The MACHO Project: Microlensing Results from 5.7 Years of LMC Observations

A.B. Tomaney; A.C. Becker; A.J. Drake; B.A. Peterson; C.A. Nelson; C.W. Stubbs; D. Minniti; D.P. Bennett; D.R. Alves; D. Welch

REVIEW

The MACHO Project: Microlensing Results from 5.7 Years of LMC Observations

Astrophysics · Submitted 15 Jan 2000 · 55 references

Pith's verdict: The paper that killed the all-MACHO halo; the core arithmetic holds, and the main things to watch are presentational — statistical-only error bars sitting next to a 20–30% systematic, and a supernova rejection made without spectra.

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arXiv IDastro-ph/0001272 (version 1)

Pith IDVPNWR2VC, Pith's permanent record of this paper and its review

CitationA.B. Tomaney, A.C. Becker, A.J. Drake, B.A. Peterson, C.A. Nelson, C.W. Stubbs, D. Minniti, D.P. Bennett, D.R. Alves, D. Welch, K.C. Freeman, K. Griest, K.H. Cook, M. Geha, M.J. Lehner, M.R. Pratt, N. Dalal, P.J. Quinn, P. Popowski, R.A. Allsman, S.L. Marshall, The MACHO Collaboration: C. Alcock, T.S. Axelrod, T. Vandehei, W. Sutherland. "The MACHO Project: Microlensing Results from 5.7 Years of LMC Observations." arXiv:astro-ph/0001272 (2000). https://pith.science/paper/VPNWR2VC

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Editor's note

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Bottom line: this is the paper that closed out the 100% MACHO halo, and the arithmetic behind that claim survives scrutiny. The 5.7-year sample, the revised optical depth of 1.2e-7, the supernova-background treatment, and the merged lightcurves for the six previously split fields are all genuinely new relative to A97. The exclusion of f=1 at 95% CL for standard halos is the durable result, and it is not fragile to the things people will worry about first. Worth your time if you work on Galactic dark matter; skim it if you don't, but cite it either way — it's the benchmark LMC number for the next decade of the field. Send it to referees; it deserves the attention and the authors clearly want the scrutiny. I'd bring it to reading group for the supernova-rejection section alone, which is a nice worked example of a background nobody had taken seriously before. Yes, I'd cite it. Yes, the thinking is honest — the authors go out of their way in §6.1.2 to explain why their own number dropped by a factor of two, which most groups would have buried. The soft spots are real but mostly presentational. Tables 8, 9, and 12 give statistical-only intervals while the abstract quotes 'an additional 20% to 30% of systematic error' separately; a reader who lifts '8% to 50%' will not realize the dominant systematic is excluded from that range. The stars-per-object normalization of 10.84 ± 2.4 scales τ and f directly and is listed first in the error budget but never folded into the quoted contours. Eight lightcurves are discarded as supernovae on template fits with no spectra, and the galaxy identifications are called subjective in the paper itself — the direction is conservative, but it is a judgment call. Event 22 is the single largest contributor to τ and sits in set B but not set A, which moves the MACHO mass between roughly 0.5 and 0.7 solar masses. The efficiency method lives in a companion paper listed as submitted, which is a real dependency for a load-bearing number. One correction to the stress-test note: the apparent 1.8× inconsistency between §6.2.1's '100 events at 100% efficiency' and Table 12's N_exp(f=1) ≈ 46 is not an internal contradiction. The two reconcile at a mean efficiency near 0.35, which is what Figure 5 shows around t̂ ≈ 100 days for m = 0.6. The note's 0.2 estimate looks eyeballed too low. Still, the paper should print the effective mean efficiency explicitly so nobody has to reconstruct it.

Referee report

Significance

This is the definitive statement of the LMC microlensing anomaly at the time of writing, and the methodological care is well above the norm for the era: two independently developed selection criteria whose differing event counts are compensated by their differing efficiencies, an explicit error budget (Table 10), a Monte Carlo efficiency built on artificial stars 2.5 magnitudes fainter than in the earlier analysis, and a new and reusable background control in the form of SN Ia template fits. The result is falsifiable in several independent ways, and the paper tests all of them: the u_min distribution (Fig. 6), the CMD positions (Fig. 7), and the spatial distribution (Fig. 8). The exclusion of a 100% MACHO halo, if it survives the points below, is a genuinely new and important bound, and the candid downward revision by a factor of two relative to A97 is handled well.

