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Journal articles on the topic 'Bondi solutions'

Author: Grafiati

Published: 6 September 2023

Last updated: 31 July 2025

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1

Ghosh, Shubhrangshu, and Prabir Banik. "Characteristics of transonic spherical symmetric accretion flow in Schwarzschild-de Sitter and Schwarzschild anti-de Sitter backgrounds, in pseudo-general relativistic paradigm." International Journal of Modern Physics D 24, no. 11 (2015): 1550084. http://dx.doi.org/10.1142/s0218271815500844.

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In this paper, we present a complete work on steady state spherically symmetric Bondi type accretion flow in the presence of cosmological constant (Λ) in both Schwarzschild-de Sitter (SDS) and Schwarzschild anti-de Sitter (SADS) backgrounds considering an isolated supermassive black hole (SMBH), with the inclusion of a simple radiative transfer scheme, in the pseudo-general relativistic paradigm. We do an extensive analysis on the transonic behavior of the Bondi type accretion flow onto the cosmological BHs including a complete analysis of the global parameter space and the stability of flow,

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2

Lynden-Bell, Donald, and Jiří Bičák. "Pressure in Lemaître–Tolman–Bondi solutions and cosmologies." Classical and Quantum Gravity 33, no. 7 (2016): 075001. http://dx.doi.org/10.1088/0264-9381/33/7/075001.

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3

Hernandez, X., L. Nasser, and A. Aguayo-Ortiz. "A New Hydrodynamic Spherical Accretion Exact Solution and Its Quasi-spherical Perturbations." Astrophysical Journal 945, no. 1 (2023): 76. http://dx.doi.org/10.3847/1538-4357/acb538.

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Abstract We present an exact γ = 5/3 spherical accretion solution that modifies the Bondi boundary condition of ρ → constant as r → ∞ to ρ → 0 as r → ∞. This change allows for simple power-law solutions on the density and infall velocity fields, ranging from a cold empty freefall condition where pressure tends to zero, to a hot hydrostatic equilibrium limit with no infall velocity. As in the case of the Bondi solution, a maximum accretion rate appears. As in the γ = 5/3 case of the Bondi solution, no sonic radius appears, this time however, because the flow is always characterized by a constan

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4

Reddy, D. R. K., and P. Innaiah. "Plane symmetric cosmological solutions of the Lyttleton-Bondi Universe." Acta Physica Hungarica 61, no. 3-4 (1987): 269–76. http://dx.doi.org/10.1007/bf03158352.

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5

Sussman, Roberto A., and Luisa G. Jaime. "Lemaître–Tolman–Bondi dust solutions in f ( R ) gravity." Classical and Quantum Gravity 34, no. 24 (2017): 245004. http://dx.doi.org/10.1088/1361-6382/aa91f5.

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6

Waters, Tim, Aycin Aykutalp, Daniel Proga, Jarrett Johnson, Hui Li, and Joseph Smidt. "Outflows from inflows: the nature of Bondi-like accretion." Monthly Notices of the Royal Astronomical Society: Letters 491, no. 1 (2019): L76—L80. http://dx.doi.org/10.1093/mnrasl/slz168.

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ABSTRACT The classic Bondi solution remains a common starting point both for studying black hole growth across cosmic time in cosmological simulations and for smaller scale simulations of active galactic nuclei (AGN) feedback. In nature, however, there will be inhomogeneous distributions of rotational velocity and density along the outer radius (Ro) marking the sphere of influence of a black hole. While there have been many studies of how the Bondi solution changes with a prescribed angular momentum boundary condition, they have all assumed a constant density at Ro. In this Letter, we show tha

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7

Costa, João L., and Filipe C. Mena. "Global solutions to the spherically symmetric Einstein-scalar field system with a positive cosmological constant in Bondi coordinates." Journal of Hyperbolic Differential Equations 18, no. 02 (2021): 311–41. http://dx.doi.org/10.1142/s0219891621500107.

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We consider a characteristic initial value problem, with initial data given on a future null cone, for the Einstein (massless) scalar field system with a positive cosmological constant, in Bondi coordinates. We prove that, for small data, this system has a unique global classical solution which is causally geodesically complete to the future and decays polynomially in radius and exponentially in Bondi time, approaching the de Sitter solution.

