An analytical model for the magnetic field in the thick shell of Galactic bubbles with uniform initial conditions

Abstract

Bubbles and super-bubbles are ubiquitous in the interstellar medium and influence their local magnetic field. Starting from the assumption that bubbles result from violent explosions that sweep matter away in a thick shell, we derive the analytical equations for the divergence-free, regular magnetic field in the shell. The explosion velocity field is assumed to be radial but not necessarily spherical, making it possible to model various-shaped bubbles. Assuming an explosion center, the magnetic field at the present time is fully determined by the initial uniform magnetic field, the present-time geometry of the bubble shell, and a radial vector field that encodes the explosion-induced displacement of matter, from its original location to its present-time location. We present the main characteristics of our magnetic-field model using a simple linear model for the radial displacements. Next, we use our analytical prescription, informed by a three-dimensional dust density map, to estimate the expected contribution of the shell of the Local Bubble, the super-bubbles in which the Sun resides, to the integrated Faraday rotation measures and synchrotron emission and compare these to full-sky observational data. We find that, while the contribution to the former is minimal, the contribution to the latter is very significant at Galactic latitudes $|b|>45^{\circ }$. Our results underline the need to take the Local Bubble into account in large-scale Galactic magnetic field studies.

arXiv commentv2: minor edits and correction for the matter density profile (Eq 20)

References in corpus (45)

• The Gaia mission
• HEALPix -- a Framework for High Resolution Discretization, and Fast Analysis of Data Distributed on the Sphere
• A 3D Dust Map Based on Gaia, Pan-STARRS 1 and 2MASS
• A New Electron Density Model for Estimation of Pulsar and FRB Distances
• A New Model of the Galactic Magnetic Field
• The LOFAR Two-metre Sky Survey -- V. Second data release
• Magnetic Fields in Spiral Galaxies
• Planck 2018 results. IV. Diffuse component separation
• Momentum Injection by Supernovae in the Interstellar Medium
• Gaia-2MASS 3D maps of Galactic interstellar dust within 3 kpc
• The Galactic Magnetic Field
• Updated Gaia-2MASS 3D maps of Galactic interstellar dust
• The origin of the Local Bubble
• A parsec-scale Galactic 3D dust map out to 1.25 kpc from the Sun
• Systematic bias in interstellar magnetic field estimates
• Using the X-ray Morphologies of Young Supernova Remnants to Constrain Explosion Type, Ejecta Distribution, and Chemical Mixing
• A New Model For The Loop-I (The North Polar Spur) Region
• Three-dimensional extinction maps: Inverting inter-calibrated extinction catalogues
• Modelling the Galactic Magnetic Field on the Plane in 2D
• Modeling SNR Cassiopeia A from the Supernova Explosion to its Current Age: The role of post-explosion anisotropies of ejecta
• Magnetic Fields in the Milky Way
• Polarised radio filaments outside the Galactic plane
• Modeling the magnetized Local Bubble from dust data
• The Structure of the Local Hot Bubble
• The Coherent Magnetic Field of the Milky Way
• Electron Density Structure of the Local Galactic Disk
• The Interstellar Magnetic Field Close to the Sun II
• Faraday rotation maps of disk galaxies
• The Local Bubble: a magnetic veil to our Galaxy
• Charting nearby dust clouds using Gaia data only
• Optical Polarization Mapping toward the interface between the Local Cavity and Loop I
• Turbulent dynamo in the two-phase interstellar medium
• The Connection between Supernova Remnants and the Galactic Magnetic Field: A Global Radio Study of the Axisymmetric Sample
• Practical Modeling of Large-Scale Galactic Magnetic Fields: Status and Prospects
• Dynamics and Energy Loss in Superbubbles
• Interstellar polarisation and extinction in the Local Bubble and the Gould Belt
• Local Bubble contribution to the 353-GHz dust polarized emission
• Starlight-polarization-based tomography of the magnetized interstellar medium: PASIPHAE's line-of-sight inversion method
• Magnetic Field Strengths and Grain Alignment Variations in the Local Bubble Wall
• Numerical studies on the link between radioisotopic signatures on Earth and the formation of the Local Bubble. II. Advanced modeling of interstellar 26Al, 53Mn, 60Fe, and 244Pu influxes as traces of past supernovae in the solar neighborhood
• The first degree-scale starlight-polarization-based tomography map of the magnetized interstellar medium
• The coherent magnetic field of the Milky Way halo, Local Bubble and Fan Region
• Faraday tomography of LoTSS-DR2 data: II. Multi-tracer analysis in the high-latitude outer Galaxy
• Synthetic dust polarization emission maps at 353 GHz for an observer placed inside a Local Bubble-like cavity
• Linear polarization study of open clusters towards the anticenter direction: Signature of the spiral arms

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• Modeling Local Bubble analogs II: Synthetic Faraday rotation maps
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