The Unsolved Mystery of the Galactic Centre GeV Excess of Gamma Rays

[@r92871]

I enjoy seeing the faces of the different paper authors and contributors when have their work on the screen

[@loopingdope]

Yeah, and it gives a bit of additional "credits", nice touch from becky

[@richarddavis2605]

Yeah me too, I think it's a nice touch

[@dmc009]

... When have their work on the screen. I enjoy that as well.

[@martinedwards2004]

Yes, the pictures make it much more personal than mere names on a page.

[@phaeton5394]

This is one of those cases where science just works so well together to find meaning for a mystery. Loved the video as always Becky!

[@beenaplumber8379]

Politics have long been set aside at research conferences. Space exploration used to be a special area for cooperation, and I'm sad to see that fall apart (Russia leaving ISS, US refusing to work with China). Science is science, and it's the minimum we can do to work together.

[@aidanmolloy3703]

Loved your talk today at UvA, your research is very interesting

[@sheenapunky]

Glad to see CTA featured in your video! A small correction: CTA has better gamma-ray angular resolution not because the array foot print is large in the traditional sense of diffraction-limited telescopes, but because the imaging atmospheric Cherenkov technique has the best angular resolution of any current gamma-ray detection techniques.

[@SolaceEasy]

All this gamma ray observing hardware owes a debt to my hiking astronomer friend, Mark Lang. Embudo forever, Mark.

[@NoSmallParts-v4w]

This is misleading. It’s not a question of diffraction. Existing operational IACT based observatories (HESS, MAGIC, VERITAS) have LAT-comparable angular resolutions, though individual array elements are worse. CTA’s impressive angular resolution will emerge from the large number of dispersed array elements, each contributing to the reconstruction of the Extensive Air-shower, and compensating for local cloud and atmospheric interference. There would be little justification in building an array otherwise.

[@martinedwards2004]

How big a price do these ground based telescopes pay in atmospheric absorption? Would we not be better off with two or more orbital telescopes using base line interferometry?

[@NoSmallParts-v4w]

@ it is highly energy dependent. Lower energy events (which are more common) produce weaker Airshowers and are harder to detect vs background. Another reason why at the larger array sizes matter. IACT simply doesn’t work in space, but the other solid-state methods do. More detectors is always better, for multiple reasons. Unfortunately in space-based astronomy you _never_ get more than 1 of anything. There were even efforts to reduce LISA down to a single spacecraft! It would certainly be good to have more LAT or ComPair instruments (fingers crossed for AmegoX) in the decadal survey), or larger variants. But since CTA has actual budget and will be an improvement I’m happy we’re at least getting some progress. And am also happy with the major discoveries Fermi has delivered.

[@noelstarchild]

Something creating gamma light has to be pretty powerful. Fascinating subject Dr. Becky, thank you and thanks to Sam too. Love your work.

[@oldguysrule5895]

Well of course. Why didn’t I think of that 😅😅. Thanks Dr Becky. My 84 year old father in law is a big fan. He does a pretty good job understanding your content, because you do such a good job sharing it with all of us. Thanks.

[@oortcloud8078]

Congratulations Dr Becky, 🏆 I've come to the conclusion that this is the *Best thumbnail expression of 2025.* I seriously can't see anyone eclipsing this marvelous insight into the mysterious world of an astrophysicist. Thank you.

[@bobjackson6669]

I love your videos. You are fun and factual. You make astrophysics fun. I send these to my grandsons and granddaughters to view. They love your videos.

[@MCsCreations]

Thanks for all the info, dr. Becky! 😊 Stay safe there with your family! 🖖😊

[@davewilliams3537]

I think we all know that an excess of gamma rays can lead to too many Hulks.

[@michielkarskens2284]

and Minions.

[@JamesOKeefe-US]

Space is hard, words are harder 😂😂😂 Thank you for this Dr. Becky, as a non astrophysicist this is my primary source for all things space and it is wonderful. Cheers from North Carolina!!

[@Soluna7]

Wow I love it when things just fit together like this, it is so cool and exciting

[@juliashouse6161]

This will be my internship subject this spring, and hopefully will follow up with a thesis!

[@Valdagast]

My guess is milli-second pulsars. Based on absolutely nothing.

[@irvingchies1626]

We're all armchair scientists here, I bet on the same with the same evidence on hand

[@kindlin]

An answer to Dark Matter.... that would be very nice tho. It would help us figure out the type of DM detector to focus on.

[@executor893]

Sadly, it's always the more boring explanation.

[@JolynBowler]

Terrific episode. Thanx 💙🌻💙

[@mrpocock]

Given the energies of those gama rays, what mass particle would that correspond to, and how does that fit into the masses of the standard model particles?

