Bibliographic record
Abstract
The optical–UV continuum of quasars is broadly consistent with the emission from a geometrically thin optically thick accretion disc (AD). The AD produces the ionizing continuum which powers the broad and narrow emission lines. The maximum AD effective temperature is given by , where M is the black hole mass, the accretion rate and fmax is set by the black hole spin a*. For a low enough value of , the AD may become too cold to produce ionizing photons. Such an object will form a lineless quasar. This occurs for a local blackbody (BB) AD with a luminosity Lopt= 1046 erg s−1 for M > 3.6 × 109 M⊙, when a*= 0, and for M > 1.4 × 1010 M⊙, when a*= 0.998. Using the AD-based , derived from M and Lopt, and the reverberation-based M, derived from Lopt and the Hβ full width at half-maximum, v, gives Teff, max∝L−0.13optv−1.45. Thus, Teff, max is mostly set by v. Quasars with a local BB AD become lineless for v > 8000 km s−1, when a*= 0, and for v > 16 000 km s−1, when a*= 0.998. Higher values of v are required if the AD is hotter than a local BB. The AD becoming non-ionizing may explain why line-emitting quasars with v > 10 000 km s−1 are rare. Weak low-ionization lines may still be present if the X-ray continuum is luminous enough, and such objects may form a population of weak line quasars (WLQ). If correct, such WLQ should show a steeply falling spectral energy distribution (SED) at λ < 1000 Å. Such an SED was observed by Hryniewicz et al. in SDSS J094533.99+100950.1, a WLQ observed down to 570 Å, which is well modelled by a rather cold AD SED. UV spectroscopy of z∼ 1–2 quasars is required to eliminate potential intervening Lyman limit absorption by the intergalactic medium and to explore if the SEDs of lineless quasars and some additional WLQ are also well fitted by a cold AD SED.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".