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Far-infrared Herschel SPIRE spectroscopy of lensed starbursts reveals physical conditions of ionized gas

Zhang, Zhi-Yu; Ivison, RJ; George, RD; Zhao, Yinghe; Dunne, L; Herrera-Camus, R; Lewis, AJR; Liu, Daizhong; Naylor, D; Oteo, Iván; Riechers, DA; Smail, Ian; Yang, Chentao; Eales, Stephen; Hopwood, Ros; Maddox, Steve; Omont, Alain; van der Werf, Paul

Far-infrared Herschel SPIRE spectroscopy of lensed starbursts reveals physical conditions of ionized gas Thumbnail


Authors

Zhi-Yu Zhang

RJ Ivison

RD George

Yinghe Zhao

L Dunne

R Herrera-Camus

AJR Lewis

Daizhong Liu

D Naylor

Iván Oteo

DA Riechers

Chentao Yang

Stephen Eales

Ros Hopwood

Steve Maddox

Alain Omont

Paul van der Werf



Abstract

The most intensively star-forming galaxies are extremely luminous at far-infrared (FIR) wavelengths, highly obscured at optical and ultraviolet wavelengths, and lie at z ≥ 1–3. We present a programme of FIR spectroscopic observations with the SPIRE FTS, as well as photometric observations with PACS, both on board Herschel, towards a sample of 45 gravitationally lensed, dusty starbursts across z ∼ 1–3.6. In total, we detected 27 individual lines down to 3 σ, including nine [CII] 158 μm lines with confirmed spectroscopic redshifts, five possible [CII] lines consistent with their FIR photometric redshifts, and in some individual sources a few [O III] 88 μm, [O III] 52 μm, [O I] 145 μm, [O I] 63 μm, [N II] 122 μm and OH 119 μm (in absorption) lines. To derive the typical physical properties of the gas in the sample, we stack all spectra weighted by their intrinsic luminosity and by their 500μm flux densities, with the spectra scaled to a common redshift. In the stacked spectra, we detect emission lines of [CII] 158 μm, [N II] 122 μm, [O III] 88 μm, [O III] 52 μm, [O I] 63 μm and the absorption doublet of OH at 119 μm, at high fidelity. We find that the average electron densities traced by the [N II] and [O III] lines are higher than the average values in local star-forming galaxies and ULIRGs, using the same tracers. From the [N II]/[CII] and [O I]/[CII] ratios, we find that the [CII] emission is likely dominated by the photodominated regions (PDR), instead of by ionized gas or large-scale shocks.

Citation

Zhang, Z., Ivison, R., George, R., Zhao, Y., Dunne, L., Herrera-Camus, R., …van der Werf, P. (2018). Far-infrared Herschel SPIRE spectroscopy of lensed starbursts reveals physical conditions of ionized gas. Monthly Notices of the Royal Astronomical Society, 481(1), 59-97. https://doi.org/10.1093/mnras/sty2082

Journal Article Type Article
Acceptance Date Jul 18, 2018
Online Publication Date Aug 6, 2018
Publication Date Aug 6, 2018
Deposit Date Oct 12, 2018
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 481
Issue 1
Pages 59-97
DOI https://doi.org/10.1093/mnras/sty2082

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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2018 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.





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