New Paper Claims Primordial Black Holes Don't Explain Dark Matter

[ohwilleke]

TL;DR Summary

One explanation for phenomena attributed to dark matter is primordial black holes (formed shortly after the Big Bang, not by stellar collapse). This paper seems to rule out that hypothesis.

A new pre-print makes a sensible and convincing, in my view, argument that phenomena attributed to dark matter are not exclusively or predominantly explained by primordial black holes formed at less than the mass of a star shortly after the Big Bang, by means other than stellar collapse. This paper doesn't rule out the possibility that primordial black holes might exist, but argues that if they do, they don't play a big role in cosmology.

Proposals for large dim objects such as brown dwarfs which are very dim from a detectable radiation perspective (called MACHOs), or dust or interstellar gas, made of ordinary matter, were ruled out as dark matter candidates long ago. So were ordinary neutrinos (called "hot dark matter").

There are some "out there" proposals that exotic electromagnetically neutral hadrons made of ordinary matter bound by the strong force (e.g. hexaquarks) could serve as dark matter if they were stable. But the strong circumstantial evidence that there are no such stable hadrons (e.g., even a really heavy one would have a mass of less than 30 GeV or so and no evidence of stable heavy hadrons have been seen at the 14 TeV of the LHC), and the lack of evidence of interactions with ordinary matter via the weak force in direct detection experiments also strongly disfavors this class of proposals at masses up to hundreds of GeVs.

Primordial black holes are the last significant proposal for dark matter particle candidates not requiring either particles beyond the Standard Model or gravitational effects beyond Newtonian gravity in the weak field (which is conventionally as a practical matter used to approximate weak field General Relativity in galaxy and galactic cluster and smaller scale cosmology settings by warm and cold dark matter cosmology theorists) to exist (of which I am aware).

Small primordial black holes can be ruled out as dark matter candidates because they would decay due to Hawking Radiation too quickly for enough of them to survive to this point from the Big Bang to the current age of the Universe.

Large primordial black holes are ruled out by micro-lensing data and other means.

There is a window between those two constraints for asteroid sized primordial black holes to constitute dark matter, but the paper whose abstract appears below purports (convincingly) to close that gap.

The paper and its abstract are as follows:

The nature of dark matter (DM) is unknown.

One compelling possibility is DM being composed of primordial black holes (PBHs), given the tight limits on some types of elementary particles as DM. There is only one remaining window of masses available for PBHs to constitute the entire DM density, 10^17 - 10^23 g.

Here, we show that the kernel population in the cold Kuiper belt rules out this window, arguing in favor of a particle nature for DM.

Amir Sirajh, Abraham Loeb, "Eliminating the Remaining Window for Primordial Black Holes as Dark Matter from the Dynamics of the Cold Kuiper Belt" arXiv (March 8, 2021) (submitted for publication).

The dynamics of objects in the Kuiper belt would seem like an excellent place to look for traces of asteroid sized dark matter clumps in the form of PBHs.

This would be aided by the fact that the local density of DM needed in the vicinity of the solar system in CDM theory is pretty well worked out (in furtherance of direct detection experiments), so the density of PBHs per volume you'd expect is provides some fairly constraining parameters on what you are looking for in those dynamics.

The body text of the paper sets forth the reasoning of their basic line of analysis of the problem:

Throughout this Letter, the local DM density is taken to be ρDM = 0.0133 ± 0.002 M⊙ pc^-3, given the local Galactic circular velocity of vP BH = 242±2 km s^-1.

We derive our constraints on gravitational perturbations by PBHs based on the small velocity dispersion of rocks observed near the midplane of our planetary system. In the Solar System, the Kuiper belt is composed of the classical belt, the scattered disk, resonant objects, and detached objects. The classical Kuiper belt is dominated by the ‘cold’ population (inclinations i < 5 ◦ ) of Kuiper belt objects (KBOs) which exhibits several distinct physical characteristics from the hot Kuiper belt and scattered disk populations, as well as a contrasting size distribution. The cold classical Kuiper belt contains a concentration of bodies called the ‘kernel’, with a uniform distribution of eccentricities from 0.03 to 0.08 and semimajor axes clustered at a = 44 . The kernel could have been formed as a byproduct of Neptune’s migration. The circular velocity of objects in the kernel is vKBO ≃ p GM⊙/a = 4.5 km s^−1 . Here, we show that the existence of the kernel eliminates the remaining window for primordial black holes as DM.

