First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole

The Event Horizon Telescope Collaboration · The Astrophysical Journal Letters / arXiv · 2019 · astronomy · 10.3847/2041-8213/ab0ec7 · record eht2019-m87-black-hole
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Where this record's text came from. faceted 2026-08 by reading the locally held text (pdftext); every evidence string verified as an exact substring of that text before merging. Claim type is coded as existence because the headline contribution is that the predicted shadow feature is there and has been imaged; the paper also contains a mechanism strand (the asymmetry attributed to relativistic beaming) and a method strand (assembling the EHT array), which the single-value facet cannot carry. Several otherwise ideal sentences — including the abstract's ring-diameter sentence and 'The inferred black hole mass strongly favors the measurement based on stellar dynamics(Gebhardt et al. 2011).' — contain invisible private-use-area characters (U+F0A0, U+F088, U+F089) from the PDF extraction and were therefore NOT quoted, since a re-typed version would fail the substring check; the facets above use only sentences verified to match character for character. Internal cross-validation across four nights, two bands and three pipelines is reported, but no external replication, hence replication status untested. 2026-08-14 and 2026-08-16 schema-0.3 passes: every quote verified as an exact substring of the staged text and anchored at merge time; concept terms verified present; every edge endpoint an existing node.

Some words in these quotes contain the wrong character. The PDF this text was extracted from substituted 1 character inside a word — a currency sign or a stray accent where a letter pair belongs, as in signi¢cantly for significantly, or a single ligature glyph, as in conﬁdence. They are valid characters in the wrong place, so they survive every encoding check. The quotes keep them for the same reason as above, and a search of this page will not find the affected words.

28 quotes on this page carry a character that renders as nothing. 123 such characters in all: a private-use glyph. The PDF this text came from used characters that survive extraction as code points no ordinary font draws, so the quote reads as though they were never there. That can change what a sentence says: a soft hyphen left by a line break puts a space inside a word, so document reads as docu ment; a flattened superscript turns 10⁹ into 109. The quotes are reproduced exactly as the extraction left them and have NOT been repaired — the meaning of such a code point belongs to the one PDF it came from, and guessing it would produce a clean, confident, unverifiable quote.

How to read this page. The article itself is not reproduced here — this paper is not cleared for redistribution, so what follows is the tag layer alone. The evidence sentences are withheld with the article. The table at the foot lists every tag the record carries; each row names the facet it belongs to, and the whose words column says whether the tag records the paper's own wording or the tagger's sentence about the paper. Every tag links to each other paper in the corpus carrying it. The machine-readable edition of the same thing is the TEI file beside this one, where the tags live in standOff, and the article is at its publisher via the link below. When we have changed our mind. Some entries in the table begin with a word in capitals and the reason for it. EVIDENCE CORRECTED — the finding still stands, but we had quoted the wrong sentence from the paper, and the quotation has been replaced with the right one. RETRACTED — the entry itself was wrong; it stays on the page, marked, with the reason, rather than being deleted. WITHDRAWN AND REPLACED — the entry was wrong, and a corrected version of it appears in the entries below. Each mark carries its own reason, in brackets, because the reasons differ from one entry to the next. An entry we have WITHDRAWN is removed from this page and kept in the record, with its reason. A line reading Audit and a date is a later re-reading of the entry against its whole sentence: DOUBTFUL means it was kept, and the reason says what is loose about it. Quotation marks inside the tagger's sentence. Where a tag is the tagger's own sentence, a phrase in quotation marks inside it is borrowed from the paper — the tagger's wording around it is not. The paper's own sentence is the evidence quote for that row; on this page it is withheld with the article, and the article is at its publisher. Nothing inside quotation marks anywhere on this page is ours: if it is quoted, it is the paper's. Whose words a concept carries. A concept entry records a term the paper itself uses, so the term, the sense given for it, and its evidence are the paper's own words, quoted where the paper fixes them. This is the opposite of a sense entry in the tag table, which is the tagger's sentence about how the paper uses a term. Where a concept entry could not be grounded in the paper's words, the entry says so on its own row.

