Modeling the Spectra of Dense Hydrogen Plasmas: Beyond Occupation Probability

TL;DR

This paper introduces a novel model for dense hydrogen plasmas aimed at improving white dwarf mass measurements, addressing discrepancies between spectroscopic and other methods, with ongoing experimental validation.

Contribution

It develops a new dense hydrogen plasma model beyond occupation probability approaches, integrating it into stellar atmosphere codes to enhance white dwarf spectral analysis.

Findings

Preliminary models show improved agreement with alternative mass measurement methods.

Experimental validation at Sandia is underway to confirm model accuracy.

Modifications to stellar atmosphere codes are in progress for implementation.

Abstract

Accurately measuring the masses of white dwarf stars is crucial in many astrophysical contexts (e.g., asteroseismology and cosmochronology). These masses are most commonly determined by fitting a model atmosphere to an observed spectrum; this is known as the spectroscopic method. However, for cases in which more than one method may be employed, there are well known discrepancies between masses determined by the spectroscopic method and those determined by astrometric, dynamical, and/or gravitational-redshift methods. In an effort to resolve these discrepancies, we are developing a new model of hydrogen in a dense plasma that is a significant departure from previous models. Experiments at Sandia National Laboratories are currently underway to validate these new models, and we have begun modifications to incorporate these models into stellar-atmosphere codes.