ALMA Lensing Cluster Survey: A spectral stacking analysis of [C II] in lensed z similar to 6 galaxies
Journal article, 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
Author
Jean Baptiste Jolly
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Kirsten Kraiberg Knudsen
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Nicolas Laporte
University of Cambridge
Johan Richard
Université de Lyon
Seiji Fujimoto
University of Copenhagen
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
Millennium Institute of Astrophysics
Eiichi Egami
University of Arizona
Daniel Espada
Universidad de Granada
SKA Organisation
Miroslava Dessauges-Zavadsky
University of Geneva
Georgios E. Magdis
University of Copenhagen
Technical University of Denmark (DTU)
Daniel Schaerer
Institut de Recherche en Astrophysique et Planétologie (IRAP)
University of Geneva
Fengwu Sun
University of Arizona
Francesco Valentino
University of Copenhagen
Wei-Hao Wang
Academia Sinica
Adi Zitrin
Ben-Gurion University of the Negev
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 652 A128Galaxy evolution: Tracing the gas fraction of star-forming galaxies
Swedish Research Council (VR) (2015-05580), 2016-01-01 -- 2019-12-31.
Subject Categories
Astronomy, Astrophysics and Cosmology
Atom and Molecular Physics and Optics
Other Physics Topics
DOI
10.1051/0004-6361/202140878