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8

Herrera, Luis, Alicia Di Prisco, and Justo Ospino. "Hyperbolically Symmetric Versions of Lemaitre–Tolman–Bondi Spacetimes." Entropy 23, no. 9 (2021): 1219. http://dx.doi.org/10.3390/e23091219.

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We study fluid distributions endowed with hyperbolic symmetry, which share many common features with Lemaitre–Tolman–Bondi (LTB) solutions (e.g., they are geodesic, shearing, and nonconformally flat, and the energy density is inhomogeneous). As such, they may be considered as hyperbolic symmetric versions of LTB, with spherical symmetry replaced by hyperbolic symmetry. We start by considering pure dust models, and afterwards, we extend our analysis to dissipative models with anisotropic pressure. In the former case, the complexity factor is necessarily nonvanishing, whereas in the latter cases

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9

Chang, Shu-Cheng. "Global existence and convergence of solutions of the Calabi flow on Einstein 4-manifolds." Nagoya Mathematical Journal 163 (September 2001): 193–214. http://dx.doi.org/10.1017/s0027763000007960.

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In this paper, firstly, we show the Bondi-mass type estimate of solutions of Calabi flow on closed 4-manifolds. Secondly, in our applications, we obtain the long time existence on closed 4-manifolds. In particular, we are able to show the asymptotic convergence of a subsequence of solutions of the Calabi flow on closed Einstein 4-manifolds.

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10

Aguayo-Ortiz, Alejandro, Emilio Tejeda, and X. Hernandez. "Choked accretion: from radial infall to bipolar outflows by breaking spherical symmetry." Monthly Notices of the Royal Astronomical Society 490, no. 4 (2019): 5078–87. http://dx.doi.org/10.1093/mnras/stz2989.

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ABSTRACT Steady-state, spherically symmetric accretion flows are well understood in terms of the Bondi solution. Spherical symmetry, however, is necessarily an idealized approximation to reality. Here we explore the consequences of deviations away from spherical symmetry, first through a simple analytic model to motivate the physical processes involved, and then through hydrodynamical, numerical simulations of an ideal fluid accreting on to a Newtonian gravitating object. Specifically, we consider axisymmetric, large-scale, small-amplitude deviations in the density field such that the equatori

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11

Tadmon, Calvin, and Sophonie Blaise Tchapnda. "On the spherically symmetric Einstein–Yang–Mills–Higgs equations in Bondi coordinates." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 468, no. 2146 (2012): 3191–214. http://dx.doi.org/10.1098/rspa.2012.0171.

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We revisit and generalize, to the Einstein–Yang–Mills–Higgs (EYMH) system, previous results of Christodoulou and Chae concerning global solutions for the Einstein-scalar field and the Einstein–Maxwell–Higgs (EMH) equations. The novelty of the present work is twofold. For one thing, the assumption on the self-interaction potential is improved. For another thing, explanation is furnished why the solutions obtained here and those proved by Chae for the EMH system decay more slowly than those established by Christodoulou in the case of self-gravitating scalar fields. Actually, this latter phenomen

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12

Bennewitz, Elizabeth R., Cristian Gaidau, Thomas W. Baumgarte, and Stuart L. Shapiro. "Dark matter heating of gas accreting onto Sgr A*." Monthly Notices of the Royal Astronomical Society 490, no. 3 (2019): 3414–25. http://dx.doi.org/10.1093/mnras/stz2781.

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ABSTRACT We study effects of heating by dark matter (DM) annihilation on black hole gas accretion. We observe that, for reasonable assumptions about DM densities in spikes around supermassive black holes, as well as DM masses and annihilation cross-sections within the standard WIMP model, heating by DM annihilation may have an appreciable effect on the accretion on to Sgr A* in the Galactic Centre. Motivated by this observation we study the effects of such heating on Bondi accretion, i.e. spherically symmetric, steady-state Newtonian accretion on to a black hole. We consider different adiabati

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13

Keto, Eric. "Stability and solution of the time-dependent Bondi–Parker flow." Monthly Notices of the Royal Astronomical Society 493, no. 2 (2020): 2834–40. http://dx.doi.org/10.1093/mnras/staa529.

