Archivi tag: Galaxies

First stars, galaxies, and black holes: now and then

Understanding the nature of the first cosmic sources is one of the key questions of Cosmology and Galaxy Formation. During the last years Cosmic Archaeology has opened the possibility to indirectly study these distant sources by catching their living fossils in the Local Universe. Continua a leggere First stars, galaxies, and black holes: now and then

Warm Dark Matter Cosmology in agreement with observations

Warm Dark Matter (WDM) is hot topic in galaxies cosmology and implies novelties in the astrophysical, cosmological particle and nuclear physics context. Warm Dark Matter Cosmology (LWDM) gives the same successfull large scale results and CMB results than Cold Dark Matter (LCDM) and succesfully agrees with the observations at the galactic and small scales. 

Continua a leggere Warm Dark Matter Cosmology in agreement with observations

Gas, Dust, and Star Formation in Galaxies from the Local to the Far Universe

Spitzer, Herschel, and Planck allowed us to make an important step forward in our understanding of the nature of galaxies. On one hand, the extensive surveys of nearby galaxies performed by Herschel studied with unprecedented details the distribution and the properties of dust, and provided key insights on the processes of dust heating and star formation in these objects. On the other hand, the deep infrared and sub-millimeter surveys revealed a large population of massive, gas-rich, intensely star-forming galaxies, which have no local analogues. Continua a leggere Gas, Dust, and Star Formation in Galaxies from the Local to the Far Universe

Baryons at low density: stellar halos around galaxies

Stellar halos are ubiquitous in luminous galaxies, but because of their faint surface brightness the detailed study of their physical properties has been difficult and, until recently, confined largely to the Milky Way (MW) and Andromeda. Since the advent of large cameras and surveys, both from ground and space, our knowledge of stellar halos is increasing. Several late and early-type galaxies had stellar halo properties traced out to hundred kiloparsecs or beyond, revealing very low luminosity extended stellar structures similar to halos of our own MW and our closest neighbor, the Andromeda galaxy. Continua a leggere Baryons at low density: stellar halos around galaxies

Revolution in Astronomy with ALMA

The Atacama Large Millimeter/submillimeter Array (ALMA) has been producing a growing number of impressive and scientifically compelling results as the most powerful mm/submm interferometer in the world. Held in central Tokyo, the aim of this four day conference is to highlight the most recent science results from ALMA obtained during the first three years of science operations, and to motivate future collaboration among researchers around the world. Continua a leggere Revolution in Astronomy with ALMA

Yale Frontier Fields Workshop

Hubble and Spitzer have observed galaxies over 95% of the way back to the Big Bang, well into the epoch of reionization and close to the dawn of galaxy formation. The most distant galaxy candidates have been discovered using two complementary observational strategies: blank field observations such as CANDELS and the Ultra Deep Field; and galaxy cluster lensing programs such as CLASH. Additional deep observations are required to discover larger samples of distant galaxies and mitigate the cosmic variance of the single UDF. Deep lensing observations can reveal even fainter sources that would otherwise be inaccessible to current telescopes. Continua a leggere Yale Frontier Fields Workshop

The Formation and Evolution of Exponential Disks in Galaxies

Exponential stellar disks are ubiquitous. The stars in both spiral and dwarf galaxies are generally found to be organized in exponential disks, even to very low surface densities and in both stellar dominated and gas dominated galactic environments. But why is this? The associated gas disks do not fall off with radius in the same manner. Furthermore, star formation is highly lumpy. How does lumpy star formation produce distributions of stars that fall off smoothly. And how are these profiles maintained over many Gyr? Continua a leggere The Formation and Evolution of Exponential Disks in Galaxies

AGN vs star formation: the fate of the gas in galaxies

How is AGN activity connected to star formation? This remains one of the key unsolved questions in astronomy and cosmology. Both processes are efficiently driven by a cold gas supply and we therefore may expect a loose connection. However, a slew of empirical and theoretical evidence suggest an unexpectedly tight symbiotic link between AGN activity and star formation, whereby the fuelling and regulation of one process is dictated by the other. The effectiveness of this fuelling and regulation and (most crucially) whether it is predominantly dictated by AGN activity or star formation is a matter is intense debate, and has important implications for the growth of galaxies and black holes over cosmic time.

The objective of this international workshop is to bring together observers and theorists to discuss the connection between AGN activity and star formation on small (<100 pc), large (~0.1-10 kpc), and cosmological scales to address the following key questions:

  • What evidence is there for a symbiotic connection between AGN activity and star formation?
  • What physical processes drive gas into the centre/how does AGN and star formation compete for cold gas?
  • How does star formation control AGN activity?
  • What impact does AGN activity have on star formation?
  • How different would the Universe look without AGNs?
  • What key tests and observations do we need to make progress in the field?

Poster of the workshop

The X-ray view of galaxy ecosystems

X-ray observations are providing exciting results about the formation and evolution of galaxies, bringing new insight into the interplay between galaxies and the diverse physical components of which they are composed, and with which they interact.  Continua a leggere The X-ray view of galaxy ecosystems