Major objections (6)

[§6.2.1 and Table 12] §6.2.1 states that for a 100% MACHO halo of mass m the expected number of events at unit efficiency is ≈100(m/M⊙)^-0.5, i.e. ≈129 for m = 0.6 M⊙; folding in the Figure 5 efficiency of order 0.2 gives ≈26 events at f = 1. Table 12 (Model S/13, no LMC halo) instead reports N_exp(MW) = 9.6 at f = 0.21, which scales to ≈46 at f = 1. The two routes to the same quantity differ by a factor of about 1.8, and the strength of the headline 95% exclusion of a 100% halo depends on which is correct. Please reconcile them explicitly, stating whether the Table 12 column is the efficiency-folded number of detected events or the number of events before efficiency, and give the implied N_exp(f = 1) for each model.
[§3.3.2 and Table 6] §3.3.2 estimates 2-6 SN interlopers in the data set, yet the Δχ²_SN-ML > 0 cut removes 8 events from set B (10, 11, 12, 16, 17, 19, 24, 26) and 2 from set A. Several removed events sit close to the threshold (event 19 at Δχ² = -3.1), as do several retained ones (event 8 at +28, event 20 at +23.9, event 15 at +45.6), so the classification is decided by a hard cut on a quantity with no stated uncertainty. Please quantify how τ and f change if the borderline events are treated as uncertain rather than as supernovae, and note that the stated <0.7% efficiency loss applies to symmetric standard microlensing events, whereas the events most at risk from this cut are precisely the asymmetric ones.
[Abstract, Tables 8, 9, 12] The 95% CL interval '8% to 50%' in the abstract and the intervals in Tables 8, 9, and 12 are statistical only. Table 10 lists the (S/O)(V<24) = 10.84 ± 2.4 normalization as a 20% systematic, and since E(t̂) = (S/O)·E_stars(t̂) in Eq. 1, τ and f scale inversely with it; a 20% shift moves the central value of f by 20% without moving the quoted interval. The abstract does state 'an additional 20% to 30% of systematic error', so this is acknowledged rather than hidden, but a reader quoting the 8-50% range will not know that it excludes the dominant systematic. Please state explicitly which intervals include systematics and, where feasible, give a combined interval. The MACHO mass is not affected in the same way, since it is set by the shape of the t̂ distribution rather than by its normalization.
[Table 3 versus Table 4] Table 4 reports blended fits that are unconstrained for at least two retained events: event 5 has A_max = 1.2×10^7 and t̂ = 109.8 d against the unblended 47.28 and 75.6 d in Table 3, and event 27 has t̂ = 3247 d and A_max = 258.9 against 50.5 d and 1.45. §5.2 acknowledges the A_max/blend degeneracy, but the paper does not say how t̂_st and τ1 (Table 7) are obtained when the blended fit is unphysical. Since events 5 and 27 contribute 8.3 and 4.9 (×10^-9) to τ, please state the procedure and confirm that these contributions are insensitive to it.
[§4] The detection efficiency is the single most load-bearing ingredient in τ, and §4 defers its derivation to Alcock et al. (2000a), listed as 'submitted to ApJ Suppl', and to Vandehei (2000), a PhD thesis. The present paper gives the curve (Fig. 5) and the normalization, but not the derivation of (S/O)(V<24) = 10.84 ± 2.4 from three HST fields plus ground-based photometry, nor the justification for the 20% error estimate. Since τ ∝ 1/(S/O), please summarize that derivation here, at least to the level needed to judge the 20% figure.
[§6.3] For the LMC-halo-only model §6.3 reports f = 1.35 (+0.6/-0.4) for set A and 1.52 (+0.6/-0.4) for set B. A MACHO fraction greater than unity lies outside the physical domain of the model as parameterized, which means the model cannot reproduce the data with any admissible halo fraction rather than that it supplies a viable alternative. The paper presents this branch as a possible non-dark-matter explanation without commenting on the unphysical best fit. Please discuss what f > 1 implies for the LMC-halo interpretation.

Minor objections (8)

[Abstract versus §6.3] The abstract says a 100% MACHO halo is ruled out 'for all except our most extreme halo model', while §6.3 says 'Even for the rather extreme model F, and no LMC halo, a 100% MACHO halo is ruled-out'. These two statements should be made consistent, and the Model F upper limit on f should be quoted explicitly.
[§4 and Table 7] The blending correction to t̂ is 20-30% in size for most events (e.g. event 22 from 229.3 to 297.8 d, event 27 from 50.5 to 65.6 d), yet §4 assigns it a 3% uncertainty. Since τ scales linearly with t̂, please justify that 3% given the size of the correction.
[Table 2] The selection-criteria table is difficult to parse: the 'Min. coverage' row mixes 'bmrN >= 7', 'rN > 0 & bN > 0', and '> 65 simul. baseline points' in a way that does not make clear which criterion uses which requirement. Please restructure it so that each column is unambiguous.
[§3.2] The counting of unique events is hard to follow: the text states 25 unique events from criteria B, including event 7 'duplicated via contamination', but event 7b does not appear in the final set B list. Please state explicitly whether 7b is counted anywhere in the efficiency or optical-depth sums.
[§5.3] A K-S probability of 2.4% (set B, disk+bar model) is described as 'mildly inconsistent' and as 'inconsistent at the 93% C.L.'; given 17 events and model-dependent predictions, the weaker phrasing would be more appropriate, or the 93% figure should be dropped.
[Table 1] The field numbering skips field 4 (it runs 3, 5, 6, ...). Please note why, or renumber, so that readers matching fields to earlier papers are not misled.
[References] Gould, Bahcall, & Flynn (1997) is given as ApJ, 486, 697, the same volume and page as Alcock et al. (1997a); Alves et al. (1999d) is cited in §6.2.2 but does not appear in the reference list; Rhie et al. (1999) and Tammann & Schröder (1990) appear in the list but are not cited in the text. There are also spelling errors in author names ('Guidice' for Giudice, 'Rosecherr' for Roscherr).
[§6.1.2] The accounting of the factor-of-two discrepancy with A97 (≈25% from the split top-6 fields, ≈10% from efficiency, ≈7% from the event 10 supernova) plus Poisson luck would be much easier to assess as a short table than as running text.