Other fields define these differently the same word, defined another way in another discipline
null-hypothesis 3 fields · variance 2 fields

Tags on this paper

Every tag the record carries, each linking to every other paper in the corpus that carries it. A tag appears here whether or not its words occur in the article — the spans below are only the ones a sentence in this paper licenses. Of the 43 concept tags on this paper, 38 are grounded in a quoted sentence. 32 carry the tagger's gloss of what the term means in this paper, which is not something the article can license.

black hole event horizon very long baseline interferometry general relativity accretion emission ring photon ring black hole shadow maximum mass prior emitting regions shadows one-way causal boundary Active galactic nuclei central bright regions low-luminosity active galactic nuclei hot, tenuous accretion flows photon capture radius Schwarzschild radius unstable circular orbit event horizon and light bending dark “shadow” crescent Event Horizon Telescope global VLBI array complex visibilities Fourier components inverse problem CLEAN inverse-modeling approach RML forward-modeling approach Top-Set geometric models GRMHD simulations turbulent, hot, magnetized disk SANE accretion flows MAD flows Standard and Normal Evolution Magnetically Arrested Disk moderate dimensionless magnetic flux geometric crescent models ring diameter null hypothesis of the Kerr metric the first images are made by four teams working independently and without interaction, in the authors' words to minimize shared bias - and each team nonetheless recovered a ring of similar diameter brightened to the south a parameter combination is admitted to the Top-Set only if it both fits the observed data AND reconstructs four known geometries - ring, crescent, filled disk, asymmetric double - from synthetic data, so the imaging parameters are validated against ground truth and not only against the object under study because the reconstructed resolutions differ between pipelines, each image is blurred with a circular Gaussian to one common and deliberately conservative resolution before use systematic baseline error is measured rather than assumed: three independent fringe-fitting pipelines, two polarizations and two frequency bands are compared against each other, and the residual disagreement between them IS the quoted systematic the two frequency bands are correlated on two separate software correlators at two institutions, and a few identical scans are passed through both so that any difference between the correlators would show up as a disagreement on the same input one highly sensitive station is used as the array's reference station, which is what enabled the ionospheric and tropospheric corrections at the other sites the absolute flux scale is refined using the array's own redundancy - pairs of telescopes that sit at the same site and therefore see the same baseline - rather than resting on each telescope's independently estimated sensitivity the simulated images are put through the same VLBI simulation, the same observing schedule and weather, the same calibration and the same imaging pipeline as the real data, so that model and observation are compared after identical processing rather than before it shadow supermassive relativistic beaming M87 dark shadow active galactic nuclei (AGNs) projected diameter central mass impact parameter b Bayesian correlation correlation coefficient hypothesis-testing mean average of median null-hypothesis null hypothesis variance observational-study

Legend

relation to other work	`claim_relations`	how this paper stands to another: agrees, contradicts, extends, qualifies
claim type	`claim_type`	the shape of the claim: existence, mechanism, method, critique, prediction, null
concept edge	`concept_edges`	an asserted relation between two concepts, with the sentence asserting it
concept	`concepts`	an idea the paper works with, quoted where the paper uses it
content tag	`content_tags`	a finding, definition, quantity, statistic or variable named in the paper
control	`controls`	an experiment run to eliminate a rival explanation
limitation	`limitations`	what the paper says its evidence cannot support
mechanism	`mechanisms`	how the reported effect is said to come about
method	`method`	how the paper produced its evidence
phenomenon	`phenomenon`	the effect or regularity under study
sense	`senses`	a distinct use of a term, quoted where the paper fixes it
unrecordable relation	`unhoused_relations`	a relation the paper asserts that this vocabulary cannot express, with the reason

The paper

The full text is not reproduced here. This article is not cleared for redistribution, so the page carries the tag layer only. Its evidence sentences are withheld; the grounding status remains with each tag, and the article itself is at https://doi.org/10.3847/2041-8213/ab0ec7. The reading view exists for the papers whose licence permits it.