[@FireAngelOfLondon]

Aren't there three possibilities? Millisecond pulsars, dark matter annihilation or a combination of the two - which would be harder to confirm as the data would be neither properly smooth nor as clumped as it would be if the pulsars are solely responsible.

[@fenwicknolan2129]

Could dark matter annihilation lead to reduced dark matter in the universe. And if so, could that result in reduced gravitational force in galaxies keeping things together which could result in galaxies falling apart

[@mw-th9ov]

Another interesting talk highlighting a important unresolved question, but this time with prospects of a resolution in the near future.

[@MrAlanRichardson]

Hi Becky, love what you do on the channel; thank you. I wondered if you turn your attention to the recent papers by Turok and collaborators which try to explain the universe without any of the fields that have been proposed but not detected (like the inflaton field and string theory). I think it is based on CPT symmetry, a mathematical antiverse and dark matter being right handed neutrinos.

[@oortcloud8078]

Hello Alan, sorry, I'm not Dr Becky, but there is an absolutely spellbinding discussion between Neil Turok and Brian Greene on the World Science Festival, which you may like to listen to, as he goes into great depth about his teams possible theory to bypass the complications imposed by a singularity. It's really fascinating and the friendly interaction between the two of them is quite absorbing, especially when I didn't really understand much about what they were saying, but it's well worth a listen. Good luck.

[@artemkras]

I am absolutely charmed by Lisa Goodenough's name.

[@cawareyoudoin7379]

Right? It has GOT to produce so many puns :D

[@blakewalsh9489]

One of the important inventors of lithium ion batteries is John B. Goodenough which is just hilarious.

[@mikeblake9761]

Love the blips at the end of the videos, especially when you see how fleeting Dr. Becky’s attention can be 😂

[@Jobobn1998]

Great explanation, as always, Dr. Becky! Love your videos!

[@neiln62]

Next time you visit California try Mount Wilson. Technical presentations are frequently performed. I think your contribution would be great.

[@krensak]

Why should dark matter particles that are identical with their antiparticles annihilate each other? Photons are also identical with their antiparticles and they do not even interact with each other, much less annihilate each other.

[@KevinSmith-yo8qb]

Photons are their own antimatter particles so they wont interact in that way.

[@krensak]

@@KevinSmith-yo8qb That is not an answer to my question but just a repetition of part of it. I said that photons are their own antimatter particles (that is what "identical" means). Dr. Becky said that dark matter particles are identical with their antiparticles, too, and that's why they annithilate each other. My point was precisely that photons are identical with their antiparticles and do *not* annihilate each other. So it cannot follow from dark matter particle being their own antiparticles that they would annihilate each other.

[@martinedwards2004]

It’s a good question. I’m not familiar with how dark matter fits in the standard model of particle physics, but clearly it’s not a fermion (quark and electron based matter) or boson (force carriers). It’s its own antiparticle, like a boson, but annihilates to produce a photon, like a fermion. Check out en.wikipedia.org/wiki/Elementary_particle for the standard model of particles.

[@krensak]

@@martinedwards2004 Dark matter is not in the standard model. And there are bosons in the standard model that aren't their own antiparticle. The W+ and the W-, for example.

[@EamonDorrian-lo1ne]

What a brilliant video, I have subscribed to you. Fantastic explanation, thank you.

[@1schawn]

Loving the Yosemite sweatshirt, Becky! It's a majestic place to visit.

[@collindwebb]

@ about 6:00 what is the spike at 0/360 coming from? That also looks like it is above expected.

[@TlalocTemporal]

I'd guess the Milly Way in the other direction. It's not a galactic center, but it's still way denser than intergalactic space.

[@imusich]

@collindwebb I had the same question. ​@@TlalocTemporal then perhaps that implies that dark matter annihilation or milli-second pulsars are not only concentrated around the center of the galaxy, but as well distributed along the galactic spiral, which would give a wider spread of GeV excess around 0°/360° ?

[@VukLazarMusic]

I'm not certain but I think the arctan function on the x axis lets us see the upper and lower half of the image all in one chart. Arctan ranges from -90 to 90, so we can normalize our image ends to that. Think of the middle (90-270) of the chart as the upper half of the galactic image and the flanking 90 degrees on the chart are as if you split the lower half of the galactic image in half, and as if opening a 2-pane window, swung them out to the upper side of the image. I don't know if that helps, or if it's true, but that's how I interpreted it. It's definitely no looking behind the telescope. You can even see some steps/divots that correspond to upper and lower parts of the same blip in the image, similar but slightly different.

[@TlalocTemporal]

@@VukLazarMusic -- This is sort of right, but also wrong. I went and looked at the paper (should have done that to begin with, but better late than never). Hooper and Goodenough are looking at a ring of sky between 9° and 10° away from the galactic center, and the x axis is just going around that ring. Imaging the hand of a clock starting at 3 o'clock, right along the milky way. That's where the graph starts on the left. As the hand rotates it passes over the milky way again at 9 o'clock, which is the middle of the graph. And finally the clock reaches 3 again at the right of the graph.

