Dark matter Definition and 935 Threads

I can't understand how dark matter can form structures from the initial near uniform distribution as shown in simulation like those of the Eagle project http://icc.dur.ac.uk/Eagle/index.php. I understand how the initial density fluctuation are amplified and dark (and ordinary) matter start to...

Hello, I have a general understanding of how we are aware of the presence of dark matter in the universe and the fact that we still don't know exactly what is that dark matter is made of. I would like to know which instruments are used to try and find an answer. For instance, from what I...

Dark matter passes through everything, but is only influenced by gravity, so in the case of a neutron star, since dark matter doesn't interfere with ordinary matter, it can just pass through it, but neutrinos might be stopped by it's density, as neutrinos can just pass through stars almost as if...

Is there any indication, such as through gravitational lensing, that dark matter has a low-mass compared to visible matter?

Can the effects of gravity possibly extend through time? Is there a natural law that forbids this? Could this be a possible explanation for dark matter?

The URL below is from Rensselaer Alumni Magazine. It is about an unexpected observation of an xenon atom decay using the equipment designed for detecting dark matter particle interactions with xenon. https://magazine.rpi.edu/at-rensselaer/dark-matter-detector-observes-rarest-event-ever-recorded

Are there any research about Dark Matter missing some Hilbert space bases or observable? Are bases or observables like spin, momentum, energy, position the basic quantum ingredients of any matter, what is the apriori explanation?

On the premise that gravity transcends time, is there any reason that the effects of gravity that we observe as dark matter simply be the effects of gravity from the mass of standard matter from the past? For example the mass of our galaxy may not be enough to explain the effects of gravity...

Hi. Could the local effects of gravity between nearby stars at the edge of a galaxy cause these stars to rotate around the centre of the galaxy more quickly than predicted if the prediction is based upon individual stars only. This effect would be similar to the way the Earth "drags" the Moon...

After watching a two-part program Everything/Nothing, a thought occurred to me when the discussion turned to particles popping in and out of 'empty' space. Could these particles be numerous enough in the vast space between stars to be responsible for the gravity holding stars together in...

My question is about dark matter and how we guess it is working. I do not have a huge understanding of this but given a few things I have been lead to understand I would like to ask a few basic questions to better understand. My question will start with antimatter; Antimatter supposedly would...

I thought this article was interesting (and here). It made me think, if a transformation is sufficient to eliminate or create Dark Matter... Then the mystery of the existence of Dark Matter would become a mystery of why all of the other distance measurements are wrong in a universe without Dark...

Summary: Dark matter, the elusive mass that makes up most of the universe, doesn’t interact with light. Is this because it travels faster than light itself? I have been working on the maths and the theory for several months now in order to discover the nature of dark matter. By rearranging and...

The summary pretty much says it all: How is dark matter, responding to gravity, thought to have formed filaments and walls--the scaffolding for the large scale structure of the universe--rather than random clumps? I can understand how scattered matter might not coalesce while exchanging...

We know that observed helium abundance constrains the amount of baryonic matter. Leaving that aside, is there any fundamental constraint on how much baryonic matter can exist in the universe, without changing the observed structures or physics of the universe? If there were only baryonic matter...

Is there a possibility that there are stars and planets that are composed entirely of DM? How would we detect such stars or planets? Well, I am not sure about stars, as the definition of a star depends on its fuel that it uses, I guess.

Hello. If we consider PBH formation from collapse of large density perturbation in the early Universe, a mass PBH depends on density contrast as And δ must be larger then . Also we have β — an abundance of black holes, it's the ratio of the PBH energy density to the total energy density, this...

Curious if the ongoing studies of black holes at the centers of galaxies, like the Event Horizon Telescope, might provide some clues about the nature of dark matter. Tried googling this, but all I get is articles debating, mostly to the negative, the hypothesis that dark matter might be...

Two recent studies have found galaxies with little or no apparent dark matter, indicating modifying gravity can't work. https://iopscience.iop.org/article/10.3847/2041-8213/ab0e8c https://iopscience.iop.org/article/10.3847/2041-8213/ab0d92/meta

How different would the universe look without dark matter? Would galaxies have formed, allowing for the existence of the solar system and life?

Hello! Dark Matter (if exists)(if it is in form of particles - collisionless) could also be attracted by Black Holes (or Neutron Stars) and form accretion disk. I would like to discuss possible properties of such hypothetical object. DM particles could be trapped and settled in around...

Not sure who this is he may be a mondian but it is an alternative view. arXiv:1903.11217 [pdf, other] Is dark matter fact or fantasy? -- clues from the data Philip D. Mannheim Comments: Essay written for the Gravity Research Foundation 2019 Awards for Essays on Gravitation Subjects...

If the distribution of elements in the universe is also the distribution of elements in the solar system for regular matter, and being dark matter so overwhelmingly prevalent in the universe, why can't we see it overwhelmingly in the solar system?

The pressure of a scalar field is: Φ˙2−V(Φ) so to have zero or negligeable pressure it needs to have equipartition of its energy in potential and kinetic form ==> the potential must be positive. In particular a mass term m2Φ2 ... could be all right: the field should tend to roll down this...

{Moderator's note: Moved to Cosmology forum.] Dark matter and the fabric of space time, Can someone with a real knowledge base of physics and the current accepted theories, please explain why the fabric of space is not the candidate for the elusive dark matter? Having read extensively about...