Every tag on this page

claim_relations 3 · claim_type 1 · concept_edges 9 · concepts 38 · content_tags 25 · controls 2 · limitations 10 · mechanisms 8 · method 1 · phenomenon 1 · senses 21 · unhoused_relations 2

Relations on this page carry a quotation for the claim. Where a relation was separately evidenced — and so tested against the vocabulary for its type — the row says so; 8 of 9 relations here carry that mark. The rest are the tagger’s reading of the sentence quoted beside them.

facet	tag	field	conf.	whose words
claim_type	existence Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`claim_type`		the paper's words
phenomenon	black hole shadow Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`phenomenon`		the paper's words
method	observational-study Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: observational-study	`method`		the paper's words
mechanisms	mechanisms Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: the first images are made by four teams working independently and without interaction, in the authors' words to minimize shared bias - and each team nonetheless recovered a ring of similar diameter brightened to the south	`mechanisms[0]`	0.85	the tagger's words
mechanisms	mechanisms Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: a parameter combination is admitted to the Top-Set only if it both fits the observed data AND reconstructs four known geometries - ring, crescent, filled disk, asymmetric double - from synthetic data, so the imaging parameters are validated against ground truth and not only against the object under study	`mechanisms[1]`	0.95	the tagger's words
mechanisms	mechanisms Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: because the reconstructed resolutions differ between pipelines, each image is blurred with a circular Gaussian to one common and deliberately conservative resolution before use	`mechanisms[2]`	0.85	the tagger's words
mechanisms	mechanisms Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: systematic baseline error is measured rather than assumed: three independent fringe-fitting pipelines, two polarizations and two frequency bands are compared against each other, and the residual disagreement between them IS the quoted systematic	`mechanisms[3]`	0.95	the tagger's words
mechanisms	mechanisms Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. about this quote: 2026-08-16: THE STAGED TEXT SCRAMBLES A NAME INSIDE THIS QUOTE. It reads "at the MIT Haystack Observatory and at fur Radioastronomie" - the words "the Max-Planck-Institut" were displaced by the extraction and appear roughly 400 characters later, mid-sentence, in "At correlation, signals were aligned ... the Max-Planck-Institut". The two institutions are MIT Haystack and the Max-Planck-Institut fur Radioastronomie. The quote is an exact substring of the staged file and the file is wrong here, not the tag. NOT a furniture crossing - the extraction reordered words WITHIN a sentence, which no guard in our tools can see, because the result is contiguous, unique and verbatim. also in: the two frequency bands are correlated on two separate software correlators at two institutions, and a few identical scans are passed through both so that any difference between the correlators would show up as a disagreement on the same input	`mechanisms[4]`	0.95	the tagger's words
mechanisms	mechanisms Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: one highly sensitive station is used as the array's reference station, which is what enabled the ionospheric and tropospheric corrections at the other sites	`mechanisms[5]`	0.85	the tagger's words
mechanisms	mechanisms Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. about this quote: 2026-08-16: THE STAGED TEXT SCRAMBLES A CITATION INSIDE THIS QUOTE. It reads "utilizing array redundancy via III), we refined the absolute network calibration (Paper amplitude calibration of telescopes" - the parenthetical "(Paper III)" has been split and its halves interleaved with the surrounding clause. Read as: "utilizing array redundancy via network calibration (Paper III), we refined the absolute amplitude calibration of telescopes that are colocated...". Verbatim of the file, and the file is wrong. Same class as [4]: a within-sentence reordering, invisible to every guard. also in: the absolute flux scale is refined using the array's own redundancy - pairs of telescopes that sit at the same site and therefore see the same baseline - rather than resting on each telescope's independently estimated sensitivity	`mechanisms[6]`	0.95	the tagger's words
mechanisms	mechanisms Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: the simulated images are put through the same VLBI simulation, the same observing schedule and weather, the same calibration and the same imaging pipeline as the real data, so that model and observation are compared after identical processing rather than before it	`mechanisms[7]`	0.95	the tagger's words
limitations	The interferometric sampling is sparse, so image reconstruction is an under-constrained inverse problem requiring extra assumptions. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. what this limits: every reconstructed image: BECAUSE THE (u, v) PLANE IS ONLY SPARSELY SAMPLED, THE INVERSE PROBLEM IS UNDER-CONSTRAINED	`limitations[0]`		the tagger's words
limitations	Visibility data lack absolute phase calibration and carry potentially large amplitude calibration uncertainties. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. what this limits: the visibility data underlying it: THE MEASURED VISIBILITIES LACK ABSOLUTE PHASE CALIBRATION AND CAN HAVE LARGE AMPLITUDE CALIBRATION UNCERTAINTIES	`limitations[1]`		the tagger's words
