Related papers: Distinguishing Active Galactic Nuclei and Star For…
In a previous paper (Veron et al. 1997) we presented medium resolution (3.4 A FWHM) spectroscopic observations of 15 "transition objects", selected for having an ambiguous location in the Veilleux & Osterbrock (1987) diagnostic diagrams,…
We present the results of ASCA observations of a heterogenous sample of 15 spiral galaxies. 8 are LINERs or low-luminosity AGN (LLAGN), 5 are starburst galaxies and 2 are normal spiral galaxies. We find that in all cases the ASCA spectra…
We present near-infrared spectra for a sample of galaxies with ambiguous optical emission line ratios. These galaxies fall between starbursts and Seyferts in the usual optical diagnostic diagrams. We find a similar result with the…
The Spitzer high resolution spectra of 72 Seyfert galaxies from the 12$\mu$m Galaxy Sample are presented and discussed. The presence of starburst components in these galaxies can be quantified by powerful mid-IR diagnostics tools (i.e.…
Results are presented of extended and refined optical identification of 181 radio/X-ray sources in the RASS-Green Bank (RGB) catalog which have been spectroscopically observed in the Sloan digital sky survey (SDSS) DR5. For 72 sources, the…
In recent surveys of Radio-loud AGN, a new sub-class of objects, known as Weak-Line Radio Galaxies (WLRGs) has emerged. These radio galaxies have only weak, low-ionization optical emission lines. In the X-ray band, these objects are much…
We study the relation of active galactic nuclei (AGNs) to star formation in their host galaxies. Our sample includes 205 Type-1 and 85 Type-2 AGNs, 162 detected with Herschel, from fields surrounding 30 galaxy clusters in the Local Cluster…
Using a new color-color diagnostic diagram in the mid infrared built from WISE data, the MIRDD, we compare narrow emission-line galaxies (NELGs) that exhibit different activity types (star-forming galaxies, SFGs, and AGNs, i.e.,LINERs, Sy2s…
We investigate spatially-resolved emission-line ratios in a sample of 219 galaxies ($0.6<z<1.3$) detected using the G102 grism on the \emph{Hubble Space Telescope} Wide Field Camera 3, taken as part of the CANDELS Ly$\alpha$ Emission at…
We investigate the emission-line properties of galaxies with red rest-frame colors using spectra from SDSS DR4. Emission lines are detected in more than half of the red galaxies. We focus on the relationship between two emission lines…
We investigate the physical cause of the great range in the ionization level seen in the spectra of narrow lined active galactic nuclei (AGN). Mean field independent component analysis identifies examples of individual SDSS galaxies whose…
We have combined HST/FOS and ground-based spectra of the Seyfert 1 galaxy NGC 5548 to study the narrow emission lines over the 1200 -- 10,000 angstrom region. All of the spectra were obtained when the broad emission line and continuum…
We present the first detailed spectroscopic study of field galaxies up to z=0.3 from the I-magnitude limited CFRS sample. In this complete sample, we find that about half of the objects are blue emission-line galaxies. Using line ratio…
The recent discovery by Fermi/LAT of high-energy (E>100 MeV) gamma rays from Narrow-Line Seyfert 1 Galaxies (NLS1s) made evident the existence of a third class of gamma-ray emitting Active Galactic Nuclei (AGN), after blazars and radio…
In a series of papers based on the FIRST and Sloan Digital Sky Surveys (SDSS), we investigate the local population of star-forming galaxies and Active Galactic Nuclei (AGN) in order to clarify the link between these two types of activity,…
This work studies the optical emission line properties and physical conditions of the narrow line region (NLR) of seven narrow-line Seyfert 1 galaxies (NLS1). Our results show that the flux carried out by the narrow component of H-beta is,…
We present mosaicked long-slit spectral maps of 18 nearby Active Galactic Nuclei (AGNs), 2 LINERs, and 4 star-forming galaxies. With the resulting data cubes taken using the Kast dual spectrograph on the 3 m Shane telescope of the Lick…
(Abridged) Spiral galaxies often have extended outflows that permeate beyond the region of the disk. Such outflows have been seen both in starburst galaxies, actively star forming galaxies and galaxies with an AGN. In the latter galaxies it…
We measure oxygen and nitrogen abundances for 14 star-forming emission line galaxies (ELGs) at 0.11<z<0.5 using Keck/LRIS optical spectroscopy. The targets exhibit a range of metallicities from slightly metal-poor like the LMC to…
According to their specific star formation rate (sSFR), galaxies are often divided into `star-forming' and `passive' populations. It is argued that the former define a narrow `Main Sequence of Star-Forming Galaxies' (MSSF) of the form…