scholarly journals Interaction of stars hosting planets with Sgr A* black hole

2019 ◽  
Vol 14 (S351) ◽  
pp. 76-79 ◽  
Author(s):  
Nazanin Davari ◽  
Roberto Capuzzo-Dolcetta ◽  
Rainer Spurzem
Keyword(s):  
Black Hole ◽  
Planetary Systems ◽  
Galactic Centre ◽  
Central Black Hole ◽  
Preliminary Results ◽  
Close Interaction ◽  
Sgr A ◽  
Ongoing Project

AbstractWe present some preliminary results of our ongoing project about planetary systems around S-stars in the vicinity of Sgr A* black hole. Since S-stars might have migrated in the Galactic Centre (GC) from elsewhere, they probably still keep their planetary systems throughout their voyage. In this work, we study the destiny of their putative planetary systems after close interaction with the central black hole of our galaxy.

scholarly journals The fate of binary stars hosting planets upon interaction with Sgr A* black hole

2020 ◽  
Vol 496 (2) ◽  
pp. 1545-1553
Author(s):  
R Capuzzo-Dolcetta ◽  
N Davari
Keyword(s):  
Black Hole ◽  
High Precision ◽  
Binary Stars ◽  
Binary Star ◽  
Planetary Systems ◽  
The Other ◽  
Supermassive Black Hole ◽  
Massive Object ◽  
Close Interaction ◽  
Sgr A

ABSTRACT Our Galaxy hosts a very massive object at its centre, often referred to as the supermassive black hole Sgr A*. Its gravitational tidal field is so intense that it can strip apart a binary star passing its vicinity and accelerate one of the components of the binary as hypervelocity star (HVS) and grab the other star as S-star. Taking into consideration that many binary star systems are known to host planets, in this paper we aim to broaden the study of the close interaction of binary stars and their planetary systems with Sgr A* massive object. Results are obtained via a high-precision N-body code including post-Newtonian approximation. We quantify the likelihood of capture and ejection of stars and planets after interaction with Sgr A*, finding that the fraction of stars captured around it is about three times that of the planets (∼49.4 per cent versus ∼14.5 per cent) and the fraction of hypervelocity planet ejection is about twice that of HVSs (∼21.7 per cent versus ∼9.0 per cent). The actual possibility of observational counterparts deserves further investigation.

scholarly journals The distribution of stars around the Milky Way’s central black hole

2017 ◽  
Vol 609 ◽  
pp. A28 ◽  
Author(s):  
H. Baumgardt ◽  
P. Amaro-Seoane ◽  
R. Schödel
Keyword(s):  
Black Hole ◽  
Adaptive Optics ◽  
Near Infrared ◽  
Stellar Dynamics ◽  
Galactic Centre ◽  
Test Case ◽  
Central Black Hole ◽  
Massive Black Hole ◽  
Giant Stars ◽  
Sgr A

Context. The distribution of stars around a massive black hole (MBH) has been addressed in stellar dynamics for the last four decades by a number of authors. Because of its proximity, the centre of the Milky Way is the only observational test case where the stellar distribution can be accurately tested. Past observational work indicated that the brightest giants in the Galactic centre (GC) may show a density deficit around the central black hole, not a cusp-like distribution, while we theoretically expect the presence of a stellar cusp. Aims. We here present a solution to this long-standing problem. Methods. We performed direct-summation N-body simulations of star clusters around massive black holes and compared the results of our simulations with new observational data of the GC’s nuclear cluster. Results. We find that after a Hubble time, the distribution of bright stars as well as the diffuse light follow power-law distributions in projection with slopes of Γ ≈ 0.3 in our simulations. This is in excellent agreement with what is seen in star counts and in the distribution of the diffuse stellar light extracted from adaptive-optics (AO) assisted near-infrared observations of the GC. Conclusions. Our simulations also confirm that there exists a missing giant star population within a projected radius of a few arcsec around Sgr A*. Such a depletion of giant stars in the innermost 0.1 pc could be explained by a previously present gaseous disc and collisions, which means that a stellar cusp would also be present at the innermost radii, but in the form of degenerate compact cores.

scholarly journals Detection of the Schwarzschild precession in the orbit of the star S2 near the Galactic centre massive black hole

2020 ◽  
Vol 636 ◽  
pp. L5 ◽  
Author(s):  
◽  
R. Abuter ◽  
A. Amorim ◽  
M. Bauböck ◽  
J. P. Berger ◽  
...  
Keyword(s):  
Black Hole ◽  
Reference Frame ◽  
Adaptive Optics ◽  
Galactic Centre ◽  
Massive Black Hole ◽  
Central Mass ◽  
Black Hole Candidate ◽  
Beam Combiner ◽  
Direct Measurements ◽  
Sgr A

