J/ApJS/269/27 DESI z≳5 quasar survey. I. New z∼4.7-6.6 QSOs (Yang+, 2023)
DESI z≳5 quasar survey.
I. A first sample of 400 new quasars at z∼4.7-6.6.
Yang J., Fan X., Gupta A., Myers A.D., Palanque-Delabrouille N., Wang F.,
Yeche C., Aguilar J.N., Ahlen S., Alexander D.M., Brooks D., Dawson K.,
de la Macorra A., Dey A., Dhungana G., Fanning K., Font-Ribera A.,
Gontcho S., Guy J., Honscheid K., Juneau S., Kisner T., Kremin A.,
Le Guillou L., Levi M., Magneville C., Martini P., Meisner A., Miquel R.,
Moustakas J., Nie J., Percival W., Poppett C., Prada F., Schlafly E.,
Tarle G., Vargas Magana M., Weaver B.A., Wechsler R., Zhou R., Zhou Z.,
Zou Hu
<Astrophys. J. Suppl. Ser., 269, 27 (2023)>
=2023ApJS..269...27Y 2023ApJS..269...27Y
ADC_Keywords: QSOs; Spectra, optical; Surveys; Redshifts
Keywords: Quasars ; Surveys ; Broad absorption line quasar
Abstract:
We report the first results of a high-redshift (z≳5) quasar survey
using the Dark Energy Spectroscopic Instrument (DESI). As a DESI
secondary target program, this survey is designed to carry out a
systematic search and investigation of quasars at 4.8<z<6.8. The
target selection is based on the DESI Legacy Imaging Surveys (the
Legacy Surveys) DR9 photometry, combined with the Pan-STARRS1 data and
J-band photometry from public surveys. A first quasar sample has been
constructed from the DESI Survey Validation 3 (SV3) and first-year
observations until 2022 May. This sample includes more than 400 new
quasars at redshift 4.7≤z<6.6, down to 21.5 magnitude (AB) in the z
band, discovered from 35% of the entire target sample. Remarkably,
there are 220 new quasars identified at z≥5, more than one-third of
existing quasars previously published at this redshift. The
observations so far result in an average success rate of 23% at z>4.7.
The current spectral data set has already allowed analysis of
interesting individual objects (e.g., quasars with damped Lyα
absorbers and broad absorption line features), and statistical
analysis will follow the survey's completion. A set of science
projects will be carried out leveraging this program, including quasar
luminosity function, quasar clustering, intergalactic medium, quasar
spectral properties, intervening absorbers, and properties of early
supermassive black holes. Additionally, a sample of 38 new quasars at
z∼3.8-5.7 discovered from a pilot survey in the DESI SV1 is also
published in this paper.
Description:
The selected z∼4.8-6.8 quasar candidates are mainly observed as
dark-time targets in the Dark Energy Spectroscopic Instrument (DESI)
main survey, which started on 2021-May-14. A minor part (1.6%) of
candidates were observed during the DESI 1% survey (SV3; in 2021
April) and the DESI SV1 (before 2021 April 4; for 27 targets
overlapped with the SV1 selection).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 63 412 The 412 new quasars from our main selection
table2.dat 61 38 The 38 new quasars from the selection during the
DESI first Survey Validation (SV1) between
2020-Dec and 2021-May
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See also:
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
II/367 : The VISTA Hemisphere Survey (VHS) catalog DR5 (McMahon+, 2020)
VII/289 : SDSS quasar catalog, sixteenth data release (DR16Q) (Lyke+, 2020)
VII/292 : DESI Legacy Imaging Surveys DR8 (Duncan, 2022)
J/ApJS/197/19 : First brown dwarfs discovered by WISE (Kirkpatrick+, 2011)
J/ApJ/755/89 : Metallicities of damped Lyα systems (Rafelski+, 2012)
J/ApJ/746/169 : Luminosity function of broad-line quasars (Shen+, 2012)
J/ApJ/764/45 : Luminosity function of broad-line quasars. II. (Kelly+, 2013)
J/ApJ/792/30 : NEOWISE magnitudes for near-Earth objects (Mainzer+, 2014)
J/ApJ/814/118 : L/T transition dwarfs with PS1 & WISE. II. (Best+, 2015)
J/ApJS/227/11 : PS1 z>5.6 quasars follow-up (Banados+, 2016)
J/ApJ/819/24 : z>4.5 QSOs with SDSS and WISE. I. Opt. spectra (Wang+, 2016)
J/AJ/155/131 : z∼5 QSO luminosity function from the CFHTLS (McGreer+, 2018)
J/ApJ/873/35 : Gemini GNIRS NIR sp. of 50 QSOs at z≳5.7 (Shen+, 2019)
J/MNRAS/494/789 : NIR and MIR photometry of known z≥5 quasars (Ross+, 2020)
J/ApJ/923/262 : NIR spectroscopic obs. of z>6.5 quasars (Yang+, 2021)
J/A+A/668/A27 : 24 new radio-bright quasars spectra (Gloudemans+, 2022)
J/A+A/659/A1 : LOFAR Two-metre Sky Survey (LoTSS) DR2 (Shimwell+, 2022)
J/ApJS/259/18 : SHELLQs. XVI. New quasars at 5.8<z<7 (Matsuoka+, 2022)
J/ApJS/265/29 : PS1 z>5.6 QSO Survey. II. Quasars follow-up (Banados+, 2023)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- --- [DESI]
6- 24 A19 --- DESI Quasar name (JHHMMSS.ss+DDMMSS.s)
26- 26 A1 --- f_DESI [bc ] Flag on DESI (1)
28- 36 F9.5 deg RAdeg Right Acsension in decimal degrees (J2000)
38- 46 F9.5 deg DEdeg Declination in decimal degrees (J2000)
48- 51 F4.2 --- z [4.4/6.6] Redshift (G1)
53- 57 F5.2 mag zmag [18.9/21.5] Apparent z-band magnitude
from Legacy Surveys
59- 63 F5.3 mag e_zmag [0.004/0.08] Uncertainty on zmag
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Note (1): Flag as follows:
b = Quasars that have also been independently discovered in
Matsuoka+ (2022, J/ApJS/259/18)
c = Quasars that have also been independently discovered in
Banados+ (2023, J/ApJS/265/29)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- --- [DESI]
6- 24 A19 --- DESI Quasar name (JHHMMSS.ss+DDMMSS.s)
26- 34 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000)
36- 44 F9.5 deg DEdeg Declination in decimal degrees (J2000)
46- 49 F4.2 --- z [3.8/5.8] Redshift (G1)
51- 55 F5.2 mag zmag [18/21.4] Apparent z-band magnitude
from Legacy Surveys
57- 61 F5.3 mag e_zmag [0.002/0.05] Uncertainty on zmag
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Global notes:
Note (G1): Redshift from visual fitting using quasar template with a typical
uncertainty of 0.03. For strong BAL quasars and WL quasars, the
uncertainty could be ∼0.05-0.1.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 01-Feb-2024