Results 11 to 20 of about 37,734 (223)
A tool to understand emission mechanisms of blazars through their high‐energy gamma‐ray emission
Astronomische Nachrichten, Volume 344, Issue 6, August 2023., 2023 The blazar SED is characterized by two energy components. Evidence suggests that the low‐energy component is generated by the synchrotron mechanism, but for the high‐energy component, the mechanism is still uncertain. Two main models have been proposed to explain this emission. According to the leptonic model, a correlation between the emission of both
Mabel Osorio +3 more
wiley +1 more source
Multiwavelength astrophysics of the blazar OJ 287 and the project MOMO
Astronomische Nachrichten, Volume 344, Issue 4, May 2023., 2023 Abstract We are carrying out the densest and longest multiyear, multiwavelength monitoring project of OJ 287 ever done. The project MOMO (Multiwavelength Observations and Modeling of OJ 287) covers wavelengths from the radio to the high‐energy regime. A few selected observations are simultaneous with those of the Event Horizon Telescope (EHT).
S. Komossa +21 more
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Extreme accretion events: TDEs and changing‐look AGN
Astronomische Nachrichten, Volume 344, Issue 4, May 2023., 2023 Abstract We present a review of the topics of X‐ray stellar tidal disruption events (TDEs) and changing‐look active galactic nuclei (AGN). Stars approaching a supermassive black hole (SMBH) can be tidally disrupted and accreted. TDEs were first discovered in the X‐ray regime and appear as luminous, giant‐amplitude flares from inactive galaxies.
S. Komossa, D. Grupe
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LRS Bianchi Type‐I String Cosmological Models in f(Q) Gravity
Journal of Mathematics, Volume 2023, Issue 1, 2023., 2023 In the current study, we studied a f(Q)‐gravitational, anisotropic, locally rotationally symmetric (LRS), Bianchi type‐I spacetime universe. We have adopted the freely chosen function fQ=Q+αQ, where α is a model‐free parameter. We assumed that the universe is filled with dusty string fluid and that the shear scalar (σ) and the expansion scalar (θ) are ...
Mukesh Kumar +5 more
wiley +1 more source
Chemical abundances in the dwarf galaxy NGC 4163 based on the nebular and auroral emission lines
Astronomische Nachrichten, Volume 343, Issue 9-10, November-December 2022., 2022 Abstract We constructed an oxygen abundance map and N/O ratio map of the unusually low excitation dwarf irregular galaxy NGC 4163 based on publicly available spectroscopy obtained by the MaNGA survey. We detected auroral emission line [O II]λλ$$ \lambda \lambda $$7320,7330 which allows us to measure chemical abundance by direct Te$$ {\mathrm{T}}_e ...
I. A. Zinchenko, L. S. Pilyugin
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Soft X‐Ray Imaging of Magnetopause Reconnection Outflows Under Low Plasma‐β Solar Wind Conditions
Geophysical Research Letters, Volume 49, Issue 19, 16 October 2022., 2022 Abstract We examined soft X‐ray emission by the solar wind charge‐exchange process around the Earth's magnetosphere using a global magnetohydrodynamic simulation model. The dayside magnetopause reconnection heats and accelerates the plasma whereby the X‐ray emission becomes as bright as ∼6 × 10−6 eV cm−3 s−1 under the southward interplanetary magnetic ...
Yosuke Matsumoto, Yoshizumi Miyoshi
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Radio Science, Volume 57, Issue 9, September 2022., 2022 Abstract This article focuses on the new generation of geodetic very long baseline interferometry (VLBI), the VLBI global observing system (VGOS), and measurements carried out during the CONT17 campaign. It uses broadband technology that increases both the number and precision of observations.
Sanam Motlaghzadeh +4 more
wiley +1 more source
Space Weather, Volume 20, Issue 3, March 2022., 2022 Abstract High‐energetic charged particles, such as solar protons, and phenomena such as Forbush decreases are eligible candidates to affect the global electric circuit. These effects have been studied by analyzing disturbances of the potential gradient in ground‐based measurements in fair weather regions. In this paper, we investigate deviations in the
J. Tacza +6 more
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Progress and Challenges in Electromechanical Coupling of Radio Telescopes
International Journal of Antennas and Propagation, Volume 2022, Issue 1, 2022., 2022 Radio astronomy is a discipline of dynamics and wonders. The vast universe has many secrets to unravel. As one of the important facilities in this discipline, radio telescopes play a key role in collecting astronomical data and unraveling mysteries.
Yuefei Yan +10 more
wiley +1 more source
Advances in High Energy Physics, Volume 2022, Issue 1, 2022., 2022 In this work, after improving the formulation of the model on particle transport within astrophysical plasma outflows and constructing the appropriate algorithms, we test the reliability and effectiveness of our method through numerical simulations on well‐studied galactic microquasars as the SS 433 and the Cyg X‐1 systems.
D. A. Papadopoulos +3 more
wiley +1 more source