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ABSTRACT Bondi and Parker derived a steady-state solution for Bernoulli’s equation in spherical symmetry around a point mass for two cases, respectively, an inward accretion flow and an outward wind. Left unanswered were the stability of the steady-state solution, the solution itself of time-dependent flows, whether the time-dependent flows would evolve to the steady state, and under what conditions a transonic flow would develop. In a Hamiltonian description, we find that the steady-state solution is equivalent to the Lagrangian implying that time-dependent flows evolve to the steady state. W

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14

Sharif, Muhammad, and Rubab Manzoor. "Lemaitre–Tolman–Bondi dust cloud collapse in Brans–Dicke gravity." Modern Physics Letters A 29, no. 35 (2014): 1450192. http://dx.doi.org/10.1142/s0217732314501922.

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This paper investigates the phenomenon of gravitational collapse of Lemaitre–Tolman–Bondi (LTB) model in the presence of Brans–Dicke (BD) scalar field with nonzero potential field. We find a class of solutions by taking perfect fluid as well as scalar field and check the validity of weak energy conditions. It turns out that two different types of singularities are formed in the presence of scalar field. We conclude that the end state of gravitational collapse turns out to be a black hole (BH) contrary to general relativity (GR).

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15

Van Acoleyen, Karel. "Lemaître–Tolman–Bondi solutions in the Newtonian gauge: from strong to weak fields." Journal of Cosmology and Astroparticle Physics 2008, no. 10 (2008): 028. http://dx.doi.org/10.1088/1475-7516/2008/10/028.

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16

Ciotti, Luca, and Silvia Pellegrini. "Fully analytical solutions for Bondi accretion in galaxies with a central Black Hole." Proceedings of the International Astronomical Union 14, S342 (2018): 5–8. http://dx.doi.org/10.1017/s1743921318005732.

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AbstractThe fully analytical solution for isothermal Bondi accretion on a black hole (MBH) at the center of JJ two-component Jaffe (1983) galaxy models is presented. In JJ models the stellar and total mass density distributions are described by the Jaffe profile, with different scale-lengths and masses, and to which a central MBH is added; all the relevant stellar dynamical properties can also be derived analytically. In these new accretion solutions the hydrodynamical and stellar dynamical properties are linked by imposing that the gas temperature is proportional to the virial temperature of

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17

Ribeiro, Marcelo B. "A Fortran code for null geodesic solutions in the Lemaı̂tre–Tolman–Bondi spacetime." Computer Physics Communications 148, no. 2 (2002): 236–41. http://dx.doi.org/10.1016/s0010-4655(02)00561-1.

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18

Lyra, Wladimir, Anders Johansen, Manuel H. Cañas, and Chao‐Chin Yang. "An Analytical Theory for the Growth from Planetesimals to Planets by Polydisperse Pebble Accretion." Astrophysical Journal 946, no. 2 (2023): 60. http://dx.doi.org/10.3847/1538-4357/acaf5b.

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Abstract Pebble accretion is recognized as a significant accelerator of planet formation. Yet only formulae for single-sized (monodisperse) distribution have been derived in the literature. These can lead to significant underestimates for Bondi accretion, for which the best accreted pebble size may not be the one that dominates the mass distribution. We derive in this paper the polydisperse theory of pebble accretion. We consider a power-law distribution in pebble radius, and we find the resulting surface and volume number density distribution functions. We derive also the exact monodisperse a

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19

Han, Qing, and Lin Zhang. "On the null-timelike boundary for Maxwell and spin-2 fields in asymptotically flat spaces." Journal of Hyperbolic Differential Equations 18, no. 02 (2021): 343–95. http://dx.doi.org/10.1142/s0219891621500119.

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We study the Maxwell equation and the spin-2 field equation in Bondi–Sachs coordinates associated with an asymptotically flat Lorentzian metric. We consider the mixed boundary/initial value problem, where the initial data are imposed on a null hypersurface and a boundary value is prescribed on a timelike hypersurface. We establish Sobolev [Formula: see text] space-time estimates for solutions and their asymptotic expansions at the null infinity.

