Results 1 to 10 of about 121,024 (252)

Active galactic nuclei. [PDF]

Proc Natl Acad Sci U S A, 1999
Active galactic nuclei are the most powerful, long-lived objects in the Universe. Recent data confirm the theoretical idea that the power source is accretion into a massive black hole. The common occurrence of obscuration and outflows probably means that the contribution of active galactic nuclei to the power density of the Universe has been ...
Fabian AC.
europepmc   +6 more sources

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

The 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, Núria Torres-Albà, Stefano Marchesi, Vittoria E. Gianolli, Xiurui Zhao, Marco Ajello, Indrani Pal, Ross Silver   +7 more
doaj   +1 more source

On the Extended Soft X-Ray and Fe Kα Emission in NGC 1068

The Astrophysical Journal
The soft X-ray excess and Fe K α emission lines are widely observed in Seyfert galaxies, with their origin still in debate. We present a detailed spatially resolved image and spectral analysis of the Seyfert 2 galaxy NGC 1068 using high-resolution ...
Songbo Gao, Hongxing Yin, Shaoming Hu
doaj   +1 more source

JWST NIRCam Imaging of NGC 4258. I. Observation Overview

The Astrophysical Journal
We present James Webb Space Telescope (JWST) Near-Infrared Camera imaging of the nearby Seyfert 1.9 galaxy NGC 4258, which hosts strong star formation regions as well as an anomalous jet-like radio structure that extends through a significant portion of ...
Travis C. Fischer, Nicholas F. Cothard, Omnarayani Nayak, Henrique R. Schmitt, Erin C. Smith, Jason Glenn   +5 more
doaj   +1 more source

On the two states of CYG X-1 and related sources [PDF]

A model for active galactic nuclei (AGN), employing quasi-spherical accretion onto a black hole, when scaled down to solar mass objects, provides a straightforward account of the bimodal spectral behavior of Cyg X-1 and the other galactic black hole ...
Kazanas, D.
core   +1 more source

On the Extremely X-Ray Variable Active Galactic Nuclei in the XMM-LSS Field

The Astrophysical Journal
We present a systematic investigation of extremely X-ray variable active galactic nuclei (AGNs) in the ≈5.3 deg ^2 XMM-SERVS XMM-LSS region. Eight variable AGNs are identified with rest-frame 2 keV flux density variability amplitudes around 6–12.
Zijian Zhang, Bin Luo, Linhua Jiang, W. N. Brandt, Jian Huang, Qingling Ni   +5 more
doaj   +1 more source

BASS. XLVIII. [Ne V] λ3427 Emission in Powerful Nearby Active Galactic Nuclei

The Astrophysical Journal
We investigate the high-ionization, narrow [Ne V ] λ 3427 line emission in a sample of over 340 ultrahard X-ray (14–195 keV) selected active galactic nuclei (AGN) drawn from the BAT AGN Spectroscopic Survey project.
Tomer Reiss, Benny Trakhtenbrot, Claudio Ricci, Franz E. Bauer, Michael J. Koss, Kohei Ichikawa, Darshan Kakkad, Richard Mushotzky, Kyuseok Oh, Alessandro Peca, Rudolf Bär, Yaherlyn Diaz, Fiona Harrison, Meredith C. Powell, Eleonora Sani, Daniel Stern, C. Megan Urry   +16 more
doaj   +1 more source

MATTER OUTFLOW FROM ACTIVE GALACTIC NUCLEI

Вестник. Серия физическая, 2008
Some problems of the theory of matter outflow from AGN in connection with the unification model of AGN are brifly discussed.
E.Y. Vilkoviskij
doaj  

Solar peculiar motion inferred from dipole anisotropy in redshift distribution of quasars appears to lie along the Galactic Centre direction. [PDF]

Sci Rep
Singal AK.
europepmc   +1 more source

Review of Passive Shielding Materials for High-Energy Charged Particles in Earth's Orbit. [PDF]

Materials (Basel)
Wang M, Wang Q, Xiao Y, Wang M, Wang J, Wang H, Chen Z.   +6 more
europepmc   +1 more source