White Dwarf IFMR Choice Shifts Old Cluster Ages by 0.6-0.8 Gyr
The paper quantifies how different white-dwarf initial-final mass relations change cooling-sequence ages of star clusters. Offsets of 0.6-0.8 Gyr appear for old, metal-poor systems and must now be treated as a systematic uncertainty in galactic archaeology. The analysis is purely theoretical and differential, based on luminosity functions that include observational errors.
Salaris, Cassisi and Bedin computed theoretical white-dwarf luminosity functions for clusters at 10 Gyr, 1 Gyr and 100 Myr using published semi-empirical IFMRs, folding in realistic photometric errors and binning. Offsets reached 0.6 plus or minus 0.2 Gyr at old ages, fell to 0.2 plus or minus 0.1 Gyr at intermediate ages, and became negligible for young populations. A separate metallicity-dependent theoretical IFMR produced an additional 0.8 Gyr underestimate when ignored for subsolar-metallicity systems. The result matters because white-dwarf cooling ages anchor the lower main-sequence turn-off ages used in galactic archaeology; even 0.5 Gyr shifts alter inferred star-formation histories and chemical-enrichment timelines for the Milky Way halo and bulge. Prior cluster-age compilations treated the IFMR as fixed, propagating an unquantified systematic into every downstream chemodynamical model. Future Gaia DR4 and JWST photometry of faint white-dwarf sequences in additional clusters will allow direct empirical tests of the IFMR variants. Revised age scales will be required before the next generation of Milky Way formation simulations can claim sub-Gyr precision.
Salaris: At least two major globular-cluster age catalogs will incorporate metallicity-dependent IFMR corrections exceeding 0.5 Gyr within 24 months of the paper's acceptance.
Sources (2)
- [1]Primary Source(https://arxiv.org/abs/2606.14826)
- [2]Supporting Source(https://arxiv.org/abs/2302.07881)