Profiled spectral lines of Keplerian rings orbiting in the regular Bardeen black hole spacetimes

AbstractConsidering the regular Bardeen black hole spacetimes, we test the observational effects of the general relativistic solutions coupled to non-linear electrodynamics (NED) by studying the photon motion in the effective geometry governed by the spacetime geometry and the NED Lagrangian. We focus our attention to the observationally important case of profiled spectral lines generated by rings radiating in a fixed frequency and orbiting the black hole along circular geodesics of the Bardeen spacetime. Such profiled spectral lines are observed in active galactic nuclei and in microquasars, giving sufficient data for the test of regular black holes. We expect that such radiating rings could arise around the Galaxy central supermassive black hole SgrA*, and the related profiled spectral lines could give important additional information to those obtained by direct observations due to the Event Horizon (GRAVITY) Telescope. We demonstrate that the profiled spectral lines of the radiating rings predict strong signatures of the NED effects on the photon motion – namely the frequency shift to the red edge of the spectrum, and narrowing of the profile, by more than one order in comparison with the case of the profiles generated purely by the spacetime geometry, for all values of the magnetic charge and the inclination angle of the observer. The specific flux is substantially suppressed and for extended Keplerian disks even the shape of the profiled line is significantly modified due to the NED effect.

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Kinematics of Molecules at the Galactic Centre

Symposium - International Astronomical Union ◽

10.1017/s007418090002684x ◽

1974 ◽

Vol 60 ◽

pp. 521-535 ◽

Cited By ~ 1

Author(s):

B. J. Robinson

Keyword(s):

Radio Emission ◽

Spectral Lines ◽

Strong Absorption ◽

Galactic Centre ◽

Lower Velocity ◽

Continuous Structure ◽

Direct Observations ◽

The Galaxy ◽

Nuclear Regions ◽

Co Emission

Dense gas clouds containing OH, CO, NH3 and H2CO are found in the inner part of the H1 nuclear disk. The molecular spectral lines allow direct observations of the kinematics of the gas near the galactic centre. Strong absorption of the thermal continuum sources by OH and H2CO shows that much of the gas on the near side of the centre can be located in a massive ‘ring’ expanding at 130 km s-1 which may have originated close to the nucleus about 106yr ago. Observations of CO emission from beyond the centre show that the far side of the ‘ring’ is expanding at a lower velocity, less than 90 km s-1. Observations of CO and NH3 emission with positive velocities for l < 360° are needed to establish whether the ‘ring’ is a continuous structure.OH and H2CO are also observed to be falling towards the centre. There is no agreement as to the location of this infalling matter.The nuclear regions of the Galaxy are compared with those of NGC 253, particularly in regard to expansional velocities, IR and radio emission, and OH absorption.

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The Intrinsic Derivative and Centrifugal Forces in General Relativity: II. Applications to Circular Orbits in Some Familiar Stationary Axisymmetric Spacetimes

International Journal of Modern Physics D ◽

10.1142/s021827189700011x ◽

1997 ◽

Vol 06 (02) ◽

pp. 143-198 ◽

Cited By ~ 63

Author(s):

Donato Bini ◽

Paolo Carini ◽

Robert T. Jantzen

Keyword(s):

General Relativity ◽

Black Hole ◽

Spin Precession ◽

General Context ◽

Centrifugal Forces ◽

Circular Orbits ◽

Spacetime Geometry ◽

Preceding Article ◽

Black Hole Spacetimes ◽

Time Splitting

The tools developed in a preceding article for interpreting spacetime geometry in terms of all possible space-plus-time splitting approaches are applied to circular orbits in some familiar stationary axisymmetric spacetimes. This helps give a more intuitive picture of their rotational features including spin precession effects, and puts related work of Abramowicz, de Felice, and others on circular orbits in black hole spacetimes into a more general context.

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Fractal analysis in biology and medicine

Dalʹnevostočnyj medicinskij žurnal ◽

10.35177/1994-5191-2020-4-85-92 ◽

2020 ◽

pp. 85-92

Keyword(s):

Fractal Analysis ◽

A Priori ◽

Research Work ◽

Structure And Function ◽

Review Article ◽

Living Systems ◽

Modern Biology ◽

Additional Information ◽

Important Additional Information ◽

And Function

The review article discusses the possibilities of using fractal mathematical analysis to solve scientific and applied problems of modern biology and medicine. The authors show that only such an approach, related to the section of nonlinear mechanics, allows quantifying the chaotic component of the structure and function of living systems, that is a priori important additional information and expands, in particular, the possibilities of diagnostics, differential diagnosis and prediction of the course of physiological and pathological processes. A number of examples demonstrate the specific advantages of using fractal analysis for these purposes. The conclusion can be made that the expanded use of fractal analysis methods in the research work of medical and biological specialists is promising.