The bottom line result from the body text is as follows:

For v(PBH) , we conservatively ignore the velocity dispersion of PBHs in the Galactic halo, which would strengthen our limit if included in addition to the circular velocity of the Sun. The improvement in our limit would be mild because of the logarithmic dependence of f(PBH) on v(PBH).

The fiducial value of ∆e reflects the lower bound of eccentricity for the observed kernel population in the cold Kuiper belt; since the kernel is described by a uniform distribution in e between 0.03 and 0.08, an eccentricity kick of ∆e ≥ 0.03 from PBH kicks over the lifetime of the Solar System is excluded. A population extending down to e = 0.03 would not exist if sub-lunar PBHs comprised DM. Our limit can be improved with future observations of the Kuiper belt.

The observed existence of the kernel therefore rules out PBHs as DM to f(PBH) < 0.36 ± 0.07 throughout the entire remaining mass window over which PBHs were previously unconstrained, 10^17 − 10^23 g, arguing in favor a particle nature for DM.

The calculations is a straightforward page and a half. Is there a flaw in the logic of the paper that I'm missing?

Are there other remaining viable explanations of dark matter particles that don't involve non-Standard Model particles or tweaks to gravity that I've overlooked?

 

[PeterDonis]

Amir Sirajh, Abraham Loeb, "Eliminating the Remaining Window for Primordial Black Holes as Dark Matter from the Dynamics of the Cold Kuiper Belt" arXiv (March 8, 2021) (submitted for publication).

This link goes to a Blogger page. Do you have a link to the arxiv page?

 

[Keith_McClary]

link to the arxiv page

https://arxiv.org/abs/2103.04995

 

[ohwilleke]

This link goes to a Blogger page. Do you have a link to the arxiv page?

My bad. Not sure how that happened. Fixed.

 

[ohwilleke]

https://arxiv.org/abs/2103.04995

Thanks.

 

[PAllen]

Well, it is rare for one paper to settle such complex topic. This paper doesn't cite any of the work involved in the following paper, which argues for a completely different mass range of PBH for dark matter, and reaches entirely conflicting conclusions.

https://arxiv.org/abs/2007.03565

 

[phinds]

Well, it is rare for one paper to settle such complex topic. This paper doesn't cite any of the work involved in the following paper, which argues for a completely different mass range of PBH for dark matter, and reaches entirely conflicting conclusions.

"In science the really interesting questions are often surrounded by people confidently asserting conflicting ideas." (Marcus here PF several years ago).

 

[kimbyd]

My understanding of PBH for dark matter is that they had ruled out such black holes being a major dark matter component except for the intermediate-mass black hole range (tens to tens of thousands of solar masses). Are they saying this mass range is ruled out in this paper?

Edit:
Answering my own question, it looks like my knowledge is out of date! It appears larger black holes were ruled out by their impact on supernovas: https://arxiv.org/abs/1712.02240

Apparently gravitational lensing from larger black holes would magnify supernovas too much to match current observations.

 

[ohwilleke]

Well, it is rare for one paper to settle such complex topic. This paper doesn't cite any of the work involved in the following paper, which argues for a completely different mass range of PBH for dark matter, and reaches entirely conflicting conclusions.

https://arxiv.org/abs/2007.03565

FWIW, I don't give much credit to this one which relies on very model dependent assumptions like a particular inflationary model, relying on a very thin data set which huge statistical uncertainties due to small sample size and no comparisons with anything resembling a null or alternative hypothesis. And it is contrary to other prior literature using a different methodology to ask the same question such as:
https://arxiv.org/abs/1712.02240 previously cited in this thread.

[Submitted on 7 Jul 2020 (v1), last revised 13 Jul 2020 (this version, v2)]
Evidence for primordial black hole dark matter from LIGO/Virgo merger rates
Karsten Jedamzik

The LIGO/Virgo collaboration has by now observed or constrained the gravitational merger rates of different classes of compact objects.

We consider the possibility that the bulk of these mergers are primordial black hole (PBH) mergers of PBHs formed during the QCD epoch making up the entirety of the dark matter.

