1. INAF - Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125, Firenze, Italy
2. European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748, Garching, Germany
3. Dipartimento di Astronomia, Università di Padova, Vicolo dell'Osservatorio, 2, I-35122 Padova, Italy
4. INAF - Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127, Bologna, Italy
5. INAF - Osservatorio Astronomico di Trieste, via Tiepolo 11, I-34131 Trieste, Italy
6. INAF - Osservatorio Astronomico di Roma, via dell'Osservatorio 2, Monteporzio, Italy

Correspondence to: A. Cimatti¹ Email: cimatti@arcetri.astro.it

More than half of all stars in the local Universe are found in massive spheroidal galaxies¹, which are characterized by old stellar populations^{2, 3} with little or no current star formation. In present models, such galaxies appear rather late in the history of the Universe 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^{2, 3}, nor if their seemingly sudden appearance when the Universe was about half its present age (at redshift z 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 (10¹¹ solar masses) spheroidal galaxies at l.6 < z < 1.9, the most distant such objects currently known. The existence of such systems when the Universe was only about 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 simulations⁴.

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