%0 Generic %1 nicastro2016diffuse %A Nicastro, F. %A Senatore, F. %A Gupta, A. %A Mathur, S. %A Krongold, Y. %A Elvis, M. %A Piro, L. %D 2016 %K cgm galaxy ionisation low whim %T Diffuse Low-Ionization Gas in the Galactic Halo Casts Doubts on $z\simeq 0.03$ WHIM Detections %U http://arxiv.org/abs/1602.03533 %X In this Letter we demonstrate that the two claims of $z0.03$ 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 $z0.03$ WHIM absorption along these two sightlines is statistically not required. Our results, however, do not rule out a small contribution from the $z0.03$ 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$= 310^5$ K and the OVII column density is N$_OV II 410^15$ cm$^-2$, twenty times smaller than the OVII column density previously reported, and now more consistent with the expectations from cosmological hydrodynamical simulations.

@misc{nicastro2016diffuse, abstract = {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$_{OV II} \le 4\times 10^{15}$ cm$^{-2}$, twenty times smaller than the OVII column density previously reported, and now more consistent with the expectations from cosmological hydrodynamical simulations.}, added-at = {2016-02-12T10:25:58.000+0100}, author = {Nicastro, F. and Senatore, F. and Gupta, A. and Mathur, S. and Krongold, Y. and Elvis, M. and Piro, L.}, biburl = {https://www.bibsonomy.org/bibtex/2e8be49a09a8173e9f3b78dbe7b66a232/miki}, description = {[1602.03533] Diffuse Low-Ionization Gas in the Galactic Halo Casts Doubts on $z\simeq 0.03$ WHIM Detections}, interhash = {476c6853894f559079d17d709ca07750}, intrahash = {e8be49a09a8173e9f3b78dbe7b66a232}, keywords = {cgm galaxy ionisation low whim}, note = {cite arxiv:1602.03533Comment: 6 pages, 2 figures, accepted by MNRAS (Letter)}, timestamp = {2016-02-12T10:25:58.000+0100}, title = {Diffuse Low-Ionization Gas in the Galactic Halo Casts Doubts on $z\simeq 0.03$ WHIM Detections}, url = {http://arxiv.org/abs/1602.03533}, year = 2016 }