Having shown in a companion paper that mergers due to the initial binary population formed in the early Universe are likely negligible, we compute current merger rates in PBH clusters in which the typical PBH resides. We consider two scenarios: (i) the PBH mass function dictated by the QCD equation of state and (ii) the PBH mass function dictated by the existence of a peak in the inflationary perturbation spectrum.

In the first scenario, which is essentially parameter free, we reproduce very well the merger rates for heavy BHs, the merger rate of mass-asymmetric BHs such as GW190814, a recently discovered merger of a 23M⊙ black hole with a 2.6M⊙ object, and can naturally explain why LIGO/Virgo has not yet observed mergers of two light PBHs from the dominant ∼1M⊙ PBH population.

In the second scenario, which has some parameter freedom, we match well the observed rate of heavy PBHs, but can currently not explain the rate for mass-asymmetric events.

In either case it is tantalizing that in both scenarios PBH merger rates made with a minimum of assumptions match most LIGO/Virgo observed rates very well.

 

[PAllen]

My point remains that among experts in the field, the question is hardly settled. It took a good many years for consensus that expansion was accelerating, for example. Cosmology does not have the luxury or repeatable experiments, and almost all interpretation of observations is model dependent. I have no opinion on the overall likelihood of PBH as dark matter, but I don't think this paper alone is going to change many minds. I note the following observations:

1) The paper you cite has not yet been published in a peer reviewed journal. The one I cited has been published in a top notch peer reviewed journal.

2) The paper I cited discusses the issue of the lensing arguments against large PBH as dark matter, so they are well aware of it. Meanwhile, the paper you cite, while uploaded after publication of the one I cite, appears to have no knowledge of it (no cite to it or similar work, that I could find)

 

[kimbyd]

My point remains that among experts in the field, the question is hardly settled. It took a good many years for consensus that expansion was accelerating, for example. Cosmology does not have the luxury or repeatable experiments, and almost all interpretation of observations is model dependent. I have no opinion on the overall likelihood of PBH as dark matter, but I don't think this paper alone is going to change many minds. I note the following observations:

1) The paper you cite has not yet been published in a peer reviewed journal. The one I cited has been published in a top notch peer reviewed journal.

2) The paper I cited discusses the issue of the lensing arguments against large PBH as dark matter, so they are well aware of it. Meanwhile, the paper you cite, while uploaded after publication of the one I cite, appears to have no knowledge of it (no cite to it or similar work, that I could find)

Skimming through the papers:
1) The initial paper posted on this thread seems to be really hard to argue against. It's stating that for black holes in the provided mass range, they'd very efficiently kick Kuiper belt objects out of their orbits. That's a very strong statement against them.
2) The primordial black hole paper (by Jedamzik) you cited there doesn't seem to be arguing against these observational limits at all. Just that the LIGO/Virgo data seems to be in favor of PBH in the 30 solar mass range. A result like that is in general only suggestive, and cannot be considered strong in any sense.
3) The paper I cited above seems to rule out primordial black holes larger than about 0.1 solar masses. If that result has held up since it was published in 2017, I just don't think the 30 solar mass range for PBHs is viable.

 

[Mary Conrads Sanburn]

THURSDAY, FEBRUARY 4, 2021
UC Berkeley researchers find 1,200 lenses to examine dark matter

A research team found more than 1,200 gravitational lenses that could potentially be used to further understand and collect data on dark matter. Dark matter can only be observed indirectly via its gravitational effects.

BY ANNIKA RAO | STAFF

LAST UPDATED FEBRUARY 4, 2021

A team including UC Berkeley researchers has found more than 1,200 potential gravitational lenses, celestial objects that have proven to be a powerful addition to astronomers’ toolkits and could help demystify the dark matter that most of the universe is composed of.

Gravitational lenses are astronomical phenomena where two galaxies or other large objects are aligned relative to a focal point, bending light through their gravitational fields in a way that creates multiple images of the galaxy, according to a press release by the Lawrence Berkeley National Laboratory, or Berkeley Lab. Since dark matter can only be observed indirectly through its gravitational effects, such lenses allow astrophysicists to track its quantity and distribution.

In May, the researchers found 355 lenses and expanded the search to more obscure parts of the data, such as lower-resolution imaging and galaxies of uncertain shape, according to Xiaosheng Huang, UCSF associate professor and lead author.