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20

BOCHICCHIO, IVANA, MAURO FRANCAVIGLIA, and ETTORE LASERRA. "A REVIEW ON THE GEOMETRIC FORMULATION OF TOLMAN–BONDI EQUATIONS IN GENERAL RELATIVITY." International Journal of Geometric Methods in Modern Physics 06, no. 04 (2009): 595–617. http://dx.doi.org/10.1142/s0219887809003709.

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This work is focused on spherically symmetric space-times. More precisely, geometric and structural properties of spatially spherical shells of a dust universe are analyzed in detail considering recent results of our research. Moreover, exact solutions, obtained for constant Ricci principal curvatures, are inferred and qualitatively analyzed through suitable classic analogies.

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21

KOZAMEH, CARLOS, EZRA T. NEWMAN, and GILBERTO SILVA-ORTIGOZA. "ON THE PHYSICAL INTERPRETATION OF ASYMPTOTICALLY FLAT GRAVITATIONAL FIELDS." International Journal of Modern Physics D 17, no. 13n14 (2008): 2599–606. http://dx.doi.org/10.1142/s0218271808014138.

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A problem in general relativity is how to extract physical information from solutions to the Einstein equations. Most often information is found from special conditions, e.g., special vector fields, symmetries or approximate symmetries. Our concern is with asymptotically flat space–times with approximate symmetry: the BMS group. For these spaces the Bondi four-momentum vector and its evolution, found at infinity, describes the total energy–momentum and the energy–momentum radiated. By generalizing the simple idea of the transformation of (electromagnetic) dipoles under a translation, we define

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22

Larrabee, Glenn J. "Lessons on measuring construct validity: A commentary on Delis, Jacobson, Bondi, Hamilton, and Salmon." Journal of the International Neuropsychological Society 9, no. 6 (2003): 947–53. http://dx.doi.org/10.1017/s1355617703960140.

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AbstractThis commentary expands on issues raised by Delis, Jacobson, Bondi, Hamilton, and Salmon, in their paper on the use of shared variance techniques to establish construct validity. Significant discussion is focused on method variance, and how this can distort the results of factor analysis. Solutions are offered for the appropriate use of factor analysis in construct validation. Examples are also provided of construct validation procedures that do not rely on correlational or shared variance techniques. (JINS, 2003, 9, 947–953.)

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23

Nakamura, Kouji. "Gauge-Invariant Perturbation Theory on the Schwarzschild Background Spacetime: Part III—Realization of Exact Solutions." Universe 11, no. 2 (2025): 52. https://doi.org/10.3390/universe11020052.

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This is the Part III paper of our series of papers on a gauge-invariant perturbation theory on the Schwarzschild background spacetime. After reviewing our general framework for the gauge-invariant perturbation theory and the proposal for gauge-invariant treatments of l=0,1 mode perturbations on the Schwarzschild background spacetime in the Part I paper, we examine the problem of whether the l=0,1 even-mode solutions derived in the Part II paper are physically reasonable. We consider the linearized versions of the Lemaître–Tolman–Bondi solution and the non-rotating C-metric. As a result, we sho

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24

Mädler, Thomas, and Ewald Müller. "The Bondi–Sachs metric at the vertex of a null cone: axially symmetric vacuum solutions." Classical and Quantum Gravity 30, no. 5 (2013): 055019. http://dx.doi.org/10.1088/0264-9381/30/5/055019.

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25

Prust, Logan J., Hila Glanz, Lars Bildsten, Hagai B. Perets, and Friedrich K. Röpke. "Morphology and Mach Number Dependence of Subsonic Bondi–Hoyle Accretion." Astrophysical Journal 966, no. 1 (2024): 103. http://dx.doi.org/10.3847/1538-4357/ad3732.

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Abstract We carry out three-dimensional computations of the accretion rate onto an object (of size R sink and mass m) as it moves through a uniform medium at a subsonic speed v ∞. The object is treated as a fully absorbing boundary (e.g., a black hole). In contrast to early conjectures, we show that for an accretor with R sink ≪ R A = 2 Gm / v ∞ 2 in a gaseous medium with adiabatic index γ = 5/3, the accretion rate is independent of Mach number and is determined only by m and the gas entropy. Our numerical simulations are conducted using two different numerical schemes via the Athena++ and Are

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26

Raga, A. C., J. Cantó, A. Castellanos-Ramírez, A. Rodríguez-González, and P. R. Rivera-Ortiz. "THE BONDI-HOYLE ACCRETION TAIL OF POINT SOURCES TRAVELLING HYPERSONICALLY THROUGH A DENSE ENVIRONMENT." Revista Mexicana de Astronomía y Astrofísica 58, no. 2 (2022): 215–22. http://dx.doi.org/10.22201/ia.01851101p.2022.58.02.04.

