Results 21 to 30 of about 161,008 (274)

Reflection in Seyfert Galaxies and the Unified Model of AGN [PDF]

, 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, Antonucci, Awaki, Barcons, Barth, Bassani, Beckmann, Beckmann, Bikmaev, Bodaghee, Brightman, Burlon, Butler, C. Ricci, Cai, Cappi, Caroli, Courvoisier, Dadina, Dadina, Della Ceca, Deluit, Deluit, Ebisawa, Eguchi, Fiore, Fiore, Gandhi, Gilli, Greenhill, Grupe, Grupe, Grupe, Grupe, Grupe, Gu, Guainazzi, Guainazzi, Guainazzi, Haardt, Haardt, Heckman, Ho, Jiménez-Bailón, Krolik, Landi, Landi, Lebrun, Longinotti, Lumsden, Magdziarz, Malizia, Malizia, Malizia, Malizia, Maoz, Maoz, Masetti, Miller, Mor, Moran, Morrison, Nagao, Narayan, Netzer, Osterbrock, Paltani, Panessa, Panessa, Pappa, Petrucci, Pfeerkorn, Pian, R. Walter, Ramos Almeida, Ramos Almeida, Rees, Ricci, Rigby, Risaliti, Risaliti, Risaliti, Risaliti, Rodriguez, Rodriguez, Rovilos, S. Paltani, Shu, T. J.-L. Courvoisier, Tomsick, Tran, Tran, Treister, Türler, Ubertini, Ueda, Veron-Cetty, Vignati, Walter, Williams, Winkler, Winter, Winter, Zdziarski, Zhang   +104 more
core   +2 more sources

Activity of the Seyfert galaxy neighbours [PDF]

Astronomy & Astrophysics, 2013
Accepted for publication in A&A. 17 pages, 4 figures. arXiv admin note: substantial text overlap with arXiv:0910.1355v1 (withdrawn)
I. Georgantopoulos, Manolis Plionis, Manolis Plionis, V. H. Chavushyan, Deborah Dultzin, Elias Koulouridis, Yair Krongold, Jonathan León-Tavares, Jonathan León-Tavares   +8 more
openaire   +4 more sources

Chemical evolution of Seyfert galaxies [PDF]

Proceedings of the International Astronomical Union, 2007
AbstractWe computed the chemical evolution of Seyfert galaxies, residing in spiral bulges, based on an updated model for the Milky Way bulge with updated calculations of the Galactic potential and of the feedback from the central supermassive black hole (BH) in a spherical approximation. We followed the evolution of bulges of masses 2 × 109 − 1011M⊙ by
S. K. Ballero, F. Matteucci, CIOTTI, LUCA   +2 more
openaire   +5 more sources

Helical Structures in Seyfert Galaxies [PDF]

International Astronomical Union Colloquium, 2002
Abstract Seyfert galaxies with Z-shaped emission filaments in the Narrow Line Region (NLR) are considered. We assume that observable Z-shaped structures and the velocity pattern of the NLR may be explained as tri-dimensional helical waves in the ionization cone.
V. V. Mustsevoi, S. N. Dodonov, S. S. Khrapov, V. L. Afanasiev, Alexei Moiseev   +4 more
openaire   +3 more sources

Accretion mode and jet collimation in active galactic nuclei

Astronomische Nachrichten, Volume 342, Issue 9-10, Page 1071-1076, November-December 2021., 2021
Abstract In this article, we summarize our recent progress in observational studies of jet collimation in active galactic nuclei. We focus on the investigation of a relation between the properties of the collimation zone and the AGN accretion mode, recently proposed by Boccardi, B., Perucho, M., Casadio, C. et al., 2021, A&A, 647, A67.
Bia Boccardi, Eftychia Madika, Luca Ricci   +2 more
wiley   +1 more source

1H 0707‐495: An AGN is dimming its X‐ray light

Astronomische Nachrichten, Volume 342, Issue 5, Page 708-714, June 2021., 2021
Abstract We report on one of the first science observations obtained during the Calibration and Verification phase of extended ROentgen Survey with an Imaging Telescope Array (eROSITA) aboard the Spectrum‐Roentgen‐Gamma (SRG) mission on the famous Narrow‐Line Seyfert 1 Galaxy 1H 0707‐495.
Thomas Boller
wiley   +1 more source

Unabsorbed Seyfert 2 galaxies [PDF]

Astronomy & Astrophysics, 2002
We present a sample of 17 type 2 Seyfert galaxies which have an X-ray column density lower than 10^{22} cm^{-2}. The Compton thin nature of these sources is strongly suggested by isotropic indicators. We estimate the fraction of these sources to be in the range of 10% - 30% of the population of type 2 Seyfert galaxies.
Francesca Panessa, Loredana Bassani
openaire   +4 more sources

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 ...
Cathie J. Clarke, Anne L. Kinney, Anne L. Kinney, J. E. Pringle, Robert Antonucci, James S. Ulvestad, Henrique R. Schmitt   +6 more
openaire   +3 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