[@VukLazarMusic]

@ Good thinking lol So is each point on the x axis the total activity over the radius of the clock (like a sonar sweep)? Or is it just the activity at the circumference point?

[@Poultryphile]

Very exciting news! I can't wait to see how this turns out.

[@jjjtpln]

Congratulations! ❤

[@eljcd]

Hello, this is your regular reminder that Dark Matter(if it exists) doesn't has any reason to annihilate with itself beyond wishful thinking of Astrophysicists. And never hear of the cusp-core problem?

[@dreamingpixles]

Either explanation is pretty mind blowing honestly

[@johnbennett1465]

If dark matter anialates, then the amount will decrease with time. Based on our current models, would this be detectable with current or near future instruments?

[@SolaceEasy]

Quite an assumption.

[@johnbennett1465]

@SolaceEasy Hu? My only assumption is that dark matter may self anialate. Since the video (and science behind it) is considering that possiblity, I don't see why a question related to this is surprising.

[@mathewmunro3770]

More matter at the centre of galaxies doesn't explain the whole original reason for inventing dark matter - that the stars at the outside of galaxies orbit the galactic centre at nearly the same velocity as the inner-stars.

[@ozzy6162]

The first correct measurement that created the need for Dark Matter was made by Zwicky in 1933 who applied the virial theorem to the Coma Cluster and found that the cluster had 400 times more mass than was visually observable. The rotation curve measurements came later as did about 7 other phenomena (so far) that requires unseen mass to make sense of them.

[@scottantonille784]

@drbecky I am so confused by the recent excitement over the dark matter stars and the galactic center GeV excess. If the mass of the dark matter particles is in the GeV range, why would we have seen no evidence of this particle at the LHC? Is there something about dark matter particles that would prevent them from forming in the collision types at the LHC? Wouldn't a dark matter particle of that mass need to be taken into account in electroweak calculations to get the right results? If an interaction or decay birthed a GeV ghost particle that only interacted with the weak force, wouldn't we notice thr missing energy?

[@hugegamer5988]

If dark matter only annihilates with itself, and at a proton mass per cubic meter or so density, you won’t have any collisions in the LHC. The interaction cross section is likely small enough you won’t create and detect the missing mass either.

[@thomasmacdiarmid8251]

I had thought that the prime basis for positing dark matter was that the excess spin speed of galaxies could only be explained by a halo of gravitating particles mostly around the exterior of the visible galaxy. Of course, they could not interact with regular matter and energy as they interact with each other because the dark matter would then shroud all the galaxies from view, or at least obscure them. But this video said that the dark matter is clumped around the center of the galaxies much as ty[ical observable matter is. But would the dark matter then be able to provide the extra spin observed, if it is not a halo as was supposedly needed?

[@michaelsommers2356]

There are many different lines of evidence that point to the existence of dark matter, not just rotation curves. Those are just the easiest to explain, and one of the first to be found.

[@CodaOrbin]

Special Request: Yearly Compilation of Bloopers

[@jessicamorgan3073]

Thanks Dr. Becky

[@anindyaguria6615]

What a coincidence! MIT Prof. Tracy Slatyer has been visiting IISc and I had so many stimulated discussions with her on this exact topic! 😂

[@ryancress5974]

In that figure 3, it looks like there’s more gamma rays detected everywhere than expected, not just the peak in the center 6:16

[@VukLazarMusic]

To be scientifically conservative, you ignore that because it's within the error bars. But human intuition being a thing, it definitely looks like a consistent upper end across the board.

[@Ed-quadF]

Thank you Dr. Becky. Almost feel that I understand this after your explanation. (although I know I don't really understand it.)

[@aproghead]

I’m not a particle physicist, but why should dark matter particles annihilate each other if they are their own antiparticle? A counter example of this is the photon which is its own antiparticle, and they absolutely don’t annihilate each other. From a brief google search particles can annihilate each other if one of the quantum numbers that describe them are opposite. E.g. the charge of an electron and a positron. So in the case of dark matter if they all have the same quantum numbers, how can they annihilate? I.e why isn’t this basically like the case of the photon?

[@Sveraken]

You can get "pair production" if a high enough energy gamma ray interacts with the nucleus of an atom. it results in an electron and positron pair and velocity. Kinda like annihilation?

[@francoislacombe9071]

If the excess of gamma rays is caused by dark matter anihilation, wouldn't it have a very narrow range of frequencies, while one caused by millisecond pulsars have a far broader one? 🤔

[@richardwilliamson1639]

In the distant future, scientists will study the videos of Dr. Becky and try to prove that she actually existed. Seems too good to be true. I'll vouch for her!😍

[@LeeSmith-cf1vo]

If dark matter is self anihalating, then presumably you could never have a concentration of it as it would immediatly destroy itself. Unless, that is, something is _creating_ dark matter?

