Determine the Type Ia supernova contribution to Abell 1413 core enrichment

Determine the Type Ia supernova fraction in the core of Abell 1413 using measurements that reliably constrain the soft-band and hard-band elemental abundance ratios, thereby resolving whether the fraction lies anywhere between 15 and 100 per cent.

Background

The paper fits the core abundance pattern with mixtures of Type Ia and core-collapse supernova yields. Although the full eight-ratio fit gives a relatively narrow Type Ia fraction, the authors argue that its constraint is driven by soft-band ratios affected by cross-calibration uncertainties. The four ratios measured directly by XRISM/Resolve yield a much broader interval, with the upper boundary reaching a purely Type Ia-enriched population.

The unresolved issue is therefore the actual enrichment fraction in the A1413 core. The authors state that observations with the XRISM gate valve open, which would provide reliable access to O, Ne, and Mg, are needed to convert the current open question into a measurement.

References

We conclude that the XRISM core spectrum of A1413 is consistent with enrichment in solar proportions, that the departures from that pattern are confined to the soft band and are most plausibly instrumental, and that the SNIa fraction is not usefully constrained by these data: the ratios with the leverage to constrain it are the ones we cannot trust, and those we can trust --- $R({\rm Ia}) = 35{+65}_{-20}$~per cent --- leave the answer open between $15$ and $100$~per cent.

— Weak cool core, weak turbulence: XRISM, XMM-Newton and Chandra spectroscopy of the core of Abell 1413  (2609.08778 - Gormez et al., 8 Sep 2026) in Section 3.5, subsection “Supernova yield fitting” (Section \ref{sec:sneratio}); reiterated in Section 6, Summary and conclusions