%0 Generic %1 ma2015milky %A Ma, Jingzhe %A Caucal, Paul %A Noterdaeme, Pasquier %A Ge, Jian %A Prochaska, J. Xavier %A Ji, Tuo %A Zhang, Shaohua %A Rahmani, Hadi %A Jiang, Peng %A Schneider, Donald P. %A Lundgren, Britt %A Pâris, Isabelle %D 2015 %K MW cold dla dust gas %T Cold gas and a Milky Way-type 2175 \AA bump in a metal-rich and highly depleted absorption system %U http://arxiv.org/abs/1509.01593 %X We report the detection of a strong Milky Way-type 2175 \AA$ $ extinction bump at $z$ = 2.1166 in the quasar spectrum towards SDSS J121143.42+083349.7 from the Sloan Digital Sky Survey (SDSS) Data Release 10. We conduct follow up observations with the Echelle Spectrograph and Imager (ESI) onboard the Keck-II telescope and the Ultraviolet and Visual Echelle Spectrograph (UVES) on the VLT. This 2175 \AA$ $ absorber is remarkable in that we simultaneously detect neutral carbon (C I), neutral chlorine (Cl I), and carbon monoxide (CO). It also qualifies as a damped Lyman alpha system. The J1211+0833 absorber is found to be metal-rich and has a dust depletion pattern resembling that of the Milky Way disk clouds. We use the column densities of the C I fine structure states and the C II/C I ratio (under the assumption of ionization equilibrium) to derive the temperature and volume density in the absorbing gas. A Cloudy photoionization model is constructed, which utilizes additional atoms/ions to constrain the physical conditions. The inferred physical conditions are consistent with a canonical cold (T $\sim$ 100 K) neutral medium with a high density ($n$(H I) $\sim$ 100 cm$^-3$) and a slightly higher pressure than the local interstellar medium. Given the simultaneous presence of C I, CO, and the 2175 \AA$ $ bump, combined with the high metallicity, high dust depletion level and overall low ionization state of the gas, the absorber towards J1211+0833 supports the scenario that the presence of the bump requires an evolved stellar population.

@misc{ma2015milky, abstract = {We report the detection of a strong Milky Way-type 2175 \AA$ $ extinction bump at $z$ = 2.1166 in the quasar spectrum towards SDSS J121143.42+083349.7 from the Sloan Digital Sky Survey (SDSS) Data Release 10. We conduct follow up observations with the Echelle Spectrograph and Imager (ESI) onboard the Keck-II telescope and the Ultraviolet and Visual Echelle Spectrograph (UVES) on the VLT. This 2175 \AA$ $ absorber is remarkable in that we simultaneously detect neutral carbon (C I), neutral chlorine (Cl I), and carbon monoxide (CO). It also qualifies as a damped Lyman alpha system. The J1211+0833 absorber is found to be metal-rich and has a dust depletion pattern resembling that of the Milky Way disk clouds. We use the column densities of the C I fine structure states and the C II/C I ratio (under the assumption of ionization equilibrium) to derive the temperature and volume density in the absorbing gas. A Cloudy photoionization model is constructed, which utilizes additional atoms/ions to constrain the physical conditions. The inferred physical conditions are consistent with a canonical cold (T $\sim$ 100 K) neutral medium with a high density ($n$(H I) $\sim$ 100 cm$^{-3}$) and a slightly higher pressure than the local interstellar medium. Given the simultaneous presence of C I, CO, and the 2175 \AA$ $ bump, combined with the high metallicity, high dust depletion level and overall low ionization state of the gas, the absorber towards J1211+0833 supports the scenario that the presence of the bump requires an evolved stellar population.}, added-at = {2015-09-08T09:48:13.000+0200}, author = {Ma, Jingzhe and Caucal, Paul and Noterdaeme, Pasquier and Ge, Jian and Prochaska, J. Xavier and Ji, Tuo and Zhang, Shaohua and Rahmani, Hadi and Jiang, Peng and Schneider, Donald P. and Lundgren, Britt and Pâris, Isabelle}, biburl = {https://www.bibsonomy.org/bibtex/2f3582205129d77c42618c125da3479ae/miki}, description = {[1509.01593] Cold gas and a Milky Way-type 2175 {\AA} bump in a metal-rich and highly depleted absorption system}, interhash = {72dce0b7142ec3687e1dc122af1c97da}, intrahash = {f3582205129d77c42618c125da3479ae}, keywords = {MW cold dla dust gas}, note = {cite arxiv:1509.01593Comment: 18 pages, 17 figures, to be published in MNRAS}, timestamp = {2015-09-08T09:48:13.000+0200}, title = {Cold gas and a Milky Way-type 2175 {\AA} bump in a metal-rich and highly depleted absorption system}, url = {http://arxiv.org/abs/1509.01593}, year = 2015 }