“(Gravitational lensing) was something that was hypothesized 60 years before it was ever seen,” said David Schlegel, a senior scientist in Berkeley Lab’s physics division who co-leads the related Dark Energy Spectroscopic Instrument, or DESI. “Einstein kind of hypothesized in the 1920s that we could see this effect … but now, we’re finding thousands of them.”

The images were discovered using machine learning techniques to scour an image survey of the universe taken for the DESI project, encompassing images that cover “about half the sky,” according to Schlegel. The team has already begun searching for more lenses in the survey’s newest release, according to Huang.

Huang said the team plans to chart the distribution and intensity of light being emitted by these lenses and higher-resolution images to determine whether these systems can truly be used as lenses. The team then plans to construct mathematical models for the systems in order to make “serious progress” toward determining the nature of dark matter, Huang added.

According to Schlegel, gravitational lenses have far broader applications than hunting for dark matter, and more lenses mean that researchers can be more selective in choosing which to use for modeling and better measure the scale and expansion of the universe.

UC Berkeley students played “significant roles” in these discoveries, according to Huang. Campus sophomore Saurav Banka provided human inspection of the lensing candidates suggested by the machine learning model to improve it. Banks said his participation in the research has inspired him to pursue a doctorate.

Campus junior Andi Gu has been with the project for a year and a half and works to develop techniques to improve the efficiency of the machine learning model.

“It’s very exciting — it’s definitely a privilege as an undergrad to get this unique opportunity,” Gu said. “My PI (Huang) has impressed upon me a sense of responsibility in that we need to make sure our results are thoroughly vetted before we put them out because they can have serious impacts on the direction of the field.”

https://www.dailycal.org/2021/02/04/uc-berkeley-researchers-find-1200-lenses-to-examine-dark-matter/

 

[Hayley Mann]

We had a long discussion with my physics teacher about this article above. Sometimes it seems to me that we will not find the answer at all, and sometimes that we are very close to the main solution to humanity.
All my childhood I was interested in black holes, what they are made of and why they are needed. It was nice to think that these were portals to other worlds. And who knows, maybe this is true.
But seriously, so far I cannot accept the new statements as the only true ones. I will wait for the official publication.

 

[Mary Conrads Sanburn]

MARCH 29, 2021
Dark matter is the most likely source of excess of gamma rays from galactic center
by INFN

In the recent past, space missions dedicated to the study of astrophysical signals in the high-energy spectrum revealed a series of enigmatic excesses not predicted by the theoretical models. In order to find an explanation for these anomalies, many solutions have been proposed. The most exciting hypothesis invokes the contribution of the elusive dark matter, the mysterious form of matter four times more abundant than baryonic matter, and of which scientists have so far detected only gravitational effects.Two recent theoretical studies carried out by Mattia di Mauro, researcher of the Turin division of INFN, one of which appeared today in Physical Review D, confirm that this explanation is compatible with measured excesses, further demonstrating that it is not disproven by potential discrepancies between theoretical and observational data. The results obtained are based on an innovative and refined analysis comparing data acquired in the last 11 years by the main instrument aboard NASA's Fermi, the Fermi Large Area Telescope (LAT), with measurements of other astronomical anomalies recorded by the orbiting Pamela detector and by the Alpha Magnetic Spectrometer experiment (AMS-02) aboard the International Space Station. Pamela and AMS are managed by international collaborations in which INFN plays a decisive role.

Starting from 2009, the year in which Fermi measurements showed a surplus of photons with energies equal to or greater than 1 GeV (2000 times the mass of an electron) coming from the center of our galaxy, the astrophysics community has tried to explain the observations in several ways, including the possible presence of thousands of weak pulsars near the galactic center and the potential gamma-ray contribution provided by dark matter. These analyses were subject to great uncertainty since they referred to models of the so-called astrophysical gamma-ray background, produced by cosmic rays or by known sources, which, although capable of including a certain variability, are subject to great error.