[@michaelshafer5192]

comparing dark matter to wind. I await your thesis

[@Wyndorn]

Okay but what about dork matter?

[@Martiandawn]

Since we still don't know what dark matter is, let alone whether or not dark matter particles annihilate each other, the hypothesis that the excess gamma radiation is created by dark matter annihilation is only moderately more plausible than the hypothesis that they are created by amorous space fairies rubbing their wings together 😂

[@andrewjones9886]

Next test i take and my math doesnt add up ill just say it was dark energÿ.

[@bushmasterflash]

Lost your drink? This is where it starts. Within years you will find yourself staring into the fridge at three AM with a hammer in one hand and a tin of cat food in the other and will be unable to clearly remember the sequence of events that led to this situation. I think I speak from experience. I can't remember.

[@hydewhyte4364]

Just a random thought train. Normal baryonic matter has mass ... that is, it bends space. Antimatter also has mass and bends space in the same way. So, when a particle of matter and a particle of antimatter meet, they're bending space like 2 particles ... then they annihilate themselves ... so what happens with the bent space?

[@Atolm4]

Total amateur here, but doesn't energy also bend space? The energy released from the annihilation of the matter would still be present and bending space.

[@oortcloud8078]

Reasonably part-time physicist here, but you're actually referring to spacetime. It's spacetime that's curved by both mass and energy. Mass tells spacetime how to curve, and spacetime tells mass how to move. Presumably, the antimatter will curve the spacetime in an anti-direction (whatever that means?) and when they annihilate, the energy released will dissipate throughout spacetime in the form of gravitational waves. That's my guess anyway! 😅

[@hydewhyte4364]

@ I've never heard of energy bending space

[@hydewhyte4364]

@ All the tests I've read about looking for the effects of gravity on antiparticles finds that there's no difference to regular matter.

[@Atolm4]

@@hydewhyte4364 all mass has an equivalent amount of energy, and that energy bends space-time the same amount as the mass would. There is a hypothetical (but unrealistic in our universe) object called a kugelblitz black hole that would be formed entirely of densely packed energy, enough to form an event horizon.

[@DooferHein]

I love your eys!

[@Fake_Blood]

Great, so now we have two undetectable particles.

[@frankharr9466]

Interesting. Thank you. Aren't there two peaks there? 180b degrees apart?

[@dennymaple4144]

Yosmite is a two hour drive from my home nice to see your sweatshirt

[@ozzy6162]

Will the Square Kilometre Array be able to settle the argument? If the distribution looks lumpy then that settles the argument. However if it appears smooth it could still mean that the measurements are not yet at the level needed to "see" the lumpiness of the sources - it will depend on the sensitivity of the SKA.

[@fukawitribe]

Have we seen an excess in GeV gamma rays from the Bullet Cluster, that maps the expected distribution of dark matter ? I thought measurements had lead to an unrealistically high annihilation cross-section ?

[@fewwiggle]

Shouldn't 'annihilation' events all have the exact same energy since they all have the same cause -- thus, a very sharp energy peak? But, the video implies that the energy is smeared out. Wouldn't that rule out dark matter particles?

[@mungohalf-brain2743]

So if dark matter is annihilating with anti dark matter the question that springs to mind is why is there any anti dark matter in the first place. All the 'ordinary' anti matter seems to have been destroyed in the very early universe. Why did the 'dark' anti matter survive?

[@danij5055]

She explained that it is hypothesized that dark matter is its own antimatter. Meaning that it would be annihilating with itself.

[@Metalkatt]

We so need a new metaphor for spin-up when rotating matter collapses. It's like the phrase "building blocks." It's time for another one to keep from overuse.

[@CYBRLFT]

Don’t need to fix what isn’t broken. If the analogy works, adding complexity isn’t smart 👀

[@Ylyrra]

It's an intuitive explanation that literally anyone whatever their level of physics knowledge can understand and has probably experienced spinning around on a polished floor as a kid. If someone comes up with a BETTER explanation than that, which is highly unlikely, then it's time to switch. The explanation isn't for people who've heard the concept before, it's for people who HAVEN'T, and you absolutely SHOULDN'T fix it to the detriment of the people it's aimed at, to suit the whims of the people who it ISN'T aimed at.

[@synonymous1079]

"is it smooth or is it clumpy" reminds me of the "will it fizzle or will it fuzz" segment on brainiac.

[@mk1st]

I love that these questions are turning out to be difficult and non obvious. It will be a sad day when we "know it all"

[@BotlheMolelekwa-ju2se]

How can you say dark matter has anti dark matter when we don't even know the properties of dark. We can't say dark matter is like normal matter if we don't know if they share some properties. Please correct me here.

