ISTRAŽIVANJE STRUKTURE AKTIVNIH GALAKTIČKIH JEZGARA: TORUS PRAŠINE

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ISTRAŽIVANJE STRUKTURE AKTIVNIH GALAKTIČKIH JEZGARA: TORUS PRAŠINE

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dc.contributor.advisor Popović, Č. Luka
dc.contributor.author Stalevski, T. Marko
dc.date.accessioned 2013-02-28T09:52:54Z
dc.date.available 2013-02-28T09:52:54Z
dc.date.issued 2012
dc.identifier.uri http://hdl.handle.net/123456789/2487
dc.description.provenance Submitted by Slavisha Milisavljevic (slavisha) on 2013-02-28T09:52:54Z No. of bitstreams: 1 Marko_Stalevski_doktorska_disertacija.pdf: 6024712 bytes, checksum: 5d06843b1fd16bb52486f411b3a2c3a0 (MD5) en
dc.description.provenance Made available in DSpace on 2013-02-28T09:52:54Z (GMT). No. of bitstreams: 1 Marko_Stalevski_doktorska_disertacija.pdf: 6024712 bytes, checksum: 5d06843b1fd16bb52486f411b3a2c3a0 (MD5) Previous issue date: 2012 en
dc.language.iso en en_US
dc.publisher Belgrade, Gent en_US
dc.title ISTRAŽIVANJE STRUKTURE AKTIVNIH GALAKTIČKIH JEZGARA: TORUS PRAŠINE en_US
mf.subject.area Astrophysics en_US
mf.subject.subarea Active galactic nuclei en_US
mf.contributor.committee Jovanović, Predrag
mf.contributor.committee Bas, martin
mf.university.faculty Mathematical, Natural science en_US
mf.document.references 272 en_US
mf.document.pages 128 en_US
mf.document.location Belgrade, Gent en_US
mf.document.genealogy-project Yes en_US
mf.description.abstract-ext Active galactic nuclei Nowadays it is widely accepted that every massive galaxy harbors a supermassive black hole (SMBH) at its center. A number of apparent correlations between SMBH mass and host galaxy structural and dynamical properties have been observed. The correlation between the masses of SMBHs and their host galactic bulges suggest a link between their growth (Kormendy & Richstone, 1995; Kormendy & Gebhardt, 2001). Active galactic nucleus (AGN) represents a phase in the life of a galaxy, during which the SMBH growth is directly observable. The term AGN encompasses a variety of energetic phenomena in galactic centers triggered by the matter spiralling into a SMBH at a relatively high rate. The radiation coming from AGNs originates in the conversion of gravitational potential energy into thermal energy as matter spirals towards the SMBH through an accretion disk (Lynden- Bell, 1969). Their luminosity can be up to 10000 greater then the total luminosity of a normal galaxy. The radiated AGN continuum covers a broad range of spectrum, from the X to radio domain, it is partially polarized and variable in time. Radiation from the central engine is ionizing the surrounding medium, creating conditions for the strong emission line spectrum, superimposed on the continuum. Sometimes, highly collimated and fast outflows (“jets”) emerge perpendicular to the accretion disk. Since the discovery of Keel (1980) that the orientation of Seyfert 1 galaxies is not random, it xxx has been recognized that the appearance of an AGN varies with the viewing angle. This has led to the picture of “orientation unification” (see Antonucci, 1993; Urry & Padovani, 1995) where the structure of AGNs is believed to be basically similar but what we see is a strong function of orientation (see Fig. 9). In this unified model, the central black hole is surrounded by a geometrically-thin accretion disk which is the source of the strong X-ray emission and UV/optical continuum (see Jovanovi´c, 2012, and references therein). Above and below the disk is the broad-line region (BLR), turbulent, rapidly-moving, dense, emission-line gas orbiting the black hole (see Gaskell, 2009, for a review). Both the accretion disk and the BLR are surrounded by a geometrically- and optically-thick, roughly toroidal structure of dust and gas (the “dusty torus”), which is absorbing the incoming radiation and re-emitting it in the infrared (IR). In addition to these components there is lower density, more slowly moving gas present on a scale similar to or significantly larger than that of the torus. This gas can be seen when it is illuminated by the cone of ionizing radiation emanating from inside the torus. It is a source of narrow emission lines and thus is know as the “narrow-line region” (NLR). The broad emission lines and the thermal continuum emission can only be seen when the torus is close to faceon and thus, such an object appears as a type 1 active galaxy. Close to edge-on orientations, the dusty torus blocks the radiation coming from the accretion disk and BLR. In this case an UV/optical bump and broad emission lines are absent and an object appears as a type 2 active galaxy. If jet of matter, ejected perpendicular to the accretion disk is present, then viewing such an object along the jet would exhibit strong non-thermal, polarized and rapidly variable continuum (see ? for an in-depth discussion on di erent types of AGN). The masses of SMBHs can be readily estimated in some types of AGN, (Dibai, 1977) and AGNs are currently our only way of studying the evolution of SMBHs over cosmic time. Furthermore, the brightest AGNs are the most luminous quasi-steady compact sources of radiation in the universe and hence they are valuable probes of cosmic evolution up to very high redshifts. In order to understand black hole growth across cosmic time and the connection between galaxies and black holes, we need to understand how AGNs work. We need to test the basic picture outlined above and, in particular, to be able to explain observations which presently challenge this picture and might force modifications of it. en_US
mf.university Belgrade, Gent en_US

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