Related papers: Constraining scalar fields with stellar kinematics…
The cosmological evolution of an interacting scalar field model in which the scalar field interacts with dark matter, radiation, and baryon via Lorentz violation is investigated. We propose a model of interaction through the effective…
Several observations suggest the existence of super-massive black holes (SMBH) at the centers of giant galaxies. However the mechanism under which these objects form remains non completely understood. In this work we review an alternative…
Real scalar fields, e.g. the axion, cannot condensate into stationary solitonic configurations to form star-like structures, eventually either dispersing or collapsing. However, by relaxing the stationarity condition on the metric, it has…
It seems necessary to suppress, at least partially, the formation of structure on subgalactic scales. As an alternative to warm or collisional dark matter, I postulate a condensate of massive bosons interacting via a repulsive interparticle…
The discovery of cosmic acceleration motivated extensive studies of dynamical dark energy and modified gravity models. Of particular interest are the scalar-tensor theories, with a scalar field dark energy non-minimally coupled to matter.…
In the framework of scalar-tensor gravity, we consider non-flat interacting quintessence cosmology where a scalar field is interacting with dark matter. Such a scalar field can be a standard or a phantom one. We use the Noether Symmetry…
Probing the existence of hypothetical particles beyond the Standard model often deals with extreme parameters: large energies, tiny cross-sections, large time scales, etc. Sometimes laboratory experiments can test required regions of…
We consider a broad class of interactions between radiation and a light scalar field, including both conformal and disformal couplings. Such a scalar field potentially acts on cosmological scales as dark energy and could also appear in…
Light bosonic scalars (e.g. axions) may form clouds around black holes via superradiant instabilities, or via accretion if they form some component of the dark matter. It has been suggested that their presence may lead to a distinctive…
As has been previously proposed, a minimal modification of the standard $SU(3)\times SU(2)\times U(1)$ theory provides a viable dark matter candidate. Such a particle, a scalar gauge singlet, is naturally self-interacting---making it of…
It is well known that Ultra-Light Dark Matter (ULDM), usually scalar fields of mass $m \sim 10^{-22}~{\rm eV}$, can solve some of the outstanding problems of the Cold Dark Matter (CDM) paradigm. Such a scalar field could have non-negligible…
Scalar fields with inverse power-law effective potentials may provide a negative pressure component to the energy density of the universe today, as required by cosmological observations. In order to be cosmologically relevant today, the…
Cosmological scaling solutions, which give rise to a scalar-field density proportional to a background fluid density during radiation and matter eras, are attractive to alleviate the energy scale problem of dark energy. In the presence of…
The exactly solvable scalar hairy black hole model (originated from the modern high-energy theory) is proposed. It turns out that the existence of black holes (BH) is strongly correlated to global scalar field, in a sense that they mutually…
The majority of the matter in the universe is still unidentified and under investigation by both direct and indirect means. Many experiments searching for the recoil of dark-matter particles off target nuclei in underground laboratories…
The behavior of fundamental fields in strong gravity or nontrivial environments is important for our understanding of nature. This problem has interesting applications in the context of dark matter, of dark energy physics or of quantum…
We investigate the static and spherically symmetric solutions of Einstein's equations for a scalar field with non-canonical kinetic term, assumed to provide both the dark matter and dark energy components of the Universe. In particular, we…
Massive boson stars are self-gravitating configurations of self-interacting scalar fields and can be modeled by a massive scalar field with a quartic self-interaction potential. It has been shown that the equation of state and static…
The reason for the present accelerated expansion of the Universe stands as one of the most profound questions in the realm of science, with deep connections to both cosmology and fundamental physics. From a cosmological point of view,…
Recent, very accurate simulations of galaxy formation have revealed that the standard cold dark matter model has great difficulty in explaining the detailed structure of galaxies. One of the major problems is that galactic halos are too…