Dark Matter Concentration in the Galactic Center

Tsiklauri, David; Viollier, Raoul D.

doi:10.1086/305753

Cited by 64 publications

(64 citation statements)

References 45 publications

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“…The first phase of these experiments yielded proper motion velocities, which increased the implied dark matter density by 3 orders of magnitude to 10 12 M /pc 3 Ghez et al 1998). This eliminated a cluster of dark objects, such as neutron stars or stellar mass black holes, as a possible explanation of the Galaxy's central dark mass concentration (Maoz et al 1998) and left only the fermion ball hypothesis (e.g., Tsiklauri & Viollier 1998, Munyaneza & Viollier 2002 as an alternative to a single supermassive black hole. The velocity dispersion measurements also localized the dark matter to ±100 mas (4 milli-pc) at a position consistent with the nominal location of the unusual radio source Sgr A* (Ghez et al 1998), whose emission is posited to arise from accretion onto a central supermassive black hole (e.g., Lo et al 1985).…”

Section: Introductionmentioning

confidence: 99%

Full Three Dimensional Orbits For Multiple Stars on Close Approaches to the Central Supermassive Black Hole

et al. 2003

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With the advent of adaptive optics on the W. M. Keck 10m telescope, two significant steps forward have been taken in building the case for a supermassive black hole at the center of the Milky Way and understanding the black hole's effect on its environment. Using adaptive optics and speckle imaging to study the motions of stars in the plane of sky with ±∼2 mas precision over the past 7 years, we have obtained the first simultaneous orbital solution for multiple stars. Among the included stars, three are newly identified (S0-16, S0-19, S0-20). The most dramatic orbit is that of the newly identified star S0-16, which passed a mere 60 AU from the central dark mass at a velocity of 9,000 km/s in 1999. The orbital analysis results in a new central dark mass estimate of 3.6(±0.4) × 10 6 (( Ro 8kpc ) 3 M . This dramatically strengthens the case for a black hole at the center of our Galaxy, by confining the dark matter to within a radius of 0.0003 pc or 1,000 R sh and thereby increasing the inferred dark mass density by four orders of magnitude compared to earlier estimates.With the introduction of an adaptive-optics-fed spectrometer, we have obtained the first detection of spectral absorption lines in one of the high-velocity stars, S0-2, one month after its closest approach to the Galaxy's central supermassive black hole. Both Br γ (2.1661 µm) and He I (2.1126 µm) are seen in absorption with equivalent widths and an inferred stellar rotational velocity that are consistent with that of an O8-B0 dwarf, which suggests that S0-2 is a massive (∼15 M ), young (<10 Myr) main sequence star. Similarly, the lack of CO detected in our first AO spectra suggest that several other of the high-velocity stars are also young. This presents a major challenge to star formation theories, given the strong tidal forces that prevail over all distances reached by these stars in their current orbits and the difficulty in migrating these stars inward during their lifetime from further out where tidal forces should no longer preclude star formation.

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Section: Introductionmentioning

confidence: 99%

Full Three Dimensional Orbits For Multiple Stars on Close Approaches to the Central Supermassive Black Hole

et al. 2003

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“…Degenerate stars of fermions in the mass range between 10 and 25 keV are particularly interesting [2], as they could explain, without resorting to the black-hole hypothesis, at least some of the features observed around the supermassive compact dark objects with masses in the range of M = 1 0 6 : 5 to 10 9:5 solar masses, that are reported to exist at the centers of a number of galaxies [3, 4, 5, 6, 7 , 8 ], including our own [9,10], and quasistellar objects (QSO) [11,12,13,14]. Indeed, there is little dierence between a supermassive black hole and a fermion star of the same mass near the OV limit, a few Schwarzschild radii away from the object [15,16].…”

Section: Introductionmentioning

confidence: 88%

Gravitational phase transition of fermionic matter in a general-relativistic framework

Bilić¹,

Viollier²

1999

Eur. Phys. J. C

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The Thomas-Fermi model at nite temperature is extended to describe a system of self-gravitating weakly interacting massive fermions in a general-relativistic framework. The existence and properties of the gravitational phase transition in this model are investigated numerically. It is shown that, by cooling a nondegenerate gas of weakly interacting massive fermions below some critical temperature, a condensed phase emerges, consisting of quasidegenerate fermion stars. For fermion masses of 10 to 25 keV, these fermion stars may very well provide an alternative explanation for the supermassive compact dark objects that are observed at galactic centers.

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“…The physics of fermion balls as a model for the dark matter distribution at galactic centers has been studied in a series of papers. [113][114][115][116][117][118][119] For realistic models an integral over a temperature distribution is required, and a boundary condition has to be used to represent the surface of the dark matter star both in real space as in momentum space. This then allows the mass of this dark matter star to increase further.…”

Section: Galaxiesmentioning

confidence: 99%

Dark Matter and Sterile Neutrinos

Biermann

Munyaneza

2008

The Eleventh Marcel Grossmann Meeting

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Dark matter has been recognized as an essential part of matter for over 70 years now, and many suggestions have been made, what it could be. Most of these ideas have centered on Cold Dark Matter, particles that are predicted in extensions of standard particle physics, such as supersymmetry. Here we explore the concept that dark matter is sterile neutrinos, particles that are commonly referred to as Warm Dark Matter. Such particles have keV masses, and decay over a very long time, much longer than the Hubble time. In their decay they produce X-ray photons which modify the ionization balance in the very early universe, increasing the fraction of molecular Hydrogen, and thus help early star formation. Sterile neutrinos may also help to understand the baryon-asymmetry, the pulsar kicks, the early growth of black holes, the minimum mass of dwarf spheroidal galaxies, as well as the shape and smoothness of dark matter halos. As soon as all these tests have been made quantitative in their various parameters, we may focus on the creation mechanism of these particles, and could predict the strength of the sharp X-ray emission line, expected from any large dark matter assembly. A measurement of this X-ray emission line would be definitive proof for the existence of may be called weakly interacting neutrinos, or WINs.

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Dark Matter Concentration in the Galactic Center

Cited by 64 publications

References 45 publications

Full Three Dimensional Orbits For Multiple Stars on Close Approaches to the Central Supermassive Black Hole

Full Three Dimensional Orbits For Multiple Stars on Close Approaches to the Central Supermassive Black Hole

Gravitational phase transition of fermionic matter in a general-relativistic framework

Dark Matter and Sterile Neutrinos

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