Problems with non-thermal models for the narrow line gamma rays reported from SS 433

Abstract

The jet/grain model proposed by Ramatyet al. (1984, hereafter abbreviated as RKL) for production of the narrow gamma-ray lines reported from SS433 is examined and shown to be untenable on numerous grounds. Most importantly: (a) The huge Coulomb collisional losses (Wc≳2×1041 erg s−1) from the jet, which would necessarily accompany non-thermal production of the gamma rays, demands a jet acceleration/collimation process acting over a very long range and with a power at least 102 times the Eddington limit for any stellar object. (b) There is a collisional thick target limit (irrespective of jet mass) to the gamma ray yield per interstellar proton. Consequently, the gamma-ray data demand an improbably high interstellar density (≳109 cm−3). (c) For the grains to be kept cool enough (≲3000 K) to survive the heating rateWc either by radiation or jet expansion would demand a ‘jet’ wider than its length and so inconsistent with narrow lines. In the case of radiative cooling, the resultant IR flux would exceed the observed values by a factor ≳104. (d) Light scattered on the jet grain mass required would be highly polarized, contrary to observations, unless the jet was optically thick to grains, again precluding their radiative cooling. (e) To avoid unacceptable precessional broadening of the gamma-ray lines demands an emitting jet length ≲0.5 days atv=0.26c. This increases the necessary mass loss rate by a factor ≅10 over the values obtained by RKL who assumed a 4-day ‘flare’. (f) The model also predicts rest energy gamma-ray lines which are not observed.