Results 61 to 70 of about 32,039 (196)

Deep Space Network Radio Science and Ground‐Based Planetary Radar in the Next Decade

Radio Science, Volume 60, Issue 7, July 2025.
Abstract The Deep Space Network (DSN) has been a core operational element of NASA's crewed and robotic exploration of the Solar System since the early 1960s. The primary role of the DSN has been to acquire telemetry and navigation data, but over the years, its radiometric and radar capabilities have expanded to form a system for obtaining unique ...
R. S. Park, J. E. Riedel, N. Rodriguez‐Alvarez, M. Brozovic, L. A. M. Benner, P. Vergados, D. Buccino, C. S. Jacobs, L. S. Locke, S. W. Asmar, R. Castano, T. J. W. Lazio, J. Jao, C. Lee   +13 more
wiley   +1 more source

Measuring spin of a supermassive black hole at the Galactic centre -- Implications for a unique spin

, 2010
We determine the spin of a supermassive black hole in the context of discseismology by comparing newly detected quasi-periodic oscillations (QPOs) of radio emission in the Galactic centre, Sagittarius A* (Sgr A*), as well as infrared and X-ray emissions ...
Abramowicz, Baganoff, Bardeen, Bardeen, Beskin, Blandford, Bélanger, Gammie, Genzel, Ghez, Gierliński, Gillessen, H. Negoro, Hamaus, Hawley, Hirose, Homan, Kato, Kato, Kato, Kato, Kato, King, M. Miyoshi, Machida, Markowitz, McKinney, Moderski, Novikov, Nowak, Okazaki, Orosz, Page, R. Matsumoto, R. Takahashi, Remillard, Schödel, Shakura, Shapiro, Takahashi, Volonteri, Wilson, Y. Kato, Yuan, Yusef-Zadeh   +44 more
core   +1 more source

Redshift‐Agnostic Machine Learning Classification: Unveiling Peak Performance in Galaxy, Star, and Quasar Classification (Using SDSS DR17)

Astronomische Nachrichten, Volume 346, Issue 5, June 2025.
ABSTRACT Classification of galaxies, stars, and quasars using spectral data is fundamental to astronomy, but often relies heavily on redshift. This study evaluates the performance of 10 machine learning algorithms on SDSS data to classify these objects, with a particular focus on scenarios where redshift information is unavailable.
Debashis Chatterjee, Prithwish Ghosh
wiley   +1 more source

Threshold drop in accretion density if dark energy is accreting onto a supermassive black hole

European Physical Journal C: Particles and Fields, 2019
Recent studies of galactic cores tell us that supermassive black holes are hosted at each of these cores. We got some evidences even. Besides, dark energy is expected to be distributed all over in our universe.
Ritabrata Biswas, Sandip Dutta
doaj   +1 more source

