Results 101 to 110 of about 50,261 (220)

Accretion, ejection and reprocessing in supermassive black holes

, 2015
This is a White Paper in support of the mission concept of the Large Observatory for X-ray Timing (LOFT), proposed as a medium-sized ESA mission. We discuss the potential of LOFT for the study of active galactic nuclei.
Bianchi, S., Cappi, M., Czerny, B., Dadina, M., De Marco, B., De Rosa, A., Dovciak, M., Giroletti, M., Karas, V., Kunneriath, D., La Franca, F., Manousakis, A., Marinucci, A., Markowitz, A., McHardy, I., Mehdipour, M., Miniutti, G., Paltani, S., Paolillo, M., Papadakis, I., Perez-Torres, M., Peterson, B., Petrucci, P. O., Piconcelli, E., Ponti, G., Risaliti, G., Rozanska, A., Salvati, M., Sobolewska, M., Svoboda, J., Tombesi, F., Trevese, D., Uttley, P., Vagnetti, F., Vaughan, S., Vignali, C., Vincent, F. H., Zdziarski, A.   +37 more
core  

X-Ray Polarization Variability of High Spectral Peak BL Lacertaes: Cases of 1ES 1959+650 and PKS 2155–304

The Astrophysical Journal Letters
The high-energy-peaked BL Lacertae objects (HBLs) are the main targets of the Imaging X-ray Polarimetry Explorer (IXPE) for investigating the mechanisms of radiation and particle acceleration in jets. In this Letter, we report the first IXPE observations
Xin-Ke Hu, Yu-Wei Yu, Jin Zhang, Tan-Zheng Wu, Ji-Shun Lian, Xiang-Gao Wang, Hai-Ming Zhang, En-Wei Liang   +7 more
doaj   +1 more source

Demography of obscured and unobscured AGN: prospects for a Wide Field X-ray Telescope

, 2010
We discuss some of the main open issues in the evolution of Active Galactic Nuclei which can be solved by the sensitive, wide area surveys to be performed by the proposed Wide Field X-ray Telescope mission.Comment: Proceedings of "The Wide Field X-ray ...
A. Comastri, C. Vignali, E. Lusso, F. Marulli, M. Brusa, P. Rosati, P. Tozzi, PAOLILLO, MAURIZIO, R. Gilli, S. Borgani, the WFXT team   +10 more
core  

Active galactic nuclei with ultrasoft X-ray emission

The Astrophysical Journal Supplement Series, 1992
The discovery of a class of AGN with clearly distinguishable soft X-ray components below 0.5 keV is reported. These AGN were detected through equivalent hydrogen column densities that are less than a few times 10 exp 20/sq cm. At least three kinds of AGN comprise this sample: low-redshift quasars and Seyfert galaxies that have only ultrasoft emission ...
F. A. Cordova, J. F. Kartje, R. J., Jr. Thompson, K. O. Mason, E. M. Puchnarewicz, F. R., Jr. Harnden   +5 more
openaire   +1 more source

A Long-term Study of Mrk 50: Appearance and Disappearance of Soft Excess

The Astrophysical Journal
We present an extensive temporal and spectral study of the Seyfert 1 AGN Mrk 50 using 15 yr (2007–2022) of multiwavelength observations from XMM-Newton, Swift, and NuSTAR for the first time.
Narendranath Layek, Prantik Nandi, Sachindra Naik, Arghajit Jana   +3 more
doaj   +1 more source

Detecting the 21 cm Forest in the 21 cm Power Spectrum

, 2014
We describe a new technique for constraining the radio loud population of active galactic nuclei at high redshift by measuring the imprint of 21 cm spectral absorption features (the 21 cm forest) on the 21 cm power spectrum.
Dillon, Joshua S., Ewall-Wice, Aaron, Hewitt, Jacqueline, Mesinger, Andrei   +3 more
core   +1 more source

Discovery of Changing-look Behavior in AGN NGC 3822: A Long-term Multiwavelength Study

The Astrophysical Journal
We present a comprehensive long-term multiwavelength study of the active galactic nucleus NGC 3822, based on 17 yr (2008–2025) of X-ray, ultraviolet (UV), and optical observations. The data set includes observations from Swift , XMM - Newton, and NuSTAR,
Narendranath Layek, Prantik Nandi, Sachindra Naik, Birendra Chhotaray, Arghajit Jana, Priyadarshee P. Dash, Neeraj Kumari, C. S. Stalin, Srikanth Bandari, S. Muneer   +9 more
doaj   +1 more source

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

[C II] emission from galactic nuclei in the presence of X-rays

, 2015
The luminosity of [C II] is used to probe the star formation rate in galaxies, but the correlation breaks down in some active galactic nuclei (AGNs). Models of the [C II] emission from galactic nuclei do not include the influence of X-rays on the carbon ...
Langer, William D., Pineda, Jorge L.
core   +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