Magnetic field versus gas density, in different physical conditions

Vallée, J. P.

doi:10.1007/bf00627277

Cited by 15 publications

(2 citation statements)

References 17 publications

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“…One possibility is that it is due to the correlation between the magnetic field strength and the gas density (Fiebig & Guesten 1989;Helou & Bicay 1993;Niklas & Beck 1997). Observationally, this correlation extends from the smallest (Fiebig & Guesten 1989) to the largest cosmic scales (Vallée 1990(Vallée , 1995, and has the form of B ∝ n k for n > 10 2 cm −3 , where B is the magnetic field strength, n the gas density, and k = 0.5 ± 0.1 (Fiebig & Guesten 1989). Since the emissivity of the nonthermal (synchrotron) radiation is proportional to B 2 , the B-versus-n correlation leads naturally to a localized (∼linear) correlation between nonthermal surface brightness and gas surface density.…”

Section: Relation Between Warm Dense Gas and Star Formationmentioning

confidence: 99%

Alma Observations of Warm Dense Gas in NGC 1614—breaking of the Star Formation Law in the Central Kiloparsec

Cao

et al. 2015

ApJ

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We present ALMA Cycle-0 observations of the CO (6-5) line emission and of the 435 μm dust continuum emission in the central kiloparsec of NGC 1614, a local luminous infrared galaxy at a distance of 67.8 Mpc (1 = 329 pc). The CO emission is well resolved by the ALMA beam (0. 26 × 0. 20) into a circumnuclear ring, with an integrated flux of f = 898 (±153) Jy km s −1 , which is 63(±12)% of the total CO (6-5) flux measured by Herschel. The molecular ring, located between 100 pc < r < 350 pc from the nucleus, looks clumpy and includes seven unresolved (or marginally resolved) knots with median velocity dispersion of ∼40 km s −1 . These knots are associated with strong star formation regions with Σ SFR ∼ 100 M yr −1 kpc −2 and Σ Gas ∼ 10 4 M pc −2 . The nondetections of the nucleus in both the CO (6-5) line emission and the 435 μm continuum rule out, with relatively high confidence, a Compton-thick active galactic nucleus in NGC 1614. Comparisons with radio continuum emission show a strong deviation from an expected local correlation between Σ Gas and Σ SFR , indicating a breakdown of the Kennicutt-Schmidt law on the linear scale of ∼100 pc.

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Section: Relation Between Warm Dense Gas and Star Formationmentioning

confidence: 99%

Alma Observations of Warm Dense Gas in NGC 1614—breaking of the Star Formation Law in the Central Kiloparsec

Cao

et al. 2015

ApJ

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“…On the other hand, the strength of the magnetic field B obtained from cosmological observations in various scales are depicted in figure 6, [34,35]. Guided these data, we have chosen the value Γ = 0.02, which means that the energy of the magnetic field is 12 percent of the kinetic energy in the baryonic form.…”

Section: Scale Dependent Magnetic Fieldmentioning

confidence: 99%

Acquired scaling relations in dark matter turbulence

Nakamichi

Morikawa

2010

J. Cosmol. Astropart. Phys.

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Many scaling relations are observed for self-gravitating systems in the universe. We explore the consistent understanding of them from a simple principle based on the proposal that the collisionless dark matter fluid terns into a turbulent state, i.e. dark turbulence, after crossing the caustic surface in the non-linear stage. The dark turbulence will not eddy dominant reflecting the collisionless property. After deriving Kolmogorov scaling laws from Navier-Stokes equation by the method similar to the one for Smoluchowski coagulation equation, we apply this to several observations such as the scale-dependent velocity dispersion, mass-luminosity ratio, magnetic fields, and massangular momentum relation, power spectrum of density fluctuations. They all point the concordant value for the constant energy flow per mass: 0.3cm 2 /sec 3 , which may be understood as the speed of the hierarchical coalescence process in the cosmic structure formation. PACS numbers: Cosmology: theory, Gravitation, Turbulence, Cosmology: dark matter, Cosmology: observations, Hydrodynamics 98.80.-k 95.35 +d 98.65.-r

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