Credit: Pedro N. Motta

Gaia–Enceladus–Sausage Timing, chemistRy and Orbit (GASTRO) is a library of simulations of GSE-like mergers with Milky Way-like host galaxies. It is built to connect the chemodynamical imprint of an early massive merger to what we observe in the Galactic halo and disk today.

The library is used to study the stellar halo assembled by the merger, the response of the host disk, and how star-forming clumps change the outcome.

Publications

The GASTRO library series:

GASTRO-BH: Effects of a Central Black Hole in GSE-like Dwarf-galaxy Mergers Around Milky Way-like Hosts Motta, P. N., Amarante, J. A. S., Limberg, G., Borbolato, L., Laporte, C. F. P., Li, Z.-Y., Santos-Lima, R., Debattista, V. P., Vicentin, M. C. Submitted, 2026 · ADS link

GASTRO Library. II. Exploring Chemical Bimodalities in Disk Galaxies with GSE-like Mergers and Massive Star-forming Clumps Amarante, J. A. S., Laporte, C. F. P., Debattista, V. P., Beraldo e Silva, L., Limberg, G., Perottoni, H. D., Li, Z.-Y., Borbolato, L., Fiteni, K., Cao, C., Deg, N., Khachaturyants, T., Liao, X. The Astrophysical Journal, 1004, 242, 2026 · ADS link

GASTRO Library. I. The Simulated Chemodynamical Properties of Several Gaia-Sausage-Enceladus-like Stellar Halos Amarante, J. A. S., Debattista, V. P., Beraldo e Silva, L., Laporte, C., Deg, N. The Astrophysical Journal, 937, 12, 2022 · ADS link

Studies using GASTRO

The Low-α Splash Population in the Milky Way Borbolato, L., Amarante, J. A. S., Perottoni, H. D., Rossi, S., Debattista, V. P., Li, Z.-Y., Deg, N., Khachaturyants, T. The Astrophysical Journal Letters, 1008, L23, 2026 · ADS link

The edge of the Milky Way’s star-forming disc: Evidence from a ‘U-shaped’ stellar age profile Fiteni, K., Anderson, S. R., Debattista, V. P., Caruana, J., Amarante, J. A. S., Gough-Kelly, S., Eyer, L., Beraldo e Silva, L., Khachaturyants, T., Cuomo, V. Astronomy & Astrophysics, 708, A252, 2026 ADS link

Simulation movies

The movies below show the evolution of the four models explored in GASTRO I. Each star particle of the merging dwarf is coloured by its [Fe/H].

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