Questions tagged [dark-matter]
Questions about the source or effects of the matter that makes up 85% of the matter in the universe but appears to only interact gravitationally.
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Does dark matter exist because as Einstein said the laws of physics should be the same inside and outside a black hole?
Spacetime is said to be time like inside a black hole ( two events can happen at the same place at different times). Spacetime is called space- like outside a black hole ( two events can happen ...
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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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If a cluster of stars in dynamical equilibrium falls into a much larger blob of dark matter, will it get hotter and expand? Will it stop?
This question is inspired by ProfRob's inspiring answer to Are there really confined Globular Clusters? in which he invokes the concept of "virialization" where a dynamical system reaches ...
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What is everything wrong with this theory of dark matter?
So I had a hypothesis about why dark matter exists, but seeing as I've just barely begun studying astrophysics its most likely chock full of misconceptions and oversights. Here's a diagram of the ...
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Orientation of the Dark Matter Halo in Andromeda Galaxy
In this paper: https://iopscience.iop.org/article/10.1088/0004-637X/789/1/62#apj496316t3
Refer to the Discussion and Concluding Remarks section. It says,
"This result also indicates that the ...
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How can we measure the amount of Dark Matter in the universe to the level of a percent?
Through phenomena that scientists have observed we know that dark matter is a big player in maintaining a constant speed of objects in a galaxy which means that dark matter is an active participant. ...
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Is dark matter made from the particles that had charge but no mass in the early part of the Big Bang
It is assumed that massless charged particles acquired mass after the early phase of the Big Bang. But could most charged particles be massless now as dark matter. They wouldn't interact with photons ...
user52290
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Dark Matter's effect on galaxy structure
One "fun fact" that's always been, well fun. Is despite what most assume, our sun does not orbit a supermassive black hole or any object at the center of our galaxy.
Recently I read an ...
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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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Could both the high incidence of supermassive Black Holes (BH) and the expansion of the universe be consequences of vacuum entanglement energy?
The notion that spacetime may emerge from entanglement between factors comprising a Hilbert space decomposition of the vacuum has been suggested by many (for example, M. Van Raamsdonk “Building up ...
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Why is the dark matter component of MOND important in central regions?
A lot of papers say that even the theory of MOND requires the existence of dark matter, particularly in the central regions. However this is a bit counterintuitive to me considering that rotation ...
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Can WIMPS be stable for a long time given that they are 60 times heavier than a proton and other particles heavier than protons decay rapidly?
WIMPS are dark matter candidates But how can they be stable for billions of years ?
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Can dark matter accumulate at Lagrange points?
Interplanetary dust can accumulate at Lagrange points .
"Kordylewski cloud - Wikipedia" https://en.m.wikipedia.org/wiki/Kordylewski_cloud
But can dark matter accumulate at Lagrange points ...
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Are vacuum fluctuations that produce dark matter correlated to fluctuations that produce baryonic matter?
When cosmic inflation began vacuum energy fluctuations created matter . But were the fluctuations that created dark matter dependent on the fluctuations that created matter ? Is the ratio of dark ...
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Has the missing dark matter in some galaxies been explained yet? [duplicate]
There are galaxies that should have dark matter to explain their existence but they do not.
"Mystery of Galaxy's Missing Dark Matter Deepens | NASA" https://www.nasa.gov/feature/goddard/2021/...
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How does superfluid dark matter keep stars orbiting at high speeds in galaxies?
According to A paper on Ultra-Light Dark Matter, Superfluid dark matter is a kind of Bose-Einstein condensate. But how does it help stars keep their high or velocities in galaxies. Can somebody ...
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Do black holes emit dark matter as Hawking radiation?
When a star made from protons neutrons and electrons becomes a black hole that black hole can emit protons neutrons and electrons as Hawking radiation.
Dark matter is unusual matter: is there any ...
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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 ...
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How does a scalar field linked to dark matter affect the fine structure constant?
Olive & Pospelov (2001) "[hep-ph/0110377] Evolution of the Fine Structure Constant Driven by Dark Matter and the Cosmological Constant" https://arxiv.org/abs/hep-ph/0110377 propose that ...
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If a supernova explodes close to the centre of the milky way does its light get blueshifted by dark matter by the time it reaches the Earth?
Does the dark matter halo of the milky way cause most of the change in wavelength or is baryonic matter responsible?
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Is there any observational evidence for dark matter vortices?
The paper here "Vortices and waves in light dark matter" https://arxiv.org/abs/2004.01188
says that in dark matter halos vortices arise. In a vortex some particles move faster than others - ...
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Is the mass function of dark matter halos fundamental or an approximation based on experimental data?
Can the halo mass function be derived from existing physics or is it just a best fit of some data?
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ultra diffuse galaxies and dark matter
There are ultra diffuse galaxies (UDGs) like, NGC 1052-DF2, NGC 1052-DF4, which seem to have very little dark matter. And on the other hand UDG dragongly 44 has lots of it.
How many UDGs are known to ...
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Can the CMB Cold Spot be explained by dark matter redshifting photons?
One explanation for the Cold Spot in the cosmic microwave background (CMB) is that dark matter is redshifting CMB photons; see Fermilab's article "Scientists move a step closer to understanding ...
user50623
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Have we discovered a Galaxy lacking in Dark matter?
This question is relevant but it was speaking about a specific discovery reported by pieter van Dokkum, and the answer then mentioned it was disputed whether the paper's conclusion is even correct.
I ...
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Galactic rotation curves data samples: how to get them?
I am aiming to introduce data Science to my High-School students and I thought about giving to them data taken from galactic rotation curves (spiral galaxies at the moment) to stude the flatness of ...
