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Old Galaxies in the Young Universe
Astrophysics · Submitted 7 Jul 2004
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim The existence of such systems when the Universe was only one-quarter of its present age, shows that the build-up of massive early-type galaxies was much faster in the early Universe than has been expected from theoretical simulations.
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The abstract, sentence by sentence
More than half of all stars in the local Universe are found in massive spheroidal galaxies, which are characterized by old stellar populations with little or no current star formation. In present models, such galaxies appear rather late as the culmination of a hierarchical merging process, in which larger galaxies are assembled through mergers of smaller precursor galaxies. But observations have not yet established how, or even when, the massive spheroidals formed, nor if their seemingly sudden appearance when the Universe was about half its present age (at redshift z \approx 1) results from a real evolutionary effect (such as a peak of mergers) or from the observational difficulty of identifying them at earlier epochs. Here we report the spectroscopic and morphological identification of four old, fully assembled, massive (>10^{11} solar masses) spheroidal galaxies at 1.6<z<1.9, the most distant such objects currently known. The existence of such systems when the Universe was only one-quarter of its present age, shows that the build-up of massive early-type galaxies was much faster in the early Universe than has been expected from theoretical simulations.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | More than half of all stars in the local Universe are found in massive spheroidal galaxies, which are characterized by old stellar populations with little or no current star formation. | background 1.00 | 0.06 | 0.03 | asserted 1.00 |
| s1 | In present models, such galaxies appear rather late as the culmination of a hierarchical merging process, in which larger galaxies are assembled through mergers of smaller precursor galaxies. | background 1.00 | 0.03 | 0.03 | asserted 0.89 |
| s2 | But observations have not yet established how, or even when, the massive spheroidals formed, nor if their seemingly sudden appearance when the Universe was about half its present age (at redshift z \approx 1) results from a real evolutionary effect (such as a peak of mergers) or from the observational difficulty of identifying them at earlier epochs. | gap 1.00 | 0.04 | 0.03 | asserted 0.54 |
| s3 | Here we report the spectroscopic and morphological identification of four old, fully assembled, massive (>10^{11} solar masses) spheroidal galaxies at 1.6<z<1.9, the most distant such objects currently known. | contribution 0.70 | 0.97 | 0.22 | asserted 1.00 |
| s4 | The existence of such systems when the Universe was only one-quarter of its present age, shows that the build-up of massive early-type galaxies was much faster in the early Universe than has been expected from theoretical simulations. | interpretation 0.99 | 0.81 | 0.90 | asserted 1.00 |
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The paper
Original abstract
More than half of all stars in the local Universe are found in massive spheroidal galaxies, which are characterized by old stellar populations with little or no current star formation. In present models, such galaxies appear rather late as the culmination of a hierarchical merging process, in which larger galaxies are assembled through mergers of smaller precursor galaxies. But observations have not yet established how, or even when, the massive spheroidals formed, nor if their seemingly sudden appearance when the Universe was about half its present age (at redshift z \approx 1) results from a real evolutionary effect (such as a peak of mergers) or from the observational difficulty of identifying them at earlier epochs. Here we report the spectroscopic and morphological identification of four old, fully assembled, massive (>10^{11} solar masses) spheroidal galaxies at 1.6<z<1.9, the most distant such objects currently known. The existence of such systems when the Universe was only one-quarter of its present age, shows that the build-up of massive early-type galaxies was much faster in the early Universe than has been expected from theoretical simulations.
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References
How the literature uses it
6 arXiv papers cite this in 7 sentences
Papers citing it · 3 sentences without a confident label
Cites it as support 1 paper
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Although this result can be controversial, there is some evidence that suggests that dark halos could be formed at high redshift [ref] .
Structure formation with scalar field dark matter: the field approach · Virialization · 1.00
Cites it as background 3 papers
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Massive quiescent galaxies at high redshifts ($z > 2$) challenge our understanding of galaxy evolution and serve as critical laboratories for testing galaxy formation and evolution models [ref] .
Morphological and Star Formation Properties of Cosmic Noon Massive Quiescent Galaxies · Introduction · 0.96
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The discovery of massive galaxies with old stellar populations at early cosmic epochs has historically acted as a key constraint on models for both galaxy formation physics and cosmology [ref] .
A massive quiescent galaxy at redshift 4.658 · Summary · 0.91
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In particular, extending the study of the most massive galaxies to progressively higher redshifts has repeatedly revolutionised our perspective on galaxy formation across the last several decades (e.g., [ref] ).
The JWST EXCELS survey: The ages and abundances of $3<z<5$ massive quiescent galaxies show that downsizing was already in place by $z\simeq4$ · Introduction · 0.93
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