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.

Filter by
Sorted by
Tagged with
0 votes
0 answers
7 views

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 ...
13 votes
1 answer
2k views

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 ...
  • 233
15 votes
3 answers
3k views

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 ...
  • 3,364
2 votes
1 answer
43 views

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 ...
  • 21
2 votes
1 answer
80 views

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 ...
  • 147
1 vote
0 answers
19 views

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
  • 11
4 votes
0 answers
66 views

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 ...
1 vote
1 answer
87 views

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. ...
  • 111
3 votes
0 answers
148 views

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 ...
  • 31
10 votes
2 answers
1k views

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 ...
  • 255
2 votes
1 answer
54 views

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?
  • 369
13 votes
2 answers
2k views

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 ...
1 vote
0 answers
74 views

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 ...
  • 1,414
21 votes
1 answer
3k views

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 ...
  • 4,161
1 vote
2 answers
200 views

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 ...
  • 4,161
1 vote
2 answers
110 views

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 ...
  • 369
3 votes
0 answers
30 views

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" ...
1 vote
2 answers
104 views

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?
1 vote
0 answers
86 views

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 ...
  • 4,161
3 votes
1 answer
87 views

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 ...
3 votes
0 answers
91 views

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 ...
4 votes
1 answer
62 views

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 ...
3 votes
1 answer
83 views

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 ...
2 votes
2 answers
137 views

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 ...
2 votes
1 answer
92 views

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 ...
16 votes
3 answers
4k views

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 ...
  • 507
1 vote
0 answers
20 views

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 (...
  • 605
1 vote
0 answers
50 views

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 ...
1 vote
0 answers
32 views

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 ...
1 vote
0 answers
64 views

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 ...
  • 191
1 vote
1 answer
322 views

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 ...
  • 621
1 vote
0 answers
50 views

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 ...
1 vote
0 answers
50 views

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 ...
  • 695
1 vote
0 answers
73 views

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 ...
  • 369
1 vote
2 answers
133 views

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 ...
  • 4,161
2 votes
1 answer
81 views

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 ...
  • 163
1 vote
2 answers
340 views

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 ...
  • 621
5 votes
1 answer
694 views

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 ...
7 votes
2 answers
277 views

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 ...
3 votes
1 answer
95 views

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 ...
2 votes
0 answers
38 views

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 ...
1 vote
3 answers
301 views

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?
  • 11
9 votes
1 answer
2k views

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, ...
3 votes
2 answers
2k views

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 ...
3 votes
3 answers
330 views

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 ...
4 votes
1 answer
221 views

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 ...
2 votes
0 answers
59 views

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 ...
  • 21
1 vote
0 answers
40 views

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 ...
3 votes
1 answer
90 views

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 ...
  • 5,444
6 votes
0 answers
58 views

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 ...
  • 2,937