| Abstract |
Quasars at $z~{\gtrsim}~1$ most often have redshifts measured from rest-frame ultraviolet emission lines. One of the most common such lines, C IV ${\lambda}1549$, shows blueshifts up to ${\approx}~5000~\rm{km~s^{-1}}$, and in rare cases even higher. This blueshifting results in highly uncertain redshifts when compared to redshift determinations from rest-frame optical emission lines, e.g., from the narrow [O III] ${\lambda}5007$ feature. We present spectroscopic measurements for 260 sources at $1.55~{\lesssim}~z~{\lesssim}~3.50$ having $-28.0~{\lesssim}~M_i~{\lesssim}~-30.0$ mag from the Gemini Near Infrared Spectrograph - Distant Quasar Survey (GNIRS-DQS) catalog, augmenting the previous iteration which contained 226 of the 260 sources whose measurements are improved upon in this work. We obtain reliable systemic redshifts based on [O III] ${\lambda}5007$ for a subset of 121 sources which we use to calibrate prescriptions for correcting UV-based redshifts. These prescriptions are based on a regression analysis involving C IV full-width-at-half-maximum intensity and equivalent width, along with the UV continuum luminosity at a rest-frame wavelength of 1350 A. Applying these corrections can improve the accuracy and the precision in the C IV-based redshift by up to ${\sim}~850~\rm{km~s^{-1}}$ and ${\sim}~150~\rm{km~s^{-1}}$, respectively, which correspond to ${\sim}~8.5$ Mpc and ${\sim}~1.5$ Mpc in comoving distance at $z~=~2.5$. Our prescriptions also improve the accuracy of the best available multi-feature redshift determination algorithm by ${\sim}~100~\rm{km~s^{-1}}$, indicating that the spectroscopic properties of the C IV emission line can provide robust redshift estimates for high-redshift quasars. We discuss the prospects of our prescriptions for cosmological and quasar studies utilizing upcoming large spectroscopic surveys. |
| Authors |
Brandon M. Matthews  , Cooper Dix , Ohad Shemmer , Michael S. Brotherton  , Adam D. Myers , I. Andruchow , W. N. Brandt , S. C. Gallagher , Richard F. Green , P. Lira , Jacob N. McLane , Richard M. Plotkin , Gordon T. Richards , Jessie C. Runnoe , Donald P. Schneider , Michael A. Strauss
|
| Journal Info |
IOP Publishing | The Astrophysical Journal , vol: 950
, iss: 2
, pages: 95 - 95
|
| Publication Date |
6/1/2023 |
| ISSN |
0004-637X |
Type |
article |
| Open Access |
gold
|
| DOI |
https://doi.org/10.3847/1538-4357/acd04c |
| Keywords |
Wide-Field Spectroscopy (Score: 0.49325)
|