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We present a model for the “Bondi-Hoyle tail” left behind by the hypersonic passage of a compact, massive object through a dense, radiative environment. We derive simple equations for the flow velocity and the mass along the tail, and obtain numerical and approximate analytical solutions for the steady state problem. We then study a time-dependent problem in which the source first travels within a dense cloud, and then emerges into a low density environment. This flow results in the production of a trail of dense gas joining the source at the point in which it emerged from the dense cloud. Thi

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27

Ciotti, Luca, and Silvia Pellegrini. "Isothermal Bondi Accretion in Jaffe and Hernquist Galaxies with a Central Black Hole: Fully Analytical Solutions." Astrophysical Journal 848, no. 1 (2017): 29. http://dx.doi.org/10.3847/1538-4357/aa8d1f.

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28

GHOSH, S. G., D. W. DESHKAR, and N. N. SASTE. "FIVE-DIMENSIONAL DUST COLLAPSE WITH COSMOLOGICAL CONSTANT." International Journal of Modern Physics D 16, no. 01 (2007): 53–64. http://dx.doi.org/10.1142/s0218271807009309.

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We study the five-dimensional spherical collapse of an inhomogeneous dust in the presence of a positive cosmological constant. The general interior solutions, in the closed form, of the Einstein field equations, i.e. the 5D Tolman–Bondi–de Sitter, is obtained which in turn is matched to the exterior 5D Schwarzschild–de Sitter. It turns out that the collapse proceeds in the same way as in the Minkowski background, i.e. the strong curvature naked singularities form and thus violate the cosmic censorship conjecture. A brief discussion on the causal structure singularities and horizons is also giv

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29

Bronnikov, Kirill A., Pavel E. Kashargin, and Sergey V. Sushkov. "Possible Wormholes in a Friedmann Universe." Universe 9, no. 11 (2023): 465. http://dx.doi.org/10.3390/universe9110465.

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We study the properties of evolving wormholes able to exist in a closed Friedmann dust-filled universe and described by a particular branch of the well-known Lemaître–Tolman–Bondi solution to the Einstein equations and its generalization with a nonzero cosmological constant and an electromagnetic field. Most of the results are obtained with pure dust solutions. It is shown, in particular, that the lifetime of wormhole throats is much shorter than that of the whole wormhole region in the universe (which coincides with the lifetime of the universe as a whole), and that the density of matter near

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30

Cruz-Osorio, Alejandro, Luciano Rezzolla, Fabio D. Lora-Clavijo, José Antonio Font, Carlos Herdeiro, and Eugen Radu. "Bondi-Hoyle-Lyttleton accretion onto a rotating black hole with ultralight scalar hair." Journal of Cosmology and Astroparticle Physics 2023, no. 08 (2023): 057. http://dx.doi.org/10.1088/1475-7516/2023/08/057.

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Abstract We present a numerical study of relativistic Bondi-Hoyle-Lyttleton (BHL) accretion onto an asymptotically flat black hole with synchronized hair. The hair is sourced by an ultralight, complex scalar field, minimally coupled to Einstein's gravity. Our simulations consider a supersonic flow parametrized by the asymptotic values of the fluid quantities and a sample of hairy black holes with different masses, angular momenta, and amount of scalar hair. For all models, steady-state BHL accretion solutions are attained that are characterized by the presence of a shock-cone and a stagnation

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31

Sussman, Roberto A., and Luis Garc$iacute$a Trujillo. "A new approach to initial value variables for the Lema$icirc$tre$ndash$Tolman$ndash$Bondi dust solutions." Classical and Quantum Gravity 19, no. 11 (2002): 2897–925. http://dx.doi.org/10.1088/0264-9381/19/11/310.

