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Detection of Hα emission from z > 3.5 submillimetre luminous galaxies with AKARI-FUHYU spectroscopy

Sedgwick, C.; Serjeant, S.; Pearson, C.; Smail, I.; Im, M.; Oyabu, S.; Takagi, T.; Matsuhara, H.; Wada, T.; Lee, H.M.; Jeong, W.-S.; White, G.J.

Detection of Hα emission from z > 3.5 submillimetre luminous galaxies with AKARI-FUHYU spectroscopy Thumbnail


Authors

C. Sedgwick

S. Serjeant

C. Pearson

M. Im

S. Oyabu

T. Takagi

H. Matsuhara

T. Wada

H.M. Lee

W.-S. Jeong

G.J. White



Abstract

We present tentative Hα emission line detections of four submillimetre-detected galaxies at z > 3.5: the radio galaxies 8C1909+722 and 4C60.07 at signal-to-noise ratios (SNRs) of 3.1 and 2.5, and two submillimetre-selected galaxies (SMGs) near the first of these at SNRs of 10.0 and 2.4, made with the AKARI space telescope as part of the Follow-Up Hayai-Yasui-Umai mission programme. These are the highest redshift Hα detections in such galaxies, made possible by AKARI's unique near-infrared spectroscopic capability. The two radio galaxies had known redshifts and surrounding structure, and we have detected broad Hα components indicating the presence of dust-shrouded quasars. We conclude that powerful active galactic nuclei (AGNs) at z > 3.5 occur in peaks of the star formation density fields, supporting a close connection between stellar mass build-up and black hole mass assembly at this redshift. We also show that 4C60.07 is a binary AGN. The Hα detections of the two SMGs are the first redshift determinations for these sources, confirming their physical association around their companion radio galaxy. The Hα-derived star formation rates (SFRs) for the SMGs are lower than their far-infrared derived SFRs by a factor of ∼10, suggesting a level of dust obscuration similar to that found in studies at ∼1 < z < 2.7.

Citation

Sedgwick, C., Serjeant, S., Pearson, C., Smail, I., Im, M., Oyabu, S., …White, G. (2013). Detection of Hα emission from z > 3.5 submillimetre luminous galaxies with AKARI-FUHYU spectroscopy. Monthly Notices of the Royal Astronomical Society, 436(1), 395-400. https://doi.org/10.1093/mnras/stt1572

Journal Article Type Article
Publication Date Nov 1, 2013
Deposit Date Apr 15, 2014
Publicly Available Date Mar 28, 2024
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 436
Issue 1
Pages 395-400
DOI https://doi.org/10.1093/mnras/stt1572
Keywords Galaxies: active, Galaxies: evolution, Galaxies: starburst, Galaxies: star formation, Infrared: galaxies.

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Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society © 2013 The Authors Published by Oxford University Press on behalf of Royal Astronomical Society. All rights reserved.





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