In this Letter we demonstrate that the two claims of z \simeq 0.03 OVII K \alpha absorption lines from Warm Hot Intergalactic Medium ( WHIM ) along the lines of sight to the blazars H 2356-309 ( Buote et al. , 2009 ; Fang et al. , 2010 ) and Mkn 501 ( Ren , Fang & Buote , 2014 ) are likely misidentifications of the z = 0 OII K \beta line produced by a diffuse Low-Ionization Metal Medium in the Galaxy ’ s Interstellar and Circum-Galactic mediums .
We perform detailed modeling of all the available high signal-to-noise Chandra LETG and XMM-Newton RGS spectra of H 2356-309 and Mkn 501 and demonstrate that the z \simeq 0.03 WHIM absorption along these two sightlines is statistically not required .
Our results , however , do not rule out a small contribution from the z \simeq 0.03 OVII K \alpha absorber along the line of sight to H 2356-309 .
In our model the temperature of the putative z = 0.031 WHIM filament is T = 3 \times 10 ^ { 5 } K and the OVII column density is N _ { OVII } { { } _ { < } \atop { } ^ { \sim } } 4 \times 10 ^ { 15 } cm ^ { -2 } , twenty times smaller than the OVII column density previously reported , and now more consistent with the expectations from cosmological hydrodynamical simulations .