In order to describe the gamma-ray excess properties more precisely and to evaluate whether it is really compatible with dark matter, the new study relied on the broadest set of data collected in the last year by the LAT, and used an analysis technique that minimizes the uncertainties of the astrophysical background by adopting multiple models. "The analysis methodology used," explains Mattia di Mauro, "has provided very relevant information about the spatial distribution of excess gamma radiation, which can explain what generates the excess of high-energy photons in the galactic center. If the excess was, for example, caused by the interaction between cosmic rays and atoms, we would expect to observe its greater spatial distribution at lower energies and its lower diffusion at higher energies due to the propagations of cosmic particles. My study, on the other hand, underlines how spatial distribution of the excess does not change as a function of energy. This aspect had never been observed before and could be explained by dark matter presence dark matter interpretation. This is because we think the particles composing the dark matter halo should have similar energies. The analysis clearly shows that the excess of gamma rays is concentrated in the galactic center, exactly what we would expect to find in the heart of the Milky Way if dark matter is in fact a new kind of particle."A second study, which will be published in the same journal, examines the validity of the dark matter hypothesis using the predictions from a larger model that describes possible particle interactions of this elusive component of the universe. A theoretical model demonstrated how the existence of dark matter particles is not disproven by other anomalies recorded in the astrophysical background. These include the excess of positrons measured by Pamela and AMS-02, if attributed to a surplus of dark matter, and the non-detection of high-energy photons from dwarf galaxies close to ours, whose stellar motions imply the presence of high concentrations of dark matter.

Di Mauro says, "Starting from the physical model developed in this second study, after considering different results for the interaction and annihilation of dark matter particles, alternatives that would precede the production of high-energy photons, we verified which of these possibilities best accorded with the galactic center's excess gamma rays, while also considering the surplus of positrons and the non-detection of gamma rays from dwarf galaxies. This comparison has made able to derive accurate properties of the dark matter, properties compatible with the galactic center excess and the upper limits found with other particle data."

https://phys.org/news/2021-03-dark-source-excess-gamma-rays.html

 

[ohwilleke]

Fermi has cried wolf before and is doing so again.

 

[PeterDonis]

Fermi has cried wolf before and is doing so again.

Unless you have some magical ability to tell exactly which cosmological measurements are correct and which are in error and by how much, you cannot possibly substantiate this claim. We all have personal opinions about how various open questions in science will come out, but please do not confuse opinion with established fact.

 

[ohwilleke]

Unless you have some magical ability to tell exactly which cosmological measurements are correct and which are in error and by how much, you cannot possibly substantiate this claim. We all have personal opinions about how various open questions in science will come out, but please do not confuse opinion with established fact.

Could FERMI be right this time?

Sure. But since it has a history of jumping to false conclusions, the claim made is very weak, and the claim is contradicted by other data, so the impact of its latest paper on the likelihood that it really has seen something this time is profoundly undermined.

There is nothing magical about noting that a particular experimental group has a track record of repeatedly making claims of seeing dark matter in the past that turned out to be something else, and inferring from that that an announcement from that particular experiment that they have seen something is less credible than an announcement from some other experiment that has a better track record of making pronouncements that stand the test of time.

Also, there are entirely non-magical ways to tell which cosmological measurements are correct, such as comparing them to constraints that the authors proposing them fail to consider and looking at what is actually claimed.

What Is Claimed?

The Mauro paper cited in the Phys.org story this time around itself states that only one very narrow dark matter interpretation is possible, that all other DM interpretations are ruled out, and that the one possibility left open can be explained by non-DM interpretations.

Further, the one possibility that Mauro leaves open (a 60 GeV DM particle decaying to a muon-antimuon pair) is ruled out by lots of other data from direct detection experiments, collider data and other cosmology measurements, that he doesn't consider, which is stronger for a 60 GeV dark matter candidate that decays to muon-antimuon pairs (and hence has some non-trivial coupling to ordinary leptonic matter) than almost any other possible WIMP mass.

Here is what Mauro is really claiming, once you wade past the headline and gratuitous hype:

