Results 21 to 30 of about 22,607 (224)
Power Spectral Density Background Estimate and Signal Detection via the Multitaper Method
Journal of Geophysical Research: Space Physics, Volume 126, Issue 2, February 2021., 2021 Abstract We present a new spectral analysis method for the identification of periodic signals in geophysical time series. We evaluate the power spectral density with the adaptive multitaper method, a nonparametric spectral analysis technique suitable for time series characterized by colored power spectral density.
S. Di Matteo, N. M. Viall, L. Kepko
wiley +1 more source
Jet Directions in Seyfert Galaxies [PDF]
The Astrophysical Journal, 2000 We present the study of the relative angle between the accretion disk (or radio jet) and the galaxy disk for a sample of Seyfert galaxies selected from a mostly isotropic property, the 60$ $m flux. For each galaxy we have a pair of points ($i$,$ $), which are the inclination of the galaxy relative to the line of sight and the angle between the jet ...
Kinney, A. L. +5 more
openaire +2 more sources
Looking for Signatures of AGN Feedback in Radio-Quiet AGN
Galaxies, 2023 In this article, we discuss the state of “AGN feedback” in radio-quiet (RQ) AGN. This study involves heterogeneous samples of nearby Seyfert and LINER galaxies as well as quasi-stellar objects (QSOs) that have been observed at low radio frequencies (few ∼
Preeti Kharb, Sasikumar Silpa
doaj +1 more source
Symposium - International Astronomical Union, 1972 The four Seyfert galaxies with systemic velocities of less than 2000 km s−1 have been observed at 21 cm with the Jodrell Bank 250-ft telescope and a 5 MHz overall bandwidth setting of the 256 channel auto-correlation spectrometer. Relatively strong signals of 0.5 f.u.
openaire +1 more source
Optical Spectroscopy of the IRAS 1-Jy Sample of Ultraluminous Infrared Galaxies [PDF]
, 1999 This paper discusses the optical spectroscopic properties of the IRAS 1-Jy sample of ultraluminous infrared galaxies (ULIGs). One hundred and eight of the 118 1-Jy ULIGs have been observed at dlambda = 8.3 AA resolution over the wavelength range ~4500 A -
Allen D. A. +14 more
core +2 more sources
Relativistic jets in narrow-line Seyfert 1 galaxies. New discoveries and open questions
EPJ Web of Conferences, 2013 Before the launch of the Fermi satellite only two classes of AGNs were known to produce relativistic jets and thus emit up to the γ-ray energy range: blazars and radio galaxies, both hosted in giant elliptical galaxies.
D’Ammando F. +4 more
doaj +1 more source
Seyfert galaxies and BeppoSAX [PDF]
Nuclear Physics B - Proceedings Supplements, 1999 The contributions that BeppoSAX is expected to give and, after one and a half year of operation, has already given to our knowledge of both type 1 and type 2 Seyfert galaxies are outlined and reviewed.
openaire +3 more sources
X-RAY VARIABILITY STUDY OF POLAR SCATTERED SEYFERT1 GALAXIES
Acta Polytechnica, 2014 We study 12 Seyfert 1 galaxies with a high level of optical polarization. Optical light emerging from the innermost regions is predominantly scattered in a polar region above the central engine directly in our line of sight.
Tobias Beuchert +6 more
doaj +1 more source
Spitzer/IRS Observations of Seyfert 1.8s and 1.9s: A Comparison with Seyfert 1s and Seyfert 2s [PDF]
, 2007 We present Spitzer Space Telescope mid-infrared spectra of 12 Seyfert 1.8 and 1.9 galaxies over the 5-38 um region. We compare the spectral characteristics of this sample to those of 58 Seyfert 1 and Seyfert 2 galaxies from the Spitzer archives.
Antonucci R. +11 more
core +3 more sources
Classifying Seyfert Galaxies with Deep Learning [PDF]
The Astrophysical Journal Supplement Series, 2021 Abstract The traditional classification for a subclass of the Seyfert galaxies is visual inspection or using a quantity defined as a flux ratio between the Balmer line and forbidden line. One algorithm of deep learning is the convolution neural network (CNN), which has shown successful classification results.
openaire +2 more sources