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Fig. 1.


Normalised RGS1 data (blue crosses) and the normalised best-fit model (red line) for the PKS 2155–304 emission absorbed with the Galactic neutral disk, hot halo and the transition temperature gas TTG (see Nevalainen et al. 2017). The normalisation is done by dividing the spectra by the best-fit model consisting of the PKS 2155–304 emission and only the Galactic neutral absorber to highlight the effect of the Galactic halo and TTG. In particular, the Galactic O IV absorption line overlaps with the O VII test line for A3 (middle panel). The dashed vertical lines indicate the centroid wavelengths of the O VII test lines assuming the redshifts of the structures A1, A2, A3, A4 and A6 (A5 is missing due to the overlap of its centroid wavelength with the instrumental feature in both RGS1 and LETG; see de Vries et al. 2003, 2015). The error bars contain both the statistical uncertainties and the systematic one (2% of the flux).

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