[@ah-spacescience1026]

4:50 During the timelapse of the gamma ray sky, it looks like an area of the gamma rays detected travels from one side of the screen and down into the galactic core. Do gamma rays flow along the magnetic field lines of the galaxy or is there another explanation for this movement?

[@sailingfabule1805]

How can we speak of dark matter annihilation when we don’t know what dark matter is ? This is hypothesis on top of hypothesis. Pretty muddy ground I would say.

[@bengoodwin2141]

We don't know which thing dark matter is, but we know several things it could be. Exploring different options is how you get to a better understanding

[@drdca8263]

It involves a hypothesis about the kind of thing dark matter is.

[@bengoodwin2141]

@drdca8263 to elaborate, one of the kinds of things we know it probably is based on process of elimination

[@williamschlosser]

@@bengoodwin2141 Elimination is right...

[@Hi_Im_Akward]

Don't understand what a hypothesis is do you?

[@jeffhallock7874]

Why do I get the feeling these new telescopes are going to produce data that will actually confuse the situation instead of solve the question.

[@williamschlosser]

New and better data solves nothing if viewed by closed minds. Plasma Cosmology is the only self-contained physical theory of the universe. Continuing to ignore it results in debates about unobservable hypotheticals like DM, that go nowhere.

[@spaceninamusic]

Hi dr b can you do talk about the 6.5 hour pulsing object please

[@platorocks842]

Thanks, Dr Becky, for bringing the mysteries of astrophysics into my loungeroom. Beats watching Married at First Sight 🤣 Now a question - Apologies if anyone has already commented on this but I’m confused about the Figure 3 Hooper & Goodenough (2011) graph at 5.50 in your video (and reading the paper in your references didn’t help ☹). The graph appears to show the galactic centre at 180 degrees along with an excess of gamma rays. The graph also appears to show a similar excess of gamma rays in the diametrically opposite direction (0 / 360 degrees), What gives?

[@Z3JohnLB]

Sounds like guesswork to me

[@imeprezime1285]

100%

[@Carusus1]

More fascination. But how do we know that dark matter is its own antimatter? If so, why has it not all self destructed by now?

[@SolaceEasy]

That's a pretty sensational last statement after the "if", Doc.

[@404Channeln0tfound]

good use of a bannana for scale

[@robertcairone3619]

Wait, doesn't dark matter concentration at the galactic center make the rotation curve problem worse?

[@m24213]

Hello Dr.Becky, great job on the video. I do have a question, it seems that the idea that Gamma Ray excess being made of dark matter and Anti Dark matter collisions is based on process of elimination (which is not a bad approach) and based on our experience on matter and anti Matter. But that seems quite a bit of leap considering that we could not even detect Dark Matter, much less Anti Dark Matter. Besides, if we assume Dark matter has some properties of matter to make the logical leap, then wouldn't the anti Dark matter be just as rare as anti matter? Do we also see any gamma rays that was known to come out matter and Anti matter collisons at this big of a scale ? I am not a Physicist, but it seems the millisecond pulsar explanation seems more realistic.

[@staffordbiggs4966]

Great video follow you in Astrophysics

[@3d1e00]

Question, if matter at the core is being accelerated to relativistic speeds due to the black hole. Would length contraction cause the electrons to emit the gamma rays?

[@Peter_Morris]

I’ve been following science my whole life. One thing that is almost universal is that when a new gadget comes online to answer a question or improve resolution, it almost always generates more mysteries than it solves. I will predict this: there will be no resolution to the question of the excess GeV gamma rays. There will be strange excesses that aren’t explained by either model, some coming from completely unexpected directions. And there will be a conviction that more research is necessary.

[@williamschlosser]

Since you are knowledgable about science, I suggest reading "Observations of Large-Scale Structures Disprove the Big Bang Hypothesis But Confirm Plasma Cosmology", a 2022 paper by Eric Lerner. Mainstream cosmology has strayed far from the empirical method, and reaches only dead ends.

[@StevenStyczinski-sy8cj]

Dr. Becky; we know we do not know everything in the universe. That is what science IS! Please give your beliefs of your present beliefs of the universes of things that make the most importance contribution to the knowledge of what you’re studying.

[@mscv]

4:49 What is flying in there from the top righht?

[@donlevoneshabanov4437]

This is our sun. The sun also emits gamma rays albeit dimly. And because of the earth's movement along its orbit, the relative position of our sun changes.

[@mscv]

@donlevoneshabanov4437 thanks.. that makes sense

[@AndyGabrielPowell]

Was the drink supplied by the Quantum Physics Lab? (Another fascinating insight to our universe. Thank you.)