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The paper

The paper claims

Five and a half years of watching 11.9 million Large Magellanic Cloud stars turned up 13 to 17 microlensing events, three to five times more than known stars can explain, and the authors read the excess as a Milky Way dark halo that is only

The reading

The MACHO collaboration monitored 11.9 million stars in the Large Magellanic Cloud for 5.7 years, hunting for the brief, symmetric brightening a compact object produces when it drifts across a star's line of sight. They found 13 to 17 such events, where the known stars along the sightline should produce only 2 to 4. If that excess is real, something dark and compact is lensing LMC stars, and the size of the excess measures how much of the Milky Way's dark halo can be made of such objects. The paper argues for roughly 20 percent, with a 95 percent confidence range of 8 to 50 percent, and reports that a halo made entirely of compact objects is excluded for every model they consider except the most extreme. That turns a yes-or-no question about dark matter being compact into a quantitative budget, and leaves most of the dark matter as something else.

What carries the argument

The argument rests on a single estimator: $

Extended reading notes

Core claim

The measured microlensing optical depth toward the LMC, for events with $2 < t < 400$ days, is $1.$2^{{+0.4}}$_{-0.3}

Load-bearing premise

Every quoted optical depth, halo fraction, and lens mass scales inversely with one measured number: the ratio of true LMC stars to detected objects, taken as $10.84

Editorial extensions

If this is right

A dark halo made entirely of compact objects is excluded at 95 percent confidence for standard halo models, so the bulk of the Galaxy's dark matter must be non-compact.
The most likely lens mass, 0.15 to 0.9 solar masses depending on the halo model, sits above the brown dwarf limit and points toward white dwarfs or low-mass stars rather than very light objects.
The total mass in compact lenses within 50 kpc, about $9 \times 10^{10}$ solar masses, is several times the mass of all known stellar components of the Galaxy.
The events are spread across the fields rather than concentrated on the LMC bar, which disfavors LMC disk self-lensing and favors an extended Milky Way or LMC halo lens population.
Supernovae in galaxies behind the LMC are a real contaminant of microlensing samples, and eight candidate events are removed on that basis, so any future dark-matter claim from this technique has to model that background.

Reading between the lines

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

If the lenses sit in an undiscovered stellar halo around the LMC rather than in the Milky Way halo, that population should eventually appear as a kinematically distinct, metal-poor set of stars; the paper notes that no such population has been convincingly observed, which makes this the cheapest way to break the degeneracy.
A halo fraction near 20 percent in white dwarfs would predict a faint cooling sequence and a chemical-enrichment history that deep proper-motion and abundance surveys could check independently of microlensing.
Because the optical depth fell by a factor of two when the exposure grew by 3.4, the field is still limited by how many events happen to fall in the window; a longer baseline will shift the bottleneck from Poisson counting to the star-to-object normalization and the halo model.
The same estimator applied to the Small Magellanic Cloud, where LMC self-lensing is absent, would separate a Milky Way halo contribution from any LMC-bound lens population.

Original abstract

We report on our search for microlensing towards the Large Magellanic Cloud (LMC). Analysis of 5.7 years of photometry on 11.9 million stars in the LMC reveals 13 - 17 microlensing events. This is significantly more than the $\sim$ 2 to 4 events expected from lensing by known stellar populations. The timescales ($\that$) of the events range from 34 to 230 days. We estimate the microlensing optical depth towards the LMC from events with $2 < \that < 400$ days to be 1.2 ^{+0.4}_ {-0.3} \ten{-7}$, with an additional 20% to 30% of systematic error. The spatial distribution of events is mildly inconsistent with LMC/LMC disk self-lensing, but is consistent with an extended lens distribution such as a Milky Way or LMC halo. Interpreted in the context of a Galactic dark matter halo, consisting partially of compact objects, a maximum likelihood analysis gives a MACHO halo fraction of 20% for a typical halo model with a 95% confidence interval of 8% to 50%. A 100% MACHO halo is ruled out at the 95% C.L. for all except our most extreme halo model. Interpreted as a Galactic halo population, the most likely MACHO mass is between $ 0.15 \msun$ and $ 0.9 \msun$, depending on the halo model, and the total mass in MACHOs out to 50 kpc is found to be 9+4-3 10^{10} msun, independent of the halo model. These results are marginally consistent with our previous results, but are lower by about a factor of two. Besides a larger data set, this work also includes an improved efficiency determination, improved likelihood analysis, and more thorough testing of systematic errors, especially with respect to the treatment of potential backgrounds to microlensing, such as supernovae in galaxies behind the LMC. [Abridged]

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, 8,649 input tokens.

