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 intrinsically polarized. We have measured a significant level of polarization in a further 7 objects but these may be heavily contaminated by Galactic interstellar p...

We discuss the spectral properties of a sample of type-2 Seyfert galaxies based upon the analysis of ASCA data. In this paper we consider the sources for which the X-ray spectra appear to be dominated by the nuclear continuum, transmitted through a large column of absorbing material. We find that both Seyfert-2 galaxies and NELGs show iron Kα line profiles indicative of reprocessing of nuclear ...

Historically, Seyfert nuclei have been considered to be radio-quiet active galactic nuclei (AGNs). We question this widely held assumption by showing that the distribution of the radio-to-optical luminosity ratio, R ≡ Lν(6 cm)/Lν(B), when properly measured for the nuclear component, places the majority of type 1 Seyfert nuclei in the category of radio-loud AGNs, defined here as objects with R ≥...

This paper is the last in a series, investigating the optical properties of a sample of mid-IR Warm Seyfert galaxies and of a control sample of mid-IR cold galaxies. In the present paper we parametrize the morphologies and interaction properties of the host galaxies and combine these with the major conclusions in our previous papers. Our results confirm that nuclear activity is linked to galact...

An optical spectropolarimetric study has shown that the detectability of polarised broad Hα in Seyfert 2 galaxies is correlated to the IRAS f 60 /f 25 flux ratio where only those Seyfert 2s with " warm " IRAS colours show polarised broad line emission. It was suggested that those Seyfert 2s with " cool " IRAS colours have highly inclined tori which obscure the broad line scattering screen. I pr...

We present low-resolution 5.5-35μm spectra for 103 galaxies from the 12μm Seyfert sample, a complete unbiased 12μm flux limited sample of local Seyfert galaxies selected from the IRAS Faint Source Catalog, obtained with the Infrared Spectrograph (IRS) on-board Spitzer Space Telescope. For 70 of the sources observed in the IRS mapping mode, uniformly extracted nuclear spectra are presented for t...

We extend the analysis presented in Tran (2001) of a spectropolarimetric survey of the CfA and 12μm samples of Seyfert 2 galaxies (S2s). We confirm that HBLR S2s tend to have hotter circumnuclear dust temperatures, show mid-IR spectra more characteristic of S1 galaxies, and are intrinsically more luminous than non-HBLR S2s. The level of obscuration and circumnuclear star formation, however, app...

It is well known that the [O ]λ5007 emission line and hard X-ray(2-10keV) luminosities are good indicators of AGN activities and that the near and mid-infrared emission of AGN originates from re-radiation of dusty clouds heated by the UV/optical radiation from the accretion disk. In this paper we present a study of the near-infrared K-band (2.2μm) properties for a sample of 65 Seyfert 2 gala...

Aims. It is well known that the [O ]λ5007 emission line and hard X-ray (2−10 keV) luminosities are good indicators of AGN activities and that the near and mid-infrared emission of AGN originates from re-radiation of dusty clouds heated by the UV/optical radiation from the accretion disk. In this paper we present a study of the near-infrared K-band (2.2 μm) properties for a sample of 65 Seyfe...

The mass of the central black holes in Seyfert galaxies and QSOs can be determined from the broad emission lines and the reverberation method. Using the measured black hole mass and the bolometric or ionizing luminosity, the accretion rate can be estimated. Compiling a sample of Seyfert 1 galaxies and QSOs with reliable central masses, estimated ionizing luminosities, and X-ray spectral slopes,...