Results 81 to 90 of about 50,208 (269)

Hard X-ray variability of active galactic nuclei [PDF]

Astronomy & Astrophysics, 2007
Aims. Active Galactic Nuclei are known to be variable throughout the electromagnetic spectrum. An energy domain poorly studied in this respect is the hard X-ray range above 20 keV. Methods. The first 9 months of the Swift/BAT all-sky survey are used to study the 14-195 keV variability of the 44 brightest AGN. The sources have been selected due to their
V. Beckmann, S. D. Barthelmy, T. J.-L. Courvoisier, N. Gehrels, S. Soldi, J. Tueller, G. Wendt   +6 more
openaire   +1 more source

Trace Element Transport and Deposition During Magmatic Degassing: The Effect on Martian Rocks and Fines

Journal of Geophysical Research: Planets, Volume 130, Issue 12, December 2025.
Abstract Martian magmas compositionally resemble those from terrestrial continental hotspot magmatic suites, characterized by low OH and high Cl and S contents. The magmatic gases exsolved from such magmas transport a variety of metal complexes and, upon cooling, precipitate vapor‐deposits into vugs and fractures within rocks and on the surfaces of ...
N. Zimmermann, M. Safari, H. Nekvasil
wiley   +1 more source

On the Properties of X-Ray Corona in Seyfert 1 Galaxies

The Astrophysical Journal
We 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, Anju A., H. Sreehari, Gitika Rameshan, C. S. Stalin, Claudio Ricci, S. Marchesi   +6 more
doaj   +1 more source

X-Ray Spectra and Time Variability of Active Galactic Nuclei [PDF]

Annual Review of Astronomy and Astrophysics, 1984
The X-ray spectra of broad line active galactic nuclei (AGN) of all types (Seyfert I's, NELG's, broadline radio galaxies) are well fit by a power law in the .5 to 100 keV band of man energy slope alpha = .68 + or - .15. There is, as yet, no strong evidence for time variability of this slope in a given object.
openaire   +1 more source

Palagonitization of Volcanic Rocks in Polar Climates: The Case of Deception Island (Antarctica)

Geochemistry, Geophysics, Geosystems, Volume 26, Issue 12, December 2025.
Abstract A detailed study of palagonitization in rocks from Deception Island—one of Antarctica's most active volcanoes—has been performed to advance our understanding of this alteration process. A detailed petrographic (optical and SEM), mineralogical (XRD), and mineral and glass spot geochemistry (EDS and EMP) characterization has been conducted on ...
Oriol Vilanova‐Pagès, Guillem Gisbert, Helena Albert, Adelina Geyer, Meritxell Aulinas, Raquel Arasanz, Jordi Ibañez‐Insa, Antonio Polo‐Sánchez, Antonio Álvarez‐Valero, Olga Prieto‐Ballesteros, Santiago Giralt   +10 more
wiley   +1 more source

BASS. XLIX. Characterization of Highly Luminous and Obscured AGNs: Local X-Ray and [Ne V]λ3426 Emission in Comparison with the High-redshift Universe

The Astrophysical Journal
We present a detailed analysis of the most luminous and obscured active galactic nuclei (AGNs) detected in the ultra-hard X-ray band (14–195 kev) by the Swift/Burst Alert Telescope. Our sample comprises 21 X-ray luminous ( ${\mathrm{log}}\,{L}_{{\rm{X}}}/
Alessandro Peca, Michael J. Koss, Kyuseok Oh, Claudio Ricci, Benny Trakhtenbrot, Richard Mushotzky, Ezequiel Treister, C. Megan Urry, Andrealuna Pizzetti, Kohei Ichikawa, Alessia Tortosa, Federica Ricci, Matilde Signorini, Darshan Kakkad, Chin-Shin Chang, Giovanni Mazzolari, Turgay Caglar, Macon Magno, Ignacio del Moral-Castro, Peter G. Boorman, Tonima T. Ananna, Fiona Harrison, Daniel Stern, David Sanders   +23 more
doaj   +1 more source

Rapakivi K‐Feldspar Megacrysts in Monzogranitic Porphyry: Evidence for Magma Recharge and Mush Rejuvenation

Geochemistry, Geophysics, Geosystems, Volume 26, Issue 12, December 2025.
Abstract The formation, storage, and evolution of granitic magmas are fundamental processes driving the growth of continental crust. While traditionally attributed to crystal fractionation in high‐melt fraction magma chambers, the model invoking low‐melt fraction crystal mushes has gained wide acceptance.
Wang Li, Xuxuan Ma, Roberto Weinberg, Liang Qiu, Zhiyong Zhu, Haibing Li   +5 more
wiley   +1 more source

NuSTAR Detection of an Absorption Feature in ESP 39607: Evidence for an Ultrafast Inflow?

The Astrophysical Journal
We report the serendipitous discovery of an absorption feature at 4.8 keV in the NuSTAR spectra of ESP 39607, a Seyfert 2 galaxy at z = 0.201, observed in 2023 May and 2024 August. The feature is detected in both observations with individual significance
Alessandro Peca, Michael J. Koss, Roberto Serafinelli, Claudio Ricci, C. Megan Urry, Giulia Cerini, Peter G. Boorman   +6 more
doaj   +1 more source

X-ray emission from active galactic nuclei [PDF]

It is often held that the X-ray emission from active galactic nuclei (AGN) arises from a region close to the central energy source. Thus X-ray observations may provide the best constraints on the central engine.
Mushotzky, R.
core   +1 more source

The nature of the infrared counterpart of IGR J19140+0951

, 2007
The INTEGRAL observatory has been (re-)discovering new X-ray sources since the beginning of nominal operations in early 2003. These sources include X-ray binaries, Active Galactic Nuclei, cataclysmic variables, etc.
Bird, Bodaghee, Bronfman, Charles, Corbet, Cox, D. C. Hannikainen, Hannikainen, Hannikainen, Hanson, Hanson, In 't Zand, J. Rodriguez, J. Schultz, Kuulkers, Lebrun, Liu, Lu, M. G. Rawlings, Nespoli, O. Vilhu, P. Muhli, Rawlings, Rodriguez, Rodriguez, Swank, Ubertini, Walter, Winkler   +28 more
core   +1 more source