The Gaia DR2 halo white dwarf population: the luminosity function, mass distribution and its star formation history

Abstract

We analyze the volume-limited nearly complete 100 pc sample of 95 halo white dwarf candidates identified by the second data release of Gaia. Based on a detailed population synthesis model, we apply a method that relies on Gaia astrometry and photometry to accurately derive the individual white dwarf parameters (mass, radius, effective temperature, bolometric luminosity and age). This method is tested with 25 white dwarfs of our sample for which we took optical spectra and performed spectroscopic analysis. We build and analyse the halo white dwarf luminosity function, for which we find for the first time possible evidences of the cut-off at its faintest end, leading to an age estimate of $\simeq 12\pm 0.5$Gyr. The mass distribution of the sample peaks at $0.589M_{\odot }$, with $71\%$ of the white dwarf masses below $0.6M_{\odot }$ and just two massive white dwarfs of more than $0.8M_{\odot }$. From the age distribution we find three white dwarfs with total ages above 12 Gyr, of which J1312-4728 is the oldest white dwarf known with an age of $12.41\pm 0.22$Gyr. We prove that the star formation history is mainly characterised by a burst of star formation that occurred from 10 to 12 Gyr in the past, but extended up to 8 Gyr. We also find that the peak of the star formation history is centered at around 11 Gyr, which is compatible with the current age of the Gaia-Enceladus encounter. Finally, $13\%$ of our halo sample is contaminated by high-speed young objects (total age<7 Gyr). The origin of these white dwarfs is unclear but their age distribution may be compatible with the encounter with the Sagittarius galaxy.

arXiv comment15 pages, 9 figures, 2 tables; accepted for publication in MNRAS

References in corpus (61)

• Planck 2015 results. XIII. Cosmological parameters
• Gaia Data Release 2. Summary of the contents and survey properties
• The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
• The MACHO Project: Microlensing Results from 5.7 Years of LMC Observations
• A $Gaia$ Data Release 2 catalogue of white dwarfs and a comparison with SDSS
• Evolutionary and pulsational properties of white dwarf stars
• The Updated BaSTI Stellar Evolution Models and Isochrones: I. Solar Scaled Calculations
• The birth of the Milky Way as uncovered by accurate stellar ages with Gaia
• Massive runaways and walkaway stars
• Three Hypervelocity White Dwarfs in Gaia DR2: Evidence for Dynamically Driven Double-Degenerate Double-Detonation Type Ia Supernovae
• A white dwarf cooling age of 8 Gyr for NGC 6791 from physical separation processes
• Pieces of the puzzle: Ancient substructure in the Galactic disk
• On the Measurement of Fundamental Parameters of White Dwarfs in the Gaia Era
• Post Common Envelope Binaries from SDSS. I: 101 white dwarf main sequence binaries with multiple SDSS spectroscopy
• The Ages of the Thin Disk, Thick Disk, and the Halo from Nearby White Dwarfs
• A White Dwarf catalogue from Gaia-DR2 and the Virtual Observatory
• 3D kinematics of white dwarfs from the SPY project II
• On the evolution of ultra-massive white dwarfs
• The Field White Dwarf Mass Distribution
• An Age Difference of 2 Gyr between a Metal-Rich and a Metal-Poor Globular Cluster
• $Gaia$ white dwarfs within 40 pc II: the volume-limited northern hemisphere sample
• White dwarf evolutionary sequences for low-metallicity progenitors: The impact of third dredge-up
• The Age of the Milky Way Inner Halo
• Discovery of high proper motion ancient white dwarfs: nearby massive compact halo objects?
• The initial-final mass relationship from white dwarfs in common proper motion pairs
• High proper motion white dwarfs and halo dark matter
• $\text{Gaia}$ white dwarfs within 40 pc I: spectroscopic observations of new candidates
• The effect of ${}^{22}$Ne diffusion in the evolution and pulsational properties of white dwarfs with solar metallicity progenitors
• The halo white dwarf population
• Monte Carlo simulations of the halo white dwarf population
• The Age of the Galactic Stellar Halo from Gaia White Dwarfs
• A study of high proper-motion white dwarfs I. Spectropolarimetry of a cool hydrogen-rich sample
• Observations of Ultracool White Dwarfs
• On the Interpretation of High Velocity White Dwarfs as Members of the Galactic Halo
• Evolutionary sequences for hydrogen-deficient white dwarfs
• The white dwarf luminosity function
• Random Forest identification of the thin disk, thick disk and halo Gaia-DR2 white dwarf population
• A Survey for Faint Stars of Large Proper Motion Using Extra Poss II Plates
• A Deep Proper Motion Catalog Within the Sloan Digital Sky Survey Footprint. II. The White Dwarf Luminosity Function
• The Halo White Dwarf WD 0346+246 Revisited
• The White Dwarf Age of NGC 2477
• Ultracool white dwarfs and the age of the Galactic disc
• First Detection of the White-Dwarf Cooling Sequence of the Galactic Bulge
• Simulating Gaia performances on white dwarfs
• The white dwarf population of NGC 6397
• A Nearby Old Halo White Dwarf Candidate from the Sloan Digital Sky Survey
• White dwarfs and Galactic dark matter
• Neural Network identification of halo white dwarfs
• 11-12 Gyr old White Dwarfs 30 parsecs Away
• A Proper Motion Survey for White Dwarfs with the Wide Field Planetary Camera 2
• The white dwarf luminosity function. I. Statistical errors and alternatives
• The white dwarf population within 40 pc of the Sun
• An ancient double degenerate merger in the Milky Way halo
• The White Dwarf Luminosity Functions from the Pan-STARRS 1 3π Steradian Survey
• Revisiting the luminosity function of single halo white dwarfs
• Proper Motion Objects in the Hubble Deep Field
• A maximum volume density estimator generalized over a proper motion-limited sample
• A Hierarchical Model for the Ages of Galactic Halo White Dwarfs
• The brightest pure-H ultracool white dwarf
• Gaia DR2 white dwarfs in the Hercules stream
• The population of single and binary white dwarfs of the Galactic bulge

