The Canada–France Imaging Survey: Reconstructing the Milky Way Star Formation History from Its White Dwarf Population

Fantin, Nicholas; Côté, Patrick; McConnachie, Alan W.; Bergeron, P.; Cuillandre, Jean-Charles; Gwyn, Stephen; Ibata, Rodrigo; Thomas, Guillaume; Carlberg, R. G.; Fabbro, S.; Haywood, M.; Lançon, A.; Lewis, Geraint F.; Malhan, Khyati; Martín, Nicolás F.; Navarro, Julio F.; Scott, Douglas; Starkenburg, Else

doi:10.3847/1538-4357/ab5521

Cited by 78 publications

(81 citation statements)

References 103 publications

(143 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Finally, we remark that the ages of counter-rotating stars in the local vicinity make a reliable estimate for the time of the GES merger event, which has been found in Belokurov et al (2020) to be about 9.5 Gyr ago. Given the clear connection between the GES merger and a starburst of short duration, the identification of a clear peak in the SFH at early times may provide a good estimate of the merger time as well (see the recent works of Nogueras-Lara et al 2019;Fantin et al 2019, that find evidence for an early burst of star formation in the disc). As stellar age measurements improve in the future (e.g.…”

Section: Discussion a N D C O N C L U S I O N Smentioning

confidence: 99%

The dual origin of the Galactic thick disc and halo from the gas-rich Gaia–Enceladus Sausage merger

Grand

Kawata

Belokurov

et al. 2020

Monthly Notices of the Royal Astronomical Society

116

106

View full text Add to dashboard Cite

We analyse a set of cosmological magneto-hydrodynamic simulations of the formation of Milky Way-mass galaxies identified to have a prominent radially anisotropic stellar halo component similar to the so-called “Gaia Sausage” found in the Gaia data. We examine the effects of the progenitor of the Sausage (the Gaia-Enceladus-Sausage, GES) on the formation of major galactic components analogous to the Galactic thick disc and inner stellar halo. We find that the GES merger is likely to have been gas-rich and contribute 10-50$\%$ of gas to a merger-induced centrally concentrated starburst that results in the rapid formation of a compact, rotationally supported thick disc that occupies the typical chemical thick disc region of chemical abundance space. We find evidence that gas-rich mergers heated the proto-disc of the Galaxy, scattering stars onto less-circular orbits such that their rotation velocity and metallicity positively correlate, thus contributing an additional component that connects the Galactic thick disc to the inner stellar halo. We demonstrate that the level of kinematic heating of the proto-galaxy correlates with the kinematic state of the population before the merger, the progenitor mass and orbital eccentricity of the merger. Furthermore, we show that the mass and time of the merger can be accurately inferred from local stars on counter-rotating orbits.

show abstract

Section: Discussion a N D C O N C L U S I O N Smentioning

confidence: 99%

The dual origin of the Galactic thick disc and halo from the gas-rich Gaia–Enceladus Sausage merger

Grand

Kawata

Belokurov

et al. 2020

Monthly Notices of the Royal Astronomical Society

116

106

View full text Add to dashboard Cite

show abstract

“…(1) the crystallization bump is predicted to start too early and (2) the amplitude of the pile-up is significantly underestimated (see also Kilic et al 2020). These problems are a source of concern for the use of white dwarfs as cosmochronometers (Winget et al 1987;Oswalt et al 1996;Fontaine et al 2001;Kalirai 2012;Hansen et al 2013;Tremblay et al 2014;Kilic et al 2017;Isern 2019;Fantin et al 2019). Core crystallization is a significant event in the evolution of a white dwarf and an accurate description of this phenomenon is needed to generate reliable theoretical cooling sequences.…”

Section: Introductionmentioning

confidence: 99%

Toward precision cosmochronology

Blouin

Daligault

Saumon

et al. 2020

A&A

View full text Add to dashboard Cite

The continuous cooling of a white dwarf is punctuated by events that affect its cooling rate. The most significant of these events is the crystallization of its core, a phase transition that occurs once the C/O interior has cooled down below a critical temperature. This transition releases latent heat, as well as gravitational energy due to the redistribution of the C and O ions during solidification, thereby slowing down the evolution of the white dwarf. The unambiguous observational signature of core crystallization–a pile-up of objects in the cooling sequence–was recently reported. However, existing evolution models struggle to quantitatively reproduce this signature, casting doubt on their accuracy when used to measure the ages of stellar populations. The timing and amount of the energy released during crystallization depend on the exact form of the C/O phase diagram. Using the advanced Gibbs–Duhem integration method and state-of-the-art Monte Carlo simulations of the solid and liquid phases, we obtained a very accurate version of this phase diagram that allows a precise modeling of the phase transition. Despite this improvement, the magnitude of the crystallization pile-up remains underestimated by current evolution models. We conclude that latent heat release and O sedimentation alone are not sufficient to explain the observations, and that other unaccounted physical mechanisms, possibly 22Ne phase separation, play an important role.

show abstract

“…Gilmore & Reid 1983), which suggests a thick-disc membership for WASP-98. If so, its age is likely to be old; for example, Fantin et al (2019) found all thick-disc stars to have formed at 9.8 ± 1.5 Gyr. This supports an age of roughly 10 Gyr for the WASP-98 system, but is unfortunately not a conclusive evidence.…”

Section: K I N E M At I C S O F T H E Wa S P -9 8 S Y S T E Mmentioning

confidence: 99%

A white dwarf bound to the transiting planetary system WASP-98

Southworth

Tremblay

Gänsicke

et al. 2020

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

WASP-98 is a planetary system containing a hot Jupiter transiting a late-G dwarf. A fainter star 12″ distant has previously been identified as a white dwarf, with a distance and proper motion consistent with a physical association with the planetary system. We present spectroscopy of the white dwarf, with the aim of determining its mass, radius and temperature and hence the age of the system. However, the spectra show the featureless continuum and lack of spectral lines characteristic of the DC class of white dwarfs. We therefore fitted theoretical white dwarf spectra to the ugriz apparent magnitudes and Gaia DR2 parallax of this object in order to determine its physical properties and the age of the system. We find that the system is old, with a lower limit of 3.6 Gyr, but theoretical uncertainties preclude a precise determination of its age. Its kinematics are consistent with membership of the thick disc, but do not allow us to rule out the thin-disc alternative. The old age and low metallicity of the system suggest it is subject to an age-metallicity relation, but analysis of the most metal-rich and metal-poor transiting planetary systems yields only insubstantial evidence of this. We conclude that the study of bound white dwarfs can yield independent ages to planetary systems, but such analysis may be better-suited to DA and DB rather than DC white dwarfs.

show abstract

The Canada–France Imaging Survey: Reconstructing the Milky Way Star Formation History from Its White Dwarf Population

Cited by 78 publications

References 103 publications

The dual origin of the Galactic thick disc and halo from the gas-rich Gaia–Enceladus Sausage merger

The dual origin of the Galactic thick disc and halo from the gas-rich Gaia–Enceladus Sausage merger

Toward precision cosmochronology

A white dwarf bound to the transiting planetary system WASP-98

Contact Info

Product

Resources

About