Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userNew Light on Dark Matter
66
0
0.0
(
0
)
Added by
Jeremiah P. Ostriker
Publication date
2003
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
Dark matter, proposed decades ago as a speculative component of the universe, is now known to be the vital ingredient in the cosmos, eight times more abundant than ordinary matter, one quarter of the total energy density and the component which has controlled the growth of structure in the universe. Its nature remains a mystery, but, assuming it is comprised of weakly interacting sub-atomic particles, is consistent with large scale cosmic structure. However, recent analyses of structure on galactic and sub-galactic scales have suggested discrepancies and stimulated numerous alternative proposals. We discuss how studies of the density, demography, history and environment of smaller scale structures may distinguish among these possibilities and shed new light on the nature of dark matter.
rate research
Read More
Some extensions of the Standard Model provide Dark Matter candidate particles with sub-GeV mass. These Light Dark Matter particles have been considered for example in Warm Dark Matter scenarios (e.g. the keV scale sterile neutrino, axino or gravitino). Moreover MeV scale DM candidates have been proposed in supersymmetric models and as source of the 511 keV line from the Galactic center. In this paper the possibility of direct detection of a Light Dark Matter candidate is investigated considering the inelastic scattering processes on the electron or on the nucleus targets. Some theoretical arguments are developed and related phenomenological aspects are discussed. Allowed volumes and regions for the characteristic phenomenological parameters of the considered scenarios are derived from the DAMA/NaI annual modulation data.
We present new deep near-infrared images of dark clouds in the Perseus molecular complex. These images show beautiful extended emission which we model as scattered ambient starlight and name ``cloudshine. The brightness and color variation of cloudshine complicates the production of extinction maps, the best tracer of column density in clouds. However, since the profile of reflected light is essentially a function of mass distribution, cloudshine provides a new way to study the structure of dark clouds. Previous work has used optical scattered light to study the density profile of tenuous clouds; extending this technique into the infrared provides a high-resolution view into the interiors of very dense clouds, bypassing the complexities of using thermal dust emission, which is biased by grain temperature, or molecular tracers, which have complicated depletion patterns. As new wide-field infrared cameras are used to study star-forming regions at greater depth, cloudshine will be widely observed and should be seen as a new high-resolution tool, rather than an inconvenience.
Detection of a surprisingly high flux of positron annihilation radiation from the inner galaxy has motivated the proposal that dark matter is made of weakly interacting light particles (possibly as light as the electron). This scenario is extremely hard to test in current high energy physics experiments. Here, however, we demonstrate that the current value of the electron anomalous magnetic moment already has the required precision to unambiguously test the light dark matter hypothesis. If confirmed, the implications for astrophysics are far-reaching.
We discuss the possibility of producing a light dark photon dark matter through a coupling between the dark photon field and the inflaton. The dark photon with a large wavelength is efficiently produced due to the inflaton motion during inflation and becomes non-relativistic before the time of matter-radiation equality. We compute the amount of production analytically. The correct relic abundance is realized with a dark photon mass extending down to $10^{-21} , rm eV$.
Very light dark matter is usually taken to consist of uncharged bosons such as axion-like particles or dark photons. Here, we consider the prospect of very light, possibly even sub-eV dark matter carrying a net charge that is (approximately) conserved. By making use of the Affleck-Dine mechanism for its production, we show that a sizable fraction of the energy density can be stored in the asymmetric component. We furthermore argue that there exist regions of parameter space where the energy density contained in symmetric particle-antiparticle pairs without net charge can to some degree be depleted by considering couplings to additional fields. Finally, we make an initial foray into the phenomenology of this scenario by considering the possibility that dark matter is coupled to the visible sector via the Higgs portal.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
