GHOST Commissioning Science Results III: Characterizing an iron-poor damped Lyman $\alpha$ system

• Main Authors: Berg, Trystyn A. M, Hayes, Christian R, Cristiani, Stefano, McConnachie, Alan, Robertson, J. Gordon, Sestito, Federico, Simpson, Chris, Waller, Fletcher, Chin, Timothy, Densmore, Adam, Diaz, Ruben J, Edgar, Michael L, Lettura, Javier Fuentes, Gómez-Jiménez, Manuel, Kalari, Venu M, Lawrence, Jon, Margheim, Steven, Pazder, John, Ruiz-Carmona, Roque, Salinas, Ricardo, Silva, Karleyne M. G, Silversides, Katherine, Venn, Kim A
• Format: Journal Article
• Language: English
• Published: 15-04-2024
• Subjects: Physics - Astrophysics of Galaxies
• DOI: 10.48550/arxiv.2404.10058

The Gemini High-resolution Optical SpecTrograph (GHOST) is a new echelle
spectrograph available on the Gemini-South telescope as of Semester 2024A. We
present the first high resolution spectrum of the quasar J1449-1227 (redshift
z_em=3.27) using data taken during the commissioning of GHOST. The observed
quasar hosts an intervening iron-poor ([Fe/H] = -2.5) damped Lyman alpha (DLA)
system at redshift z=2.904. Taking advantage of the high spectral resolving
power of GHOST (R~55000), we are able to accurately model the metal absorption
lines of the metal-poor DLA and find a supersolar [Si/Fe], suggesting the DLA
gas is in an early stage of chemical enrichment. Using simple ionization
models, we find that the large range in the C IV/Si IV column density ratio of
individual components within the DLA's high ionization absorption profile can
be reproduced by several metal-poor Lyman limit systems surrounding the
low-ionization gas of the DLA. It is possible that this metal-poor DLA resides
within a complex system of metal-poor galaxies or filaments with inflowing gas.
The high spectral resolution, wavelength coverage and sensitivity of GHOST
makes it an ideal spectrograph for characterizing the chemistry and kinematics
of quasar absorption lines.