Questions tagged [cosmic-string]
Questions about properties, dynamics and phenomenology of cosmic strings and superstrings.
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Is the spinning Cosmic String spacetime totally vicious?
The spacetime $(M,g)$ is given locally at each point by the metric:
$$g= -(dt + a \, d \phi)^2 + d\rho^2 + \kappa^2 \rho^2 \, d\phi^2 + dz^2 \ \text{where} \ \ a > 0$$
This is the spacetime of a ...
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What is the manifold topology of a spinning Cosmic String?
Given the following metric which is that of a rotating Cosmic String:
$$g=-c^2 dt^2 + d\rho^2 + (\kappa^2 \rho^2 - a^2) d\phi^2 - 2ac d \phi dt + dz^2.$$
can one determine the manifold topology ...
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The Lebesgue covering dimension of the Cosmic String interval topology
Take the spacetime $(M,g)$ that satisfies Einstein's Field Equations exactly where $g$ is locally:
$$g= - c^2 dt^2 + d \rho^2 + (\kappa^2 \rho^2 - a^2) d \phi^2 - 2 ac d\phi dt + dz^2 \ $$
in the ...
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Metric of a rotating Cosmic String
I searched on the internet superficially but I couldn't find it.
Is there any reference that find the solution to Einstein's Field Equations for a rotating Cosmic String?
Personally haven't got the ...
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Cosmic string in real space
I am considering $U(1)$ global cosmic string.
In the case of wine-bottle potential with real field ($\phi$), it is known that there exists a static solution that corresponds to cosmic string (or ...
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Analytic formulae for the gravitational field of a cosmic string/domain wall?
Is there any analytical approximate (newtonian, postnewtonian) formulae for the gravitational field/potential of cosmic strings/domain walls?
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Cosmic Strings as Topological Defects (heuristics)
I have a lot of troubles to understand heuristically the principle behind Kibble's model for genesis of cosmic strings via Kibble mechanism. More precisely I not understand how to interpret following ...
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Could inhomogeneties and/or topological defects break the fundamental symmetries of the universe?
I have heard that some types of inhomogeneties and topological defects (like cosmic strings) in cosmology have been proposed to be able to break fundamental symmetries of nature such as the Poincaré, ...
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Understanding the units of cosmic string number density
I am reading this old paper: https://arxiv.org/pdf/1309.6637.pdf and trying to work out the units in equation 63. It gives the number density of cosmic strings in the radiation era as
$$
\frac{n(\ell,...
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How does the Higgs field energy state relate to the tension of a Cosmic String?
I understand these cracks are massless objects, but if a string has an apparent mass from its warping of spacetime, how does this relate to the higher energy value of the Higgs field the Cosmic String ...
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Cosmic strings increasing internal energy as the Universe expands?
I was reading an article by Edward Harrison, which tackles the problems of conservation of energy at cosmological scales.
At some part (point 2.4) he cites several article, including one by Rees and ...
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What if a cosmic string is eaten by two black holes?
What happens if you have a long cosmic string, each end of which is swallowed by a different blackhole, and the black holes have trajectories that will take them further away from eachother?
WHat ...
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Can cosmological defects escape a black hole?
Based on my understanding, anything that can't move faster than light can't get out of a black hole, but space can since it can move faster than light (hence cosmic inflation is exponentiated).
Also, ...
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Using a stress-energy tensor in linearized Einstein equations
I am using a known stress-energy tensor to try to find $h_{\mu\nu}$, the small deviations from flat space in the linearized Einstein formalism. In harmonic gauge,
$$
\square h_{\mu\nu}=-16\pi GT_{\mu\...
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Can a cosmic string pass through the earth undetected?
The metric around a straight, static and infinitely long cosmic string is flat except for the topological deficit in the angular coordinate, as described for example here. As a result, there is no ...
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Could Gott's Cosmic String Time Machine hypothetically be used as a poor man's Alcubierre drive?
I have read much speculation about Gott's theoretical use of cosmic strings for time travel, but if the colliding cosmic strings accelerated the spacecraft faster than light, as Gott theorizes, could ...
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Energy density of a cosmic string in the Abelian Higgs Model (Nielsen-Olesen Vortex)
my question is what the energy density of a cosmic string in the abelian higgs model is? I have different sources (Scholarpedia Cosmic Strings, the book "Cosmic Strings and Topological Defects&...
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Tension of a String
does anybody know a general relation between the tension of a string and it's energy density? I am at the moment learning about topological cosmic strings and calculated the energy density, now I do ...
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Why is general relativity in (2+1) dimensions different from cylindrical systems in (3+1) dimensional GR?
The gravitational potential $\Phi$ of an infinite rod in newtonian gravity is $\Phi \sim \ln(r)$. This is the same as the gravitational potential of a point charge in two-dimensional Newtonian gravity ...
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How does a Cosmic String accelerate a Black Hole?
I've read that a Cosmic String could accelerate a Black Hole, but I'm not exactly sure how that works. Is the Black Hole pulled along the length of the String? I've also heard it could accelerate ...
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Cosmic string gravity assist?
Could a spacecraft hypothetically use the gravity of a cosmic string to carry itself along the length of the string?
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Circling a Cosmic string in less than 360 degrees for faster space travel?
I've red that Cosmic strings would warp space such that one could circle a cosmic string in less than 360 degrees. How few degrees?
If a ship were to circle a cosmic string in a spiral pattern, saving ...
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Cosmic strings, domain walls, and magnetic monopoles are topological defects, but what's defecting?
