Saltar para o conteúdo principal

FCCNFCT Digital Services

Access the national information on scientific and technological funding in Portugal

Activity Funded

Unraveling the evolutionary history of the Milky Way with Galactic Archaeology

Revelando a história evolutiva da Via Láctea com recurso à Arqueologia Galáctica

Reference
2024.15303.PEX
Project Start Date
2026-02-16
Project End Date
2027-08-15
Principal Investigator
Scientific Area
Exact sciences
Funding Program
Concurso para Projetos de Investigação de caráter Exploratório em Todos os Domínios Científicos 2024

Abstract

Unraveling the evolutionary history of the Milky Way has been a long-standing problem in contemporary astrophysics [2,27,29,30]. Our galaxy is a complex jigsaw puzzle, harboring several major stellar populations that comprise the disk, bulge, bar, and halo. These populations have distinct kinematic and chemical properties that capture unique epochs of formation and the different processes shaping their evolution. The aim of Galactic Archaeology [17,28,31,42] is to reconstruct this assembly history from the present-day chemo-kinematics of the stars that make up such populations. As with any archaeological endeavor, the ability to measure the timeline of past events is of paramount importance to Galactic archaeology. Asteroseismology [8,11,23], or the study of stars by the observation of their natural oscillations, offers a way of measuring stellar ages with unparalleled precision and accuracy, thus adding a new dimension to Galactic population studies. This project – ArqueoGal – will make use of seismic stellar ages to break degeneracies in chemo-kinematic models and hence address the multidimensional problem of Galactic assembly. Disk Dichotomy The Galactic disk is the defining component of the Milky Way [16,32,33], gathering the bulk of its baryonic content. Therefore, it plays a central role in Galactic archaeology. Evidence of the presence of geometrically thin (small scale height) and thick (large scale height) disks has been known for several decades [2]. Early works suggested that the kinematically hotter, thick-disk stars also had a systematically higher abundance of a-process elements relative to iron, [a/Fe], an important tracer of the star-formation timescale and efficiency. However, later studies, based on larger, kinematically-selected samples, revealed a significant overlap in [a/Fe] between the two disks. Further insight was to be provided by large-scale spectroscopic surveys, which identified a gap in the [a/Fe]-[Fe/H] plane, bringing to light two separate sequences referred to as the a-poor and a-rich disks [1,16]. Notably, there is an age difference between stars belonging to the a-poor and a-rich disks [15,31], with stars in the former being typically ~2 Gyr old, while those in the latter peak at ~11 Gyr. Age is, therefore, the distinctive factor between the two disk components. Disk Assembly Various models of the assembly of the disk have been proposed to explain the observational evidence. It has been argued that the bimodal distribution of [a/Fe] in the solar neighborhood is a result of radial migration [17,32,33], with a-rich stars originating in the inner disk. Alternatively, this bimodality may reflect an abrupt formation of the a-rich disk, e.g., via a two-infall process [16], whereby the a-rich disk forms early on from fast gas accretion and the a-poor disk then builds up by means of a slower gas-infall rate. Moreover, cosmological N-body simulations have found that multiple, minor gas-rich mergers can result in a kinematically hot, compact, thick, and old disk (a-rich), with a kinematically colder, more extended, thinner, and younger disk (a-poor) beginning to form at a later epoch once merger activity subsides. These simulations also predict the much debated flaring of the disk in the outer Galaxy [32-34]. Aim, Methods, and Innovation ArqueoGal will produce the first all-sky, high-resolution chrono-chemo-kinematic map of the Milky Way disk extending beyond the solar neighborhood. This will enable us to address a number of key open questions in Galactic archaeology, namely, (i) the origin of the two chemically distinct populations of the disk, (ii) the dynamical processes leading to disk flaring, and (iii) the efficiency of radial migration across the disk. We will use luminous, red-giant stars to probe the disk into the kiloparsec regime. Seismic ages will be measured for these stars based on photometry from NASA’s TESS mission [10,15,44]. Next, we will combine stellar ages with astrometry and kinematics from ESA’s Gaia mission [20], as well as chemical abundances from the APOGEE survey [41,43], prior to performing Galactic modeling calculations [22,32,33]. The temporal dimension brought by asteroseismology constitutes the scientific innovation aspect of this project. Furthermore, a methodological innovation will be introduced with the development of an Artificial Intelligence tool for the automated classification of stellar populations. Impact and Timeliness ArqueoGal will take us beyond the state of the art by enabling the time-resolved investigation of Galactic assembly. The team is highly internationalized, interdisciplinary, and world-leading in the fields of Galactic archaeology and asteroseismology. Crucially, this project will leverage the team members’ leadership within TESS and Gaia. Moreover, ArqueoGal has the potential to build a long-lasting legacy, with implications for the science definition of the forthcoming ESA’s PLATO mission and ESO’s 4MOST survey.

Institutions

Main Institutions

  • Instituto de Astrofísica e Ciências do Espaço (IA)

Other Institutions

  • Department of Physics and Astronomy "Galileo Galilei", University of Padova (DFA-UNIPD)
  • Department of Physics and Astronomy "Augusto Righi", University of Bologna (DIFA-UNIBO)

Funding 59.935,98 €

Fundação para a Ciência e a Tecnologia (FCT) - Portugal

59.935,98 €