Results 101 to 110 of about 22,530 (230)

New Infrared Seyfert Galaxies

open access: yes, 1998
We present optical spectra for new infrared Seyfert galaxies obtained with the 2.16m telescope at Beijing Astronomical Observatory (BAO). After wavelength and flux calibration, they are classified by the degree of nuclear activity: nine Seyfert 2 and three Seyfert 3 galaxies.
Gu, Q. -S.   +3 more
openaire   +2 more sources

IRAS observations of active galaxies [PDF]

open access: yes, 1986
The IRAS survey gives an unbiased view of the infrared properties of the active galaxies. Seyfert galaxies occupy much the same area in color-color plots as to normal infrared bright galaxies, but extend the range towards flatter 60 to 25 mm slopes ...
AR Sandage   +11 more
core   +2 more sources

Optical colour maps of Seyfert galaxies [PDF]

open access: yesAstronomy and Astrophysics Supplement Series, 1998
9 pages, 26 figures, LaTeX, uses l-aa.sty, psfig.sty. A&AS, accepted. Grayscale JPEGs included, original color figures (gif or ps format) can be obtained only by anonymous ftp from ftp://oj287.astro.utu.fi/pub ...
openaire   +2 more sources

A Systematic Search for Active Galactic Nuclei Obscuration Variability in the Chandra Archive

open access: yesThe Astrophysical Journal
The nature of the obscuring material in active galactic nuclei (AGN) can be studied by measuring changes in the line-of-sight column density, N _H,LOS , over time. This can be accomplished by monitoring AGN over long periods of time and at all timescales.
Isaiah S. Cox   +7 more
doaj   +1 more source

IceCube Search for Neutrino Emission from X-Ray Bright Seyfert Galaxies

open access: yesThe Astrophysical Journal
The recent IceCube detection of TeV neutrino emission from the nearby active galaxy NGC 1068 suggests that active galactic nuclei (AGNs) could make a sizable contribution to the diffuse flux of astrophysical neutrinos. The absence of TeV γ -rays from NGC
R. Abbasi   +424 more
doaj   +1 more source

Reflection in Seyfert Galaxies and the Unified Model of AGN

open access: yes, 2011
We present a deep study of the average hard X-ray spectra of Seyfert galaxies. We analyzed all public INTEGRAL IBIS/ISGRI data available on all the 165 Seyfert galaxies detected at z200keV, and a photon index of Gamma ~1.8.
Antonucci   +104 more
core   +1 more source

The Origin of [OII] in Post-Starburst and Red-Sequence Galaxies in High-Redshift Clusters [PDF]

open access: yes, 2010
We present the first results from a near-IR spectroscopic campaign of the Cl1604 supercluster at z~0.9 and the cluster RX J1821.6+6827 at z~0.82 to investigate the nature of [OII] 3727A emission in cluster galaxies at high redshift. Of the 401 members in
A. Shapley   +67 more
core   +2 more sources

Evidence for Neutrino Emission from X-Ray Bright Seyfert Galaxies in the Southern Hemisphere Using Enhanced Starting Track Events with IceCube

open access: yesThe Astrophysical Journal Letters
IceCube recently reported the observation of TeV neutrinos from the nearby Seyfert galaxy NGC 1068, and the corresponding neutrino flux is significantly higher than the upper limit implied by observations of GeV–TeV gamma rays.
R. Abbasi   +430 more
doaj   +1 more source

Correlations between environmental parameters and nuclear activity [PDF]

open access: yes
The occurrence and quantitative properties of Seyfert 1 and Seyfert 2 galaxies as a function of the galaxy environment were studied in a systematic way.
Fricke, K. J., Kollatschny, W.
core   +1 more source

The Unified Model of Active Galactic Nuclei: II. Evolutionary Connection

open access: yes, 2007
(Abbreviated) We assemble a sample composed of 243 nearby Seyfert galaxies with redshifts $z\le 0.05$ to test the unification scheme. The sample contains 94 BLS1s, 44 NLS1s, 36 X-ray absorbed HBLR S2s, 42 X-ray absorbed non-HBLR S2s and 27 X-ray ...
Antonucci R. R. J.   +19 more
core   +1 more source

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