Subaru High-z Exploration of Low-luminosity Quasars (SHELLQs). XIV. A Candidate Type II Quasar at z=6.1292
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Subaru High-z Exploration of Low-luminosity Quasars (SHELLQs). XIV. A Candidate Type II Quasar at z=6.1292. / Onoue, Masafusa; Matsuoka, Yoshiki; Kashikawa, Nobunari; Strauss, Michael A.; Iwasawa, Kazushi; Izumi, Takuma; Nagao, Tohru; Asami, Naoko; Fujimoto, Seiji; Harikane, Yuichi; Hashimoto, Takuya; Imanishi, Masatoshi; Lee, Chien-Hsiu; Shibuya, Takatoshi; Toba, Yoshiki.
I: Astrophysical Journal, Bind 919, Nr. 1, 61, 29.09.2021.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Subaru High-z Exploration of Low-luminosity Quasars (SHELLQs). XIV. A Candidate Type II Quasar at z=6.1292
AU - Onoue, Masafusa
AU - Matsuoka, Yoshiki
AU - Kashikawa, Nobunari
AU - Strauss, Michael A.
AU - Iwasawa, Kazushi
AU - Izumi, Takuma
AU - Nagao, Tohru
AU - Asami, Naoko
AU - Fujimoto, Seiji
AU - Harikane, Yuichi
AU - Hashimoto, Takuya
AU - Imanishi, Masatoshi
AU - Lee, Chien-Hsiu
AU - Shibuya, Takatoshi
AU - Toba, Yoshiki
PY - 2021/9/29
Y1 - 2021/9/29
N2 - We present deep Keck/MOSFIRE near-infrared spectroscopy of a strong Ly alpha emitting source at z = 6.1292, HSC J142331.71-001809.1, which was discovered by the SHELLQS program from imaging data of the Subaru Hyper Suprime-Cam (HSC) survey. This source is one of five objects that show narrow (FWHM < 500 km s(-1)) and prominent (Ly alpha > 1044 erg s(-1)) Ly alpha emission lines at absolute 1450 angstrom continuum magnitudes of M-1450 similar to-22 mag. Its rest-frame Ly alpha equivalent width (EW) is 370 +/- 30 angstrom. In the 2 hr Keck/MOSFIRE spectrum in Y band, the high-ionization C IV lambda lambda 1548,1550 doublet emission line was clearly detected with FWHM = 120(-20)(+20) km s(-1) and a total rest-frame EW of 37(-5)(+6) angstrom. We also report the detection of weak continuum emission, and the tentative detection of O III]lambda lambda 1661,1666 in the 4 hr J-band spectrum. Judging from the UV magnitude, line widths, luminosities, and EWs of Ly alpha and C IV, we suggest that this source is a reionization-era analog of classical type-II AGNs, although there is a possibility that it represents a new population of AGN/galaxy composite objects in the early universe. We compare the properties of J1423-0018 to intermediate-redshift type-II AGNs and C IV emitters seen in z = 6-7 galaxy samples. Further observations of other metal emission lines in the rest-frame UV or optical, along with X-ray follow-up observations of the z = 6-7 narrow-line quasars, are needed for more robust diagnostics and to determine their nature.
AB - We present deep Keck/MOSFIRE near-infrared spectroscopy of a strong Ly alpha emitting source at z = 6.1292, HSC J142331.71-001809.1, which was discovered by the SHELLQS program from imaging data of the Subaru Hyper Suprime-Cam (HSC) survey. This source is one of five objects that show narrow (FWHM < 500 km s(-1)) and prominent (Ly alpha > 1044 erg s(-1)) Ly alpha emission lines at absolute 1450 angstrom continuum magnitudes of M-1450 similar to-22 mag. Its rest-frame Ly alpha equivalent width (EW) is 370 +/- 30 angstrom. In the 2 hr Keck/MOSFIRE spectrum in Y band, the high-ionization C IV lambda lambda 1548,1550 doublet emission line was clearly detected with FWHM = 120(-20)(+20) km s(-1) and a total rest-frame EW of 37(-5)(+6) angstrom. We also report the detection of weak continuum emission, and the tentative detection of O III]lambda lambda 1661,1666 in the 4 hr J-band spectrum. Judging from the UV magnitude, line widths, luminosities, and EWs of Ly alpha and C IV, we suggest that this source is a reionization-era analog of classical type-II AGNs, although there is a possibility that it represents a new population of AGN/galaxy composite objects in the early universe. We compare the properties of J1423-0018 to intermediate-redshift type-II AGNs and C IV emitters seen in z = 6-7 galaxy samples. Further observations of other metal emission lines in the rest-frame UV or optical, along with X-ray follow-up observations of the z = 6-7 narrow-line quasars, are needed for more robust diagnostics and to determine their nature.
KW - LY-ALPHA-EMITTERS
KW - DIGITAL SKY SURVEY
KW - ACTIVE GALACTIC NUCLEUS
KW - X-RAY
KW - OPTICAL-PROPERTIES
KW - STAR-FORMATION
KW - RADIO GALAXY
KW - AGN FEEDBACK
KW - BLACK-HOLE
KW - REDSHIFT
U2 - 10.3847/1538-4357/ac0f07
DO - 10.3847/1538-4357/ac0f07
M3 - Journal article
VL - 919
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1
M1 - 61
ER -
ID: 281222667