On the Non-relativistic Origin of Red-skewed Iron Lines in CV, Neutron
  Star and Black Hole Sources
  We perform the analysis of the iron K_alpha lines detected in three sources
representing of three types of accreting compact sources: cataclysmic variable
(CV) GK Per, neutron star (NS) Serpens X-1 and black hole (BH) GX 339-4. We
find, using data from Epic-PN Camera on-board XMM-Newton observatory,that the
iron K_alpha emission line in GK Per has a noticeable red-skewed profile. We
compare the GK Per asymmetric line with the red-skewed lines observed by
XMM-Newton in Serpens X-1 and GX 339-4. The observation of the K_alpha emission
with red-skewed features in CV GK Per cannot be related to the redshift effects
of General Relativity (GR). Therefore, if the mechanism of the K_alpha-line
formation is the same in CVs, NSs and BHs then it is evident that the GR
effects would be ruled out as a cause of red skewness of K_alpha line. The line
reprocessing in an outflowing wind has been recently suggested an alternative
model for a broad red-shifted iron line formation. In the framework of the
outflow scenario the red-skewed iron line is formed in the strong extended wind
due to its illumination by the radiation emanating from the innermost part of
the accreting material. In this Paper we demonstrate that the asymmetric shapes
of the lines detected from these CV, NS and BH sources are well described with
the wind (outflow) model. While this fact is hard to reconcile with the
relativistic models, it is consistent with the outflowing gas washing out high
frequency modulations of the radiation presumably originated in the innermost
part of the source.