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32

Bhatti, M. Zaeem-ul-Haq, and Z. Yousaf. "Gravitational collapse and dark universe with LTB geometry." International Journal of Modern Physics D 26, no. 06 (2016): 1750045. http://dx.doi.org/10.1142/s0218271817500456.

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The objective of this paper is to examine the influence of polynomial [Formula: see text] dark sector cosmic terms on the collapse of electrically charged Lemaître–Tolman–Bondi geometry. We explored a class of solutions for [Formula: see text] field equations in the existence of electromagnetic field and under the constraint of constant curvature scalar. The influence of [Formula: see text] model on the dynamics of collapsing object have been discussed by studying its black hole and cosmological horizons. Also, the effects of these dark sources on the time interval between the corresponding si

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33

Ramírez-Velásquez, J. M., L. Di G. Sigalotti, R. Gabbasov, J. Klapp, and E. Contreras. "Bondi accretion for adiabatic flows onto a massive black hole with an accretion disc." Astronomy & Astrophysics 631 (October 11, 2019): A13. http://dx.doi.org/10.1051/0004-6361/201935917.

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We present the classical Bondi accretion theory for the case of non-isothermal accretion processes onto a supermassive black hole (SMBH), including the effects of X-ray heating and the radiation force due to electron scattering and spectral lines. The radiation field is calculated by considering an optically thick, geometrically thin, standard accretion disc as the emitter of UV photons and a spherical central object as a source of X-ray emission. In our analysis, the UV emission from the accretion disc is assumed to have an angular dependence, and the X-ray radiation from the central object i

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Bishop, Nigel T. "Linearized solutions of the Einstein equations within a Bondi–Sachs framework, and implications for boundary conditions in numerical simulations." Classical and Quantum Gravity 22, no. 12 (2005): 2393–406. http://dx.doi.org/10.1088/0264-9381/22/12/006.

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35

Ghosh, Shubhrangshu, Souvik Ghose, Kalyanbrata Pal, Arunabha Bhadra, and Tapas K. Das. "Spherical Accretion in the Schwarzschild Spacetime in the Newtonian Analogous Construct." Astrophysical Journal 978, no. 2 (2025): 155. https://doi.org/10.3847/1538-4357/ad901f.

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Abstract The velocity-dependent Newtonian analogous potentials (NAPs) corresponding to general relativistic (GR) spacetimes accurately capture most of the relativistic features, including all classical tests of GR, effectively representing spacetime geometries in Newtonian terms. The NAP formulated by Tejeda & Rosswog (TR13) for Schwarzschild spacetime has been applied to the standard thin accretion disk around a black hole (BH) as well as in the context of streamlines of noninteracting particles accreting onto a Schwarzschild BH, showing good agreement with the exact relativistic solution

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36

Saw, Vee-Liem. "Asymptotically simple spacetimes and mass loss due to gravitational waves." International Journal of Modern Physics D 27, no. 01 (2017): 1730027. http://dx.doi.org/10.1142/s0218271817300270.

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The cosmological constant [Formula: see text] used to be a freedom in Einstein’s theory of general relativity (GR), where one had a proclivity to set it to zero purely for convenience. The signs of [Formula: see text] or [Formula: see text] being zero would describe universes with different properties. For instance, the conformal structure of spacetime directly depends on [Formula: see text]: null infinity [Formula: see text] is a spacelike, null, or timelike hypersurface, if [Formula: see text], [Formula: see text], or [Formula: see text], respectively. Recent observations of distant supernov

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37

Costa, João C., Rodrigo Duarte, and Filipe C. Mena. "Improved decay estimates and C2-asymptotic stability of solutions to the Einstein-scalar field system in spherical symmetry." Journal of Hyperbolic Differential Equations 20, no. 04 (2023): 853–902. http://dx.doi.org/10.1142/s021989162350025x.

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We investigate the asymptotic stability of solutions to the characteristic initial value problem for the Einstein (massless) scalar field system with a positive cosmological constant. We prescribe spherically symmetric initial data on a future null cone with a wider range of decaying profiles than previously considered. New estimates are then derived in order to prove that, for small data, the system has a unique global classical solution. We also show that the solution decays exponentially in (Bondi) time and that the radial decay is essentially polynomial, although containing logarithmic fac

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38

Hanski, M. O., P. Teerikorpi, T. Ekholm, et al. "Evidence for dark matter on different scales from the KLUN galaxy sample." International Astronomical Union Colloquium 174 (2000): 457–61. http://dx.doi.org/10.1017/s0252921100055457.