An excess of γ rays in the data measured by the Fermi Large Area Telescope in the direction of the Galactic center has been reported in several publications. This excess, labeled as the Galactic center excess (GCE), is detected analyzing the data with different interstellar emission models, point source catalogs and analysis techniques. The characteristics of the GCE, recently measured with unprecedented precision, are all compatible with dark matter particles (DM) annihilating in the main halo of our Galaxy, even if other interpretations are still not excluded. We investigate the DM candidates that fit the observed GCE spectrum and spatial morphology. We assume a simple scenario with DM annihilating into a single channel but we inspect also more complicated models with two and three channels. We perform a search for a γ-ray flux from a list of 48 Milky Way dwarf spheroidal galaxies (dSphs) using state-of-the-art estimation of the DM density in these objects. Since we do not find any significant signal from the dSphs, we put upper limits on the annihilation cross section that result to be compatible with the DM candidate that fits the GCE. However, we find that the GCE DM signal is excluded by the AMS-02 p¯ flux data for all hadronic and semi-hadronic annihilation channels unless the vertical size of the diffusion halo is smaller than 2 kpc -- which is in tension with radioactive cosmic ray fluxes and radio data. Furthermore, AMS-02 e+ data rule out pure or mixed channels with a component of e+e−. The only DM candidate that fits the GCE spectrum and is compatible with constraints obtained with the combined dSphs analysis and the AMS-02 p¯ and e+ data annihilates purely into μ+μ−, has a mass of 60 GeV and roughly a thermal cross section.

Matti Di Mauro, Martin Wolfang Winkler, "Multimessenger constraints on the dark matter interpretation of the Fermi-LAT Galactic center excess" (January 26, 2021).

The body of the Mauro paper also relies heavily on the argument that the gamma ray excess, if caused by DM annihilation would be consistent with an NFW distribution of DM, despite the fact that numerous lensing and dynamical reconstructions of inferred DM halo distributions are strongly inconsistent with the NFW distribution. See, e.g., Pengfei Li, et al., "A comprehensive catalog of dark matter halo models for SPARC galaxies" (January 30, 2020) (Accepted for publication in ApJS) (NFW profiles are generally a poor fit to inferred galactic halo shapes); Maria Selina Nitschai, et al., "First Gaia dynamical model of the Milky Way disc with six phase space coordinates: a test for galaxy dynamics" (April 21, 2020) (Accepted for publication in MNRAS) ("the dark halo slope [of the Milky Way] must be significantly steeper than αDM=−1 (NFW)."); Antonino Del Popolo et al., "Correlations between the Dark Matter and Baryonic Properties of CLASH Galaxy Clusters" (August 6, 2018); Rodrigues, et al. (2017) (NFW inferred dark matter halo shape is a poor fit to more than 75% of galaxies and an indifferent fit to the remainder, even in large galaxies where the usual justifications for deviations from the NFW shaped halo expected for collisionless dark matter are weaker); Thomas E. Collett, et al., "A precise extragalactic test of General Relativity." 360 (6395) Science 1342-1346 (2018) DOI: 10.1126/science.aao2469 (pay per view). (preprint available here) ("Our current data cannot distinguish between highly concentrated dark matter, a steep stellar mass-to-light gradient or an intermediate solution, but E325 is definitely not consistent with an NFW dark matter halo and constant stellar mass-to-light ratio."); Marie Korsaga, et al., "GHASP: an Hα kinematics survey of spiral galaxies - XII. Distribution of luminous and dark matter in spiral and irregular nearby galaxies using Rc-band photometry" (September 17, 2018) (most galaxies can't be described by NFW); Kyriakos Grammatikos, Vasiliki Pavlidou, "Getting the tiger by the tail: Probing the turnaround radius of structures with outer halo density profiles" (September 17, 2018) (noting that "Diemer & Kravtsov (2014), proved that the outskirts of simulated halos exhibit strong deviation from the commonly used density profiles of inner regions (NFW, Einasto), which manifests itself through a steep drop in the power law locally describing the density profile over a narrow interval of radii."); Lin Wang, Da-Ming Chen, Ran Li "The total density profile of DM halos fitted from strong lensing" (July 31, 2017) (DM halos don't have NFW profiles), and Katz (MINRAS 2017) (accord).

So the theoretically model he's based his claim upon a fit of the data to is also inconsistent with observational evidence.

Fermi's Poor Track Record

What is Fermi's track record?

CDMS suggests a WIMP mass of 8.6 GeV; AMS-02 indicates 300 GeV or more; and we also have the Weniger line at Fermi which would imply a WIMP mass around 130-150 GeV. These numbers are apparently inconsistent with each other.

Via Lubos Motl (April 2013).