What the abstract itself states, as probabilities: claims first 0.03 · states limitation 0.91 · human participants 0.01 · controlled comparison 0.35 · randomized assignment 0.01 · states quantitative result 0.99 · compares with prior results 0.98 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v1. Results and the main claim are underlined; show every role.

We report on our search for microlensing towards the Large Magellanic Cloud (LMC). Analysis of 5.7 years of photometry on 11.9 million stars in the LMC reveals 13 - 17 microlensing events. This is significantly more than the $\sim$ 2 to 4 events expected from lensing by known stellar populations. The timescales ($\that$) of the events range from 34 to 230 days. We estimate the microlensing optical depth towards the LMC from events with $2 < \that < 400$ days to be 1.2 ^{+0.4}_ {-0.3} \ten{-7}$, with an additional 20% to 30% of systematic error. The spatial distribution of events is mildly inconsistent with LMC/LMC disk self-lensing, but is consistent with an extended lens distribution such as a Milky Way or LMC halo. Interpreted in the context of a Galactic dark matter halo, consisting partially of compact objects, a maximum likelihood analysis gives a MACHO halo fraction of 20% for a typical halo model with a 95% confidence interval of 8% to 50%. A 100% MACHO halo is ruled out at the 95% C.L. for all except our most extreme halo model. Interpreted as a Galactic halo population, the most likely MACHO mass is between $ 0.15 \msun$ and $ 0.9 \msun$, depending on the halo model, and the total mass in MACHOs out to 50 kpc is found to be 9+4-3 10^{10} msun, independent of the halo model. These results are marginally consistent with our previous results, but are lower by about a factor of two. Besides a larger data set, this work also includes an improved efficiency determination, improved likelihood analysis, and more thorough testing of systematic errors, especially with respect to the treatment of potential backgrounds to microlensing, such as supernovae in galaxies behind the LMC. [Abridged]

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#	sentence	role	the authors' own work	states the main conclusion	strength
s0	We report on our search for microlensing towards the Large Magellanic Cloud (LMC).	contribution 0.99	0.94	0.02	asserted 0.69
s1	Analysis of 5.7 years of photometry on 11.9 million stars in the LMC reveals 13 - 17 microlensing events.	result 0.97	0.97	0.14	asserted 1.00
s2	This is significantly more than the $\sim$ 2 to 4 events expected from lensing by known stellar populations.	result 0.84	0.66	0.15	asserted 1.00
s3	The timescales ($\that$) of the events range from 34 to 230 days.	result 1.00	0.92	0.02	asserted 1.00
s4	We estimate the microlensing optical depth towards the LMC from events with $2 < \that < 400$ days to be 1.2 ^{+0.4}_ {-0.3} \ten{-7}$, with an additional 20% to 30% of systematic error.	result 1.00	0.97	0.10	asserted 0.99
s5	The spatial distribution of events is mildly inconsistent with LMC/LMC disk self-lensing, but is consistent with an extended lens distribution such as a Milky Way or LMC halo.	result 0.56	0.93	0.07	hedged possibility 0.79
s6	Interpreted in the context of a Galactic dark matter halo, consisting partially of compact objects, a maximum likelihood analysis gives a MACHO halo fraction of 20% for a typical halo model with a 95% confidence interval of 8% to 50%.	interpretation 0.73	0.95	0.64	asserted 0.77
s7	A 100% MACHO halo is ruled out at the 95% C.L. for all except our most extreme halo model.	result 0.82	0.93	0.14	asserted 1.00
s8	Interpreted as a Galactic halo population, the most likely MACHO mass is between $ 0.15 \msun$ and $ 0.9 \msun$, depending on the halo model, and the total mass in MACHOs out to 50 kpc is found to be 9+4-3 10^{10} msun, independent of the halo model.	result 0.52	0.97	0.22	asserted 0.88
s9	These results are marginally consistent with our previous results, but are lower by about a factor of two.	result 0.62	0.68	0.06	hedged possibility 0.87
s10	Besides a larger data set, this work also includes an improved efficiency determination, improved likelihood analysis, and more thorough testing of systematic errors, especially with respect to the treatment of potential backgrounds to microlensing, such as supernovae in galaxies behind the LMC. [Abridged]	contribution 0.58	0.93	0.03	asserted 0.99

What kind of paper the classifier reports this is: empirical study 1.00 · evidence from observation or experiment 0.71.