Wikipedia describes the distribution of Dark Matter as a halo around our galaxy. Are there any laws or equations on the distribution of dark matter? From what I have read, dark matter does not clump into stars, since it cannot radiate energy. It cannot be seen or directly observed. Does it repel...

New observations of Compact Elliptical Galaxy Mrk 1216 show a very high apparently dark matter fraction based upon the intragalaxy dynamics of stars in the galaxy, relative to the baryonic mass of the galaxy inferred from typical mass to light ratios for galaxies of that type. The inferred...

From the rotation curve of spiral galaxy it is found that the entire mass is not concentrated at the centre but for large distance from the central core it varies linearly with r for which the velocities(rotational) of the objects far from the central core remains nearly constt. and near to the...

I'm wondering if the galactic rotation curves could be attributed to a deviation of the metric of spacetime from the ideal Schwarzschild metric. The Schwarzschild-metric is a well tested good approximation for the regions near the central mass - but at the outer space, far away from the...

https://arxiv.org/abs/1901.05973 It seems like there is some thing unexplained here, what is going on?

I am interested in having a dialogue with persons familiar with MOND (modified Newtonian Dynamics as proposed by Israeli physicist Mordehai Milgrom). Also, how MOND fits with Erik Vanderlinde's theory of Emergent Gravity. I am an engineer by training, but enjoy physics as a hobby. Specifically...

https://arxiv.org/pdf/1901.03711.pdf I wonder if this is an observational problem or if many other galaxies will be found to have no dark matter?

Hello, I often read that hot dark matter is constrained by structure formation issues. But I'm now wondering why it is not constrained by the CMB data itself because such hot dark matter should belong to radiation (with density evolving as 1/a^4 rather than 1/a^3) so for instance when we...

Dr James Farnes of Oxford's e-Research Centre recently proposed a new model which unifies dark energy and dark matter into a single phenomenon - a fluid which possesses "negative mass". https://news.sky.com/story/mystery-of-dark-matter-may-have-been-solved-by-oxford-scientists-11572089 The paper...

Hello everyone, By considering the effects of the gravitational time dilation the speed of the inner stars must be higher for the local observer than for the external one. So why the gravitational time dilation can not potentially explain the galaxy rotation curve? I already read that the...

I'm writing a thesis for my high school research paper on dark matter. It's difficult to come up with a claim that is argumentative, engaging, and related to the research I've done on the scientific process in relation to theories about dark matter. Do you think I could reasonably argue that...

Hello! In most papers that present exclusion plots as cross section versus mass, the plot has a specific shape in which mostly the cross section decreases with mass. I am a bit confused why. If you assume that the density and speed of DM is constant, shouldn't a higher mass (and hence a higher...

One approach that has been proposed to replicate the description of dark matter phenomena in galaxies with a gravity modification that is set forth in a simplified manner in the phenomenological toy model theory MOND is to do so through a variation on Einstein's General Relativity known as...

I read that 1. dark matter has to be concentrated in galaxies; 2. McGaugh & Co discovered a precise relationship between visible-ordinary matter and the calculated sum of ordinary + dark matter from thorough observation of actual acceleration of more than 150 galaxies. 3. First experiments to...

I would like to discuss the topic of light (photons) being emitted from stars potentially being the source of dark energy and dark matter. Photons have mass and velocity; therefore they will affect space time, and their impact could have an effect on objects causing acceleration. Would love to...

Any thoughts on this paper? https://arxiv.org/abs/1712.07962

Both of these webpages show snippets comparing the HSC map of dark matter to the Planck map of dark matter, as well as a graphic showing the time evolution of the dark matter over time: https://www.livescience.com/63711-3d-dark-matter-map.html...

This paper says they do. but I have been lead to believe that DM only interacts with gravity https://arxiv.org/abs/1811.08843 What is the standard view?

Hello! I read several papers about different model of DM beyond basic WIMPs and axions but haven't found a lot about DM effects on baryon asymmetry. I was wondering, is it possible to have a type of DM that decays (or at least it did a lot in the past) preferably more to matter than antimatter...

Hello! I am currently applying for graduate schools in the USA and during my undergraduate career I was mainly involved in Dark Matter research. However, my research focused on testing different models (experimentally or using numerical simulations) and doing some basic calculations, basically...

A new experiment (it's true a small scale one with the possibility of being brought to a much larger scale) has failed to find any sign of Dark Matter (DM), like all the other experiments before (at least the ground based one). AMS seems to have found some important extra anti-protons and...

I have a Theory providing an alternative behavior of gravity and an explanation for the perception of dark matter. The math works at least in the large scale (not quantum). How do I publish this for the physics world to see? I want my Nobel Prize (joking). Legitimate answers would be highly...

Do you know if there is any theory/model where dark matter is considered as a gas? Bullet Cluster suggests that dark matter travels with visible matter and forms halos around galaxies, clusters, etc. It is possible to consider these halos as dark matter atmospheres of massive objects/structures?

let's imagine that we can create a black hole from dark matter. Is it going to be different from the ordinary black hole(which is created by ordinery matter)?

I want to start by saying that I'm in no way trying to say that Dark Matter isn't a real pehonomenon in space. I also have no intention to sway one way or another. However, I feel like most scientiests are swaying towards the 'dark matter' is some kind of WIMP or such. It's much easier to read...