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Feedback effects of remnant accretion on collapsar disk mass and energy budget

Quantify the feedback effects on the collapsar disk’s mass and energy budget resulting from accretion onto the collapsed remnants (neutron stars or black holes) embedded within the disk.

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Background

Super-critical accretion onto compact remnants can produce strong outflows and alter accretion dynamics, potentially affecting disk evolution and the feasibility of forming and merging sub-solar mass neutron stars.

The authors identify this as an explicit uncertainty requiring quantitative assessment to understand the global energy and mass budget of the system.

References

Although our estimates paint a plausible story, a number of uncertainties remain, particularly with regards to: (a) whether the stripped progenitor stars of collapsars can possess sufficient angular momentum to create massive ≳ M ⊙ disks at large radii ≳ 100 R g around the central black hole; (b) whether the criterion for forming gravitationally-bound objects is in fact satisfied by a combination of neutrino and alpha particle dissociation cooling in a full multi-dimensional turbulent disk environment; (c) the resulting mass spectrum of the bound clumps, and whether clump-fissioning or gas-aided capture leads to binary NS formation; (d) the evolution of the disk electron fraction due to pair captures prior and during gravitational collapse, and how this impacts the masses of the NSs that form; (e) feedback effects on the disk mass and energy budget from accretion onto the collapsed remnants.

— Fragmentation in Gravitationally-Unstable Collapsar Disks and Sub-Solar Neutron Star Mergers (2407.07955 - Metzger et al., 10 Jul 2024) in Section 3, Summary