Related papers: The Cloudy Universe
Probing the growth of structure from the epoch of hydrogen recombination to the formation of the first stars and galaxies is one of the most important uncharted areas of observational cosmology. Far-IR spectroscopy covering $\lambda$…
The Universe's early thermal history is poorly constrained, and it is possible that it underwent a period of early matter domination driven by a heavy particle or an oscillating scalar field that decayed into radiation before the onset of…
In many clusters of galaxies there is evidence for cooling flows which deposit large quantities of cool gas in the central regions. A fraction of this gas might accumulate as dense cool clouds. The aim of this communication is to discuss…
We present a new scenario for the development of the Universe after the Big Bang, built on the conjecture that a vast majority of the primordial quark matter did not undergo a phase transition to normal nuclear matter, but rather split up…
In popular cold dark matter cosmological scenarios, stars may have first appeared in significant numbers around a redshift of 10 or so, as the gas within protogalactic halos with virial temperatures in excess of 20,000 K (corresponding to…
Newtonian mechanics indicates that galaxies and galaxy clusters are much more massive than we would have guessed from their luminosities, with the discrepancy being generally attributed to dark matter halos. An alternative hypothesis is…
[Abridged] Over the past two decades observations and theoretical simulations have established a global frame-work of galaxy formation and evolution in the young Universe. Galaxies formed as baryonic gas cooled at the centres of collapsing…
Microlensing has established itself as a powerful new method for the detection of baryonic dark matter in the Galaxy. The theory of microlensing is sketched and its similarity with the optical effect of twinkling is explained. The bulk of…
Stellar halos may hold some of the best preserved fossils of the formation history of galaxies. They are a natural product of the merging processes that probably take place during the assembly of a galaxy, and hence may well be the most…
If dark halos are composed of dense gas clouds, as has recently been inferred, then collisions between clouds lead to galaxy evolution. Collisions introduce a core in an initially singular dark matter distribution, and can thus help to…
We discuss the diffuse emission of gamma rays and neutrinos from galaxy clusters in the viable models for structure formation in the universe. We use a self-consistent picture for cluster formation and evolution starting from a primordial…
It is demonstrated that clusters of galaxies are able to keep cosmic rays for a time exceeding the age of the Universe. This phenomenon reveals itself by the production of the diffuse flux of high energy gamma and neutrino radiation due to…
Molecular clouds at very high latitudes ($b > 60^o$) away from the Galactic plane are considered rare and not conventional sites of star formation. Contrary to this, the recent discovery of high latitude embedded Clusters can possibly…
Several lines of evidence suggest that some of the dark matter may be non-baryonic: the non-detection of various plausible baryonic candidates for dark matter inferred, e.g., from galaxy rotation curves and from cluster of galaxy velocity…
A better understanding of the formation of large-scale structure in the Universe is arguably the most pressing question in cosmology. The most compelling and promising theoretical paradigm, Inflation + Cold Dark Matter, holds that the…
Unhappily, there has been a maelstrom of problems for dark matter theories over the last few years and many serious difficulties still have no resolution in sight. This article reviews the evidence for dark matter in galaxies. The haloes…
Wide-area deep imaging surveys have discovered large numbers of extremely low surface brightness dwarf galaxies, which challenge galaxy formation theory and, potentially, offer new constraints on the nature of dark matter. Here we discuss…
The most luminous galaxies in the present Universe are found at the centers of the most massive dark matter haloes, rich galaxy clusters. In the LCDM cosmology, such massive halo cores are present at redshift z=6 with a comoving number…
We present X-ray and weak lensing observations of the merging cluster system 1E0657-556. Due to the recently collision of a merging subcluster with the main cluster, the X-ray plasma has been displaced from the cluster galaxies in both…
Recent spacecraft observations exploring solar system properties impact standard paradigms of the formation of stars, planets and comets. We stress the unexpected cloud of microscopic dust resulting from the DEEP IMPACT mission, and the…