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The KLUN (Kinematics of the Local UNiverse) sample of 6600 spiral galaxies is used in studying dark matter on different scales: •The Morphological Type dependence of the zero-point of the Tully-Fisher relation indicates mass to light ratio M/L ≈ 9 − 16 on galactic scales.•Preliminary results from a study of selection effects influencing double galaxies give a larger value M/L ≈ 30 − 50.•Study of the Perseus-Pisces supercluster, using Malmquist bias corrected TF distances and Tolman-Bondi solutions indicates M/L ≈ 200 − 600 for large clusters. Similar results were obtained in our previous work

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39

Umemura, Masayuki, and Jun Fukue. "Cosmological Spherical Accretion via External Radiation Drag." Publications of the Astronomical Society of Japan 46, no. 6 (1994): 567–74. https://doi.org/10.1093/pasj/46.6.567.

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Abstract The spherically symmetric gas accretion regulated by external radiation drag is investigated under the steady-state approximation. As for the gravitational force, the dark-matter/point mass potentials as well as the self-gravity are considered. The radiation drag force is proportional to the velocity vector v as –βv, where β is a coefficient which is determined by the intensity of the radiation fields. We seek steady solutions under the assumption that β is constant spatially and temporally. The analyses are separately made for a cold regime where the gas pressure is ignored and for a

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40

Kim, Do Young, Anthony N. Lasenby, and Michael P. Hobson. "An alternative approach to modelling a cosmic void and its effect on the cosmic microwave background." Monthly Notices of the Royal Astronomical Society 488, no. 3 (2019): 4081–92. http://dx.doi.org/10.1093/mnras/stz1979.

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ABSTRACT We apply our tetrad-based approach for constructing spherically symmetric solutions in general relativity to modelling a void, and compare it with the standard Lemaître–Tolman–Bondi (LTB) formalism. In particular, we highlight the importance of considering the velocity as well as the density profile in constraining voids. We apply our approach to construct models for the void observed in the direction of Draco in the WISE–2MASS galaxy survey, and a corresponding cosmic microwave background (CMB) temperature decrement in the Planck data in the same direction. We find that the present-d

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Bellino, Vito Flavio, and Giampiero Esposito. "Fractional linear maps in general relativity and quantum mechanics." International Journal of Geometric Methods in Modern Physics 18, no. 10 (2021): 2150157. http://dx.doi.org/10.1142/s0219887821501577.

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This paper studies the nature of fractional linear transformations in a general relativity context as well as in a quantum theoretical framework. Two features are found to deserve special attention: the first is the possibility of separating the limit-point condition at infinity into loxodromic, hyperbolic, parabolic and elliptic cases. This is useful in a context in which one wants to look for a correspondence between essentially self-adjoint spherically symmetric Hamiltonians of quantum physics and the theory of Bondi–Metzner–Sachs transformations in general relativity. The analogy therefore

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Arnau i Córdoba, Josep Vicent, and Màrius Josep Fullana i Alfonso. "Resolution of Initial Value Problems of Ordinary Differential Equations Systems." Mathematics 10, no. 4 (2022): 593. http://dx.doi.org/10.3390/math10040593.

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In this work, we present some techniques applicable to Initial Value Problems when solving a System of Ordinary Differential Equations (ODE). Such techniques should be used when applying adaptive step-size numerical methods. In our case, a Runge-Kutta-Fehlberg algorithm (RKF45) has been employed, but the procedure presented here can also be applied to other adaptive methods, such as N-body problems, as AP3M or similar ones. By doing so, catastrophic cancellations were eliminated. A mathematical optimization was carried out by introducing the objective function in the ODE System (ODES). Resizin

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YOO, JAEWON, and YUKI WATANABE. "THEORETICAL MODELS OF DARK ENERGY." International Journal of Modern Physics D 21, no. 12 (2012): 1230002. http://dx.doi.org/10.1142/s0218271812300029.