The star S2 orbiting the compact radio source Sgr A* is a precision probe of the gravitational field around the closest massive black hole (candidate). Over the last 2.7 decades we have monitored the star’s radial velocity and motion on the sky, mainly with the SINFONI and NACO adaptive optics (AO) instruments on the ESO VLT, and since 2017, with the four-telescope interferometric beam combiner instrument GRAVITY. In this Letter we report the first detection of the General Relativity (GR) Schwarzschild Precession (SP) in S2’s orbit. Owing to its highly elliptical orbit (e = 0.88), S2’s SP is mainly a kink between the pre-and post-pericentre directions of motion ≈±1 year around pericentre passage, relative to the corresponding Kepler orbit. The superb 2017−2019 astrometry of GRAVITY defines the pericentre passage and outgoing direction. The incoming direction is anchored by 118 NACO-AO measurements of S2’s position in the infrared reference frame, with an additional 75 direct measurements of the S2-Sgr A* separation during bright states (“flares”) of Sgr A*. Our 14-parameter model fits for the distance, central mass, the position and motion of the reference frame of the AO astrometry relative to the mass, the six parameters of the orbit, as well as a dimensionless parameter fSP for the SP (fSP = 0 for Newton and 1 for GR). From data up to the end of 2019 we robustly detect the SP of S2, δϕ ≈ 12′ per orbital period. From posterior fitting and MCMC Bayesian analysis with different weighting schemes and bootstrapping we find fSP = 1.10 ± 0.19. The S2 data are fully consistent with GR. Any extended mass inside S2’s orbit cannot exceed ≈0.1% of the central mass. Any compact third mass inside the central arcsecond must be less than about 1000 M⊙.

scholarly journals 10.2. High proper motions in the vicinity of Sgr A∗: unambiguous evidence for a massive central black hole

1998 ◽  
Vol 184 ◽  
pp. 433-434
Author(s):  
A. M. Ghez ◽  
B. L. Klein ◽  
C. McCabe ◽  
M. Morris ◽  
E. E. Becklin
Keyword(s):  
Black Hole ◽  
Milky Way ◽  
Galactic Center ◽  
Robust Method ◽  
Proper Motions ◽  
Central Black Hole ◽  
Milky Way Galaxy ◽  
The Galaxy ◽  
Sgr A

Although the notion that the Milky Way galaxy contains a supermassive central black hole has been around for more than two decades, it has been difficult to prove that one exists. The challenge is to assess the distribution of matter in the few central parsecs of the Galaxy. Assuming that gravity is the dominant force, the motion of the stars and gas in the vicinity of the putative black hole offers a robust method for accomplishing this task, by revealing the mass interior to the radius of the objects studied. Thus objects located closest to the Galactic Center provide the strongest constraints on the black hole hypothesis.

scholarly journals The secular evolution of discrete quasi-Keplerian systems

2018 ◽  
Vol 609 ◽  
pp. A38 ◽  
Author(s):  
J.-B. Fouvry ◽  
C. Pichon ◽  
P.-H. Chavanis
Keyword(s):  
Black Hole ◽  
Landau Equation ◽  
Collective Effects ◽  
Galactic Centre ◽  
Central Black Hole ◽  
Massive Black Hole ◽  
Secular Evolution ◽  
Gauss Method ◽  
And Diffusion ◽  
Keplerian Systems

A discrete self-gravitating quasi-Keplerian razor-thin axisymmetric stellar disc orbiting a massive black hole sees its orbital structure diffuse on secular timescales as a result of a self-induced resonant relaxation. In the absence of collective effects, such a process is described by the recently derived inhomogeneous multi-mass degenerate Landau equation. Relying on Gauss’ method, we computed the associated drift and diffusion coefficients to characterise the properties of the resonant relaxation of razor-thin discs. For a disc-like configuration in our Galactic centre, we showed how this secular diffusion induces an adiabatic distortion of orbits and estimate the typical timescale of resonant relaxation. When considering a disc composed of multiple masses similarly distributed, we have illustrated how the population of lighter stars will gain eccentricity, driving it closer to the central black hole, provided the distribution function increases with angular momentum. The kinetic equation recovers as well the quenching of the resonant diffusion of a test star in the vicinity of the black hole (the “Schwarzschild barrier”) as a result of the divergence of the relativistic precessions. The dual stochastic Langevin formulation yields consistent results and offers a versatile framework in which to incorporate other stochastic processes.

