TY - JOUR
T1 - A Wide and Deep Exploration of Radio Galaxies with Subaru HSC (WERGS). III. Discovery of a z = 4.72 Radio Galaxy with the Lyman Break Technique
AU - Yamashita, Takuji
AU - Nagao, Tohru
AU - Ikeda, Hiroyuki
AU - Toba, Yoshiki
AU - Kajisawa, Masaru
AU - Ono, Yoshiaki
AU - Tanaka, Masayuki
AU - Akiyama, Masayuki
AU - Harikane, Yuichi
AU - Ichikawa, Kohei
AU - Kawaguchi, Toshihiro
AU - Kawamuro, Taiki
AU - Kohno, Kotaro
AU - Lee, Chien Hsiu
AU - Lee, Kianhong
AU - Matsuoka, Yoshiki
AU - Niida, Mana
AU - Ogura, Kazuyuki
AU - Onoue, Masafusa
AU - Uchiyama, Hisakazu
N1 - Publisher Copyright:
© 2020. The American Astronomical Society. All rights reserved.
PY - 2020/8
Y1 - 2020/8
N2 - We report a discovery of a z = 4.72 radio galaxy, HSC J083913.17+011308.1, using the Lyman break technique with the Hyper Suprime-Cam Subaru Strategic Survey (HSC-SSP) catalog for Very Large Array Faint Images of the Radio Sky at Twenty centimeter radio sources. The number of known high-z radio galaxies (HzRGs) at z > 3 is quite small to constrain the evolution of HzRGs so far. The deep and wide-area optical survey by HSC-SSP enables us to apply the Lyman break technique to a large search for HzRGs. For an HzRG candidate among pre-selected r-band dropouts with a radio detection, a follow-up optical spectroscopy with the Gemini Multi-Object Spectrographs (GMOS)/Gemini has been performed. The obtained spectrum presents a clear Lyα emission line redshifted to z = 4.72. The spectral energy distribution fitting analysis with the rest-frame UV and optical photometries suggests the massive nature of this HzRG with . The small equivalent width of Lyα and the moderately red UV colors indicate its dusty host galaxy, implying a chemically evolved and dusty system. The radio spectral index does not meet a criterion for an ultra-steep spectrum, α1400325 of -1.1 and α1400150 of -0.9, demonstrating that the HSC-SSP survey compensates for a subpopulation of HzRGs that are missed in surveys focusing on an ultra-steep spectral index.
AB - We report a discovery of a z = 4.72 radio galaxy, HSC J083913.17+011308.1, using the Lyman break technique with the Hyper Suprime-Cam Subaru Strategic Survey (HSC-SSP) catalog for Very Large Array Faint Images of the Radio Sky at Twenty centimeter radio sources. The number of known high-z radio galaxies (HzRGs) at z > 3 is quite small to constrain the evolution of HzRGs so far. The deep and wide-area optical survey by HSC-SSP enables us to apply the Lyman break technique to a large search for HzRGs. For an HzRG candidate among pre-selected r-band dropouts with a radio detection, a follow-up optical spectroscopy with the Gemini Multi-Object Spectrographs (GMOS)/Gemini has been performed. The obtained spectrum presents a clear Lyα emission line redshifted to z = 4.72. The spectral energy distribution fitting analysis with the rest-frame UV and optical photometries suggests the massive nature of this HzRG with . The small equivalent width of Lyα and the moderately red UV colors indicate its dusty host galaxy, implying a chemically evolved and dusty system. The radio spectral index does not meet a criterion for an ultra-steep spectrum, α1400325 of -1.1 and α1400150 of -0.9, demonstrating that the HSC-SSP survey compensates for a subpopulation of HzRGs that are missed in surveys focusing on an ultra-steep spectral index.
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U2 - 10.3847/1538-3881/ab98fe
DO - 10.3847/1538-3881/ab98fe
M3 - Article
AN - SCOPUS:85087893487
VL - 160
JO - Astronomical Journal
JF - Astronomical Journal
SN - 0004-6256
IS - 2
M1 - 60
ER -