Consider, with respect to Fermi, for example:

*Dmitry Gorbunov, Peter Tinjakov, "On the offset of a DM Cusp and the interpretation of the 130 GeV line as a DM signal"
* 130 GeV Fermi line as systemic error.
* Javier Reynoso-Cordova, et al. "On the origin of the gamma-ray emission from Omega Centauri: Milisecond pulsars and dark matter annihilation" (Submitted on 15 Jul 2019) arXiv:1907.06682("the total number of MSPs needed to produce the gamma-ray flux is compatible with the known (but not confirmed) MSP candidates observed in X-rays").
* Samuel K. Lee, et al., "Evidence for unresolved gamma-ray point sources in the Inner Galaxy." Phys. Rev. Lett. (February 3, 2016) (Millisecond pulsars were determined to be the source of a previously reported Fermi DM signal); Xiuhui Tan, Manuel Colavincenzo "Bounds on WIMP dark matter from galaxy clusters at low redshift" (Submitted on 16 Jul 2019) ("we correlate Fermi diffuse gamma-ray maps with catalogues of galaxy clusters. . . . No evidence for a DM signal is identified.").

Direct Detection Limitations

Dark dark matter detection experiments have ruled out particles that make up most of hypothetical dark matter particles having weak force interaction coupling constants equal to Standard Model neutrinos at masses of up to about 10 TeV (i.e. 10,000 GeV). Direct DM detection exclusion is maximal at the 60 GeV threshold Mauro considers not ruled out by other data.

See also Jester's blog:

Collider Limitations

The LHC and previous collider experiments have also comprehensively probed the possibility of DM candidates or other BSM particles at the 60 GeV mass which is the only annihilating DM mass that other astronomy constraints that are considered by Mauro don't rule out.

Pretty much all candidates at that mass are excluded. Yet, annihilating DM candidates (unlike truly sterile DM which has no non-gravitational interactions), such as a 60 GeV particle that could decay to a muon-antimuon pair should also show up at the LHC or the LEP but is excluded in the relevant mass ranges because any experiment that sees muon-antimuon annihilations with event energies of 60 GeV or more should produce such a particle since all particle physics couplings are reversible with enough energy. Put another way, a Feynman diagram can be rotated in any direction in space-time without changing its validity. Among the current LHC exclusions (per the Particle Data Group as the 95% confidence level) are

R-Party conserving limits
Gluino > 2000 GeV
Heavy Neutral Higgs (scalar or pseudoscalar) > 1496 GeV
First and Second Generation Squark > 1250 GeV
Charged Higgs > 1103 GeV
Double Charged Higgs > 723 GeV (and here)
Neutralino > 580 GeV
Selectron > 107 GeV
Sneutrino > 94 GeV
Chargino > 94 GeV
Smuon > 94 GeV
Stau > 81.9 GeV
R-Parity violating limits
Gluino > 2260 GeV
First and Second Generation Squark > 1600 GeV
Heavy Neutral Higgs (scalar or pseudoscalar) > 1496 GeV
Stop > 1190 GeV
Charged Higgs > 1103 GeV
Double Charged Higgs > 723 GeV (and here)
Neutralino > 580 GeV
Smuon > 410 GeV
Selectron > 410 GeV
Sbottom > 370 GeV
Sneutrino > 94 GeV
Chargino > 94 GeV
Stau > 81.9 GeV
Limits on Next Generation or Parallel Gauge Bosons
Axigluons > 6100 GeV
Diquarks > 6000 GeV
W' > 5200 GeV
Z' > 4500 GeV
Leptoquarks > 1755 GeV
Right handed W bosons > 715 GeV
With Respect to Fourth Generation Standard Model Charged Particles
(Note that there are theoretical reasons in the Standard Model that there must be a fourth generation of each Standard Model fermion if there is a fourth generation of any Standard Model fermions.
b' > 1530 GeV
t' > 1280 GeV
tau' > 100.8 GeV
tau' neutrinos > 45 GeV (from Z boson decays).

Also while the LHC has seen some modest lepton universality violations, its data strongly rules out the possibility of any process that decays purely to muons to the exclusion of electrons.

Dark Matter Stability Bounds

The bounds on the minimum dark matter mean lifetime of 3.57*10^24 seconds. This is roughly 10^17 years. By comparison the age of the universe is roughly 1.38 * 10^9 years. This means that dark matter (if it exists) is at least as stable as anything other than a proton, which has an experimentally determined mean lifetime of at least 10^33 years. https://arxiv.org/abs/1504.01195 This means that all dark matter candidates that are not perfectly stable or at least metastable are ruled out. Decaying dark matter and dark matter with any significant annihilation cross section are inconsistent with observation.