limitations	The geometric crescent fits measure the size of the emitting region, not the size of the shadow itself, and may be biased. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. what this limits: every diameter quoted from the crescent fits: THEY MEASURE Quotation withheld	`limitations[2]`		the tagger's words
limitations	Physically very different theoretical models fit the data equally well, so a good fit does not select a preferred model. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. what this limits: any inference from goodness of fit to physics: ALTHOUGH THE FIT TO THE OBSERVATIONS IS EQUALLY GOOD IN THE THREE CASES, THEY REFER TO RADICALLY DIFFERENT PHYSICAL SCENARIOS	`limitations[3]`		the tagger's words
limitations	The illustrative thin-ring model used to interpret the visibility amplitudes does not account for all features of the data. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. what this limits: the illustrative thin-ring model: IT IS ONLY ILLUSTRATIVE AND DOES NOT FIT ALL FEATURES IN THE DATA	`limitations[4]`		the tagger's words
limitations	The headline mass is an average across three different modelling methods, not a single measurement. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. what this limits: the mass value as one measurement: it is the average of geometric models, GRMHD models and image domain ring extraction	`limitations[5]`	1.0	the tagger's words
limitations	The ring diameter depends on which extraction method is used, and the paper gives a range for that reason. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. what this limits: a single ring-diameter value: the paper states the value depends on the extraction method and gives a range accordingly	`limitations[6]`	1.0	the tagger's words
limitations	The observed ring diameter tracks the mass only up to several other factors, including instrument resolution and the structure of the emitting region. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. what this limits: converting the observed diameter directly to a mass: it also depends on observing resolution, spin vector, inclination, and the size and structure of the emitting region	`limitations[7]`	1.0	the tagger's words
limitations	Only some exotic alternatives to a black hole are excluded, and the exclusion depends on an assumed maximum-mass prior. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. what this limits: the result as excluding alternatives to black holes generally: only some exotic compact objects are excluded, and that rests on the maximum mass prior	`limitations[8]`	1.0	the tagger's words
limitations	The distance to M87 is adopted from other work rather than measured here, and it enters the mass. Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. what this limits: the mass as independent of external inputs: the distance is adopted from three stellar population measurements reported elsewhere	`limitations[9]`	1.0	the tagger's words
controls	three independent imaging pipelines run on the same data, cross-compared against each other and against the two polarizations and the two frequency bands Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. eliminates: an artefact of one reduction chain - a ring produced by the algorithm rather than present in the sky. Three teams that never shared a pipeline have to agree before the image stands · outcome (stated by the tagger, no quotation): held	`controls[0]`	0.85	the tagger's words
controls	a Top-Set of imaging parameter combinations kept only if they BOTH fitted the observed data AND recovered accurate images from synthetic data with a known answer Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. eliminates: parameters tuned until the expected picture appears - the synthetic data has a ground truth, so a setting that flatters the real data but fails the known case is discarded · outcome (stated by the tagger, no quotation): held	`controls[1]`	0.85	the tagger's words
concepts	emission ring Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: emission ring	`concepts[5]`		the paper's words
concepts	photon ring Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: photon ring	`concepts[6]`		the paper's words
concepts	black hole shadow Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: black hole shadow	`concepts[7]`		the paper's words
concepts	maximum mass prior Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: maximum mass prior	`concepts[8]`		the paper's words
concepts	emitting regions Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: emitting regions	`concepts[9]`		the paper's words
concepts	shadows Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: shadows	`concepts[10]`		the paper's words
concepts	one-way causal boundary Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: one-way causal boundary	`concepts[11]`	0.95	the paper's words
concepts	Active galactic nuclei Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: Active galactic nuclei	`concepts[12]`	0.95	the paper's words
concepts	central bright regions Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: central bright regions	`concepts[13]`	0.95	the paper's words
concepts	low-luminosity active galactic nuclei Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: low-luminosity active galactic nuclei	`concepts[14]`	0.95	the paper's words
concepts	hot, tenuous accretion flows Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: hot, tenuous accretion flows	`concepts[15]`	0.95	the paper's words
concepts	photon capture radius Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: photon capture radius	`concepts[16]`	0.95	the paper's words
concepts	Schwarzschild radius Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: Schwarzschild radius	`concepts[17]`	0.95	the paper's words
