Hubble as a Unique Discovery Engine of the Fate of Massive Stars and Black Hole Formation

How stellar-mass black holes are formed is an open question in astrophysics, with very limited observational constraints. The new analysis still awaits peer review, but it already lays out the central claim clearly.

The significance lies in astrophysics becomes persuasive only when an observed signal can be tied to a physically defensible explanation. Compact objects such as neutron stars and black holes are natural laboratories for extreme physics, but the distance and complexity of these systems make interpretation difficult without multi-wavelength coverage and careful modeling. A detection without a mechanism is only half a result. the other half comes from showing that the signal fits quantitatively inside a coherent physical picture rather than merely being consistent with a broad family of models. It is not known which types of stars are more likely to produce black holes, and whether the formation process is accompanied by strong or weak electromagnetic transients - or. Recent theoretical work predicts that many stellar-mass black holes form from hot, UV-luminous massive stars, including Wolf-Rayet-like progenitors, and searches focused primarily.

While the coming decade will bring major advances in time-domain astronomy through Rubin/LSST, Roman, JWST, and wide-field transient surveys, none of these combines UV. HST uniquely enables direct searches for disappearing hot massive stars associated with black-hole formation.

We outline a roadmap for extending HST's role in this area into the 2030s through a dedicated, large program to re-image nearby galaxies in the UV and identify candidate. Theoretical event rates imply that the nearby galaxy population accessible to HST should yield of order one detectable black-hole-forming disappearance event per year.

Extending HST operations into the 2030s would therefore provide crucial insights into the unsolved problem of black hole formation. Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy.

The broader interest lies in turning an observational clue into something that can be weighed against competing models of the underlying physics. Astrophysics does not have the luxury of controlled experiments; everything is inferred from radiation that traveled across cosmic distances under conditions that cannot be reproduced in a terrestrial laboratory. This makes the interpretation chain longer and more uncertain than in bench science, but it also means that a well-constrained measurement of an extreme object carries theoretical information that no earthbound experiment can provide.

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Because this is still a preprint, the result should be read with genuine interest and proportionate caution. Peer review is not a guarantee of correctness, but it is a process that forces authors to respond to technical criticism from specialists who have no stake in a particular outcome. Preprints that survive that process, often with substantive revisions, emerge with a stronger evidential base than the version that first appeared. Until that stage is complete, the responsible reading keeps uncertainty explicitly visible rather than treating the claims as established findings.

The next step is to see whether independent datasets and physical modeling converge on the same interpretation. Multi-wavelength follow-up, combining X-ray, radio and optical data where possible, is typically what separates a compelling detection from a robust physical characterization. In high-energy astrophysics, results that initially looked definitive have been revised when data from a second messenger arrived; the current result should be read with that history in mind. Until peer review and independent follow-up address those open questions, skepticism is not a failure of appreciation for the work; it is part of how science decides what to keep.

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