Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userGravitational radiation from monopoles connected by strings
50
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Monopole-antimonopole pairs connected by strings can be formed as topological defects in a sequence of cosmological phase transitions. Such hybrid defects typically decay early in the history of the universe but can still generate an observable background of gravitational waves. We study the spectrum of gravitational radiation from these objects both analytically and numerically, concentrating on the simplest case of an oscillating pair connected by a straight string.
rate research
Read More
Monopole-antimonopole pairs connected by strings and monopole-string networks with $N>2$ strings attached to each monopole can be formed at phase transitions in the early universe. In such hybrid defects, monopoles accelerate under the string tension and can reach ultrarelativistic Lorentz factors, $gammagg 1$. We study the radiation of gauge quanta by accelerating monopoles. For monopoles with a chromomagnetic charge, we also discuss the high-energy hadron production through emission of virtual gluons and their subsequent fragmentation into hadrons. The relevant parameter for gauge boson radiation is $M/a$, where $M$ is the boson mass and $a$ is the proper acceleration of the monopole. For $Mll a$, the gauge bosons can be considered as massless and the typical energy of the emitted quanta is $Esimgamma a$. In the opposite limit, $Mgg a$, the radiation power is exponentially suppressed and gauge quanta are emitted with a typical energy $Esimgamma M$ in a narrow range $Delta E/Esim (a/M)^{1/2}$. Cosmological monopole-string networks can produce photons and hadrons of extremely high energies. For a wide range of parameters these energies can be much greater than the Planck scale.
We study the formation of monopoles and strings in a model where SU(3) is spontaneously broken to U(2)=[SU(2)times U(1)]/ZZ_2, and then to U(1). The first symmetry breaking generates monopoles with both SU(2) and U(1) charges since the vacuum manifold is CC P^2. To study the formation of these monopoles, we explicitly describe an algorithm to detect topologically non-trivial mappings on CC P^2. The second symmetry breaking creates ZZ_2 strings linking either monopole-monopole pairs or monopole-antimonopole pairs. When the strings pull the monopoles together they may create stable monopoles of charge 2 or else annihilate. We determine the length distribution of strings and the fraction of monopoles that will survive after the second symmetry breaking. Possible implications for topological defects produced from the spontaneous breaking of even larger symmetry groups, as in Grand Unified models, are discussed.
We consider strings with the Nambu action as extremal surfaces in a given space-time, thus, we ignore their back reaction. Especially, we look for strings sharing one symmetry with the underlying space-time. If this is a non-null symmetry, the problem of determining the motion of the string can be dimensionally reduced. We get exact solutions for the following cases: straight and circle-like strings in a Friedmann background, straight strings in an anisotropic Kasner background, different types of strings in the metric of a gravitational wave. The solutions will be discussed.
We have studied the main features of the gravitational radiation generated by an astrophysical system constituted of three compact objects attracting one another (only via gravitational interaction) in such a manner that stable orbits do exist. We have limited our analysis to systems that can be treated with perturbative methods. We show the profile of the gravitational waves emitted by such systems. These results can be useful within the framework of the new gravitational astronomy which will be made feasible by means of the new generation of gravitational detectors such as LISA in a no longer far future.
We investigate the possibility of observing very low frequency (VLF) electromagnetic radiation produced from the vacuum by gravitational waves. We review the calculations leading to the possibility of vacuum conversion of gravitational waves into electromagnetic waves and show how this process evades the well-known prohibition against particle production from gravitational waves. Using Newman-Penrose scalars, we estimate the luminosity of this proposed electromagnetic counterpart radiation coming from gravitational waves produced by neutron star oscillations. The detection of electromagnetic counterpart radiation would provide an indirect way of observing gravitational radiation with future spacecraft missions, especially lunar orbiting probes.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