concepts	unstable circular orbit Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: unstable circular orbit	`concepts[18]`	0.95	the paper's words
concepts	event horizon and light bending Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: event horizon and light bending	`concepts[19]`	0.95	the paper's words
concepts	dark “shadow” Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: dark “shadow”	`concepts[20]`	0.95	the paper's words
concepts	crescent Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: crescent	`concepts[21]`	0.95	the paper's words
concepts	Event Horizon Telescope Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: Event Horizon Telescope	`concepts[22]`	0.95	the paper's words
concepts	global VLBI array Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: global VLBI array	`concepts[23]`	0.95	the paper's words
concepts	complex visibilities Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: complex visibilities	`concepts[24]`	0.95	the paper's words
concepts	Fourier components Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: Fourier components	`concepts[25]`	0.95	the paper's words
concepts	inverse problem Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: inverse problem	`concepts[26]`	0.95	the paper's words
concepts	CLEAN Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: CLEAN	`concepts[27]`	0.95	the paper's words
concepts	inverse-modeling approach Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: inverse-modeling approach	`concepts[28]`	0.95	the paper's words
concepts	RML Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: RML	`concepts[29]`	0.95	the paper's words
concepts	forward-modeling approach Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: forward-modeling approach	`concepts[30]`	0.95	the paper's words
concepts	Top-Set Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: Top-Set	`concepts[31]`	0.95	the paper's words
concepts	geometric models Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: geometric models	`concepts[32]`	0.95	the paper's words
concepts	GRMHD simulations Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: GRMHD simulations	`concepts[33]`	0.95	the paper's words
concepts	turbulent, hot, magnetized disk Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: turbulent, hot, magnetized disk	`concepts[34]`	0.95	the paper's words
concepts	SANE accretion flows Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: SANE accretion flows	`concepts[35]`	0.95	the paper's words
concepts	MAD flows Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: MAD flows	`concepts[36]`	0.95	the paper's words
concepts	Standard and Normal Evolution Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: Standard and Normal Evolution	`concepts[37]`	0.95	the paper's words
concepts	Magnetically Arrested Disk Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: Magnetically Arrested Disk	`concepts[38]`	0.95	the paper's words
concepts	moderate dimensionless magnetic flux Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: moderate dimensionless magnetic flux	`concepts[39]`	0.95	the paper's words
concepts	geometric crescent models Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: geometric crescent models	`concepts[40]`	0.95	the paper's words
concepts	ring diameter Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: ring diameter	`concepts[41]`	0.95	the paper's words
concepts	null hypothesis of the Kerr metric Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: null hypothesis of the Kerr metric	`concepts[42]`	0.95	the paper's words
unhoused_relations	SANE accretion flows → Standard and Normal Evolution Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. SANE expands to Standard and Normal Evolution. Acronym-expansion fits none of the eight relation types.	`unhoused_relations[0]`	0.95	the tagger's words
unhoused_relations	MAD flows → Magnetically Arrested Disk Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. MAD expands to Magnetically Arrested Disk. Acronym-expansion fits none of the eight relation types.	`unhoused_relations[1]`	0.95	the tagger's words
senses	emission ring - the bright ring of radiation that appears alongside the dark shadow, and is what the instrument resolves Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[0]`	1.0	the tagger's words
senses	shadow - what the observed image is said to be consistent with, rather than what was directly measured Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[1]`	1.0	the tagger's words
senses	photon ring - the lensed orbit at the critical impact parameter, which supplies most of the radiation in the observed ring Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[2]`	1.0	the tagger's words
senses	Event horizon - one-way causal boundary in spacetime from which not even light escapes Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[3]`	0.95	the tagger's words
senses	Active galactic nucleus - central bright region that can outshine its host galaxy's stars Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[4]`	0.95	the tagger's words
senses	Low-luminosity AGN - local nucleus fed by a hot, tenuous, low-rate accretion flow Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[5]`	0.95	the tagger's words
senses	Photon-capture radius - critical radius larger than the Schwarzschild event-horizon radius Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[6]`	0.95	the tagger's words
senses	Photon ring - lensed feature produced at the unstable critical photon orbit Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[7]`	0.95	the tagger's words
senses	Dark shadow / bright emission ring - paired appearance caused by event horizon plus light bending Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[8]`	0.95	the tagger's words
senses	Crescent - ring appearance shaped by rapid rotation and relativistic beaming Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[9]`	0.95	the tagger's words
