Catálogo de publicaciones - libros

We analyse the effects of central AGN heating on the formation of galaxy clusters by means of hydrodynamical simulations. Besides self-gravity of dark matter and baryons, our approach includes radiative cooling and heating processes of the gas component and a multiphase model for a self-consistent treatment of star formation and SNe feedback [1]. Additionally, we incorporate a periodic feedback mechanism in the form of hot buoyant bubbles, injected into the ICM during the active phases of accreting central AGN. We find that AGN heating can substantially affect the properties of the stellar and gaseous components, in particular reducing the mass deposition rate onto the central cD galaxy, thereby offering an energetically plausible solution to the cooling flow problem.

We analyse the effects of central AGN heating on the formation of galaxy clusters by means of hydrodynamical simulations. Besides self-gravity of dark matter and baryons, our approach includes radiative cooling and heating processes of the gas component and a multiphase model for a self-consistent treatment of star formation and SNe feedback [1]. Additionally, we incorporate a periodic feedback mechanism in the form of hot buoyant bubbles, injected into the ICM during the active phases of accreting central AGN. We find that AGN heating can substantially affect the properties of the stellar and gaseous components, in particular reducing the mass deposition rate onto the central cD galaxy, thereby offering an energetically plausible solution to the cooling flow problem.

We present Space Telescope observations of the z=2.38 Lyα-emitter over-densityassociated with galaxy cluster J2143-4423, the largest known structure (110 Mpc)above z=2.We imaged 22 of the 37 known Lyα-emitters within the filament-like structure,using the MIPS 24μm band. We detected 6 of the Lyα-emitters, including 3 of the 4 clouds of extended (>50kpc) Lyα emission, also known as Lyα Blobs.Conversion from rest-wavelength 7μm to total far-infrared luminosityusing locally derived correlations suggests all the detected sources are in the class of ULIRGs, with some reaching Hyper-LIRG energies. Lyα blobs frequently show evidence for interaction, either in imaging,or the proximity of multiple MIPS sources within the Lyα cloud. This connection suggests that interaction or even mergers may be related to the production of Lyα blobs. A connection to mergersdoes not in itself help explain the origin of the Lyα blobs, as most of the suggested mechanisms for creating Lyα blobs (starbursts, AGN, cooling flows) could alsobe associated with galaxy interactions.

I review the observational status and the main implications of the correlation between GRBs peak energy E, the photon energy at which the intrinsic (i.e. corrected for cosmological redshift) νFν spectrum peaks, andisotropic equivalent radiated energy E. This correlation, discovered by Amati et al. (2002) based on BeppoSAX measurementsand confirmed and extended to X–ray rich GRBs and X–ray Flashes (XRF) by HETE–2 measurements, can be used to constrain the parameters of the models for the prompt emission of GRBs, is a challenging test for jet and GRB/XRF unification models, provides hints on the nature of sub-classes of GRBs (e.g. short, sub–energetic), is commonly adopted as an input or a test for GRB synthesis models and can be also used to build up GRB redshift estimators.

A semi-analytic approach to the relativistic transport equation with isotropic diffusion and consistent radiative losses is presented. It is based on the eigenvalue method first introduced in Kirk & Schneider [5]and Heavens & Drury [3]. We demonstrate the pitch-angle dependence of the cut-off in relativistic shocks.

The propagation of electromagnetic signals of pulsars through the non-stationary gravitational field of the stellar globular clusters formed by an ensemble of arbitrarily distributed stars are discussed. The expression for the relativistic time delay of pulsars radiation in such fields are derived taking into account the negligible aberration corrections. The obtained results are considered in the application to the globular cluster NGC 104 (Tucanae 47) for the cases of the small and large impact parameters.

The shape and the intensity of the 6.4 keV iron line bring unique information on the geometrical and physical properties of the supermassive black hole and the surrounding accreting gas at the very center of Active Galactic Nuclei. While there is convincing evidence of a relativistically broadened iron line in a few nearby bright objects, their properties at larger distances are basically unknown. We have searched for the presence of iron lines by fully exploiting observations in the deep fields. The line is clearly detected in the average spectra of about 250 sources stacked in several redshift bins over the range z=0.5-4.0. We discuss their average properties with particular emphasis on the presence and intensity of a broad component.

We present the light curves of the components of gravitationally lensed source SBS1520+530 in R band, obtained during the interval 2001-2005 with the 1.5 m Russian-Turkish Telescope RTT150 at TÜBİTAK National Observatory of Turkey. The time delay of brightness fluctuations between the two components of the gravitationally double-imaged quasar corresponding to 2001-2002 period of observations is determined. Using all the available data, at least two microlensing events, one of them with long-time linear behavior and second one with duration of a few hundred days, are detected.

The expansion of the electron-positron plasma in the GRB phenomenon is compared and contrasted in the treatments of Mèszàros, Laguna and Rees, of Shemi, Piran and Narayan, and of Ruffini et al.. The role of the correct numerical integration of the hydrodynamical equations, as well as of the rate equation for the electron-positron plasma loaded with a baryonic mass, are outlined and confronted for crucial differences.

In this contribution I review the mechanism proposed earlier for producing a gamma-ray burst from the rapidly spinning neutron star in an X-ray binary (Spruit 1999), with a discussion of some more recent developments and outstanding issues.