[@Tylemaker19]

Just had to comment to say "Goodenough" is an amazing last name

[@kidmohair8151]

interesting. i have just come SpaceTime's shallow dive into the possibility that primordial black holes might be the explanation for dark matter, to this... today is dark matter day, for me at least.

[@anirudhagarwal9361]

The bigger the telescope, the higher the resolution. I worked in satellite manufacturing and based on the how many satellites are needed for other applications, it could be possible to make a combined "telescope" out of 100s of sensors piggybacking on those satellites. It will propel astronomy into a new age with unparalleled resolution and collection area. Please let me know if you're interested to discuss further. I can email you again with further details. 😊 I have previously sent 2 emails.

[@Georgewilliamherbert]

To do that you need sub-wavelength positioning and timing between the detectors.

[@francoislacombe9071]

At 5:32 in the upper right part of the image, we see a gamma ray source moving in an arc from right to left. That has to be a solar system object, which one would that be?

[@DrDeuteron]

big difference btw X and gamma rays is: X-rays are emitted as thermal blackbody radiation (in space, in nukes), but a 1 GeV gamma? That would require 12 Trillion K. That's hotter than quark gluon plasma, so you gotta come up with some kind of mechanism,

[@StephGV2]

What is the expected electron volt measurement of Hawking Radiation? If it can evaporate a black hole like a leaky tire filled with mass-energy, it must be a lot of energy.

[@artificercreator]

Interesting, thanks for the info

[@stusue9733]

I'd like to see a graph with the different between prediction and measured as a %. Eyeballing there seem to be plenty of places along that graph that have the same ballpark difference. How is 300 to 500 in the center different from 50 to 90 at 20 degrees? What am I missing?

[@MarkSwope]

What do the increases in Gamma rays at 0 deg and 360 deg indicate? The predictions appear to be exceeded by measurements there, too.

[@gordonwallin2368]

Cheers from the Pacific West Coast of Canada.

[@Mr.Anders0n_]

Say hi to Fraser for me

[@Pistolsatsean]

Idk man if the problem is that the black line on the graph doesn't fit the purple points... Just move the line up. Seriously though, it looks like the solution should apply everywhere not just at galactic nuclei

[@KieranLeCam]

I'd be cautious with concluding anything about dark matter when we don't even know what it is. There could easily be new physics that explain this excess. But it's good to remain positive about the future! :)

[@williamschlosser]

DM is a mathematical patch to cover the difference between the amount of matter required to support LCDM and the amount of real matter in the universe (only about 5%). For a new physics based on reality, i.e. proven EM forces, try Plasma Cosmology.

[@KieranLeCam]

@williamschlosser I'll keep an open mind, but my logical point was that if you have options A and B, that the evidence points more to option B, it doesn't actually mean the truth is option B. It could mean it's option C, that in our model has the same features as option B. And we have reason to think it's option C D E F etc, because we don't understand what option B is in the first place. Plasma cosmology at first glance seems like it's trying to explain everything with just EM. I'm not sure that's how we should approach problem solving. I'd much rather oscillate between mathematical abstraction (like math concepts like geometry, forces applied, spaces, etc), and direct observation and experiments. PC seems to just be taking the EM knowledge and trying to apply it everywhere rather than look at an observation discrepancy and create math that may work to explain it, and test it. This doesn't mean it's not part of the solution, but I find it limiting to assume we know the answer before we know the answer, and only test things based on large preconceptions, rather than a series of small, logical, and experimental tests, that all seem to line up with one another. This doesn't mean we won't have to make huge leaps, but those leaps need to then be justified, by those many small logical steps. In essence you only leap, when a small step isn't enough. And PC seems to leap, without justifying why a smaller step wasn't enough. In my opinion.

[@williamschlosser]

@@KieranLeCam Read "Observations of Large-Scale Structures Contradict the Predictions of the Big Bang Hypothesis But Confirm Plasma Theory", a 2022 paper by Eric Lerner. I find it persuasive but I can't do the math. Waiting for someone who can to respond to it, but so far no one has tried.

[@KieranLeCam]