Cited by in corpus (24)

• A catalogue of white dwarfs in Gaia EDR3
• Spectral classification of the 100 pc white dwarf population from Gaia-DR3 and the Virtual Observatory
• Triage of the Gaia DR3 astrometric orbits. I. A sample of binaries with probable compact companions
• White dwarf-main sequence binaries from Gaia EDR3: the unresolved 100pc volume-limited sample
• Uncertain Times: The Redshift-Time Relation from Cosmology and Stars
• Constraining the solar neighbourhood age-metallicity relation from white dwarf-main sequence binaries
• Kinematic properties of white dwarfs. Galactic orbital parameters and age-velocity dispersion relation
• Testing White Dwarf Age Estimates using Wide Double White Dwarf Binaries from Gaia EDR3
• Local stellar formation history from the 40 pc white dwarf sample
• A hidden population of white dwarfs with atmospheric carbon traces in the Gaia bifurcation
• The White Dwarfs of the Old, Solar Metallicity Open Star Cluster Messier 67: Properties and Progenitors
• Discovery of a resolved white dwarf-brown dwarf binary with a small projected separation: SDSS J222551.65+001637.7AB
• Testing the mass-radius relation of white dwarfs in common proper motion pairs I.Hydrogen-dominated atmospheres
• J0526+5934: a peculiar ultra-short period double white dwarf
• Observations of Microlensed Images with Dual-field Interferometry: On-sky Demonstration and Prospects
• Kinematic origin of white dwarfs in the solar neighborhood
• Revisiting astrophysical bounds on continuous spontaneous localization models
• Dark Matter in White Dwarfs: Implications for Their Structure
• Deciphering the explosion mechanism of Type Ia SNe using their remnants II: a deep dive into double detonations with SNR 0509-67.5
• Gaia white dwarfs with infrared excess I. The 100 pc catalogue
• Using Binary Population Synthesis to Calculate the Yields of Low- and Intermediate-Mass Binary Populations at Low Metallicity
• Exploring faint white dwarfs and the luminosity function with Subaru HSC and SDSS in Stripe 82
• Revisiting constraints on asymmetric dark matter from collapse in white dwarf stars
• A new method to retrieve the star formation history from white dwarf luminosity functions -- an application to the Gaia catalogue of nearby stars