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How would "dark matter", subject only to gravity, behave?
If we were to hypothesise that the Universe contained a significant mass of "dark matter" particles subject only to gravity, presumably general relativity would give us a good idea of how ...
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Is there more dark matter than we previously thought?
With the recent Nature publication showing that M dwarfs did not form in prior epochs as frequently as we had thought, what implications does this have on galaxy mass estimates and, by extension, the ...
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Proportion of dark energy, dark matter, matter
According to the article "Dark Matter" https://en.wikipedia.org/wiki/Dark_matter the current Lambda-CDM model estimates the total mass-energy content of the universe consists of 68.2% dark ...
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When did the first cold dark matter halos begin to originate?
I know that these dark matter halos should have been created in an early universe because during the formation of galaxies, the baryonic matter was too hot to form gravitationally self-bound objects ...
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what does it mean to have momentum suppressed cross section
What does it mean to have momentum suppressed cross section and zero momentum transference in direct and indirect detection of dark matter
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What is the contribution of star-produced axions to the dark matter budget of the Milky Way?
I try to follow the discussion of axions since Peccei, Quinn, Wilzcek and Weinberg. What I still don't understand is how much the speculated stellar production of axions could add to the galactic dark ...
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Could dark matter be ordinary cool matter far away? [duplicate]
We tend to think of the universe as the visible universe, but there could be large amounts of eventually hierarchically ordered, normal, matter that we can only observe at relatively close distances.
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How do star orbits, density wave theory and dark matter distribution work together?
I got confused while trying to combine these 3 concepts. Would love to hear some detailed explanation.
Density wave theory states that spiral arms are formed by tilted elliptic orbits. Bertrand's ...
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Could we detect dark matter by black holes gaining unexplained mass?
Dark matter is said to interact only gravitationally, so it won't commonly form black holes by itself. But if a black hole is already there, and dark matter encounters the event horizon, it should go ...
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Is there any method that enables us to observe the 3D large-scale spatial distribution of the dark matter?
Can we get the three-dimensional spatial distribution of dark matter through gravitational lensing?
If not, is there any other way?
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Is Dark Matter possible if there is dynamical friction?
If dark matter existed: wouldn't it slow down the orbital velocity of stars in galactic disks by dynamical friction more than it would accelerate them through additional mass? The original orbital ...
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How can Deep MOND regime apply inside a star?
As I understand it, Milgrom's MOND model can be interpreted in one way by saying that Newton's Law of Gravitation on its own is insufficient to predict the gravitational acceleration when acceleration ...
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Why doesn't dark matter clump strongly in the center of galaxies, since it doesn't feel either radiation pressure or the Pauli exclusion effect?
Dark matter is described as being spread not only throughout a galaxy, but also around it in a halo of some sort that extends far beyond the visible parts of the galaxy...
In fact, dark matter haloes ...
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What is a 'square' Kelvin degree? μ$K^2$? In terms of the cosmic microwave background's (CMB's) temperature fluctuations?
From what I have read and seen, the minute temperature fluctuations in the CMB are measured in microKelvin, or μK.
However, many charts and graphs show μK2, or 'microKelvin-squared'.
Do they simply ...
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Why is the probability dP of finding an object (e.g. galaxy) in an infinitesmal volume dV equal to \overline{n}dV?
As pointed out by many cosmology lectures, such as Eq. (63) of Cosmology II-8 Structure Formation, and Eq. (3.1) of A Detailed Look at Estimators for the Two-Point Correlation Function, the ...
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Mass resolution in cosmological simulations [duplicate]
I've been reading papers about different cosmological simulations and they all talk about the "mass resolution" of those. Can someone please explain what does "mass resolution" ...
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Could primordial black holes explain the SMBH in the galactic centers?
If there were enough primordial black holes (with the right mass) they could explain dark matter. Could they explain the gargantuan monster holes in the center of galaxies?
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Why do most astrophysicists believe the cosmic microwave background (CMB) provides the best evidence for dark matter? What, exactly, IS that evidence?
I frequently read that the cosmic microwave background contains the best overall evidence for the existence of dark matter, and conversely against alternative gravity theories like MOND.
However, I ...
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Is the dark matter/baryonic matter ratio the same in galaxies with supermassive black holes?
My hypothesis is that if the ratio of dark matter/matter in galaxies with supermassive(weighing billions of suns) black holes are higher the black hole itself would be made of a large portion of dark ...
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Does the presence of dark matter in the Milky Way significantly distort our parallax based measurements of distance?
According to accepted astronomical wisdom, dark matter represents a large fraction of the total mass of the Milky Way. And thanks to Papa Einstein, we know that light rays can be bent when passing ...
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Which galaxies have the most well known / estimated dark matter halos?
For this I guess you need
accurate circular velocity measurements of the stars in the galaxy
a decent luminosity profile for the galaxy
some analysis which looks at the discrepancy between the two
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Is there a consistent missing mass ratio for Galaxy Clusters?
The Coma Cluster is what famously lead Fritz Zwicky to the conclusion that Dark Matter exists. As the velocities of the galaxies within the cluster were too fast for them to remain within orbit of ...
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At what distance does MOND Modified Newtonian Dynamics take effect?
At what distance does MOND Modified Newtonian Dynamics take effect? I understand MOND is described in relation to very slow accelerations, which is related to distance. It is mentioned it has an ...
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In what ways does dark matter help in "binding" celestial bodies together in a Galaxy?
Earlier in history, it was said that the celestial bodies in galaxies were bound by "mutual gravity". There is still a common misconception that the gravity of supermassive black holes binds ...
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