Constraining Compact Object Formation with 2M0521
Bibliographic record
Abstract
Abstract We show that the recently discovered binary 2M05215658+4359220 (2M0521), comprising a giant star (GS) orbiting a suspected black hole (BH) in an ∼80 day orbit, may be instrumental in shedding light on uncertain BH-formation physics and can be a test case for studying wind accretion models. Using binary population synthesis with a realistic prescription for the star formation history and metallicity evolution of the Milky Way, we analyze the evolution of binaries containing compact objects (COs) in orbit around GSs with properties that are similar to 2M0521. We find ∼102–103 CO–GS binaries in the Milky Way observable by Gaia and 0–12 BH–GS and 0–1 neutron star–GS binaries in the Milky Way with properties that are similar to 2M0521. We find that all CO–GSs with P orb < 5 yr, including 2M0521, go through a common envelope (CE), and hence form a class of higher-mass analogs to white dwarf post-CE binaries. We further show how the component masses of 2M0521-like binaries depend strongly on the supernova-engine model that we adopt. Thus, an improved measurement of the orbit of 2M0521, imminent with Gaia’s third data release, will strongly constrain its component masses and as a result inform supernova-engine models that are widely used in binary population synthesis studies. These results have widespread implications for the origins and properties of CO binaries, especially those detectable by the Laser Interferometer Gravitational-Wave Observatory and the Laser Interferometer Space Antenna. Finally, we show that the reported X-ray nondetection of 2M0521 is a challenge for wind accretion theory, making 2M0521-like CO–GS binaries a prime target for further study with accretion models.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".