The ALPINE-ALMA [CII] Survey: A Triple Merger at z~4.56

G. C. Jones; M. Bethermin; Y. Fudamoto; M. Ginolfi; P. Capak; P. Cassata; A. Faisst; O. Le Fevre; D. Schaerer; J. Silverman; L. Yan; S. Bardelli; M. Boquien; A. Cimatti; M. Dessauges-Zavadsky; M. Giavalisco; C. Gruppioni; E. Ibar; Y. Khusanova; A. M. Koekemoer; B. C. Lemaux; F. Loiacono; R. Maiolino; P. A. Oesch; F. Pozzi; D. Riechers; G. Rodighiero; M. Talia; L. Vallini; D. Vergani; G. Zamorani; E. Zucca

doi:10.1093/mnrasl/slz154

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arXiv · 1908.07777

The ALPINE-ALMA [CII] Survey: A Triple Merger at z~4.56

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Abstract

We report the detection of [CII]158um emission from a system of three closely-separated sources in the COSMOS field at z~4.56, as part of the ALMA Large Program to INvestigate CII at Early times (ALPINE). The two dominant sources are closely associated, both spatially (1.6"~11kpc) and in velocity (~100km/s), while the third source is slightly more distant (2.8"~18kpc, ~300km/s). The second strongest source features a slight velocity gradient, while no significant velocity gradient is seen in the other two sources. Using the observed [CII] luminosities, we derive a total log(SFR_[CII]/[Msol/year])=2.8+/-0.2, which may be split into contributions of 59%, 31%, and 10% from the central, east, and west sources, respectively. Comparison of these [CII] detections to recent zoom-in cosmological simulations suggests an ongoing major merger. We are thus witnessing a system in a major phase of mass build-up by merging, including an on-going major merger and an upcoming minor merger, which is expected to end up in a single massive galaxy by z~2.5.

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G. C. Jones, M. Bethermin, Y. Fudamoto, M. Ginolfi, P. Capak, P. Cassata, A. Faisst, O. Le Fevre, D. Schaerer, J. Silverman, L. Yan, S. Bardelli, M. Boquien, A. Cimatti, M. Dessauges-Zavadsky, M. Giavalisco, C. Gruppioni, E. Ibar, Y. Khusanova, A. M. Koekemoer, B. C. Lemaux, F. Loiacono, R. Maiolino, P. A. Oesch, F. Pozzi, D. Riechers, G. Rodighiero, M. Talia, L. Vallini, D. Vergani, G. Zamorani, E. Zucca. 2019-08-21. The ALPINE-ALMA [CII] Survey: A Triple Merger at z~4.56. https://doi.org/10.1093/mnrasl%2Fslz154

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