Results 121 to 130 of about 74,488 (217)
Test for Echo: X-Ray Reflection Variability in the Seyfert-2 Active Galactic Nucleus NGC 4388
The Astrophysical JournalWe report on a study of the narrow Fe K α line and reflection spectrum in the well-known Seyfert-2 active galactic nucleus (AGN), NGC 4388. X-ray spectra summed from two extensive NICER monitoring campaigns, separated by years, show strong evidence of ...
Ben Gediman +6 more
doaj +1 more source
"Fermi" bubbles are bursting from our galaxy. Their origins remain a mystery. [PDF]
Proc Natl Acad Sci U S A, 2023 Mann A.
europepmc +1 more source
On the Properties of X-Ray Corona in Seyfert 1 Galaxies
The Astrophysical JournalWe carried out a uniform and systematic analysis of a sample of 112 nearby bright Seyfert 1 type active galactic nuclei, the observations of which were carried out by the Nuclear Spectroscopic Telescope Array between 2013 August and 2022 May.
Indrani Pal +6 more
doaj +1 more source
The Astrophysical JournalWe present serendipitous simultaneous radio and X-ray light curves of the dwarf Seyfert galaxy UGC 6728 spanning 5 yr. The X-ray light curve exhibits a flaring period, followed by a gradual rise and decline.
Krista Lynne Smith +2 more
doaj +1 more source
The Astrophysical JournalTo facilitate new studies of galaxy-merger-driven fueling of active galactic nuclei (AGNs), we present a catalog of 387 AGNs that we have identified in the final population of over 10,000 z < 0.15 galaxies observed by the Sloan Digital Sky Survey-IV ...
Julia M. Comerford +9 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
The Astrophysical Journal LettersThe 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 +7 more
doaj +1 more source
A Long-term Study of Mrk 50: Appearance and Disappearance of Soft Excess
The Astrophysical JournalWe 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 +3 more
doaj +1 more source
Uncovering the Active Galactic Nuclei in Low-Ionization Nuclear Emission-Line Regions with Spitzer
, 2007 The impact of active galactic nuclei on low-ionization nuclear emission-line regions (LINERs) remains a vigorous field of study. We present preliminary results from a study of the mid-infrared atomic emission lines of LINERs with the Spitzer Space ...
Contursi, Alessandra +8 more
core
Discovery of Changing-look Behavior in AGN NGC 3822: A Long-term Multiwavelength Study
The Astrophysical JournalWe 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 +9 more
doaj +1 more source