senses	Event Horizon Telescope - global 1.3-mm VLBI array for imaging M87* and Sgr A* shadows Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[10]`	0.95	the tagger's words
senses	Complex visibility - Fourier component of the sky brightness distribution at a sampled spatial frequency Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[11]`	0.95	the tagger's words
senses	Inverse problem - image reconstruction under-constrained by sparse EHT spatial-frequency sampling Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[12]`	0.95	the tagger's words
senses	CLEAN - inverse-modeling deconvolution of the interferometer point-spread function Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[13]`	0.95	the tagger's words
senses	RML - forward-modeling search favoring data-consistent smooth or compact images Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[14]`	0.95	the tagger's words
senses	Top-Set - cross-pipeline images consistently showing an asymmetric ring near 40 microarcseconds Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[15]`	0.95	the tagger's words
senses	GRMHD simulation - turbulent magnetized Kerr-disk model predicting a shadow and asymmetric emission ring Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[16]`	0.95	the tagger's words
senses	SANE flow - Standard and Normal Evolution accretion with moderate magnetic flux Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[17]`	0.95	the tagger's words
senses	MAD flow - Magnetically Arrested Disk comparison regime with stronger field and larger funnel Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[18]`	0.95	the tagger's words
senses	Geometric crescent model - direct visibility fit for ring diameter and fractional width Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[19]`	0.95	the tagger's words
senses	Kerr-metric null hypothesis - assumption that the M87* black hole is described by Kerr geometry Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`senses[20]`	0.95	the tagger's words
claim_relations	builds-on → general relativity (Kerr black hole shadow prediction) Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`claim_relations[0]`		the tagger's words
claim_relations	extends → Doeleman et al. 2012; Akiyama et al. 2015 (earlier 1.3 mm VLBI measurements of M87*) Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`claim_relations[1]`		the tagger's words
claim_relations	builds-on → Falcke et al. 2000a (prediction that a black hole shadow plus emission ring should be detectable with VLBI) Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`claim_relations[2]`		the tagger's words
concept_edges	photon ring —part-of→ emission ring Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. strength of the relation: 1 also in: photon ring · emission ring	`concept_edges[0]`		the tagger's words
concept_edges	emitting regions —distinct-from→ shadows Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. the relation itself is separately evidenced · strength of the relation: 1 · note: RE-GROUNDS the record's 'emission ring --distinct-from--> black hole shadow', whose span named neither endpoint. Endpoints are the words of the sentence that states the distinction; 'normalised' maps them onto the concepts the record already has. · the relation stated: what was measured is the size of the EMITTING REGION, not the size of the shadow also in: emitting regions · shadows	`concept_edges[2]`		the tagger's words
concept_edges	photon capture radius —distinct-from→ Schwarzschild radius Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. the relation itself is separately evidenced · strength of the relation: 1 · note: The paper explicitly states that the photon-capture radius is larger than the Schwarzschild radius. also in: photon capture radius · Schwarzschild radius	`concept_edges[3]`	0.95	the tagger's words
concept_edges	unstable circular orbit —causes→ photon ring Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. the relation itself is separately evidenced · strength of the relation: 1 · note: Photons on the unstable critical orbit are said to produce the lensed photon ring. also in: unstable circular orbit · photon ring	`concept_edges[4]`	0.95	the tagger's words
concept_edges	event horizon and light bending —causes→ dark “shadow” Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. the relation itself is separately evidenced · strength of the relation: 1 · note: The paper states that event horizon plus light bending leads to the dark shadow's appearance. also in: event horizon and light bending · dark “shadow”	`concept_edges[5]`	0.95	the tagger's words
concept_edges	event horizon and light bending —causes→ emission ring Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. the relation itself is separately evidenced · strength of the relation: 1 · note: The same unhedged mechanism is stated to lead to the accompanying bright emission ring. also in: event horizon and light bending · emission ring	`concept_edges[6]`	0.95	the tagger's words
concept_edges	CLEAN —is-a→ inverse-modeling approach Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. the relation itself is separately evidenced · strength of the relation: 1 · note: The paper explicitly states that CLEAN is an inverse-modeling approach. also in: CLEAN · inverse-modeling approach	`concept_edges[7]`	0.95	the tagger's words
concept_edges	RML —is-a→ forward-modeling approach Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. the relation itself is separately evidenced · strength of the relation: 1 · note: The paper explicitly states that RML is a forward-modeling approach. also in: RML · forward-modeling approach	`concept_edges[8]`	0.95	the tagger's words