What was examined, and what was not

sources read

arXiv listing abstract v1

not examined

full text
figures and tables
references and citing sentences
relations to other papers

levels run

P abstract

not run

S sections
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C citations
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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

Figures

**Figure 1.** — An R-band image of the LMC, 8.2 degrees on a side (G. Bothun, private communication), showing the locations of the 30 MACHO fields used here. Also shown are the locations of the 17 microlensing candidates discussed in the text

**Figure 2.** — Illustration of the cuts used to select microlensing candidate

**Figure 3.** — Illustration of the cuts used to select microlensing candidate

**Figure 4.** — The lightcurves for the 29 candidates (25 stars) in

**Figure 5.** — Microlensing detection efficiency (normal

**Figure 6.** — The upper (lower) panel shows the cumula

**Figure 7.** — Candidate microlensing events. The open circles indicate the p

**Figure 8.** — The upper (lower) panel shows the cumula

**Figure 10.** — Measured microlensing optical depth is

**Figure 11.** — Measured microlensing optical depth is

**Figure 12.** — Likelihood contours for MACHO mass m and halo fraction f for Model S which has a typical size halo. See A96 for details of the model. The plus sign shows the maximum likelihood estimate and the contours enclose regions of 68%, 90%, 95%, and 99% probability. The panels are labeled according to which set of selection criteria (A or B) is used, and whether or not an LMC halo with MACHO fraction f is included. 51

**Figure 13.** — Likelihood contours for MACHO mass m and halo fraction f for Model B which has a very large dark halo. See A96 for details of the model. The plus sign shows the maximum likelihood estimate and the contours enclose regions of 68%, 90%, 95%, and 99% probability. The panels are labeled according to which set of selection criteria (A or B) is used, and whether or not an LMC halo with MACHO fraction f is included

Showing 12 of the paper's 13 figures. See all figures in the PDF ↗ Figures reproduced from arXiv:astro-ph/0001272 by the authors.

References

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Weinberg, M., submitted to ApJ (astro-ph/9905305)

View on Pith Pith review arXiv
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Woods, E., & Loeb, A., 1998, ApJ, 508, 760

View on Pith 1998

Forward citations

Cited by 45 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

On Bimodality in the Eccentricity Distribution of Galactic Double Neutron Stars
astro-ph.SR 2026-07 conditional novelty 7.0 of 10

A broken neutron-star remnant mass relation plus weak ultra-stripped supernova kicks can reproduce the apparent eccentricity gap in Galactic double neutron stars.
Dust stars in the minimal exponential measure model
gr-qc 2025-05 conditional novelty 7.0 of 10

Dust can form stable horizonless compact objects in the MEMe modified gravity model, offering a dark matter candidate and a mechanism that suppresses black hole formation below about 10^-11 solar masses.
Primordial Black Hole Dark Matter and the LIGO/Virgo observations
astro-ph.CO 2020-06 conditional novelty 7.0 of 10

Three-body interactions in primordial black hole clusters suppress the predicted solar-mass merger rate by roughly five orders of magnitude, so QCD-era PBHs may still constitute all dark matter without violating LIGO/...
Structure Formation and Exotic Compact Objects in a Dissipative Dark Sector
hep-ph 2018-12 conditional novelty 7.0 of 10

A two-particle dissipative dark sector fragments into compact objects spanning a few to millions of solar masses, with mass and compactness calculable from the dark-electron mass, dark-photon mass, and dark fine-struc...
Poisson Clustering and Seed Effect of PBHs: Implications for Microlensing, Gravitational Waves, Little Red Dots and Ultra-Faint Dwarf Galaxies
astro-ph.CO 2026-10 conditional novelty 6.0 of 10

Poisson and seed clustering of primordial black holes with an extended mass function can produce structures that resemble ultra-faint dwarf galaxies, little red dots, and account for gravitational-wave merger rates, p...

Show 40 more citing papers

Primordial Asymmetries, Primordial Equation of State & Primordial Black Holes
astro-ph.CO 2026-08 conditional novelty 6.0 of 10

Lepton flavour asymmetries alter the early-universe equation of state, reshaping the predicted primordial black hole mass spectrum and favouring a spectral index n_s <= 0.99 in current gravitational-wave merger data.
Self-gravitating quantum stars with a globally relevant Bohm potential
hep-th 2026-05 conditional novelty 6.0 of 10

The equilibrium radius of self-gravitating dark fermion stars is determined by the fermion mass once the total mass is given, with the Bohm potential supplying outward pressure for heavier species and inward tension f...
Primordial Black Hole from Tensor-induced Density Fluctuation: First-order Phase Transitions and Domain Walls
astro-ph.CO 2026-05 unverdicted novelty 6.0 of 10

Tensor perturbations from FOPT and domain-wall sources are claimed to induce second-order scalar perturbations large enough to form primordial black holes, potentially all of the dark matter.
Simulations of PBH formation at the QCD epoch and comparison with the GWTC-3 catalog
astro-ph.CO 2022-09 conditional novelty 6.0 of 10

Simulating primordial black hole formation with the time-varying QCD equation of state lowers and broadens the predicted peak near one to three solar masses, and the resulting merger rates are broadly compatible with ...
Stellar Disruption of Axion Miniclusters in the Milky Way
astro-ph.GA 2020-11 conditional novelty 6.0 of 10

