Related papers: Dark matter from cosmic defects on galactic scales…
Cosmic strings are topological defects possibly formed in the early Universe, which may be observable due to their gravitational effects on the cosmic microwave background radiation or gravitational wave experiments. To this effect it is…
The potential role of cosmic topological defects has raised interest in the astrophysical community for many years now. In this set of notes, we give an introduction to the subject of cosmic topological defects and some of their possible…
This paper presents a brief review of the evidence for dark matter in the Universe on the scales of galaxies. In the interests of critically and objectively testing the dark matter paradigm on these scales, this evidence is weighed against…
In this work, we consider the possibility that the dynamical dark energy hinted at by recent DESI data may be mimicked by the effects of additional components in the universe, potentially arising from topological defects. We find that the…
Topological defects are ubiquitous in condensed-matter physics but only hypothetical in the early universe. In spite of this, even an indirect evidence for one of these cosmic objects would revolutionize our vision of the cosmos. We give…
We discuss scenarios in which the galactic dark matter in spiral galaxies is described by a long range coherent field which settles in a stationary configuration that might account for the features of the galactic rotation curves. The…
The existence of "dark matter", inferred from the observed rotation curves of galaxies, is a hypothesis which is widely regarded as problematic. This paper proposes an alternative hypothesis based on the space-time geometry near a rotating…
Vector perturbations sourced by topological defects can generate rotations in the lensing of background galaxies. This is a potential smoking gun for the existence of defects since rotation generates a curl-like component in the weak…
Astrophysical observations are pointing out huge amounts of dark matter and dark energy needed to explain the observed large scale structures and cosmic accelerating expansion. Up to now, no experimental evidence has been found, at…
If the Universe underwent a cosmic phase transition, it may have left behind a network of cosmic strings. When these strings arise from the breaking of a gauge symmetry, their decay produces a significant stochastic background of…
Topological defects, in particular cosmic strings, give rise to an interesting mechanism for generating the primordial perturbations in the early Universe which are required to explain the present structure. An overview of the cosmic string…
In this thesis, we investigate some aspects of dark matter phenomenology and its predictive power in explaining the flattening of galaxy rotation curves at large distances. After outlining the Standard Model of particle physics, its…
Cosmic strings are one-dimensional topological defects which could have been formed in the early stages of our Universe. They triggered a lot of interest, mainly for their cosmological implications: they could offer an alternative to…
The success of the Lambda-CDM model on large scales does not extend down to galaxy scales. We list a dozen problems of the dark matter hypothesis, some of which arise in specific models for the formation of structure in the universe, while…
The cold dark matter model successfully explains both the emergence and evolution of cosmic structures on large scales and, when we include a cosmological constant, the properties of the homogeneous and isotropic Universe. However, the cold…
I use a combination of state-of-the-art numerical simulations and analytic modelling to discuss the scaling properties of cosmic defect networks, including superstrings. Particular attention is given to the role of extra degrees of freedom…
We review the topic of rotation curves of spiral galaxies emphasizing the standard interpretation as evidence for the existence of dark matter halos. Galaxies other than spirals and late-type dwarfs may also possess great amounts of dark…
The nature of the cosmological dark matter remains elusive. Recent studies have advocated the possibility that dark matter could be composed of ultra-light, self-interacting bosons, forming a Bose-Einstein condensate in the very early…
We suggest that the conventional need for overwhelming amounts of astrophysical dark matter should be regarded as a warning to standard gravity rather than as merely a challenge to it, and show that the systematics of galactic rotation…
In this talk, I will discuss the mechanism of nonthermal production of the neutralino cold dark matter from the decay of cosmic strings and the embedded defects, the $\pi$ and $\eta^\prime$ strings in the strong interaction sector of the…