Galaxies as stochastic systems: why the next breakthrough in galaxy evolution requires one hundred million spectra

Fuente: arXiv
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Autores principales: Tacchella, Sandro, Belokurov, Vasily, Bevins, Harry T. J., Maiolino, Roberto, Peiris, Hiranya V., Pozzetti, Lucia, Sargent, Mark T.
Formato: Preprint
Publicado: 2025
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author Tacchella, Sandro
Belokurov, Vasily
Bevins, Harry T. J.
Maiolino, Roberto
Peiris, Hiranya V.
Pozzetti, Lucia
Sargent, Mark T.
author_facet Tacchella, Sandro
Belokurov, Vasily
Bevins, Harry T. J.
Maiolino, Roberto
Peiris, Hiranya V.
Pozzetti, Lucia
Sargent, Mark T.
contents Each galaxy is observed only once along its life, making galaxy evolution fundamentally an inverse statistical problem: time-dependent physics must be inferred from ensembles of single-epoch snapshots. To move beyond descriptive scaling relations toward physical regulation mechanisms of star formation, quenching, chemical enrichment and black hole growth, galaxies must be treated as realizations of a stochastic process whose hyper-parameters (e.g., correlation timescales, burstiness, duty cycles) are inferred hierarchically. This demands both depth and scale: continuum S/N sufficient for absorption-line ages and chemistry, and samples far larger than those in SDSS, DESI, 4MOST or MOONS, which provide either depth or size but not both across $0<z<3$. Once the relevant axes of mass, redshift, environment, structure and evolutionary phase are populated, the requirement naturally rises from $10^7$ to $\sim10^8$ galaxies. This is the regime where stochastic hyper-parameters can be well constrained and where comparisons to simulations and cosmological forward models become limited by theory rather than observations. We outline the science enabled by such a programme and the corresponding requirements for a future ESO wide-field spectroscopic facility capable of delivering tens to hundreds of millions of rest-UV-optical spectra over $0\lesssim z\lesssim3$.
format Preprint
id arxiv_https___arxiv_org_abs_2512_15841
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Galaxies as stochastic systems: why the next breakthrough in galaxy evolution requires one hundred million spectra
Tacchella, Sandro
Belokurov, Vasily
Bevins, Harry T. J.
Maiolino, Roberto
Peiris, Hiranya V.
Pozzetti, Lucia
Sargent, Mark T.
Instrumentation and Methods for Astrophysics
Astrophysics of Galaxies
Each galaxy is observed only once along its life, making galaxy evolution fundamentally an inverse statistical problem: time-dependent physics must be inferred from ensembles of single-epoch snapshots. To move beyond descriptive scaling relations toward physical regulation mechanisms of star formation, quenching, chemical enrichment and black hole growth, galaxies must be treated as realizations of a stochastic process whose hyper-parameters (e.g., correlation timescales, burstiness, duty cycles) are inferred hierarchically. This demands both depth and scale: continuum S/N sufficient for absorption-line ages and chemistry, and samples far larger than those in SDSS, DESI, 4MOST or MOONS, which provide either depth or size but not both across $0<z<3$. Once the relevant axes of mass, redshift, environment, structure and evolutionary phase are populated, the requirement naturally rises from $10^7$ to $\sim10^8$ galaxies. This is the regime where stochastic hyper-parameters can be well constrained and where comparisons to simulations and cosmological forward models become limited by theory rather than observations. We outline the science enabled by such a programme and the corresponding requirements for a future ESO wide-field spectroscopic facility capable of delivering tens to hundreds of millions of rest-UV-optical spectra over $0\lesssim z\lesssim3$.
title Galaxies as stochastic systems: why the next breakthrough in galaxy evolution requires one hundred million spectra
topic Instrumentation and Methods for Astrophysics
Astrophysics of Galaxies
url https://arxiv.org/abs/2512.15841