TY - JOUR
T1 - Gemini Near Infrared Spectrograph-Distant Quasar Survey
T2 - Augmented Spectroscopic Catalog and a Prescription for Correcting UV-based Quasar Redshifts
AU - Matthews, Brandon M.
AU - Dix, Cooper
AU - Shemmer, Ohad
AU - Brotherton, Michael S.
AU - Myers, Adam D.
AU - Andruchow, I.
AU - Brandt, W. N.
AU - Gallagher, S. C.
AU - Green, Richard
AU - Lira, Paulina
AU - McLane, Jacob N.
AU - Plotkin, Richard M.
AU - Richards, Gordon T.
AU - Runnoe, Jessie C.
AU - Schneider, Donald P.
AU - Strauss, Michael A.
N1 - Funding Information:
This work is supported by National Science Foundation grants AST-1815281 (B. M. M., C. D., O. S.) and AST-1815645 (M. S. B., A. D. M., J. N. M.). W.N.B. acknowledges support from NSF grant AST-2106990. We thank an anonymous referee for thoughtful and valuable comments that helped improve this paper. This work was enabled by observations made from the Gemini North telescope, located within the Maunakea Science Reserve and adjacent to the summit of Maunakea. We are grateful for the privilege of observing the universe from a place that is unique in both its astronomical quality and its cultural significance. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. We thank Paul Hewett for helpful contributions of redshift data.
Publisher Copyright:
© 2023. The Author(s). Published by the American Astronomical Society.
PY - 2023/6/1
Y1 - 2023/6/1
N2 - Quasars at z ≳ 1 most often have redshifts measured from rest-frame ultraviolet emission lines. One of the most common such lines, C iv λ1549, shows blueshifts up to ≈5000 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] λ5007 feature. We present spectroscopic measurements for 260 sources at 1.55 ≲ z ≲ 3.50 having -28.0 ≲ M i ≲ - 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] λ5007 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 Å. Applying these corrections can improve the accuracy and the precision in the C iv-based redshift by up to ∼850 km s-1 and ∼150 km s-1, respectively, which correspond to ∼8.5 and ∼1.5 Mpc in comoving distance at z = 2.5. Our prescriptions also improve the accuracy of the best available multifeature redshift determination algorithm by ∼100 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.
AB - Quasars at z ≳ 1 most often have redshifts measured from rest-frame ultraviolet emission lines. One of the most common such lines, C iv λ1549, shows blueshifts up to ≈5000 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] λ5007 feature. We present spectroscopic measurements for 260 sources at 1.55 ≲ z ≲ 3.50 having -28.0 ≲ M i ≲ - 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] λ5007 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 Å. Applying these corrections can improve the accuracy and the precision in the C iv-based redshift by up to ∼850 km s-1 and ∼150 km s-1, respectively, which correspond to ∼8.5 and ∼1.5 Mpc in comoving distance at z = 2.5. Our prescriptions also improve the accuracy of the best available multifeature redshift determination algorithm by ∼100 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.
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U2 - 10.3847/1538-4357/acd04c
DO - 10.3847/1538-4357/acd04c
M3 - Article
AN - SCOPUS:85163802451
SN - 0004-637X
VL - 950
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 95
ER -