We use a large, heterogeneous sample of local active galactic nuclei (AGN) that includes Seyfert 1s, Seyfert 2s and PG quasars to investigate for the first time the relation between black hole mass (MBH) and mid-infrared nuclear emission. We find a clear relation between MBH and 10μm nuclear luminosity for these local AGNs. There are no significant differences between type 1 and type 2 objects,...

Using Rossi X-ray Timing Explorer Seyfert 1 and 1.2 data spanning 9 years, we study correlations between X-ray spectral features. The sample consists of 350 time-resolved spectra from 12 Seyfert 1 and 1.2 galaxies. Each spectrum is fitted to a model with an intrinsic powerlaw X-ray spectrum produced close to the central black hole that is reprocessed and absorbed by material around the black ho...

We use high signal-to-noise ratio long-slit spectra in the λλ3600-4700 Å range of the twenty brightest northern Seyfert 2 galaxies to study the variation of the stellar population properties as a function of distance from the nucleus. In order to characterize the stellar population and other continuum sources (e.g. featureless continuum FC) we have measured equivalent widths Ws of six absorptio...

The Deep Survey instrument on the Extreme Ultraviolet Explorer satellite (EUVE ) obtained long, nearly continuous soft X-ray light curves of 5–33 days duration for 14 Seyfert galaxies and QSOs. We present a uniform reduction of these data, which account for a total of 231 days of observation. Several of these light curves are well suited to a search for periodicity or QPOs in the range of hours...

Beginning in 1999 January, the bright, strongly variable Narrow-Line Seyfert 1 (NLS1) galaxy Akn 564 has been observed by RXTE once every ∼4.3 days. It was also monitored every ∼3.2 hr throughout 2000 July. These evenly-sampled observations have allowed the first quantitative comparison of long and short time-scale X-ray variability in an NLS1 and the derivation of an X-ray Power Density Spectr...

Several authors recently explored the Black-Hole mass (MBH) vs. stellar velocity dispersion (σ∗) relationship for Narrow Line Seyfert 1 galaxies (NLS1s). Their results are more or less in agreement and seem to indicate that NLS1s fill the region below the fit obtained by Tremaine et al. (2002), showing a range of σ∗ similar to that of Seyfert 1 galaxies, and a lower MBH . Until now the [O iii] ...

The nearby Seyfert galaxy NGC 7213 has been imaged in Hα and HI with the CTIO 1.5 m telescope and with the Australia Telescope Compact Array (ATCA), respectively. Optically NGC 7213 looks undisturbed and relatively featureless but the continuum-subtracted Hα image shows a 19 kpc long filament located approximately 18.6 kpc from the nucleus. The Hα filament could be neutral gas photo-ionized by ...

The VLA has been used at 3.6 and 20 cm to image a sample of about 50 early-type Seyfert galaxies with recessional velocities less than 7,000 km s −1 and total visual magnitude less than 14.5. Emission-line ([OIII] and Hα+[NII]) and continuum (green and red) imaging of this sample has been presented in a previous paper. In this paper, we present the radio results, discuss statistical relationshi...

The large-scale environment is believed to affect the evolution and intrinsic properties of galaxies. It offers a new perspective on narrow-line Seyfert 1 galaxies (NLS1) which have not been extensively studied in this context before. We study a large and diverse sample of 960 NLS1 galaxies using a luminosity-density field constructed using Sloan Digital Sky Survey. We investigate how the large...

Recent ROSAT studies of narrow-line Seyfert 1 galaxies revealed these objects (with FWHM Hβ ≤ 2000 km s−1) generally show steeper soft X-ray spectra than broad line Seyfert 1’s and that there are noAGNwith broad lines and steep X-ray spectra. We derive a simple theoretical model which explains this observed correlation between the line width and the spectral index for Seyfert 1 galaxies. Assumi...