Poloidal Magnetic Fields in Galactic Central Regions

Lesch, H.; Crusius-Wätzel, A. R.; Schlickeiser, R.; Wielebinski, R.

doi:10.1017/s0074180900190618

Cited by 5 publications

(5 citation statements)

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“…The maintenance of such a current, and the confinement of the field, might be accomplished by the Lorentz forces accompanying the quasi-steady radial inflow or outflow (or both) of gas through a vertical magnetic field (e.g. Lesch et al 1989), although the physical elements of such a dynamo mechanism still require elaboration. One hypothesis for the vertical field at the Galactic center, which is appealing both for its simplicity and its seeming inevitability, is that of Sofue & Fujimoto (1987).…”

Section: The Galactic Center Magnetospherementioning

confidence: 99%

The Galactic Center Environment

Morris

Serabyn

1996

Annu. Rev. Astron. Astrophys.

891

905

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The central half kiloparsec region of our Galaxy harbors a variety of phenomena unique to the central environment. This review discusses the observed structure and activity of the interstellar medium in this region in terms of its inevitable inflow toward the center of the Galactic gravitational potential well. A number of dissipative processes lead to a strong concentration of gas into a "Central Molecular Zone" of about 200-pc radius, in which the molecular medium is characterized by large densities, large velocity dispersions, high temperatures, and apparently strong magnetic fields. The physical state of the gas and the resultant star formation processes occurring in this environment are therefore quite unlike those occurring in the large-scale disk. Gas not consumed by star formation either enters a hot X ray-emitting halo and is lost as a thermally driven galactic wind or continues moving inward, probably discontinuously, through the domain of the few parsec-sized circumnuclear disks and eventually into the central parsec. There, the central radio source SgrA * currently accepts only a tiny fraction of the inflowing material, likely as a result of a limit cycle wherein the continual inflow of matter provokes star formation, which in turn can temporarily halt the inflow via mass-outflow winds.

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Section: The Galactic Center Magnetospherementioning

confidence: 99%

The Galactic Center Environment

Morris

Serabyn

1996

Annu. Rev. Astron. Astrophys.

891

905

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“…The spectrum of electrons that must be contained within the Milky Way's radio filaments in order to produce their extremely hard synchrotron emission has long been a challenge to explain astrophysically. Since the 1980s, observations of radio filaments have revealed a turnover at ∼10 GHz in the synchrotron spectrum, implying an electron energy spectrum that is strongly peaked (sometimes described in the radio astronomy literature as "monoenergetic" [46,47]) at an energy of approximately ∼10 GeV, propagating in a magnetic field on the order of 100 µG [46,48,49]. The leading astrophysical mechanism proposed to explain these spectra FIG.…”

Section: Synchrotron Emission From the Inner Galaxy's Radio Filamentsmentioning

confidence: 99%

The empirical case for 10-GeV dark matter

Hooper

2012

Physics of the Dark Universe

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In this article, I summarize and discuss the body of evidence which has accumulated in favor of dark matter in the form of approximately 10 GeV particles. This evidence includes the spectrum and angular distribution of gamma rays from the Galactic Center, the synchrotron emission from the Milky Way's radio filaments, the diffuse synchrotron emission from the Inner Galaxy (the "WMAP Haze") and low-energy signals from the direct detection experiments DAMA/LIBRA, CoGeNT and CRESST-II. This collection of observations can be explained by a relatively light dark matter particle with an annihilation cross section consistent with that predicted for a simple thermal relic (σv ∼ 10 −26 cm 3 /s) and with a distribution in the halo of the Milky Way consistent with that predicted from simulations. Astrophysical explanations for the gamma ray and synchrotron signals, in contrast, have not been successful in accommodating these observations. Similarly, the phase of the annual modulation observed by DAMA/LIBRA (and now supported by CoGeNT) is inconsistent with all known or postulated modulating backgrounds, but are in good agreement with expectations for dark matter scattering. This scenario is consistent with all existing indirect and collider constraints, as well as the constraints placed by CDMS. Consistency with xenon-based experiments can be achieved if the response of liquid xenon to very low-energy nuclear recoils is somewhat suppressed relative to previous evaluations, or if the dark matter possesses different couplings to protons and neutrons.

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“…• To produce the distinctive spectrum of synchrotron emission that is observed from the Milky Way's non-thermal radio filaments [8], dark matter annihilations must inject an extremely hard spectrum of electrons (sometimes described in the radio literature as "monoenergetic" [27,28]). Dark matter which annihilates to e + e − a significant fraction of the time can accommodate both the observed characteristics of the radio filaments, as well as the WMAP/Planck Haze [9], and could also potentially account for much of the excess isotropic radio background [29].…”

Section: Introductionmentioning

confidence: 99%

Dark forces and light dark matter

2012

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We consider a simple class of models in which the dark matter, X, is coupled to a new gauge boson, φ, with a relatively low mass (m φ ∼ 100 MeV − 3 GeV). Neither the dark matter nor the new gauge boson have tree-level couplings to the Standard Model. The dark matter in this model annihilates to φ pairs, and for a coupling of gX ≈ 0.06 × (mX /10 GeV) 1/2 yields a thermal relic abundance consistent with the cosmological density of dark matter. The φ's produced in such annihilations decay through a small degree of kinetic mixing with the photon to combinations of Standard Model leptons and mesons. For dark matter with a mass of ∼10 GeV, the shape of the resulting gamma-ray spectrum provides a good fit to that observed from the Galactic Center, and can also provide the very hard electron spectrum required to account for the observed synchrotron emission from the Milky Way's radio filaments. For kinetic mixing near the level naively expected from loop-suppressed operators ( ∼ 10 −4 ), the dark matter is predicted to scatter elastically with protons with a cross section consistent with that required to accommodate the signals reported by DAMA/LIBRA, CoGeNT and CRESST-II.PACS numbers: 95.35.+d; FERMILAB-PUB-12-XXX

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Poloidal Magnetic Fields in Galactic Central Regions

Cited by 5 publications

References 0 publications

The Galactic Center Environment

The Galactic Center Environment

The empirical case for 10-GeV dark matter

Dark forces and light dark matter

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