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Mounting observational data confirm that about 73% of the energy density consists of dark energy which is responsible for the current accelerated expansion of the Universe. We present observational evidences and dark energy projects. We then review various theoretical ideas that have been proposed to explain the origin of dark energy; they contain the cosmological constant, modified matter models, modified gravity models and the inhomogeneous model. The cosmological constant suffers from two major problems: one regarding fine-tuning and the other regarding coincidence. To solve them there aros

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Xu, Wenrui. "Simple Convective Accretion Flows (SCAFs): Explaining the ≈ −1 Density Scaling of Hot Accretion Flows around Compact Accretors." Astrophysical Journal 954, no. 2 (2023): 180. http://dx.doi.org/10.3847/1538-4357/ace892.

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Abstract Recent simulations find that hot gas accretion onto compact accretors is often highly turbulent and diskless, and shows a power-law density profile with slope α ρ ≈ −1. These results are consistent with observational constraints, but do not match existing self-similar solutions of radiatively inefficient accretion flows. We develop a theory for this new class of accretion flows, which we dub simple convective accretion flows (SCAFs). We use a set of hydrodynamic simulations to provide a minimalistic example of SCAFs, and develop an analytic theory to explain and predict key flow prope

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Ranjbar, Razieh, and Shahram Abbassi. "Slowly Rotating Accretion Flow Around Supermassive Black Holes in Elliptical Galaxies: Case With Outflow." Astrophysical Journal 954, no. 2 (2023): 117. http://dx.doi.org/10.3847/1538-4357/ace163.

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Abstract Observational evidence and many numerical simulations show the existence of winds (i.e., uncollimated outflows) in the accretion systems of elliptical galaxy centers. One of the primary aims of this study is to investigate the solutions of slowly rotating accretion flows around supermassive black holes with outflows. This paper presents two distinct physical regions, supersonic and subsonic, which extend from the outer boundary to the black hole. In our numerical solution, the outer boundary is chosen beyond the Bondi radius. Due to strong gravity, we ignore outflow (i.e., s = 0) in t

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Ganelin, Aleksandr E. "Early 20th Century Studio and Theatre Innovations of Vs. E. Meyerhold and S. E. Radlov." Vestnik of Saint Petersburg University. Arts 11, no. 3 (2021): 393–409. http://dx.doi.org/10.21638/spbu15.2021.303.

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The experience of the pedagogical work of the Studio Vsevolod Meyerhold on Borodinskaya Street (1914–1917) to a large extent can be considered one of the important sources of the methodological and pedagogical model inherent in the modern Leningrad — Petersburg theatre school. The education principles of the synthetic actor and director, developed within the studio, combined innovations in the work of teachers and their students both at individual stages of the pedagogical process and on the path to creating a “new” theatre, in a broad understanding of this phenomenon of cultural life at the b

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Korkina, M. P., and E. M. Kopteva. "Generalization of Tolman–Bondi solution." Astronomical School’s Report 8, no. 1 (2012): 31–33. http://dx.doi.org/10.18372/2411-6602.08.1031.

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Sagdullayevna, Dexkanova Nilufar, and Isakov Abidjon Odiljonovich. "GREEN ECONOMY AND TRANSFORMATIONS IN AGRICULTURE: PROBLEMS AND SOLUTIONS." International Journal Of Management And Economics Fundamental 4, no. 12 (2024): 38–46. https://doi.org/10.37547/ijmef/volume04issue12-04.

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In this article, sustainable agricultural activities have a significant impact on food independence, economic independence of the country's regions and sustainable growth of agricultural regions. It is concluded that the use of innovative technologies of the "green" economy in agriculture should be implemented on the basis of state support mechanisms, including raising funds through "green" bonds, as well as the opportunity to participate in targeted events and scientific research.

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Berg, T. G. Owe. "BONDS IN WATER AND AQUEOUS SOLUTIONS." Annals of the New York Academy of Sciences 125, no. 2 (2006): 298–316. http://dx.doi.org/10.1111/j.1749-6632.1965.tb45399.x.

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Matsuda, Takuya, Hiromu Isaka, and Yukimasa Ohsugi. "Bondi–Hoyle–Lyttleton accretion flow revisited: Analytic solution." Progress of Theoretical and Experimental Physics 2015, no. 11 (2015): 113E01. http://dx.doi.org/10.1093/ptep/ptv148.

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