1,721,021 research outputs found
Multilayer photoionization models of the nuclear and circumnuclear regions of type 2 AGN
No full textWe present an overview of the physical conditions occurring in the nuclear and circumnuclear regions of nearby Active Galactic Nuclei of type 2 (z<0.1) and the results of simulation, using multicomponent photoionization models. The comparison of calculated with observed line ratios, measured in the spectra of a sample of around 1300 type 2 active galaxies, is critically discussed
Kinematics in Seyfert Galaxies for testing the activity interaction relation
No full textWhile it is largely demonstrated that interaction can trigger activity, it is not yet possible to estabilish whether there is a one-to-one relation between activity and interaction. Indeed the results of the statistical studies that show an excess of physical companions among Seyfert galaxies are still controversial. In this poster we present our project of a systematic investigation of the global kinematical properties of a sample of nearby (z < 0.03) isolated active and non active galaxies aimed at unveiling features caused by past interactions. We show preliminary results about two active galaxies of our sample, NGC 6300 and Mrk 1157
Spectrophotometric study of nearby Seyfert nuclei
No full textWe present new results about the spectrophotometric study of the nuclear regions in nearby (z<0.03) Seyfert galaxies. The observations were carried out using the Multi Pupil Fiber Spectrograph (MPFS), the integral field unit mounted at the 6-m telescope of the Special Astrophysical Observatory (Russia). The main purpose of this work is to test the Unified Model in nearby AGNs through the investigation of the the gaseous/stellar environment close the active nucleus. In particular, we show emission line ratio maps, included excitation maps ([O III]/Halpha ), which allowed us to trace the regions with different degrees of ionization, to identify ionization cones and/or circum-nuclear star forming regions, and to study in detail their physical properties
Morphology and Photometry of Isolated Seyfert Galaxies
No full textAn unresolved and intriguing problem about active galactic nuclei is the mechanism responsible for nuclear triggering and fueling. Until now there is not a unique solution that can completely explain this phenomenon. We present preliminary results about morphological and photometric analysis of a sample of 35 nearby (z<0.035) and isolated Seyfert galaxies, observed through broad-band BVR filters at the 1.8-m Vatican Telescope and the 2.2-m ESO-La Silla Telescope. We analyzed photometric and morphological parameters and, using GALFIT software, we obtained two-dimensional decomposition of the luminosity profiles
Investigating the nuclear regions in Seyfert galaxies with 3D spectroscopy
No full textWe present preliminary interesting results stemming from a study of the nuclear and circum-nuclear regions of a sample of nearby Seyfert galaxies. Integral Field Spectroscopy was applied as a method of investigation, and data were used to analyze the physics of the ionized gas. Reconstructed continuum and emission line images of the observed galaxies revealed the presence of an extended S-shape ionization cone in Mrk 3, a circumnuclear HII star forming region in Mrk 744, and strong shock ionization around the nucleus of NGC 7319
The hidden nature of narrow line Seyfert 1 galaxies
No full textNarrow-Line Seyfert 1 (NLS1) galaxies are relatively rare objects among type 1 nearby Active Galactic Nuclei (AGNs), and after almost two decades since their first classification, they are still a matter of debate. Their peculiar properties, like narrow permitted emission lines (FWHM < 2000 km/s), steep slopes and rapid variability in the soft X-ray domain, and the optical / UV Big Blue Bump shifted towards higher energy, are currently iinterpreted as indications of active nuclei younger than "classical" Seyfert 1 (S1) galaxies, powered by smaller supermassive black holes (M < 1E6 - 1E7 solar masses), and accreting at higher
rates. To date this paradigm is not yet proved. Other possible scenarios were proposed and several authors challenged this topic from different points of view. Here we present a short review about the spectroscopic properties of NLS1s and recent results obtained within our group in investigating the BH-bulge relation of AGNs as a test for the NLS1-paradigm
A host galaxy study of southern narrow-line Seyfert 1 galaxies
Full text linkWe studied seven nearby narrow-line Seyfert 1 (NLS1) galaxies in J and Ks bands with redshifts varying from 0.019 to 0.092. This is the first multi-source study targeting the hosts of southern NLS1 galaxies. Our data were obtained with the FourStar instrument of the 6.5 m Magellan Baade telescope at the Las Campanas Observatory (Chile). The aim of our study is to determine the host galaxy morphologies of these sources by using GALFIT. We were able to model six out of the seven sources reliably. Our conclusion is that all of the reliably modelled sources are disk-like galaxies, either spirals or lenticulars. None of these sources present an elliptical morphology. Our findings are in agreement with the hypothesis that disk-like galaxies are the main host of jetted NLS1 galaxies. Taking advantage of observations in two bands, we also produced a J − Ks colour map of each source. Five of the six colour maps show significant dust extinction near the core of the galaxy - a feature often seen in gamma-ray-detected jetted NLS1 galaxies, and interpreted to be a consequence of a past minor merger
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