Related papers: The Diagnostics and Possible Evolution in Active G…
Local galaxies from the Sloan Digital Sky Survey are used to provide additional support for an evolutionary pathway in which AGN activity is associated with star-formation quenching. Composite, Seyfert 2 and LINER galaxies account for…
This paper is the fourth in a series, studying the optical properties of a sample of mid-IR Warm Seyfert galaxies and of a control sample of mid-IR cold galaxies. The present paper is devoted to the analysis of the colour distributions…
We present optical spectropolarimetry of the nuclei of 36 Seyfert 1 galaxies, obtained with the William Herschel and the Anglo-Australian Telescopes from 1996 to 1999. In 20 of these, the optical emission from the active nucleus is…
We analyse the integral-field spectroscopy data for the $\approx10,000$ galaxies in final data release of the MaNGA survey. We identify 188 galaxies for which the emission lines cannot be described by single Gaussian components. These…
We study the environment of active galaxies and compare it with that of star forming and normal galaxies. We extracted from the Fourth Data Release (DR4) of the Sloan Digitaly Sky Survey (SDSS) the galaxies in the redshift range 0.05 \le z…
We analyze the physical properties of post-starburst AGN SDSS J085338.27+033246.1 according to its optical spectrum and discuss its implications on AGN's evolution. The spectra PCA method is developed to extract emission lines and…
We analyzed a sample of $\sim$113,000 galaxies ($\rm z < 0.3$) from the Sloan Digital Sky Survey, divided into star-forming, composite, Seyfert, and LINER types, to explore the relationships between UV-to-optical colors ($\rm u-r$), star…
We present spectra of 6 type 1 Seyfert galaxies, 2 Seyfert 2, a starburst galaxy and a compact narrow line radiogalaxy, taken in two spectral ranges centered around the near--IR CaII triplet (CaT) (at ~8600 Angstroms), and the Mgb stellar…
We present near-IR integral field spectroscopy of a sample of 31 Seyfert and LINER galaxies which were selected both to span a wide range of nuclear magnitudes and to possess roughly equal numbers of Seyfert type 1 and 2 nuclei. Moderate…
We investigate 'activity' and 'quiescence' in galaxies at relatively high redshifts by modelling the line(and continuum) spectra of each object. The models account consistently for photoionization and shocks. We claim that the starburst…
The Unified Model of Active Galactic Nuclei (AGN) has provided a successful explanation for the observed diversity of AGN in the local Universe. However, recent analysis of multi-wavelength spectral and image data suggests that the Unified…
In order to perform a more complete census of active galactic nuclei (AGN) in the local Universe, we investigate the use of the HeII~$\lambda 4685$ emission line diagnostic diagram by Shirazi & Brinchmann (2012) in addition to the standard…
This paper presents a quantification of the X-ray variability amplitude for 79 ASCA observations of 36 Seyfert 1 galaxies. We find that consideration of sources with the narrowest permitted lines in the optical band introduces scatter into…
We present a spectroscopic study with the derivation of the physical properties of 37 Balmer break galaxies, which have the necessary lines to locate them in star-forming-AGN diagnostic diagrams. These galaxies span a redshift range from…
The optical spectra of Seyfert galaxies are often dominated by emission lines excited by both star formation and AGN activity. Standard calibrations (such as for the star formation rate) are not applicable to such composite (mixed) spectra.…
We present HST/ACS observations of ten galaxies that host narrow-line Seyfert 1 (NLS1) nuclei, believed to contain relatively smaller mass black holes accreting at high Eddington ratios. We deconvolve each ACS image into a nuclear point…
The variability of active galactic nuclei (AGN) has long held the promise of shedding light on their detailed structure, and possibly other astrophysical phenonema. Different emission mechanisms lead to different patterns of variability in…
I review the relationship between star formation and black hole building, based on spectroscopic observations of the stellar population in active galactic nuclei (AGNs) and their host galaxies. My emphasis is on large, well-defined local…
The Hubble Space Telescope WFPC2 is being used to obtain high-resolution images in the V and I bands for several thousand distant galaxies as part of the Medium Deep Survey (MDS). An important scientific aim of the MDS is to identify…
We present Spitzer measurements of the aromatic (also known as PAH) features for 35 Seyfert galaxies from the revised Shapley-Ames sample and find that the relative strengths of the features differ significantly from those observed in…