concept_edges	SANE accretion flows —distinct-from→ MAD flows Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. the relation itself is separately evidenced · strength of the relation: 1 · note: The paper distinguishes the two regimes by magnetic flux, initial field strength, and funnel opening angle. also in: SANE accretion flows · MAD flows	`concept_edges[9]`	0.95	the tagger's words
content_tags	1.3 — EHT observing wavelength Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.quantities[0]`		the tagger's words
content_tags	42±3 — diameter of the bright emission ring Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.quantities[1]`		the tagger's words
content_tags	10:1 — ring brightness vs central depression Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.quantities[2]`		the tagger's words
content_tags	(6.5±0.7)e9 — derived central black-hole mass of M87 Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.quantities[3]`		the tagger's words
content_tags	4 — days over which the ring stayed stable Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.quantities[4]`		the tagger's words
content_tags	230 — observing frequency equivalent to 1.3 mm Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.quantities[5]`		the tagger's words
content_tags	the image matches the shadow of a Kerr black hole predicted by GR Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.findings[0]`		the tagger's words
content_tags	ring brightness asymmetry is explained by relativistic beaming Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.findings[1]`		the tagger's words
content_tags	the result is powerful evidence for supermassive black holes in galaxy centers Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.findings[2]`		the tagger's words
content_tags	the ring diameter scales with the capture radius and so with the black hole's mass, but also depends on observing resolution, spin, inclination and the emitting region Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above.	`content_tags.findings[3]`		the tagger's words
content_tags	projected diameter Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: projected diameter	`content_tags.variables[0]`		the tagger's words
content_tags	central mass Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. about this quote: THE NUMBER IN THIS QUOTE IS CORRUPTED IN THE STAGED TEXT AND THE TRUE VALUE IS NOT WHAT IT READS. The superscript was flattened into the line: the paper says 6.5 x 10^9 solar masses and the staged text says 'x 109'. 'Me' is 'M_sun' with the solar-mass symbol rendered as an 'e', and each '\uf0a0' is a private-use non-breaking space. The quote was previously cut at 'mass of M', immediately before the value - extended here so the phrase is complete, and annotated because a variables tag that carries a wrong number silently is worse than one that carries none. Repair needs the source PDF. also in: central mass	`content_tags.variables[1]`		the tagger's words
content_tags	photon capture radius Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: photon capture radius	`content_tags.variables[2]`		the tagger's words
content_tags	impact parameter b Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: impact parameter b	`content_tags.variables[3]`		the tagger's words
content_tags	event horizon Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: event horizon	`content_tags.definitions[0]`		the tagger's words
content_tags	dark shadow Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: dark shadow	`content_tags.definitions[1]`		the tagger's words
content_tags	Event Horizon Telescope Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: Event Horizon Telescope	`content_tags.definitions[2]`		the tagger's words
content_tags	active galactic nuclei (AGNs) Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: active galactic nuclei (AGNs)	`content_tags.definitions[3]`		the tagger's words
content_tags	Bayesian Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: Bayesian	`content_tags.statistics[0]`		the tagger's words
content_tags	correlation Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: correlation	`content_tags.statistics[1]`		the tagger's words
content_tags	hypothesis-testing Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. about this quote: THE QUOTE CONTINUES A SENTENCE THAT THIS COPY CUTS IN TWO - a page footer stands between it and the words it follows, which read 'Third, because'. also in: hypothesis-testing	`content_tags.statistics[2]`		the tagger's words
content_tags	mean Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: mean	`content_tags.statistics[3]`		the tagger's words
content_tags	median Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. about this quote: THE QUOTE CONTINUES A SENTENCE THAT THIS COPY CUTS IN TWO - the caption of Figure 1 and a page footer stand between it and the words it follows, which read 'Weather was uniformly good to excellent with nightly'. also in: median	`content_tags.statistics[4]`		the tagger's words
content_tags	null-hypothesis Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. about this quote: THE QUOTE CONTINUES A SENTENCE THAT THIS COPY CUTS IN TWO - a page footer stands between it and the words it follows, which read 'Third, because'. also in: null-hypothesis	`content_tags.statistics[5]`		the tagger's words
content_tags	variance Quotation withheld — this record is not cleared for redistribution. The sentence is in the paper at the link above. also in: variance	`content_tags.statistics[6]`		the tagger's words

Interpretive choices

Tags that could not be placed in the text:

none — every tag was located in the text

What was deliberately not tagged, and why, is recorded per paper by the tagger. Where a paper has no such record, this page says so rather than implying that nothing was declined.