Archivi tag: active galactic nuclei

A 3D View on Galaxy Evolution

To decipher the underlying processes that shape galaxies over time, we need to uncover their physical properties and the conditions controlling them. This in turn requires in-depth measurements of the stars, gas and dust, inside as well as surrounding the galaxies. Continua a leggere A 3D View on Galaxy Evolution

La formazione stellare nelle galassie attive

La radiosorgente brillante 3C 219. L’oggetto al centro dell’immagine (color blu) è il suo nucleo attivo che viene alimentato dall’attività del buco nero supermassiccio. In rosso è mostrata l’emissione radio estesa. Le osservazioni in banda infrarossa di un campione completo di oggetti simili, che hanno un’età di circa 7 miliardi di anni, indicano che l’attività nucleare domina la luminosità della galassia, sebbene la formazione stellare sia attiva. Credit: NRAO and Parijskij et al.

Un gruppo di astronomi del Center for Astrophysics (CfA) di Harvard, ha utilizzato il telescopio spaziale Herschel per analizzare l’emissione infrarossa di 64 sorgenti radio/X brillanti che hanno un nucleo attivo e una massa stellare pari a più di 100 miliardi di masse solari. Lo scopo era quello di determinare quanta luminosità osservata in queste galassie è dovuta all’attività del nucleo attivo rispetto a quella causata dai processi di formazione stellare. La radiazione infrarossa è emessa dalla polvere che viene riscaldata da questi due processi e i dettagli dell’emissione, come ad esempio la sua temperatura tipica, possono fornire delle indicazioni importanti sui contributi relativi ai due processi. Continua a leggere La formazione stellare nelle galassie attive

The Extremes of Black Hole Accretion

Some of the most energetic processes seen in the Universe arise close to a super-massive black hole such as relativistic jets and winds. These are now known to play a key role in determining the growth of galaxies across cosmic time, but the mechanisms by which they are launched remain unclear. Continua a leggere The Extremes of Black Hole Accretion

Probing Active Galactic Nuclei with Radio Techniques

Active galactic nuclei (AGNs) derive their power from accretion onto supermassive black holes located in the centers of galaxies.  Many phenomena connected with active galaxies derive from physical processes associated with the central engine’s accretion flow, which, depending on the mass accretion rate and possibly other parameters, such as black hole spin, generate outflows and relativistic jets.  The energy output from the nucleus, whether it be radiative or kinetic, may have a profound influence on the evolution of the host galaxy and its larger scale environment. Continua a leggere Probing Active Galactic Nuclei with Radio Techniques

The Evolving Blazar Paradigm

The international meeting “The Evolving Blazar Paradigm” is a follow up of our previous Krakow meetings focused on the physics of astrophysical jets in AGN and in the Galactic sources “Challenges of Relativistic Jets” (2006)” and “Understanding Relativistic Jets” (2011). Continua a leggere The Evolving Blazar Paradigm

Galaxies Inside and Out

The aim of the workshop is to discuss the latest developments on the studies of galaxies, including new results and current and upcoming surveys, combined with an overview of the themes covered in the workshop, outlined below.  Continua a leggere Galaxies Inside and Out

The Role of Hydrogen in the Evolution of Galaxies

As the most abundant element in the Universe, hydrogen is an ubiquitous tracer of structures at various scales and plays a fundamental role in galaxy formation. Accretion of hydrogen from the intergalactic medium (IGM) feeds galaxies with the raw material necessary for the formation of stars. Continua a leggere The Role of Hydrogen in the Evolution of Galaxies

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