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Stable circular orbits in Kaluza-Klein black hole spacetimes

Physical Review D ◽

10.1103/physrevd.103.124004 ◽

2021 ◽

Vol 103 (12) ◽

Author(s):

Shinya Tomizawa ◽

Takahisa Igata

Keyword(s):

Black Hole ◽

Circular Orbits ◽

Black Hole Spacetimes ◽

Kaluza Klein

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Effects of supernovae feedback and black hole outflows in the evolution of Dwarf Spheroidal Galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s174392132000215x ◽

2020 ◽

Vol 15 (S359) ◽

pp. 280-282

Author(s):

Gustavo Amaral Lanfranchi ◽

Anderson Caproni ◽

Jennifer F. Soares ◽

Larissa S. de Oliveira

Keyword(s):

Black Hole ◽

Homogeneous Medium ◽

Massive Black Hole ◽

Dwarf Spheroidal Galaxies ◽

Stellar Feedback ◽

Gas Removal ◽

The Galaxy ◽

Main Driver ◽

Ia Supernovae ◽

Jet Structure

AbstractThe gas evolution of a typical Dwarf Spheroidal Galaxy is investigated by means of 3D hydrodynamic simulations, taking into account the feedback of type II and Ia supernovae, the outflow of an Intermediate Massive Black Hole (IMBH) and a static cored dark matter potential. When the IMBH’s outflow is simulated in an homogeneous medium a jet structure is created and a small fraction of the gas is pushed away from the galaxy. No jet structure can be seen, however, when the medium is disturbed by supernovae, but gas is still pushed away. In this case, the main driver of the gas removal are the supernovae. The interplay between the stellar feedback and the IMBH’s outflow should be taken into account.

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On the formation and stability of fermionic dark matter halos in a cosmological framework

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3986 ◽

2020 ◽

Author(s):

Carlos R Argüelles ◽

Manuel I Díaz ◽

Andreas Krut ◽

Rafael Yunis

Keyword(s):

Black Hole ◽

Dark Matter ◽

Space Distribution ◽

Coarse Grained ◽

Dark Matter Halos ◽

The Core ◽

The Galaxy ◽

Gravitating Systems ◽

The Given ◽

First Time

Abstract The formation and stability of collisionless self-gravitating systems is a long standing problem, which dates back to the work of D. Lynden-Bell on violent relaxation, and extends to the issue of virialization of dark matter (DM) halos. An important prediction of such a relaxation process is that spherical equilibrium states can be described by a Fermi-Dirac phase-space distribution, when the extremization of a coarse-grained entropy is reached. In the case of DM fermions, the most general solution develops a degenerate compact core surrounded by a diluted halo. As shown recently, the latter is able to explain the galaxy rotation curves while the DM core can mimic the central black hole. A yet open problem is whether this kind of astrophysical core-halo configurations can form at all, and if they remain stable within cosmological timescales. We assess these issues by performing a thermodynamic stability analysis in the microcanonical ensemble for solutions with given particle number at halo virialization in a cosmological framework. For the first time we demonstrate that the above core-halo DM profiles are stable (i.e. maxima of entropy) and extremely long lived. We find the existence of a critical point at the onset of instability of the core-halo solutions, where the fermion-core collapses towards a supermassive black hole. For particle masses in the keV range, the core-collapse can only occur for Mvir ≳ E9M⊙ starting at zvir ≈ 10 in the given cosmological framework. Our results prove that DM halos with a core-halo morphology are a very plausible outcome within nonlinear stages of structure formation.

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Demography of galactic technosignatures

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3450 ◽

2020 ◽

Vol 500 (2) ◽

pp. 2278-2288

Author(s):

Claudio Grimaldi

Keyword(s):

Statistical Estimation ◽

Milky Way ◽

Comprehensive Overview ◽

Direct Observations ◽

The Galaxy ◽

Electromagnetic Emissions ◽

Average Longevity

ABSTRACT Probabilistic arguments about the existence of technological life beyond Earth traditionally refer to the Drake equation to draw possible estimates of the number of technologically advanced civilizations releasing, either intentionally or not, electromagnetic emissions in the Milky Way. Here, we introduce other indicators than Drake’s number ND to develop a demography of artificial emissions populating the Galaxy. We focus on three main categories of statistically independent signals (isotropic, narrow beams, and rotating beacons) to calculate the average number NG of emission processes present in the Galaxy and the average number of them crossing Earth, $\bar{k}$, which is a quantity amenable to statistical estimation from direct observations. We show that $\bar{k}$ coincides with ND only for isotropic emissions, while $\bar{k}$ can be orders of magnitude smaller than ND in the case of highly directional signals. We further show that while ND gives the number of emissions being released at the present time, NG considers also the signals from no longer active emitters but whose emissions still occupy the Galaxy. We find that as long as the average longevity of the emissions is shorter than about 105 yr, NG is fully determined by the rate of emissions alone, in contrast to ND and $\bar{k}$ which depend also on the emission longevity. Finally, using analytic formulas of NG, ND, and $\bar{k}$ determined for each type of emission processes here considered, we provide a comprehensive overview of the values these quantities can possibly achieve as functions of the emission birthrates, longevities, and directionality.

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