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REVIEW

A Fundamental Relation Between Supermassive Black Holes and Their Host Galaxies

Astrophysics · Submitted 4 Jun 2000 · 2 references

Pith's verdict: The M–σ paper: the slope of 4.8 is the durable part, and the 'negligible intrinsic scatter' claim is the part that does not survive scrutiny.

T0 · AI review

How this review was made: An AI referee (selfhosted/deepseek-v4.1-flash) read the paper on October 29, 2026 and answered a fixed list of questions about it. T0 is the starting level every paper gets. The levels describe how deeply Pith has checked the paper, never the authors.

  1. T0 AI review An AI read the paper and answered a fixed list of questions.
  2. T1 Audit Automatic checks that the references and files the paper relies on exist and match.
  3. T2 Compute The paper's code or calculations re-run with the same results.
  4. T3 Formal statement The claims written out in a formal math language a computer can read.
  5. T4 Proof Those claims proved, and the proof checked by computer.

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· 3 major objections · 8 minor · Ask about this paper · The compiled record · Read the full review →
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arXiv IDastro-ph/0006053 (version 2)
Pith ID6M3PP4YV, Pith's permanent record of this paper and its review
CitationLaura Ferrarese (UCLA) & David Merritt (Rutgers University). "A Fundamental Relation Between Supermassive Black Holes and Their Host Galaxies." arXiv:astro-ph/0006053 (2000). https://pith.science/paper/6M3PP4YV
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Referee report
The paper

The paper claims

Black hole mass tracks the random motions of bulge stars, not the bulge's brightness, and the fit is tight enough that one low-resolution spectrum predicts the mass.

The reading

The paper asks what property of a galaxy actually sets the mass of its central black hole. Using twelve galaxies whose black hole masses are measured directly — the Milky Way's own centre, the water-maser disk in NGC 4258, and ten galaxies resolved with the Hubble Space Telescope — the authors fit black hole mass against the central velocity dispersion $sigma_c$ of the host bulge and find $M_*{BH} propto sigma_c^{4.8 pm 0.5}$, a relation far tighter than the older correlation with bulge blue luminosity. The scatter about that line is no larger than the quoted measurement errors allow, which is the part that carries weight: it says there is little room left for any second variable hiding in the data. If the relation is real, a single modest-resolution measurement of a galaxy's stellar velocity dispersion gives its black hole mass to roughly thirty percent, and the growth of the black hole is tied to the depth of the potential well it sits in rather than to how many stars the bulge contains.

What carries the argument

The machinery is a bivariate linear regression that allows for intrinsic scatter as well as errors in both variables (Akritas & Bershady 1996), applied with black hole mass as the dependent variable and either bulge absolute magnitude $B^0_T$ or aperture-corrected central velocity dispersion $sigma_c$ as the independent one. The aperture correction, which brings every dispersion to the equivalent of a radius $r_e/8$ following Jorgensen, Franx & Kjaergaard (1995), is small, rarely above five percent, and the authors check that it changes neither slope nor intercept. The comparison between the two independent variables is what makes the argument: the same sample, the same fitting method, two different galaxy properties, and only one of them produces a residual scatter that the error bars can account for.

Extended reading notes

Core claim

The central claim is Eq. (1): $log M_*{BH} = 4.80(pm 0.54),log sigma_c - 2.9(pm 1.3)$, with $M_*{BH}$ in solar masses and $sigma_c$ in km/s, fitted to the twelve galaxies of Sample A. The reduced chi-squared of that fit is 0.8, i.e. the spread about the line is consistent with the stated measurement errors alone, whereas the same galaxies scatter far more widely about the $M_*{BH}$–luminosity plane. The authors argue the correlation is not an artifact of the black hole perturbing the stars whose motions are being measured: substituting the rms velocity $v_*{rms}$ at a quarter of the effective radius, well outside the black hole's gravitational reach, leaves the slope unchanged. They also report that the Magorrian et al. (1998) masses, derived from ground-based stellar kinematics, sit systematically above the Sample A line, some by two orders of magnitude, and they read that offset as evidence that those mass estimates are upper limits rather than detections.

Load-bearing premise

The twelve galaxies were chosen because the observations resolved the black hole's sphere of influence, and that radius grows with black hole mass, so the sample is not independent of the quantity being predicted.