scholarly journals Possible Evidence for a Binary Massive Black Hole in the Galactic Nucleus

1996 ◽  
Vol 169 ◽  
pp. 285-286
Author(s):  
E.J.A. Meurs
Keyword(s):  
Black Hole ◽  
Emission Line ◽  
Velocity Component ◽  
Orbital Motion ◽  
Galactic Centre ◽  
Line Profiles ◽  
Radial Velocity Component ◽  
Massive Black Hole ◽  
Ir Stars ◽  
Sgr A

The Galactic Centre candidate Sgr A∗ may exhibit a 40 km/s radial velocity component, which is not observed for OH/IR stars around the centre. This could be interpreted as orbital motion of one member of a binary massive black hole. In other galaxies such pairs may be inferred from radio jet precession and emission line profiles.

scholarly journals Low radio frequency spectrum of Sgr-A*

2016 ◽  
Vol 11 (S322) ◽  
pp. 54-55
Author(s):  
Subhashis Roy
Keyword(s):  
Radio Frequency ◽  
Flux Density ◽  
Frequency Spectrum ◽  
Spectral Index ◽  
Radio Telescope ◽  
Major Axis ◽  
Galactic Centre ◽  
Preliminary Results ◽  
Radio Frequency Spectrum ◽  
Sgr A

AbstractWe observed the Galactic centre (GC) region with the partially upgraded Giant Metrewave Radio Telescope (GMRT) using a wideband system in frequency ranges of 300– 500 MHz with 16 antennas. Preliminary results are presented here. Sgr-A* is clearly detected down to 450 MHz. Sgr-A West slowly disappears at lower frequencies across the band. By taking cross-cuts across the known major-axis of Sgr-A*, we measure its total flux density across the band to be 0.4 Jy consistent with what is expected from earlier results. It clearly indicates lack of absorption from Sgr-A West. Its spectral index is consistent with its higher frequency value of +0.3.

scholarly journals Acceleration of particles up to PeV energies at the galactic centre

2016 ◽  
Vol 12 (S324) ◽  
pp. 317-321
Author(s):  
Stefano Gabici ◽  
Felix A. Aharonian ◽  
Emmanuel Moulin ◽  
Aion Viana
Keyword(s):  
Black Hole ◽  
High Energy ◽  
Galactic Cosmic Rays ◽  
Galactic Centre ◽  
Acceleration Of Particles ◽  
Supermassive Black Hole ◽  
Centre Region ◽  
Very High Energy ◽  
Sgr A ◽  
Very High

AbstractRecent very high energy observations of the galactic centre region performed by H.E.S.S. revealed the presence of a powerful PeVatron. This is the first of such objects detected, and its most plausible counterpart seems to be associated to Sgr A*, the supermassive black hole in the centre of our galaxy. The implications of this discovery will be discussed, in particular in the context of the problem of the origin of galactic cosmic rays.

scholarly journals A Search for Post-Collapse Cores

1985 ◽  
Vol 113 ◽  
pp. 73-76
Author(s):  
S. Djorgovski ◽  
H. Penner
Keyword(s):  
Black Hole ◽  
Globular Cluster ◽  
Surface Photometry ◽  
Central Black Hole ◽  
Preliminary Results ◽  
The Galaxy ◽  
Cluster Cores

We report the preliminary results of a surface photometry survey of globular cluster cores. Two new cores with post-collapse morphology have been found, and two possible candidates. The estimated fraction of clusters with this core morphology in the Galaxy is only a few percent. Most clusters do not show a morphology similar to the predictions of the central black hole models.

scholarly journals Dark matter heating of gas accreting onto Sgr A*

2019 ◽  
Vol 490 (3) ◽  
pp. 3414-3425 ◽  
Author(s):  
Elizabeth R Bennewitz ◽  
Cristian Gaidau ◽  
Thomas W Baumgarte ◽  
Stuart L Shapiro
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Steady State ◽  
Cross Sections ◽  
Accretion Rate ◽  
Supermassive Black Holes ◽  
Galactic Centre ◽  
Appreciable Effect ◽  
Sgr A

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 adiabatic indices for the gas, and different power-law exponents for the DM density profile. We find that typical transonic solutions with heating have a significantly reduced accretion rate. However, for many plausible parameters, transonic solutions do not exist, suggesting a breakdown of the underlying assumptions of steady-state Bondi accretion. Our findings indicate that heating by DM annihilation may play an important role in the accretion onto supermassive black holes at the centre of galaxies, and may help explain the low accretion rate observed for Sgr A*.

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