Search Publications
Can we really pick and choose? Benchmarking various selections of Gaia Enceladus/Sausage stars in observations with simulations
Grand, Robert J. J.; Fattahi, Azadeh; Carrillo, Andreia +2 more
Large spectroscopic surveys plus Gaia astrometry have shown us that the inner stellar halo of the Galaxy is dominated by the debris of Gaia Enceladus/Sausage (GES). With the richness of data at hand, there are a myriad of ways these accreted stars have been selected. We investigate these GES selections and their effects on the inferred progenitor …
Small-scale stellar haloes: detecting low surface brightness features in the outskirts of Milky Way dwarf satellites
Smith, Simon E. T.; Hayes, Christian R.; Sestito, Federico +5 more
Dwarf galaxies are valuable laboratories for dynamical studies related to dark matter and galaxy evolution, yet it is currently unknown just how physically extended their stellar components are. Satellites orbiting the Galaxy's potential may undergo tidal stripping by the host, or alternatively, may themselves have accreted smaller systems whose d…
200 000 candidate very metal-poor stars in Gaia DR3 XP spectra
Limberg, Guilherme; Ji, Alexander P.; Koposov, Sergey E. +1 more
Very metal-poor stars ($\rm [Fe/H] \lt -2$) in the Milky Way are fossil records of early chemical evolution and the assembly and structure of the Galaxy. However, they are rare and hard to find. Gaia DR3 has provided over 200 million low-resolution (R ≈ 50) XP spectra, which provides an opportunity to greatly increase the number of candidate metal…
RR Lyrae from binary evolution: abundant, young, and metal-rich
Belokurov, Vasily; Bobrick, Alexey; Iorio, Giuliano +3 more
RR Lyrae are a well-known class of pulsating horizontal branch stars widely used as tracers of old, metal-poor stellar populations. However, mounting observational evidence shows that a significant fraction of these stars may be young and metal-rich. Here, through detailed binary stellar evolution modelling, we show that all such metal-rich RR Lyr…
Gaia DR3 data consistent with a short bar connected to a spiral arm
Steinmetz, M.; Khoperskov, S.; Minchev, I. +8 more
We use numerical simulations to model Gaia DR3 data with the aim of constraining the Milky Way (MW) bar and spiral structure parameters. We show that both the morphology and the velocity field in MW-like galactic disc models are strong functions of time, changing dramatically over a few tens of Myr. This suggests that by finding a good match to th…
SPICE: the connection between cosmic reionization and stellar feedback in the first galaxies
Pakmor, Rüdiger; Costa, Tiago; Bhagwat, Aniket +2 more
We present SPICE, a new suite of radiation-hydrodynamic, cosmological simulations targeting the epoch of reionization. The goal of these simulations is to systematically probe a variety of stellar feedback models, including 'bursty' and 'smooth' forms of supernova energy injection, as well as poorly explored physical scenarios such as hypernova ex…
Semi-analytic modelling of Pop. III star formation and metallicity evolution - I. Impact on the UV luminosity functions at z = 9-16
Qin, Yuxiang; Balu, Sreedhar; Wyithe, J. Stuart B. +1 more
We implemented Population III (Pop. III) star formation in mini-haloes within the MERAXES semi-analytic galaxy formation and reionization model, run on top of a N-body simulation with L = 10 h-1 cMpc with 20483 particles resolving all dark matter haloes down to the mini-haloes (~105 M⊙). Our modelling in…
Towards an astronomical foundation model for stars with a transformer-based model
Bovy, Jo; Leung, Henry W.
Rapid strides are currently being made in the field of artificial intelligence using transformer-based models like Large Language Models (LLMs). The potential of these methods for creating a single, large, versatile model in astronomy has not yet been explored. In this work, we propose a framework for data-driven astronomy that uses the same core …
Initial-final mass relation from white dwarfs within 40 pc
Tremblay, Pier-Emmanuel; Cunningham, Tim; W. O'Brien, Mairi
We present an initial-final mass relation derived from the spectroscopically complete volume-limited 40 pc sample of white dwarfs. The relation is modelled using population synthesis methods to derive an initial stellar population which can be fit to the observed mass distribution of white dwarfs. The population synthesis accounts for binary evolu…
Radial halo substructure in harmony with the Galactic bar
Belokurov, Vasily; Evans, N. Wyn; Dillamore, Adam M.
Overdensities in the radial phase space $(r,v_{\rm r})$ of the Milky Way's halo have previously been associated with the phase-mixed debris of a highly radial merger event such as Gaia Sausage-Enceladus. We present and test an alternative theory in which the overdense 'chevrons' are instead composed of stars trapped in resonances with the Galactic…