The Formation and Evolution of the First Massive Black Holes

, 2004
The first massive astrophysical black holes likely formed at high redshifts (z>10) at the centers of low mass (~10^6 Msun) dark matter concentrations.
A Cattaneo, A Cavaliere, A Gould, A Heger, A Jenkins, A Kashlinsky, A Kogut, A Lidz, A Soltan, A Songaila, A Venkatesan, A Wandel, AA Thoul, AC Fabian, AJ Barger, AR King, AR King, AW Graham, B Ciardi, B Ciardi, BJ Carr, CF Gammie, CF Gammie, CJ Willott, CL Bennett, CS Kochanek, D Eisenstein, D Galli, D Lynden-Bell, D Lynden-Bell, D Merritt, D Proga, DC Heggie, DE Berk Van den, DM Alexander, DM Alexander, DN Spergel, DQ Lamb, DR Garnett, E Quataert, EE Salpeter, EJM Colbert, ET Vishniac, F Haardt, F Hoyle, F Palla, F Walter, FA Rasio, G Efstathiou, G Efstathiou, G Kauffmann, G Quinlan, GA Shields, GJ Wasserburg, GL Granato, GM Fuller, GP Holder, GT Richards, H Baumgardt, H Kang, H Kang, H Netzer, H Susa, H Zhao, HM Lee, I Igumenshchev, I Shlosman, J Arons, J Binney, J Comerford, J Goodman, J Magorrian, J Miralda-Escudé, J Silk, J Silk, J Stone, J Tumlinson, J-H Woo, JA Sellwood, JA Tyson, JE Gunn, JF Navarro, JM Shull, JM Stone, JP Ostriker, K Gebhardt, K Gebhardt, K Menou, K Menou, L Ciotti, L Ciotti, L Ferrarese, L Ferrarese, L Ferrarese, L Hui, LL Spitzer Jr, M Dijkstra, M Elvis, M Fukugita, M Kaplinghat, M Milosavljevic, M Saijo, M Shibata, M Tegmark, M Vestergaard, M Vestergaard, M Volonteri, M Zaldarriaga, MC Begelman, MC Begelman, MC Begelman, MC Begelman, MC Begelman, MC Begelman, MG Haehnelt, MG Haehnelt, MG Haehnelt, MG Haehnelt, MJ Kukula, MJ Rees, MJ Rees, NI Shakura, NY Gnedin, NY Gnedin, NY Gnedin, O Blaes, P Hut, P Kaaret, P Madau, P Madau, P Madau, P Madau, P Martini, P Martini, P McDonald, P Monaco, P Salucci, P Valageas, P Väisänen, PA Shaver, PJ Armitage, PR Shapiro, PR Shapiro, Q Yu, Q Yu, R Barkana, R Barkana, R Cen, R Cen, RD Blandford, RD Blandford, RF Mushotzky, RH Becker, RK Islam, RK Sheth, RL White, RP Marel Van der, RP Marel Van der, RP Marel Van der, RV Wagoner, S Croom, S Kaspi, S Lepp, S Wyithe, S Wyithe, S Wyithe, S Wyithe, SA Hughes, SDM White, SE Woosley, SF Portegies Zwart, SL Shapiro, SL Shapiro, SP Oh, SP Oh, SP Oh, SP Oh, SR Heap, T Abel, T Abel, T Abel, T Abel, T Hirasawa, T Kitayama, T Matsuda, T Matteo Di, T Miyaji, T Theuns, TA Small, V Bromm, V Bromm, V Bromm, WC Saslaw, WH Press, X Fan, X Fan, X Fan, X Fan, X Wu, YB Zel’dovich, Z Haiman, Z Haiman, Z Haiman, Z Haiman, Z Haiman, Z Haiman, Z Haiman, Z Haiman, Z Haiman, Z Haiman, Z Haiman, Z Haiman, Z Haiman, Z Haiman, Z Haiman   +214 more
core   +1 more source

Stochastic Quantum Mechanics in Curved Spaces: Application to Schwarzschild Black Holes

Astronomische Nachrichten, Volume 346, Issue 3-4, March-May 2025.
ABSTRACT In this work, we start from the hypothesis that the universe lives in a Gravitational Wave Background (GWB). From this hypothesis, it follows that space–time is not locally flat because we have to take into account the fluctuations of the GWB in space–time. This implies that sufficiently small particles will feel these oscillations, preventing
Juan S. Jerez‐Rodriguez, Tonatiuh Matos   +1 more
wiley   +1 more source

Gravitational lensing by deformed Horava-Lifshitz black hole in rainbow gravity

Physics Letters B
In this study, we investigate the gravitational lensing effects of deformed Horava-Lifshitz black holes, considering both strong and weak-field limit approximations and incorporating the impact of rainbow functions.
Aniruddha Ghosh, Ujjal Debnath
doaj   +1 more source

Searching for ultra-light bosons and constraining black hole spin distributions with stellar tidal disruption events

Nature Communications, 2022
Stellar tidal disruption events (TDEs) occur when stars pass close enough to supermassive black holes. Here, the authors show that future searches TDEs have potential to uncover the existence of ultralight bosons.
Peizhi Du, Daniel Egaña-Ugrinovic, Rouven Essig, Giacomo Fragione, Rosalba Perna   +4 more
doaj   +1 more source

Interplay of Magnetic Reconnection and Current Sheet Kink Instability in the Earth's Magnetotail

Geophysical Research Letters, Volume 52, Issue 2, 28 January 2025.
Abstract Magnetic reconnection and current sheet kink instability often develop concurrently in current sheets, yet their dynamic interplay remains unclear. We investigate their interaction in the magnetotail of a 3D global magnetospheric hybrid‐Vlasov simulation. We identify the instability growth and saturation phase and estimate the evolution of the
G. Cozzani, M. Alho, I. Zaitsev, H. Zhou, S. Hoilijoki, L. Turc, M. Grandin, K. Horaites, M. Battarbee, Y. Pfau‐Kempf, U. Ganse, K. Papadakis, M. Palmroth   +12 more
wiley   +1 more source

Gravitational lensing by a quantum deformed Schwarzschild black hole

European Physical Journal C: Particles and Fields, 2021
We investigate the weak and strong deflection gravitational lensing by a quantum deformed Schwarzschild black hole and find their observables. These lensing observables are evaluated and the detectability of the quantum deformation is assessed, after ...
Xu Lu, Yi Xie
doaj   +1 more source