Monte Carlo simulations show stellar encounters destroy most axion miniclusters in the inner Milky Way, while roughly half to nearly all survive at the Solar radius depending on the assumed internal density profile.
Evidence for primordial black hole dark matter from LIGO/Virgo merger rates
astro-ph.CO 2020-07 conditional novelty 6.0 of 10

Primordial black holes formed during the QCD epoch, if they constitute all dark matter, would merge in clusters at rates comparable to those LIGO/Virgo has observed.
Early Structure Formation in $\Lambda$PBH Cosmologies
astro-ph.CO 2019-07 conditional novelty 6.0 of 10

Mixed primordial-black-hole and particle dark matter simulations from the radiation era to redshift 99 show that halo abundances follow Poisson statistics and that induced black-hole velocities are too small to change...
Revisiting constraints on asteroid-mass primordial black holes as dark matter candidates
astro-ph.CO 2019-06 accept novelty 6.0 of 10

A reanalysis of microlensing, stellar capture, and white dwarf ignition constraints finds that none excludes primordial black holes in the asteroid-mass window from making up all of the dark matter.
Constraints on Earth-mass primordial black holes from OGLE 5-year microlensing events
astro-ph.CO 2019-01 conditional novelty 6.0 of 10

Earth-mass primordial black holes at roughly one percent of the dark matter abundance can reproduce the six ultrashort OGLE microlensing events, and the same dataset sets the tightest upper bound on primordial black h...
CMB bounds on disk-accreting massive Primordial Black Holes
astro-ph.CO 2017-07 conditional novelty 6.0 of 10

If accretion disks form around stellar-mass primordial black holes in the dark ages, CMB data exclude them as the dominant dark matter above roughly 2 solar masses, about two orders of magnitude stronger than spherica...
Hunting for Dark Particles with Gravitational Waves
hep-ph 2016-05 conditional novelty 6.0 of 10

LIGO at design sensitivity could probe dark bosons in the 60 MeV to 3 GeV range and dark fermions in the 0.1 to 2 GeV range, if such particles form solar-mass exotic compact objects.
A Comprehensive Search for Dark Matter Annihilation in Dwarf Galaxies
astro-ph.CO 2014-10 accept novelty 6.0 of 10

No gamma-ray excess appears in a joint analysis of 20 Milky Way dwarf galaxies, and the resulting cross section limits fall below the thermal relic value for dark matter masses below roughly 26 to 35 GeV in the quark ...
OGLE-2013-BLG-1125/MOA-2013-BLG-584: Discovery of a gas giant orbiting an M dwarf
astro-ph.EP 2026-10 conditional novelty 5.0 of 10

A Saturn-mass planet of about 105 Earth masses orbits a 0.14 solar-mass M dwarf about 1 kpc away, discovered through gravitational microlensing.
Primordial Black Holes from Supercooled Phase Transitions
hep-ph 2023-05 conditional novelty 5.0 of 10

Supercooled first-order phase transitions lasting more than about 15% of a Hubble time (beta/H <~ 7) should produce primordial black holes in observable numbers, independent of how long the supercooling lasts.
Voyager 1 $e^\pm$ Further Constrain Primordial Black Holes as Dark Matter
astro-ph.HE 2018-07 conditional novelty 5.0 of 10

Voyager 1 measurements of low-energy cosmic-ray electrons and positrons limit primordial black holes below 10^16 grams to under 0.1% of the Galactic dark matter.
Primordial black holes with an accurate QCD equation of state
astro-ph.CO 2018-01 conditional novelty 5.0 of 10

The QCD equation of state softening boosts primordial black hole formation around one solar mass by at least two orders of magnitude, peaking near 0.7 solar masses.
Seven Hints for Primordial Black Hole Dark Matter
astro-ph.CO 2017-11 conditional novelty 5.0 of 10

Seven cosmic anomalies are argued to converge on dark matter made of primordial black holes with a lognormal mass spectrum peaked near three solar masses.
Understanding caustic crossings in giant arcs: characteristic scales, event rates, and constraints on compact dark matter
astro-ph.CO 2017-09 conditional novelty 5.0 of 10

A point-mass lens embedded in a cluster's magnification field explains the Icarus transient as a magnified blue supergiant and excludes compact dark matter above roughly 10 percent of the mass for lens masses between ...
Primordial black hole constraints for extended mass functions
astro-ph.CO 2017-05 accept novelty 5.0 of 10

Widening the primordial black hole mass spectrum tightens rather than relaxes the observational limits on their share of dark matter, leaving at most about 10 percent once all bounds are counted.
Primordial Black Holes as Dark Matter
astro-ph.CO 2016-07 conditional novelty 5.0 of 10

Primordial black holes can still supply all the dark matter in two mass windows, but only if their mass spectrum is extended and tuned to slip between the lensing and dynamical bounds.
A History of Dark Matter
astro-ph.CO 2016-05 accept novelty 5.0 of 10