Wikipedia gives an explanation of cosmic strings that I'm sure would be very helpful if I had a major in topology, but alas I do not. I know that a topological defect is any sort of discontinuity in a ...
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Spacetime with a point defect
What is the metric for a spacetime with a point defect? Spacetime metric with line defects are well-known, they are basically Cosmic strings. Is anyone aware of an example for spacetime with point ...
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Why would partial derivatives not commute inside an axionic cosmic string?
In this 1985 paper by Callan and Harvey, Eq. $11$ seems to claim that in the presence of an infinitely extended string-like topological defect, partial derivatives do not commute on the string:
$$
[\...
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Schwarzschild with cosmic strings: How can I visualize the string?
Geometrically, you can talk about a cosmic string in Schwarzschild black hole with this metric $[1]$:
$$ds^{2} = -\Big(1- \frac{r_{s}}{r}\Big) dt^{2} + \frac{1}{\Big(1- \frac{r_{s}}{r}\Big)}dr^{2} + ...
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Attraction near a straight cosmic string
I'm having an interpretational issue with the particles behavior around a straight cosmic string.
Consider the infinite cylindrical universe described by the following metric:
$$\tag{1}
ds^2 = dt^2 - ...
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Gravitational attraction/repulsion of cosmic strings and domain walls
It is well known that straight static cosmic strings don't produce any gravitational effects on test-particles, and that static flat domain walls are repulsive. This can be seen from the linearized ...
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Cosmic string solution to general relativity
I'm having a difficulty in finalizing a resolution of the Einstein equation for a static cosmic string. I start with the following metric ansatz, for a static straight string oriented along the $z$ ...
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What are the two different $\mathbb{S}^n$ in the construction of the homotopy group $\pi_n(\mathbb{S}^n)$ that classifies topological defects?
According to Mukhanov's Physical Foundations of Cosmology,
Homotopy groups give us a useful unifying description of topological defects. Maps of the $n$-dimensional sphere $\mathbb{S}^n$ into a ...
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Straight cosmic string energy-momentum tensor and the cosmic strings EoS
Consider a simple infinite straight "cosmic" string of negligible thickness, in flat spacetime. The string energy-momentum tensor has the following components (in the string proper frame, ...
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How to create a cosmic string?
I know about cosmic strings. They are 1-D topological defects in space-time which may had been created during the symmetry breaking phase transition during the big bang. But my question is : Are ...
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Gauge cosmic strings and large gauge transformations
I've been going around in circles (hah) about how gauged cosmic strings work (I've been using Preskill's notes for the most part). The global string scenario makes sense to me, since different points ...
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Does Goldstone theorem have anything to do with Cosmic string
Cosmic strings are formed due to topological defects during symmetry breaking phase transition in early universe.
While Goldstone theorem states whenever we have continuous symmetry and it is ...
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How many cosmic strings are there in the Universe?
While researching cosmic strings, one often encounters terminology ranging from "scaling solutions" to "correlation lengths". As a newcomer, one of the first questions I have had is "how many cosmic ...
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Cosmic strings and ground state degeneracy in SSB
There are two conflicting perceptions that I have regarding the notion of ground state post-SSB. Consider the Higgs mechanism e.g. for the electroweak theory.
On the one hand, we say that the vacuum ...
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What's the connection between cosmic strings and the strings hypothesized in string theory?
I read somewhere that Edward Witten, the (once) big hotshot of string theory, said that the discovery of cosmic strings (at the beginning of this Wikipedia article it is written: "Not to be confused ...
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What is a String Wall?
This question has nothing to do with sound waves, physical strings or walls...
I am reading: https://arxiv.org/abs/1709.07091
It states
"In the post-inflationary PQ symmetry breaking scenario, ...
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I've read a cosmic string can accelerate a mass. Can someone explain how it works?
In the book Brief Answers to the Big Questions: the final book from Stephen Hawking Hawking describes cosmic strings as follows;
They are like rubber bands as they are under great tension, ...
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Candidates for cosmic strings
What are the observed candidates for cosmic strings (or other defects), that are not ruled out? With references if possible.
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Black hole and the cosmic string
For a regular black hole, the mass and energy of the black hole are identical（according to first law of black hole thermodynamics), but for a black hole with a cosmic string this is not satisfied. ...
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Basic question on Cosmic Strings
What is the typical size of Cosmic String Loops?
If a loop is formed today, what are the restrictions on its size?
I would like to know if there is a distribution of cosmic strings depending on its ...
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Gravitational lensing and cosmic strings
Say we have a straight cosmic string lying along the $z$-axis, with energy-momentum tensor
$$T_{\mu\nu}=\mu\delta(x)\delta(y)\operatorname{diag}(1,0,0,-1)\tag{1}\label{1}$$
for some small positive ...
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Kalb-Ramond action and topological string radiation
Let's have simple scalar $\Phi$ action involves spontaneously symmetry breaking in a form
$$
\tag 1 S = \int d^{4}x\left( |\partial_{\mu}\psi|^{2} + \psi^{2}|\partial_{\mu}\theta |^{2} - \frac{\lambda}...
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Global cosmic strings evolution
Recently I've read about axion string. It can be shown that the energy per unit length of the string located along $z$ axis is
$$
\mu = 2 \pi f_{a}^{2}\ln\left( \frac{L}{\delta}\right),
$$
where $L$ ...
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Cosmic string & grandfather paradox
Cosmic string was proposed several decades ago and there are claims stating it can span across the length of the universe and is less than an atom thick. How does a broken pieces of these cosmic ...
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