University of Hertfordshire

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Chronos: A NIR spectroscopic galaxy survey to probe the most fundamental stages of galaxy evolution

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  • I. Ferreras
  • M. Cropper
  • R. Sharples
  • J. Bland-Hawthorn
  • G. Bruzual
  • S. Charlot
  • C. J. Conselice
  • S. Driver
  • J. Dunlop
  • A. M. Hopkins
  • S. Kaviraj
  • T. Kitching
  • F. La Barbera
  • O. Lahav
  • A. Pasquali
  • S. Serjeant
  • J. Silk
  • R. Windhorst
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Original languageEnglish
Pages (from-to)729-764
Number of pages36
JournalExperimental Astronomy
Early online date18 Jul 2021
Publication statusE-pub ahead of print - 18 Jul 2021


We propose a dedicated, ultra-deep spectroscopic survey in the near infrared (NIR), that will target a mass-limited sample of galaxies during two of the most fundamental epochs of cosmic evolution: the formation of the first galaxies (at z ≳ 6; cosmic dawn), and at the peak of galaxy formation activity (at redshift z∼1–3; cosmic noon). By way of NIR observations (λ= 0.8–2μ m), it is possible to study the UV Lyman-α region in the former, and the optical rest-frame in the latter, allowing us to extract fundamental observables such as gas and stellar kinematics, chemical abundances, and ages, providing a unique legacy database covering these two crucial stages of cosmic evolution. The need to work in the NIR at extremely low flux levels makes a ground-based approach unfeasible due to atmospheric emission and absorption. Only with the largest facilities of the future (e.g. ELT) will be possible to observe a reduced set of targets, comprising at most of order thousands of galaxies. Likewise, from space, the small field of view of JWST and its use as a general purpose facility will yield a rather small set of high quality NIR spectra of distant galaxies (in the thousands, at best). Our project (codename Chronos) aims to produce ∼1 million high quality spectra, with a high S/N in the continuum, where information about the underlying stellar populations is encoded. The main science drivers are: The connection between the star formation history and the mass assembly history. The role of AGN and supernova feedback in shaping the formation histories of galaxies, with a quantitative estimate of quenching timescales. The formation of the first galaxies. The source of reionization. Evolution of the metallicity-mass relation, including [α/Fe] and individual abundances. Precision cosmology through detailed studies of the “baryon physics” of galaxy formation, probing the power spectrum over scales k∼1 Mpc− 1.


© Crown 2021. This article is licensed under a Creative Commons Attribution 4.0 International License.

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