%0 Generic %1 zheng2017revealing %A Zheng, Y. %A Peek, J. E. G. %A Putman, M. E. %A Werk, J. K. %D 2017 %K CGM MW %T Revealing the Milky Way's Hidden Circumgalactic Medium with the COS Quasar Database for Galactic Absorption Lines %U http://arxiv.org/abs/1710.10703 %X Every quasar (QSO) spectrum contains absorption-line signatures from the interstellar medium (ISM), disk-halo (D/H) interface, and circumgalactic medium (CGM) of the Milky Way (MW) along its line of sight. We analyze a sample of 119 QSO spectra observed with the Cosmic Origins Spectrograph on board the Hubble Space Telescope, and examine the significance of the SiIV absorption at $|v|<100$ km s$^-1$ in the MW's CGM. We build a 3D kinematic model of the D/H interface based on the commonly adopted 1D flat-slab model and compare it with the observed SiIV column density profiles seen toward the QSOs. 113 of the 119 QSO sightlines show a significant column density excess in addition to the SiIV predicted by the 3D D/H model. We incorporate gas inflows, halo lagging, and turbulent broadening in the model and find that the additional kinematics only mildly affect the significance of the SiIV excess. This excess most likely resides in the extended MW's CGM and was previously hidden by the absorption due to the nearby ISM and D/H interface. We conduct an order-of-magnitude calculations for the CGM mass, including the gas hidden at $|v|<100$ km s$^-1$, and find a total mass of $\sim2\times10^10\ M_ødot\ (R_CGM160\ kpc)^2$. Our mass estimate suggests the MW hosts a similarly massive CGM as other $L^*$ galaxies at low redshifts. In conducting this study, we produced a carefully continuum-normalized spectral dataset, the COS Quasar Database for Galactic Absorption Lines (COS-GAL), which we release to the public. COS-GAL is based on a subset of the HST Spectroscopic Legacy Archive (Peeples et al. 2017), consisting of 403 QSOs observed with G130M and/or G160M gratings. For each of the QSOs, we provide the normalized continuum, individual ion line spectra, and HI 21cm emission lines extracted from the currently available all-sky HI surveys.

@misc{zheng2017revealing, abstract = {Every quasar (QSO) spectrum contains absorption-line signatures from the interstellar medium (ISM), disk-halo (D/H) interface, and circumgalactic medium (CGM) of the Milky Way (MW) along its line of sight. We analyze a sample of 119 QSO spectra observed with the Cosmic Origins Spectrograph on board the Hubble Space Telescope, and examine the significance of the SiIV absorption at $|v|<100$ km s$^{-1}$ in the MW's CGM. We build a 3D kinematic model of the D/H interface based on the commonly adopted 1D flat-slab model and compare it with the observed SiIV column density profiles seen toward the QSOs. 113 of the 119 QSO sightlines show a significant column density excess in addition to the SiIV predicted by the 3D D/H model. We incorporate gas inflows, halo lagging, and turbulent broadening in the model and find that the additional kinematics only mildly affect the significance of the SiIV excess. This excess most likely resides in the extended MW's CGM and was previously hidden by the absorption due to the nearby ISM and D/H interface. We conduct an order-of-magnitude calculations for the CGM mass, including the gas hidden at $|v|<100$ km s$^{-1}$, and find a total mass of $\sim2\times10^{10}\ M_{\odot}\ (\frac{R_{\rm CGM}}{\rm 160\ kpc})^2$. Our mass estimate suggests the MW hosts a similarly massive CGM as other $L^*$ galaxies at low redshifts. In conducting this study, we produced a carefully continuum-normalized spectral dataset, the COS Quasar Database for Galactic Absorption Lines (COS-GAL), which we release to the public. COS-GAL is based on a subset of the HST Spectroscopic Legacy Archive (Peeples et al. 2017), consisting of 403 QSOs observed with G130M and/or G160M gratings. For each of the QSOs, we provide the normalized continuum, individual ion line spectra, and HI 21cm emission lines extracted from the currently available all-sky HI surveys.}, added-at = {2017-10-31T10:15:46.000+0100}, author = {Zheng, Y. and Peek, J. E. G. and Putman, M. E. and Werk, J. K.}, biburl = {https://www.bibsonomy.org/bibtex/29c01c5d12cbbd00215c66bd1c9bb4934/miki}, description = {[1710.10703] Revealing the Milky Way's Hidden Circumgalactic Medium with the COS Quasar Database for Galactic Absorption Lines}, interhash = {ceaa2b20b4f1ca1e557c43708e5d0f8c}, intrahash = {9c01c5d12cbbd00215c66bd1c9bb4934}, keywords = {CGM MW}, note = {cite arxiv:1710.10703Comment: Submitted to ApJ. Comments are welcome}, timestamp = {2017-10-31T10:15:46.000+0100}, title = {Revealing the Milky Way's Hidden Circumgalactic Medium with the COS Quasar Database for Galactic Absorption Lines}, url = {http://arxiv.org/abs/1710.10703}, year = 2017 }