ALMA Lensing Cluster Survey: A spectral stacking analysis of [C II] in lensed z similar to 6 galaxies
Artikel i vetenskaplig tidskrift, 2021

Context. The properties of galaxies at redshift z>6 hold the key to our understanding of the early stages of galaxy evolution and can potentially identify the sources of the ultraviolet radiation that give rise to the epoch of reionisation. The far-infrared cooling line of [C II] at 158 mu m is known to be bright and correlate with the star formation rate (SFR) of low-redshift galaxies, and hence is also suggested to be an important tracer of star formation and interstellar medium properties for very high-redshift galaxies. Aims. With the aim to study the interstellar medium properties of gravitationally lensed galaxies at z>6, we search for [C II] and thermal dust emission in a sample of 52 > 6 galaxies observed by the ALMA Lensing Cluster Survey. Methods. We perform our analysis using LINESTACKER, stacking both [C II] and continuum emission. The target sample is selected from multiple catalogues, and the sample galaxies have spectroscopic redshift or low-uncertainty photometric redshifts (sigma(z)<0.02) in nine galaxy clusters. Source properties of the target galaxies are either extracted from the literature or computed using spectral energy distribution fitting. Both weighted-average and median stacking are used, on both the full sample and three sub-samples. Results. Our analyses find no detection of either [C II] or continuum. An upper limit on L-[CII] is derived, implying that [C II] remains marginally consistent for low-SFR z>6 galaxies but likely is under-luminous compared to the local L-[CII]-SFR relationship. We discuss potential biases and possible physical effects that may be the cause of the non-detection. Further, the upper limit on the dust continuum implies that less than half of the star formation is obscured.

galaxies: evolution galaxies: star formation

galaxies: statistics

galaxies: high-redshift

galaxies: formation

radio lines: galaxies


Jean Baptiste Jolly

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

Kirsten Kraiberg Knudsen

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

Nicolas Laporte

University of Cambridge

Johan Richard

Université de Lyon

Seiji Fujimoto

Köpenhamns universitet

Kotaro Kohno

University of Tokyo

Yiping Ao

Chinese Academy of Sciences

University of Science and Technology of China

Franz E. Bauer

Pontificia Universidad Catolica de Chile

Instituto Milenio de Astrofísica

Eiichi Egami

University of Arizona

Daniel Espada

Universidad de Granada

SKA Organisation

Miroslava Dessauges-Zavadsky

Université de Genève

Georgios E. Magdis

Köpenhamns universitet

Danmarks Tekniske Universitet (DTU)

Daniel Schaerer

Institut de Recherche en Astrophysique et Planétologie (IRAP)

Université de Genève

Fengwu Sun

University of Arizona

Francesco Valentino

Köpenhamns universitet

Wei-Hao Wang

Academia Sinica

Adi Zitrin

Ben-Gurion University of the Negev

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 652 A128

Galaxers utveckling: Spår av gas i stjärnbildande galaxer

Vetenskapsrådet (VR) (2015-05580), 2016-01-01 -- 2019-12-31.


Astronomi, astrofysik och kosmologi

Atom- och molekylfysik och optik

Annan fysik



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