A Curved Magnetic Field in the Ring-like Shell of Bubble N4

Chen, Zhiwei; Jiang, Zengjie; Tamura, Motohide; Kwon, Jungmi; Roman-Lopes, Alexandre

doi:10.3847/1538-4357/aa65d3

Cited by 24 publications

(35 citation statements)

References 27 publications

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“…By applying a decomposition of the plane-of-the-sky magnetic field as a function of distance, as we have presented in this analysis, in a much larger sky fraction, this statistical correlation may become stronger. The alignment of the plane-of-the-sky magnetic field in the IVC with the curvature of the bubble-like gaseous structure resembles that found in works studying H II regions (e.g., Chen et al 2017).…”

Section: Ivc Lvc Lvcsupporting

confidence: 73%

Demonstration of Magnetic Field Tomography with Starlight Polarization toward a Diffuse Sightline of the ISM

Panopoulou

Tassis

Skalidis

et al. 2019

ApJ

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The availability of large data sets with stellar distance and polarization information will enable a tomographic reconstruction of the (plane-of-the-sky-projected) interstellar magnetic field in the near future. We demonstrate the feasibility of such a decomposition within a small region of the diffuse interstellar medium (ISM). We combine measurements of starlight (R-band) linear polarization obtained using the RoboPol polarimeter with stellar distances from the second Gaia data release. The stellar sample is brighter than 17 mag in the R-band and reaches out to several kiloparsecs from the Sun. H I emission spectra reveal the existence of two distinct clouds along the line of sight. We decompose the line-of-sight-integrated stellar polarizations to obtain the mean polarization properties of the two clouds. The two clouds exhibit significant differences in terms of column density and polarization properties. Their mean plane-of-the-sky magnetic field orientation differs by 60°. We show how our tomographic decomposition can be used to constrain our estimates of the polarizing efficiency of the clouds as well as the frequency dependence of the polarization angle of polarized dust emission. We also demonstrate a new method to constrain cloud distances based on this decomposition. Our results represent a preview of the wealth of information that can be obtained from a tomographic map of the ISM magnetic field.

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Section: Ivc Lvc Lvcsupporting

confidence: 73%

Demonstration of Magnetic Field Tomography with Starlight Polarization toward a Diffuse Sightline of the ISM

Panopoulou

Tassis

Skalidis

et al. 2019

ApJ

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“…For example, Pavel and Clemens (2012) combine radio recombination line surveys for H II regions with near-IR polarimetry and find that young H II regions have their long axes preferentially aligned with the mean magnetic field of the galactic disk around them. Chen et al (2017) measure the orientation of the magnetic field in the molecular gas ring N4, which traces the edges of an H II region, using near-IR polarimetry of background stars. They find that, exactly as the simulations predict, the magnetic field orientation on the plane of the sky is preferentially tangential to the ring, with 16/21 of the field orientation vectors lying within 30 • of this direction, and 10/21 lying within 10 • .…”

Section: Photoionizationmentioning

confidence: 99%

The Role of Magnetic Fields in Setting the Star Formation Rate and the Initial Mass Function

Krumholz

Federrath

2019

Front. Astron. Space Sci.

159

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Star-forming gas clouds are strongly magnetized, and their ionization fractions are high enough to place them close to the regime of ideal magnetohydrodyamics on all but the smallest size scales. In this review we discuss the effects of magnetic fields on the star formation rate (SFR) in these clouds, and on the mass spectrum of the fragments that are the outcome of the star formation process, the stellar initial mass function (IMF). Current numerical results suggest that magnetic fields by themselves are minor players in setting either the SFR or the IMF, changing star formation rates and median stellar masses only by factors of ∼ 2−3 compared to non-magnetized flows. However, the indirect effects of magnetic fields, via their interaction with star formation feedback in the form of jets, photoionization, radiative heating, and supernovae, could have significantly larger effects. We explore evidence for this possibility in current simulations, and suggest avenues for future exploration, both in simulations and observations.

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“…E-mail: sergio.martin@physics.ox.ac.uk (SMA) Moreover, observations hint that magnetic fields are critical for several other processes in galaxies. For instance, they are crucial ingredients in the propagation of cosmic rays (Dubois & Commerçon 2016;Wittor et al 2017;Alves Batista et al 2017) and the generation of jets, not to mention key contributors to the processes of star formation (Li et al 2009;Hennebelle & Iffrig 2014;Hull et al 2017) and feedback, both stellar (Chen et al 2017;Ntormousi et al 2017) and from Active Galactic Nuclei (Bambic et al 2018).…”

Section: Introductionmentioning

confidence: 99%

A three-phase amplification of the cosmic magnetic field in galaxies

Martin-Alvarez

Devriendt

Slyz

et al. 2018

Monthly Notices of the Royal Astronomical Society

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Arguably the main challenge of galactic magnetism studies is to explain how the interstellar medium of galaxies reaches energetic equipartition despite the extremely weak cosmic primordial magnetic fields that are originally predicted to thread the intergalactic medium. Previous numerical studies of isolated galaxies suggest that a fast dynamo amplification might suffice to bridge the gap spanning many orders of magnitude in strength between the weak early Universe magnetic fields and the ones observed in high redshift galaxies. To better understand their evolution in the cosmological context of hierarchical galaxy growth, we probe the amplification process undergone by the cosmic magnetic field within a spiral galaxy to unprecedented accuracy by means of a suite of constrained transport magnetohydrodynamical adaptive mesh refinement cosmological zoom simulations with different stellar feedback prescriptions. A galactic turbulent dynamo is found to be naturally excited in this cosmological environment, being responsible for most of the amplification of the magnetic energy. Indeed, we find that the magnetic energy spectra of simulated galaxies display telltale inverse cascades. Overall, the amplification process can be divided in three main phases, which are related to different physical mechanisms driving galaxy evolution: an initial collapse phase, an accretion-driven phase, and a feedback-driven phase. While different feedback models affect the magnetic field amplification differently, all tested models prove to be subdominant at early epochs, before the feedback-driven phase is reached. Thus the three-phase evolution paradigm is found to be quite robust vis-a-vis feedback prescriptions.

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A Curved Magnetic Field in the Ring-like Shell of Bubble N4

Cited by 24 publications

References 27 publications

Demonstration of Magnetic Field Tomography with Starlight Polarization toward a Diffuse Sightline of the ISM

Demonstration of Magnetic Field Tomography with Starlight Polarization toward a Diffuse Sightline of the ISM

The Role of Magnetic Fields in Setting the Star Formation Rate and the Initial Mass Function

A three-phase amplification of the cosmic magnetic field in galaxies

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