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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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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What is the estimated density of the dark matter?
What is the estimated density of the dark matter? Some clumps of dark matter might have higher density and others might have lower density. So what is the estimated density range of dark matter?
Is it ...
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How does the gravitational interaction between dark a matter bulge and an ordinary matter disk affects stability over time?
From Cosmology it is known that a spherical bulge of Dark Matter, that only interacts gravitationally, surrounds the nucleus of each galaxy, that has a spinning disc component of ordinary matter. How (...
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Distribution of dark matter
Searching to understand how dark matter is distributed, I find many references like this:
https://www.bbc.com/news/science-environment-57244708
Basically they state that dark matter exists wherever we ...
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Can primordial black holes comprise not only dark matter but also account for dark energy? [duplicate]
Hawking proposed primordial black holes might comprise dark matter. They certainly contribute then to dark energy via their mass and other energies; e.g. gravitational and kinetic. Does this account ...
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How did cosmic inflation even occur?
I wanted to ask this question that which inflation model shall i believe?
Following below will be MY UNDERSTANDING (MAY NOT BE CORRECT) OF IT:
I read "A Brief History of Time" and in chapter ...
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Is a black hole found in the centre of the low-surface-brightness and dark-matter-free galaxy AGC 114905
Per information found on Internet:
AGC 114905 was discovered while observing the constellation Pisces with the VLA ground-based radio telescope. The galaxy is about 250 million light-years distant ...
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Stellar and gaseous surface mass density spiral galaxies
I have a database with more than 1000 rotation curves of spiral and lenticular galaxies (xxx-gxx notation is ESOxxx-G0xx). I am working on dark matter mass modeling and I would like to know whether ...
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Can the Dark Matter / Energy problem be plausibly reframed as an ignorance of gravity problem?
I understand Dark Matter was originally proposed to explain the rotation rate of galaxies. The rate was not explained by observed matter, ergo there must be unobserved matter. An alternate explanation ...
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Are there galaxy clusters or dark matter halos in the void?
The void usually refers to the region of the Universe where the overdensity $\delta(x)$ is less than zero. What I'm curious about is whether there are virialized objects, like galaxy clusters or dark ...
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Does the density of a black hole decrease after releasing a large amount of Hawking radiation?
Is is true that the smaller a 'regular', stellar-mass black hole is, the denser it is inside of its event horizon? After all, if you look up (or calculate) the Schwarzschild radii of the Sun and the ...
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People Working on Dark Matter Simulations
I am interested in simulations regarding dark matter. I am looking for more details and reading material on the same. I was really hoping to get some guidance from someone working in that field. Can ...
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Could dark matter exist in the Universe in the form of sufficiently dense objects?
Albert Sneppen's publication
"Divergent Reflections around the Photon Sphere of a Black Hole" provides the math related to the issue which in common language could be described as "how ...
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Would the stars look different if many primordial black holes were present?
Suppose that there are many primordial black holes. These are point masses which have a small probability to collide with stars let alone themselves.
They are formed in the early universe and could ...
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Can dark matter be normal matter after all? [duplicate]
MACHO's and RAMBO's are both baryonic (and leptonic) forms of matter that can't be observed by their nature. They barely emit or reflect light. Black holes, neutron stars, or brown dwarfs (or groups ...
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Scalar field displacement from the minimum of the potential gives rise to particles/dark matter, why?
The paper Lyman-alpha Constraints on Ultralight Scalar Dark Matter by Kobayashi et al. says, at the beginning of Section 3.1:
A light scalar field stays frozen at its initial field value in the early ...
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Looking for analytical expression of Cosmic Variance - Poisson distribution?
I have an expression of Matter Angular power spectrum which can be computed numerically by a simple rectangular integration method (see below). I make appear in this expression the spectroscopic ...
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Is the dark matter just regular matter out of the observable universe?
Could it be that darkmatter is actually the gravitational influence of regular matter that is situated out of the observable universe?
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How can dark matter be observed?
Look at this picture:
It looks as if dark matter is observed. But what is actually observed? doesn't this picture prove MOND and emergent gravity (both assuming a different gravity tied to normal, ...
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How can the (in my eyes quite ridiculous) conjecture of Sheldrake be disproven? [closed]
In this question on the physics site, it is asked if astronomical objects can be conscious. Now, in a sense, every object has to be "conscious" somehow, as every object is composed of the ...
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Was there a formula-first hypothesis for gravity?
Being a mathematician I wonder, has there been an attempt to blindly approximate a formula for gravitational attraction that would match the data, based on "normal" matter we can see plus ...
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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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How to derive density and mass from the pseudo isothermal model for mapping the density profile for dark matter?
I recently read about dark matter haloes and ways to profile their density. I came across this model called the pseudo isothermal model for the halo and I wanted to know how you would model the ...
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Is there software to calculate/plot decomposed rotation curves from observational data (FITS, etc)? [closed]
I have observation data of galaxies (in FITS format). From the FITS data, I want to calculate & plot the decomposed rotation curves as pictured below. Is there a software package that will do that ...
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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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What fraction of matter is not bound to the galaxies, groups and clusters that we see?
We know that most of the matter in the universe has collapsed into galaxies and galaxies into groups and clusters and that a lot of matter is presently in clusters between the galaxies. But, what ...
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