The acceptance of dark matter was a decades-long convergence of cluster dynamics, galaxy rotation curves, nucleosynthesis bounds, and particle theory, not a single discovery by Zwicky or Rubin.
Asymmetric Dark Matter Stars
hep-ph 2015-07 conditional novelty 5.0 of 10

Fermionic asymmetric dark matter with Yukawa self-interactions can form compact stars whose maximum stable mass ranges from about 10^-18 to order one solar mass, depending on whether the force is attractive or repulsive.
New cosmological constraints on primordial black holes
astro-ph.CO 2009-12 accept novelty 5.0 of 10

Updated big-bang-nucleosynthesis and gamma-ray-background limits on the primordial black hole abundance dominate the mass range 10^9 to 10^17 g, except near 10^13 to 10^14 g where cosmic microwave background damping i...
WIMP Annihilation and Cooling of Neutron Stars
astro-ph 2007-08 conditional novelty 5.0 of 10

WIMP annihilation inside a neutron star can balance photon cooling and flatten the star's internal temperature at roughly 10^4 K for ages beyond 10 million years.
Dark Matter from new Technicolor Theories
hep-ph 2006-08 conditional novelty 5.0 of 10

The lightest neutral technibaryon in a minimal walking technicolor model can account for 10 to 65 percent of dark matter, with a mass around 1.4 to 3.3 TeV, if its asymmetry tracks the baryon asymmetry.
Primordial Black Hole Triggered Type Ia Supernovae II: Comparison with Supernova Remnants and Galactic Chemical Evolution
astro-ph.HE 2026-06 unverdicted novelty 4.0 of 10

PBH-triggered SN Ia models across metallicities match some observed light curves and remnants, constrain the explosion channel fraction via chemical evolution modeling, and indicate PBHs as a potentially major early-u...
The Dark Dimension, the Swampland, and the Dark Matter Fraction Composed of Primordial Black Holes
hep-th 2022-06 conditional novelty 4.0 of 10

If the universe has a single micron-scale extra dimension, primordial black holes evaporate more slowly, extending the all-dark-matter mass window down to 10^14 grams.
Generalised constraints on the curvature perturbation from primordial black holes
astro-ph.CO 2009-03 accept novelty 4.0 of 10

Primordial black hole abundance limits constrain the amplitude of the primordial curvature power spectrum to roughly 10^-2 to 10^-1 across a wide range of small scales.
Primordial black hole constraints with Hawking radiation -- a review
astro-ph.CO 2022-06 accept novelty 3.0 of 10

A comprehensive review of how Hawking evaporation of primordial black holes converts into abundance constraints, covering baryogenesis, BBN, the CMB, diffuse photon and neutrino backgrounds, cosmic rays, and final bursts.
Primordial Black Holes as Dark Matter: Recent Developments
astro-ph.CO 2020-06 unverdicted novelty 3.0 of 10

Primordial black holes in specific mass ranges could account for some or all dark matter while resolving structure-formation and seed problems in standard cosmology.
Primordial Black Holes - Perspectives in Gravitational Wave Astronomy -
astro-ph.CO 2018-01 accept novelty 3.0 of 10

Gravitational-wave observations of binary black hole mergers provide a new, independent probe of primordial black holes, complementing electromagnetic searches.
Massive Primordial Black Holes as Dark Matter and their detection with Gravitational Waves
astro-ph.CO 2017-02 conditional novelty 3.0 of 10

Primordial black holes with a broad mass spectrum peaking near tens of solar masses could account for the dark matter and for LIGO's unexpectedly heavy merging black holes.
Is there a new physics between electroweak and Planck scales?
hep-th 2007-08 conditional novelty 3.0 of 10

The paper argues that the Standard Model plus three sub-electroweak singlet fermions and a light inflaton can explain neutrino masses, dark matter, baryon asymmetry, and inflation without any new scale between the wea...
Stellar microlensing surveys as a probe of Primordial Black Holes: status and prospects
astro-ph.GA 2026-02 unverdicted novelty 2.0 of 10

Stellar microlensing surveys exclude compact objects between 10^{-11} and 10^4 solar masses from making up all dark matter under standard assumptions.
Dark Matter
hep-ph 2024-06 unverdicted novelty 2.0 of 10

A review summarizing current observational, experimental, and theoretical results on dark matter.
Cosmology and Fundamental Physics with the Euclid Satellite
astro-ph.CO 2016-06 accept novelty 2.0 of 10

Euclid's weak lensing and galaxy clustering surveys are forecast to pin the dark energy equation of state to about one percent and to test modified gravity, neutrino mass, and primordial non-Gaussianity.
Dark matter direct-detection experiments
physics.ins-det 2015-09 conditional novelty 2.0 of 10

Direct dark matter detection has improved by many orders of magnitude in cross-section sensitivity with no confirmed WIMP signal, and liquid xenon now leads at high mass while low-threshold bolometers lead below 10 GeV.
Mirror dark matter: Cosmology, galaxy structure and direct detection
astro-ph.CO 2014-01 conditional novelty 2.0 of 10

Mirror dark matter with kinetic mixing near 10^-9 is presented as a single-parameter framework that can reproduce early-universe cosmology, spiral-galaxy halo scaling relations, and several direct-detection anomalies.
Formation of Supermassive Black Holes
astro-ph.CO 2010-03 conditional novelty 2.0 of 10

The formation mechanism of massive black hole seeds remains unknown, but three channels (Population III remnants, direct gas collapse, and runaway stellar collisions) are viable and future gravitational-wave and infra...
Non-Baryonic Dark Matter - Observational Evidence and Detection Methods
hep-ph 2000-02 accept novelty 2.0 of 10

Observations require a non-baryonic dark matter component at roughly 20 to 40 percent of the critical density, and the leading particle candidates are axions, supersymmetric neutralinos, and massive neutrinos.