@@williamschlosser Alright I read the paper. There's a few things to say. First, I don't master much of the math in this paper. I tend to think math is logic written in symbolic form. Meaning the words written need to make as much sense as the math, as they too are logical. And there are a few things to say here about the ideas. The math that follows those ideas may or may not check out. You'll have to ask someone who knows these symbols and conventions better than I. I'm wary of overly complicated symbols though. Math isn't about hiding your patterns, but about showing them. But I digress. First the author rests his argument on how filamentation of galaxies on large scales is caused. He points to simulations, with artificial viscosity, meant to include every known small effect, including Electromagnetism, being the cause in those simulations, of filamentation. Currently this filamentation is attributed to Dark Matter. The author points out Dark Matter isn't necessary. Only the pinching of EM fields mainly, aligned properly, pinches the gas together into filaments. A feature of this model is it doesn't require the universe to be a certain age, helping us to explain how structures have gotten so large in the amount of time predicted by the big bang theory. This is when I have an issue. Because the big bang theory was theorized to explain the expansion of the universe, observed via redshift. The only mention of redshift in this paper in via the letter z, on the bottom axis of a graph. And it's not clear to me that the core issue of the increase of redshift as a function of distance is mentioned. Which is the whole reason for tracking back the expansion speed, to a single point, called the big bang. Instead the author simply says "if we get rid if the Big Bang Hypothesis" and Lambda CDM (cold dark matter, our current general model of cosmology) we don't need an age requirement, and there's no issue, and so if I can recreate the filaments we see without dark matter, then this shows Plasma Cosmology is better than Lambda CDM, and the Big Bang Hypothesis". But there's a big gap here. Why ignore the redshift observations? There's no mention of this in the paper. Only structure sizes. The original theory does apparently mention that the universe may expand and contract. But this paper does not, and doesn't go into those details, which are very much necessary to explain away the universe's expansion. But worse, the expansion and contraction of the original theory do not give unlimited time such as the trillion years or 100 billion years mentioned in the paper, to form structures, as the original theory mentions a point of "annihilation pressure" (causing a new expansion) when matter of a previous stage of the universe collapsed back from any large structures they may have created. So you'd need all structure to annihilate, to cause expansion, yet somehow remain intact to not have the time limit for large structure creation, the main feature distinguishing this paper's version of Plasma Cosmology from the Big Bang Theory. Secondly and pretty importantly, there is no mention of the CMB, the Cosmic Microwave Background, and power spectrum (how many temperature variations of each size there are, i.e. how many blobs in the CMB there are, of each size), and we still expect, plasma universe or no, that the CMB 1) is the early universe's temperature variations, measured in microkelvin (A millionth of a kelvin, which is the same relative size as a degree Celsius), and 2) will not have had time to form magnetic fields to pinch anything. And yet in the CMB, the power spectrum requires Dark Matter, meaning more gravity, to explain the number of blobs of temperature variation of a certain size we see. This is, as far as I know the main criticism the originator of Plasma Cosmology, Hannes Alfvén, received when he released this idea in the 1960s. I learned he's a Nobel prize laureate, so it's not like he is saying nonsense, but you still need to break down every idea, no matter who pitches it. Additionally, in this paper it's mentioned angular momentum needs to "transfer". Assumed: to create filaments. This to me is odd, because angular momentum is simply regular momentum, between two objects, that are placed in such a way the movement they have towards one another, if there is attraction between both objects, is not strong enough to cause their mutual collision, implied, because some other attraction deviates those straight line collisions. These objects then begin spinning around one another, and this is the continued acceleration of an object's own momentum, towards the other object. Objects of roughly equal mass will simply create stable orbits around one another. In order for matter to collapse into angular momentum systems, all you need is matter distributed in such a way to not have ALL matter rush in a straight line towards ALL other matter at once. In simulations, no doubt much of the shapes we see are due to matter coalescing in clumps, and the closest clumps clumping together, faster than further clumps can clump together. Meaning everything is in the process of being attracted to everything else, but because of the slight unbalance of the universe's initial starting conditions (made obvious by the CMB), there is an imbalance of how things clump together. If you look at the CMB, you can even see straight arrangements of temperature variations, that look "filamenty". This is because many circular blobs next to one another may not, due to the limit of the speed of light, arrange themselves into bigger blobs straight away. I could easily interpret filaments as incomplete clumps, and no doubt if you zoomed out, you'd find regions with more filaments that looked like clumps of filaments, and so on. So filamentation does not need to spread from a clump, outwards, it can result from simply, the initial conditions of the distribution of Matter before star formation. This doesn't mean Plasma need not play a role in accentuating certain features, but saying it's all due to Plasma seems like an overreach. Plus the paper mentions plasma travels parallel to EM fields, yet EM fields go in circles, so how to get filaments to leave those parallel lines is unclear. It might be mentioned in the paper or math, but much like the word redshift isn't mentioned only "z", it feels like this paper is not very clear. This might be a feature of many papers, and we require expertise to understand, which perhaps I lack. But in my experience, if you're unrigorous, you may miss Important details. Everyone makes mistakes and slips, but the paper mentions a couple times that the age of the universe is 12.8 billion years old, not 13.8, then rounds it to 14 later on. If these figures are justified, and it is I who does not understand, perhaps some clarity would have been nice. I'm not a fan of lack of clarity or rigor, but it's not the most pressing issue. Just perhaps a sign the math and jargon are hiding poor logic. If you're not an expert, it's always good to learn how to use circumstantial evidence to help make a decision you absolutely need to make, before you can understand the subject matter well enough to debunk with direct evidence. Although I'll let you decide I you wish to do that. That's just my own style. It works for me, although in a messy way. And finally, concerning the speed of matter and Plasma on the edge of galaxies: the author says we do not need to explain this via dark matter, I.e. more gravity, but by Plasma being accelerated by EM fields, since we observe stars moving around slower than the gas, that is Plasma on the edge of the galaxy. But if we assume F=ma, simple Newtonian mechanics, then the same momentum on massive and less massive objects will result in the less massive objects being displaced further. And in a galactic environment, there is likely an average momentum of all things in it. So a planet, or star, or gas particle, either via gravity, or electromagnetic displacement, or temperature pressure will impart momentum to other objects. Assume this momentum is uniform, and you have an average force F. If F = ma the acceleration will be higher or lower depending on the mass. I'm assuming, although I'll admit I don't know for sure, since this is Newtonian mechanics, that this is taken into account to measure that stars AND gas/plasma move around faster than they should, resulting in faster speeds. But if not, there is still a final issue, if rotation speeds are due to plasma acceleration only, you would expect the accelerating plasma to be shot out of the galaxy, as there is no gravitational force keeping it there. The reason why rotation speed of rim matter is high, and yet doesn't leave the galaxy with respect to its visible momentum, is because we assume it is gravity that keeps the stars clumped together, and "drags them" back inwards towards the galaxy, counteracting the expected centrifugal force with only regular Einsteinian/Newtonian gravity. Perhaps gas does leave the galaxy, though you'd still expect stars not to clump. It's not only rotation speed that matters, but attraction between stars that keep the galaxy together that's apparently increased. I may be wrong, and perhaps got some details mixed up or incorrect, but I think that's it. So all in all, I think I'd need specific data on why everything needs plasma to work. It looks like we still need to address a gravity related problem. Thanks for reading! And don't forget to think for yourself, I too may be wrong in places! I am like you, learning!

