Galactic Nuclei

L. Kaper, E.P.J. van den Heuvel, P.A. Woudt (Eds.), Black Holes in Binaries and Galactic Nuclei Diagnostics, Demography and Formation... 

D. E. Osterbrock and G. J. Ferland, Astrophysics of Gaseous Nebulae and Active Galactic Nuclei, University Science Books, Mill Valley, Cal., 2006, is another classic text, indispensable for studies of emission nebulae. 

We now have clear evidence of non-thermal processes in the sky. A whole panoply of violent activities is revealed to the watchful eye of our radio. X-ray and gamma-ray telescopes. Supernova remnants, pulsars, active galactic nuclei and gamma bursts emit radiation that has clearly nothing to do with thermal activity, for their spectra bear no resemblance to those of heated bodies. 

The final word has not yet been said regarding the distribution of dark matter at the Galactic Center, or around black holes and other compact objects in general. This is one of the exciting points of contact between the study of dark matter and the study of the formation and evolution of galactic nuclei. 

Acorn worm Acoustics Actinides Action potential Activated complex Active galactic nuclei Acupressure Acupuncture... 

V0I.693 D. Alloin, R. Johnson, P. Lira (Eds.), Physics of Active Galactic Nuclei at all Scales V0I.694 H. Schwoerer, J. Magill, B. Beleites (Eds ), Lasers and Nuclei... 

Active galactic nuclei can be readily identified both via their mid-infrared colors and as point source residuals in two-dimensional modelling. 

The idea of extracting energy from black holes has been proposed by Penrose thirtyhve years ago and followed by a cascade of energy extraction models. Nowadays it is known that from almost all Active Galactic Nuclei (AGNs) which harbour a supermassive (M > 105 x M ) Kerr black hole, focused jets of hot gas shoot into space at relativistic speed. How much energy can these jets get from the black hole or its accretion disk is a question which arises by itself. 

The catalogue of quasars and active galactic nuclei 10th edition [3], We used the BL Lac objects. Conditions magnitude < 18, the flux at 6cm > 0.17Jy, redshift> 0.1... 

Figure 32. Summary of our current knowledge of abundances at high redshift. The metallicity is plotted on the j/-axis on a log scale relative to the solar reference the latter is shown as the broken horizontal line at 0.0 and corresponds to approximately 2% of the baryons being incorporated in elements heavier than helium. The x-axis shows the typical linear dimensions of the strucures to which the abundance measurements refer, from the central regions of active galactic nuclei on scales of 10-100 pc to the intergalactic medium traced by the Lya forest on Mpc scales. Generally speaking, these typical linear scales are inversely proportional to the overdensities of the structures considered relative to the background.

Abstract. Recent research has made clear the exceptional importance of spectropolarimetry in the study of physical conditions in atmospheres and circumstellar envelopes of different kinds of stars, in galactic nuclei and to obtain knowledge about interstellar matter. The goal of this brief review is to illnstrate the field with several examples and to present new revelations made nsing gronnd-based spectropolarimetry with large telescopes. I conclude with a short description of a newly proposed spectropolarimeter for the WSO/UV mission. 

Spectropolarimetry has proven to be an important tool in the development of unified theories of active galactic nuclei (AGN). Its strength is that it provides an alternative view of the inner regions of the active nucleus. This allows for the study the stracture and kinematics of both polarizing materials and the emission source. Examples of polarization spectra of two active galaxies NGC 5548 and Was 45 are given in Fig. 15. The observations of NGC 5548 were made in 1997 and Was 45 in 1999 with the 1.2m William Hershel Telescope. 

Another interesting problem is the determination of the nature of low ionization nuclear emission-line regions (LINERs) found in 38% of nearby emission-hne galactic nuclei. The results of the observations of one such galaxy NGC 1052 are shown in Fig. 16. The observations were obtained in 1997 with the 10m Keck-II telescope. It shows a rise of polarization flux in the wings of the H line (panel c). This is the first detection of a polarized broad... 

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