Questions tagged [particles]
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25 questions
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Could antihelium detected by the International Space Station be produced by quasars or magnetars?
Antihelium is very rare.
There is a video here about antihelium detected above Earth's atmosphere.
Anti helium detected by the ISS
Decaying dark matter is one possible source of antihelium suggested ...
user61160
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When a black hole evaporates in its last moments, will it emit the same amount of particles and anti-particles?
Black holes are expected to evaporate due to Hawking radiation. Since Hawking temperature is inversely proportional to the mass of the black hole, as it would gradually lose mass with time they would ...
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Can there be free electrons in interstellar gas in the long term?
If I'm not mistaken, in interstellar gas, there can be clouds of free electrons (not "attached" to any atomic nucleus)
But can they stay like that indefinetely? Or will they inevitably end ...
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Is an alpha particle cosmic ray more easily deflected on its journey than a proton? Or vice versa?
Has everyone heard about the cosmic ray that hit Utah recently with an energy of about 240 EeV? Making it the third-highest-energy of all time? Scientists say it seems to have come from a void, and ...
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If w bosons can create dark matter neutrinos by decay, can they also create dark energy?
Dark energy is often associated with vacuum energy fluctuations. But the experimentally measured Casimir effect suggests that there is almost no vacuum energy.Because most of the vacuum energy is ...
user52681
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Why are WIMP dark matter particles, if Majorana-like, expected to annihilate upon contact? But not neutrinos?
I have heard a lot recently about so-called 'dark stars'; stars that are formed with the help of the gravitational pull of dark matter, or perhaps entirely from self-annihilating Majorana-type dark ...
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When two galaxies with dark matter halos merge do they provide evidence for fermionic or bosonic dark matter?
If dark matter is made from fermions these should collide and cause dark matter to become denser in some places than others Bosons wont collide in this way so there should a different effect .So is ...
user50918
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Hubble expansion rate and reaction rates
I've come across sentences like
...the reaction
rates (the number of reactions per particle per unit time) must
be larger than the cosmic expansion rate $H(t)$ in order for the
particles to maintain ...
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Total scattered flux and polarization for a ring of dust particles close to a star
I have an important problem and maybe some of you can help me with the following question:
I have a mathematical expression for the total scattered flux in Jansky and the total linear polarized flux (...
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How much does the Higgs field contribute to the energy of empty space?
The Higgs field was not spontaneously broken when the universe was young and hot (like I am not...:)). At the very high temperature that existed back then, the Higgs' energy of the Higgs field was non-...
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How can we know the density of particles in interstellar or intergalactic space and could that density form dark matter?
It is assumed that the density of particles in the empty space between stars or galaxies is extremely low. But how do we know this density? The space surrounding the Sun is contaminated by cosmic ...
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Directionality of solar flares
I have read a number of articles about Coronal Mass Ejections (CME) and solar flares and I’m trying to establish how directional the radiation from them is.
I am aware that radiation from these solar ...
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Could Sgr A* be a core of dark matter instead of a supermassive black hole?
A recent paper (related news) shows that Sgr A* at the center of the Milky Way galaxy could be a dark matter core, instead of a supermassive black hole, according to their calculation using the ...
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Astrophysical particle spectroscopy; narrow-line particle sources (charged or uncharged) for things other than photons? Have any been detected?
Is Cosmic Ray Astronomy a thing?
Is there an equivalent of the red shift effect for cosmic rays?
have got me thinking and under this answer I've commented:
That's a good point; there aren't as many ...
- 30.7k
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How do we know or predict which particles were present before Big Bang Nucleosynthesis occurred?
I'm reading Carroll and Ostlie's "An Introduction to Modern Astrophysics". In the BBN section, they describe that the universe contains a mixture of photons, electron-positron pairs, and ...
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What consequences does a positive muon anomalous magnetic moment have for astronomy?
On April 7th, 2021, the muon $(g-2)$ collaboration published Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm, a result which made it to standard news, partly under headlines ...
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Absorption of light by matter
What determines whether or not photons can be absorbed by matter? Intuitively, the answer is that a charged particle can absorb photons (whether it's positively or negatively charged), and neutral ...
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What are the sources of antimatter particles in the magnetosphere?
The PAMELA instrument detected antimatter particles in the Earth's magnetosphere. What are the sources of these particles?
The answer to Source of high energy cosmic particles outlines the sources ...
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Have there been studies of "old photons" to see just how constant things like Planck constant has been?
The question Are photons aged? and answers therein have got me thinking:
I vaguely remember hearing something about experiments where "old photons" were collected by large telescopes from very ...
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What is happening with these solar particles detected near the Sun that is so newsworthy?
Phys.org's Team identifies low-energy solar particles from beyond Earth near the Sun links to the open access ApJ article Properties of Suprathermal-through-energetic He Ions Associated with Stream ...
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How are neutrinos produced in blazar jets?
I was watching the press release about measuring neutrinos and gamma rays from a distant blazar. One of the presenters mentioned that the neutrinos are associated with very high energy protons caught ...
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How exactly does Hawking radiation decrease the mass of black holes?
From what I understand so far, when one of virtual particles crosses the event horizon and the other does not, they can not annihilate each other. The latter wanders off into the universe (btw, is it ...
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Possible to use tachyons to explore black hole?
I read on a Wikipedia article lately that tachyons are theoretical particles which always travel at or above the speed of light. That means that when one passes us, we see two images, a blue shifted ...
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What could be past the particle horizon?
Forgive any kind of "dumb" question I may ask as this is a new interest of mine and I know it's purely hypothetical.
If one were able to surpass light speed and the expansion of space to go beyond ...
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Dark Matter Particle Candidates
Dark matter appears to dominate the matter component of the universe as compared to luminous, or baryonic, matter. Though it does not interact electromagnetically (it doesn't absorb, scatter, or emit ...
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