How later papers used it

161 later papers cite it

Evidence: substantial. 156 of the citing papers share no author with it, and 24 of those carry a confident label from Pith's citation classifier.

Pith read 22 of the 228 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

1 later paper by other authors is listed below: 1 used its data or values.

Uses its data or values 1 of 22 papers with this label

We update the microlensing constraints from the EROS-2 LMC bright stars sample [ref] and the MACHO Collaboration 5.7 year results [ref] , and summarise our updated constraints in table [ref].

Updating the MACHO fraction of the Milky Way dark halo with improved mass models (2018) · Summary · 0.96

How the literature uses it

86 arXiv papers cite this in 139 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 · 96 sentences without a confident label

Contests it 3 papers

Although the new Milky Way rotation curves were clearly incompatible with the standard flat rotation model adopted by [ref] , they were nonetheless noisy, with unexpected departures from a smooth profile which suggested possible artefacts in the data.

Reanalysis of the MACHO constraints on PBH in the light of Gaia DR3 data · Introduction · contest 0.86
Early indications from the MACHO collaboration that a significant fraction of the Milky Way halo could be in the form of roughly Solar Mass COs [ref] were not confirmed by EROS [ref] and OGLE [ref] .

Stellar microlensing surveys as a probe of Primordial Black Holes: status and prospects · Summary · contest 0.79
The MACHO collaboration studied microlensing events towards the Large Magellanic Cloud (LMC) and initially reported evidence that MACHOs of mass $(0.15-0.9)$ M$_⊙$ comprise (8-50) % of the total halo DM [ref] , but it was later found that their dataset was contaminated by variable stars [ref] .

Constraining galactic structures of mirror dark matter · Gravitational lensing · contest 0.86

Uses its method or tool 1 paper

Surveys with a large exposure expect to observe events due to stars in the MW disc and/or LMC, and in this case constraints on the CO mass and halo fraction are calculated using the likelihood [ref] : [equation] where $N_obs$ is the number of observed events and $t̂_i$ are their timescales.

Stellar microlensing surveys as a probe of Primordial Black Holes: status and prospects · Differential event rate and parameter constraints · 0.95

Uses its data or values 16 papers

The results of this survey are well known [ref] , and include the detection of some 13 unambiguous microlensing events, identified as solar mass compact bodies.

Reanalysis of the MACHO constraints on PBH in the light of Gaia DR3 data · Introduction · 0.86
For the LMC dark halo, Refs. [ref] take $ρ_0 = 0.0223 / pc^3$ and $a=2$.

Tests of Dark MACHOs: Lensing, Accretion, and Glow · Optical depth and microlensing constraints · 1.00
There was no known motivation at the time of [ref] to seek light curves of longer duration.

Remarks on Dark Matter Constituents with Many Solar Masses · Introduction · 0.90

Compares with it 1 paper

This is consistent with the results of MACHO collaboration [ref] .

Spontaneous Mirror Parity Violation, Common Origin of Matter and Dark Matter, and the LHC Signatures · Higgs Potential and Spontaneous Symmetry Breaking · 0.95

Cites it as support 1 paper

The detection of several microlensing events at LMC (Large Magellanic Cloud) is possibly another significant evidence of baryonic DM in the Milky Way galaxy [ref] .

Compact objects and dark matter dynamics in astroparticle physics · Nature of Dark Matter · 0.97

Cites it as background 16 papers

Surveys such as the Expérience de Recherche d’Objets Sombres (EROS) [ref] , the MAssive Compact Halo Objects (MACHO) [ref] , the Optical Gravitational Lensing Experiment (OGLE) [ref] , and the Microlensing Observations in Astrophysics (MOA) [ref] collaborations play pivotal roles in these constraint efforts.

Axion star condensation around primordial black holes and microlensing limits · Introduction · 0.84
In the years following the publication of the MACHO results [ref] , a number of groups set out to make direct measurements of the the Milky Way rotation curve using observations of velocity dispersion in samples of halo star populations.

Reanalysis of the MACHO constraints on PBH in the light of Gaia DR3 data · Introduction · 0.94
Key backgrounds are supernovae in background galaxies and variable stars [ref] .

Stellar microlensing surveys as a probe of Primordial Black Holes: status and prospects · General principles · 0.82

Discussion

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