Effects of Magnetic Fields on Gas Dynamics and Star Formation in Nuclear Rings

Moon, Sung Joon; Kim, Woong-Tae; Kim, Chang-Goo; Ostriker, Eve C.

doi:10.3847/1538-4357/acc250

Cited by 7 publications

(2 citation statements)

References 86 publications

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“…If we include magnetic field in our models, this would require an even lower bar pattern speed to fit the observed shock features. On the other hand, Moon et al (2023) investigated the effects of magnetic field on the nuclear ring in barred galaxies and found that the existence of magnetic field largely suppresses the star formation on the nuclear ring and helps produce a circumnuclear disk. This may help to explain the relatively weak star formation activity in the central 500 pc of the M31 bulge (Dong et al 2018).…”

Section: Systematic Uncertainty In Gas and Stellar-dynamical Modelsmentioning

confidence: 99%

Bar-driven Gas Dynamics of M31

Feng,

Li,

Shen

et al. 2024

ApJ

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The large-scale gaseous shocks in the bulge of M31 can be naturally explained by a rotating stellar bar. We use gas dynamical models to provide an independent measurement of the bar pattern speed in M31. The gravitational potentials of our simulations are from a set of made-to-measure models constrained by stellar photometry and kinematics. If the inclination of the gas disk is fixed at i = 77°, we find that a low pattern speed of 16–20 km s−1 kpc−1 is needed to match the observed position and amplitude of the shock features, as shock positions are too close to the bar major axis in high Ω b models. The pattern speed can increase to 20–30 km s−1 kpc−1 if the inner gas disk has a slightly smaller inclination angle compared with the outer one. Including subgrid physics such as star formation and stellar feedback has minor effects on the shock amplitude, and does not change the shock position significantly. If the inner gas disk is allowed to follow a varying inclination similar to the H i and ionized gas observations, the gas models with a pattern speed of 38 km s−1 kpc−1, which is consistent with stellar-dynamical models, can match both the shock features and the central gas features.

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Section: Systematic Uncertainty In Gas and Stellar-dynamical Modelsmentioning

confidence: 99%

Bar-driven Gas Dynamics of M31

Feng,

Li,

Shen

et al. 2024

ApJ

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“…It is also discussed how the bar potential contributes to the gas distribution and motion via the magnetic field in the Galactic center region (Kim & Stone 2012). Recently, Moon et al (2023) performed 3D MHD numerical simulations under the magnetized inflowing gas along a dust lane into the Galactic center region, which is expected from the stellar bar. They reported that the amplified magnetic field plays a substantial role in the suppression of star formation in the nuclear ring region and the excitation of inflows from the ring to the nuclear disk.…”

Section: Application To Milky Way-the Stellar Barmentioning

confidence: 99%

MHD Simulation in Galactic Center Region with Radiative Cooling and Heating

Kakiuchi,

Suzuki,

Inutsuka

et al. 2024

ApJ

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We investigate the role of magnetic field on the gas dynamics in a galactic bulge region by three-dimensional simulations with radiative cooling and heating. While a high-temperature corona with T > 106 K is formed in the halo regions, the temperature near the midplane is ≲104 K following the thermal equilibrium curve determined by the radiative cooling and heating. Although the thermal energy of the interstellar gas is lost by radiative cooling, the saturation level of the magnetic field strength does not significantly depend on the radiative cooling and heating. The magnetic field strength is amplified to 10 μG on average and reaches several hundred microgauss locally. We find the formation of magnetically dominated regions at midlatitudes in the case with the radiative cooling and heating, which is not seen in the case without radiative effect. The vertical thickness of the midlatitude regions is 50–150 pc at the radial location of 0.4–0.8 kpc from the Galactic center, which is comparable to the observed vertical distribution of neutral atomic gas. When we take the average of different components of energy density integrated over the galactic bulge region, the magnetic energy is comparable to the thermal energy. We conclude that the magnetic field plays a substantial role in controlling the dynamical and thermal properties of the galactic bulge region.

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Magnetic field morphology and evolution in the Central Molecular Zone and its effect on gas dynamics

Tress,

Sormani,

Girichidis

et al. 2024

A&A

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The interstellar medium in the Milky Way's Central Molecular Zone (CMZ) is known to be strongly magnetised, but its large-scale morphology and impact on the gas dynamics are not well understood. We explore the impact and properties of magnetic fields in the CMZ using three-dimensional non-self gravitating magnetohydrodynamical simulations of gas flow in an external Milky Way barred potential. We find that: (1) The magnetic field is conveniently decomposed into a regular time-averaged component and an irregular turbulent component. The regular component aligns well with the velocity vectors of the gas everywhere, including within the bar lanes. (2) The field geometry transitions from parallel to the Galactic plane near $z=0$ to poloidal away from the plane. (3) The magneto-rotational instability (MRI) causes an in-plane inflow of matter from the CMZ gas ring towards the central few parsecs of $0.01 that is absent in the unmagnetised simulations. However, the magnetic fields have no significant effect on the larger-scale bar-driven inflow that brings the gas from the Galactic disc into the CMZ. (4) A combination of bar inflow and MRI-driven turbulence can sustain a turbulent vertical velocity dispersion of $ on scales of $20 in the CMZ ring. The MRI alone sustains a velocity dispersion of $ Both these numbers are lower than the observed velocity dispersion of gas in the CMZ, suggesting that other processes such as stellar feedback are necessary to explain the observations. (5) Dynamo action driven by differential rotation and the MRI amplifies the magnetic fields in the CMZ ring until they saturate at a value that scales with the average local density as $B 102 \, (n/10^3 \ G $. Finally, we discuss the implications of our results within the observational context in the CMZ.

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Effects of Magnetic Fields on Gas Dynamics and Star Formation in Nuclear Rings

Cited by 7 publications

References 86 publications

Bar-driven Gas Dynamics of M31

Bar-driven Gas Dynamics of M31

MHD Simulation in Galactic Center Region with Radiative Cooling and Heating

Magnetic field morphology and evolution in the Central Molecular Zone and its effect on gas dynamics

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