[@barryscully1820]

Are the specific frequencies/wavelengths of the gamma rays produced by the annihilation of the black matter particles expected to be identical to that of the millimetre pulsar gamma rays? If they are not, are we unable to distinguish between them due to our current instruments or due to redshift and the distance not being known so that we only observe a distribution of gamma rays over a small spectrum of frequencies?

[@barryscully1820]

Oh, and thank you for these youtube clips that allow me a glimpse back into some of the interesting physics that I miss since leaving academia so long ago.

[@robertcairone3619]

Gonna have to call it "not so dark matter" going forwards.

[@ansakyt]

"when it's dark, it's very very dark, but when it's light, it's GAMMA!"

[@Ylyrra]

Lisa Goodenough must get heartily sick of people joking that she should have been an engineer instead with that name. Which is why I'm not making that joke. 👀

[@buca512boxer]

That cannot be taken as proof of dark matter annihilation yet, hence no evidence of dark matter yet.

[@williamhawkins542]

What if some of the matter in the universe existed before the big bang and wasn't part of it?

[@jamiepearson532]

Looking at this, if dark matter *is* able to anililate and *is* doing so constantly, then could the accelerating expansion of the universe (typically understood to show dark energy) be the combined effect of gamma ray radiation pressure with other effects mentioned on this channel previously? Additionally if the mass of dark matter is decreasing then the pull of gravity is decreasing, and so the dark energy required to explain the accelerating expansion would be less.

[@chongli297]

This is really exciting! If it does turn out to be dark matter annihilation does the CTA telescope give us a chance to pinpoint the exact wavelength of gamma ray and hence learn something about the energy and mass of dark matter particles? Could we then have some direction for how we might search for these particles here on earth with a collider like LHC?

[@flymypg]

I've worked developing sensors for high-energy photons. One of our greatest "curses" is Compton Scattering, where even a mono-energetic coherent source will see its spectrum blurred into a distribution of some sort by any intervening material, including the sensor itself! The distribution will be Gaussian if you are lucky, meaning you can then deconvolve the signal. If we subtract out the "model" galactic gammas from the Fermi observations, what is the energy distribution of the residual? Does it fit any known or expected distribution(s)? Or could it be a combination of different distributions, indicating multiple processes contributing to the excess? Subtracting spectra is fraught with error! Doing statistics on the difference of other statistics is not for the faint of heart. However, when done correctly, the results can be truly outstanding. In the case of one of my instruments, a seemingly so-so sensor suddenly became the best in its class due to its great acquisition statistics, which then permitted huge amounts of additional processing to be performed, leading to high-confidence results. In one case, it was a solid *derived* detection of electron-positron annihilation (generating a pair of 511 MeV gammas), which, when coincident in the detector (!!), yielded a 1.022 GeV detection, in an environment where it was not expected. What is Fermi *actually* measuring? Can we infer a more specific source from the "GeV excess"? I'd love to know how much "meat" there is on the bones of those Fermi observations.