Other Related Data Points

*Tesla E. Jeltema and Stefano Profumo, "Dark matter searches going bananas: the contribution of Potassium (and Chlorine) to the 3.5 keV line" (August 7, 2014). Proposed warm dark matter annihilation signals turned out to be false alarms as also noted here: https://arxiv.org/abs/1408.1699 and https://arxiv.org/abs/1408.4115

* Alyson Brooks, "Re-Examining Astrophysical Constraints on the Dark Matter Model" (July 28, 2014) (ruling out pretty much all cold dark matter models except "warm dark matter" (WDM) and Self-Interacting Dark Matter (SIDM) on the basis of astrophysical galaxy dynamics constraints).

* Torsten Bringmann, et al., "Strong constraints on self-interacting dark matter with light mediators" (December 2, 2016):

Coupling dark matter to light new particles is an attractive way to combine thermal production with strong velocity-dependent self-interactions. Here we point out that in such models the dark matter annihilation rate is generically enhanced by the Sommerfeld effect, and we derive the resulting constraints from the Cosmic Microwave Background and other indirect detection probes. For the frequently studied case of s-wave annihilation these constraints exclude the entire parameter space where the self-interactions are large enough to address the small-scale problems of structure formation.

 

[PeterDonis]

Could FERMI be right this time?

Sure.

Exactly. Which means your claim that they are crying wolf again is your opinion, not established fact. So you should state it as such.

 

[ohwilleke]

Exactly. Which means your claim that they are crying wolf again is your opinion, not established fact. So you should state it as such.

The fact that they have cried wolf before is an established fact. The fact that they are doing so again, while not an "established fact" is an overwhelmingly likely conclusion given the established facts and given the weak claims that is made in the first place.

It is hardly a wild and crazy application of Occam's Razor to observe that when the proponent of a dark matter explanation for the Fermi-LAT gamma ray excess acknowledges that it can be explained without perfectly ordinary well established Standard Model physics and particles, and admits that all sorts of dark matter (including its previous 130 GeV line claim) are ruled out by the evidence, that he is on very thin ice, particularly when he sole remaining proposal is ruled out by lots of other data that he doesn't discuss.

We can't absolutely rule out that protons are held together by Tinkerbell and Peter Pan, while neutrons are held together by Santa Claus and the Tooth Fairy, and that all other hadrons are the product of hypnotism practiced on all HEP physicists in graduate school. But when the exhaustively experimentally validated Standard Model explains the same phenomena, should we really take someone proposing this alternative seriously?

 

[PeterDonis]

The fact that they are doing so again, while not an "established fact" is an overwhelmingly likely conclusion

In your opinion. There is no need to go off into the weeds about Santa Claus and other fictions.

This is an open area of research. That means there is no "established fact" yet. You have your opinion and we all understand what it is.

 

[Mary Conrads Sanburn]

Dark matter could warm the hearts of lonely old planets, scientists predict

By Adrian Cho
Mar. 26, 2021 , 5:10 PM

Dark matter might be raising the temperature of planets outside our Solar System, a pair of physicists predicts. Space telescopes already in the works should be able to spot the effect, they say, potentially enabling scientists to trace how the mysterious stuff is distributed within our Milky Way Galaxy.

“In science, we rarely get a brand-new idea,” says Sara Seager, a planetary scientist at the Massachusetts Institute of Technology (MIT), who was not involved in the work. “So, I think it’s great to see this overlapping intersection of dark matter and exoplanets.”

For decades, astrophysicists have thought that invisible dark matter must envelop each galaxy, much as glass surrounds the swirl of color in the center of a marble. Dark matter’s gravity is needed to explain why stars in fast-spinning galaxies don’t fly into space.

...

Posted in: PhysicsSpace
doi:10.1126/science.abi7290
https://www.sciencemag.org/news/2021/03/dark-matter-could-warm-hearts-lonely-old-planets-scientists-predict#:~:text=To reveal the relatively small,be several billion years old.&text=Dark matter annihilations could raise,or more, the researchers estimate