ b = 2.58 × 10 −22 gcm −3 at injection)
instead gives d 1 ≈ 47.6d 0 , which is factor of 5.6 larger. This
value clearly overestimates the distance where recollimation
was found to occur (see Figs. 4, 6, or 8 in our paper).
关键词：enhydrodynamicsrelativistic processesISM: jets and outflowsX-rays: binarieserrata, addenda