Editorial extensions

If this is right

  • Black hole masses can be estimated for large galaxy samples from existing stellar velocity dispersion measurements, without spatially resolved kinematics, opening population studies that were previously limited to a dozen objects.
  • If the slope is near five, then combining the Faber–Jackson relation $L propto sigma^4$ with the early-type mass-to-light scaling $M propto L^{5/4}$ gives $M_*{BH}$ roughly proportional to bulge mass, i.e. a roughly universal baryon-to-black-hole conversion fraction.
  • The same $sigma^5$ scaling follows from models in which quasar outflows halt accretion once the outflow energy matches the bulge binding energy, so the observed slope is a natural test of that feedback picture.
  • Correlation studies built on the Magorrian et al. (1998) masses, such as Merriefield, Forbes & Terlevich (2000), should be re-examined, since those masses appear to be biased high for distant galaxies.
  • The relation should not be extrapolated to black holes below roughly $10^5$ solar masses, where the formation channel may differ.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • The sample was assembled from galaxies in which the black hole's sphere of influence was spatially resolved, and that radius scales as $G M_*{BH}/sigma^2$; a sample selected that way preferentially keeps large black holes at a given dispersion, so an independent test using galaxies selected purely by distance or by observability, with no reference to black hole mass, would be the cleanest check on
  • Because the relation predicts mass from a quantity measurable in a single low-resolution spectrum, it converts every nearby early-type galaxy with a published dispersion into a black hole mass estimate, which is the practical reason the result propagated so widely.
  • The systematic upward offset of the ground-based stellar-kinematic masses is itself a claim about measurement, not about black holes: if it is right, the same bias should appear in any other mass estimator whose resolution element is larger than the sphere of influence, and that is checkable galaxy by galaxy.
Original abstract

The masses of supermassive black holes correlate almost perfectly with the velocity dispersions of their host bulges, M(BH) ~ sigma^alpha, where alpha =4.8 +/- 0.5$. The relation is much tighter than the relation between M(BH) and bulge luminosity, with a scatter no larger than expected on the basis of measurement error alone. Black hole masses estimated by Magorrian et al. (1998) lie systematically above the M(BH)-sigma relation defined by more accurate mass estimates, some by as much as two orders of magnitude. The tightness of the M(BH)-sigma relation implies a strong link between black hole formation and the properties of the stellar bulge.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13.0 via TypeSafe API, question bank abstract-p1-20260923, 2026-09-23: 1 request, 3,695 input tokens.

What the abstract itself states, as probabilities: claims first 0.03 · states limitation 0.15 · human participants 0.02 · controlled comparison 0.15 · randomized assignment 0.01 · states quantitative result 0.98 · compares with prior results 0.96 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v2. Results and the main claim are underlined; .

The masses of supermassive black holes correlate almost perfectly with the velocity dispersions of their host bulges, M(BH) ~ sigma^alpha, where alpha =4.8 +/- 0.5$. The relation is much tighter than the relation between M(BH) and bulge luminosity, with a scatter no larger than expected on the basis of measurement error alone. Black hole masses estimated by Magorrian et al. (1998) lie systematically above the M(BH)-sigma relation defined by more accurate mass estimates, some by as much as two orders of magnitude. The tightness of the M(BH)-sigma relation implies a strong link between black hole formation and the properties of the stellar bulge.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 The masses of supermassive black holes correlate almost perfectly with the velocity dispersions of their host bulges, M(BH) ~ sigma^alpha, where alpha =4.8 +/- 0.5$. result 1.00 0.67 0.68 asserted 1.00
s1 The relation is much tighter than the relation between M(BH) and bulge luminosity, with a scatter no larger than expected on the basis of measurement error alone. result 1.00 0.75 0.16 asserted 1.00
s2 Black hole masses estimated by Magorrian et al. (1998) lie systematically above the M(BH)-sigma relation defined by more accurate mass estimates, some by as much as two orders of magnitude. result 0.91 0.39 0.07 asserted 1.00
s3 The tightness of the M(BH)-sigma relation implies a strong link between black hole formation and the properties of the stellar bulge. interpretation 1.00 0.54 0.59 asserted 0.76

What kind of paper the classifier reports this is: empirical study 1.00 · evidence from analysis of existing data 0.75.

What was examined, and what was not

sources read
  • arXiv listing abstract v2
not examined
  • full text
  • figures and tables
  • references and citing sentences
  • relations to other papers
levels run
  • P abstract
not run
  • S sections
  • T body sentences
  • C citations
  • R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

References
How later papers used it

681 later papers cite it

Evidence: substantial. 677 of the citing papers share no author with it, and 38 of those carry a confident label from Pith's citation classifier.

Pith read 39 of the 767 citing sentences, choosing only those whose citation markers point at this paper alone, and wrote the paraphrases from them. The summary, the counts, the evidence level, the links and the quotes come from code; the summary counts the papers listed below. A later paper is listed under a label when Pith's citation classifier gives one of its sentences that label at probability 0.8 or more (0.95 for support), Pith's reading finds that the citing paper itself did it, and a second check confirms the paraphrase against the sentence. This section lists uses only. It does not list criticism or disagreement, so their absence here says nothing about how the paper has been received. Papers that share an author with this one are listed apart, under "By the same authors". A quote is the citing authors' own sentence, shown when their paper's licence is CC BY, CC BY-SA or CC0. JSON

Uses its method or tool 3 of 15 papers with this label
Uses its data or values 1 of 9 papers with this label
  • Fit the normalization A to the observational data of this paper for each alpha varied between 3.5 and 5.

    AGN feedback in dwarf galaxies? (2017) · 0.81 · paraphrased: the licence does not allow quoting

How the literature uses it

107 arXiv papers cite this in 119 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 80 sentences without a confident label

Uses its method or tool 3 papers
Uses its data or values 1 paper
Compares with it 1 paper
Cites it as support 1 paper
Cites it as background 32 papers

Discussion

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