%0 Generic %1 masribas2016metalline %A Mas-Ribas, Lluís %A Miralda-Escudé, Jordi %A Pérez-Ràfols, Ignasi %A Arinyo-i Prats, Andreu %A Noterdaeme, Pasquier %A Petitjean, Patrick %A Schneider, Donald P. %A York, Donald G. %A Ge, Jian %D 2016 %K composite dla lines metal %T The Mean Metal-line Absorption Spectrum of Damped Lyman Alpha Systems in BOSS %U http://arxiv.org/abs/1610.02711 %X We study the average absorption spectrum of the Damped Lyman Alpha system (DLA) population at $z ~ 2.5$ by stacking normalized, rest-frame shifted spectra of $27\,000$ DLAs from the Data Release 12 of the BOSS survey of SDSS-III. We list measurements of the mean equivalent width of 50 individual metal absorption lines in 5 intervals of DLA hydrogen column density $N_\rm HI$, and overall mean equivalent widths for an additional 13 absorption features from groups of strongly blended lines. We show that the mean equivalent width of low-ionization lines increases with $N_HI$ as expected, but this increase is much weaker or non-existent for high-ionization lines. We develop a theoretical model to infer mean column densities from the equivalent widths of partially saturated lines, based on the presence of multiple absorption components observed in high-resolution spectra. We use this model to infer mean column densities in DLAs of 14 low-ionization species, as well as for AlIII, SIII, SiIII, CIV, SiIV, NV and OVI. In addition, we use an approximate derivation for separating the contributions of several lines to blended absorption features, and infer mean equivalent widths and column densities from lines of the additional species NI, ZnII, CII$^*$, FeIII, and SIV. These measurements do not suffer from the superposition of the Lyman forests, owing to the large number of DLAs that are stacked. Several of these mean column densities of metal lines in DLAs are obtained for the first time; their values generally agree with measurements of individual DLAs from high-resolution, high signal-to-noise ratio spectra when they are available.

@misc{masribas2016metalline, abstract = {We study the average absorption spectrum of the Damped Lyman Alpha system (DLA) population at $z ~ 2.5$ by stacking normalized, rest-frame shifted spectra of $\sim 27\,000$ DLAs from the Data Release 12 of the BOSS survey of SDSS-III. We list measurements of the mean equivalent width of 50 individual metal absorption lines in 5 intervals of DLA hydrogen column density $N_{\rm HI}$, and overall mean equivalent widths for an additional 13 absorption features from groups of strongly blended lines. We show that the mean equivalent width of low-ionization lines increases with $N_{\rm HI}$ as expected, but this increase is much weaker or non-existent for high-ionization lines. We develop a theoretical model to infer mean column densities from the equivalent widths of partially saturated lines, based on the presence of multiple absorption components observed in high-resolution spectra. We use this model to infer mean column densities in DLAs of 14 low-ionization species, as well as for AlIII, SIII, SiIII, CIV, SiIV, NV and OVI. In addition, we use an approximate derivation for separating the contributions of several lines to blended absorption features, and infer mean equivalent widths and column densities from lines of the additional species NI, ZnII, CII${}^{*}$, FeIII, and SIV. These measurements do not suffer from the superposition of the Lyman forests, owing to the large number of DLAs that are stacked. Several of these mean column densities of metal lines in DLAs are obtained for the first time; their values generally agree with measurements of individual DLAs from high-resolution, high signal-to-noise ratio spectra when they are available.}, added-at = {2016-10-11T09:32:16.000+0200}, author = {Mas-Ribas, Lluís and Miralda-Escudé, Jordi and Pérez-Ràfols, Ignasi and Arinyo-i Prats, Andreu and Noterdaeme, Pasquier and Petitjean, Patrick and Schneider, Donald P. and York, Donald G. and Ge, Jian}, biburl = {https://www.bibsonomy.org/bibtex/2ae47438b66d8a6b20b76e7a491f97584/miki}, description = {[1610.02711] The Mean Metal-line Absorption Spectrum of Damped Lyman Alpha Systems in BOSS}, interhash = {4b9db1aa26d28ea58ddd0612ac6835e8}, intrahash = {ae47438b66d8a6b20b76e7a491f97584}, keywords = {composite dla lines metal}, note = {cite arxiv:1610.02711Comment: 34 pages, 16 figures and 9 tables. Submitted to ApJ}, timestamp = {2016-10-11T09:32:16.000+0200}, title = {The Mean Metal-line Absorption Spectrum of Damped Lyman Alpha Systems in BOSS}, url = {http://arxiv.org/abs/1610.02711}, year = 2016 }