Structure, dynamical impact and origin of magnetic fields in nearby galaxies in the SKA era

Beck, Rainer; Bomans, D. J.; Colafrancesco, S.; Dettmar, R.‐J.; Ferrière, K.; Fletcher, Andrew; Heald, G.; Heesen, V.; Horellou, C.; Krause, M.; Lou, Yu‐Qing; Mao, Sui Ann; Paladino, R.; Schinnerer, E.; Sokoloff, Dmitry; Stil, J. M.; Tabatabaei, F. S.

doi:10.22323/1.215.0094

Cited by 15 publications

(19 citation statements)

References 65 publications

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“…Present-day radio telescopes allow us to observe only the nearest and brightest galaxies with such a resolution. Increasing the galaxy sample will have to wait for the Square Kilometre Array (SKA) [80].…”

Section: Conclusion Discussion and Future Directions Of Researchmentioning

confidence: 99%

Revisiting the Equipartition Assumption in Star-Forming Galaxies

Seta¹,

Beck

2019

Galaxies

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Energy equipartition between cosmic rays and magnetic fields is often assumed to infer magnetic field properties from the synchrotron observations of star-forming galaxies. However, there is no compelling physical reason to expect the same. We aim to explore the validity of the energy equipartition assumption. After describing popular arguments in favour of the assumption, we first discuss observational results that support it at large scales and how certain observations show significant deviations from equipartition at scales smaller than ≈ 1 kpc , probably related to the propagation length of the cosmic rays. Then, we test the energy equipartition assumption using test-particle and magnetohydrodynamic (MHD) simulations. From the results of the simulations, we find that the energy equipartition assumption is not valid at scales smaller than the driving scale of the ISM turbulence (≈ 100 pc in spiral galaxies), which can be regarded as the lower limit for the scale beyond which equipartition is valid. We suggest that one must be aware of the dynamical scales in the system before assuming energy equipartition to extract magnetic field information from synchrotron observations. Finally, we present ideas for future observations and simulations to investigate in more detail under which conditions the equipartition assumption is valid or not.

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Section: Conclusion Discussion and Future Directions Of Researchmentioning

confidence: 99%

Revisiting the Equipartition Assumption in Star-Forming Galaxies

Seta¹,

Beck

2019

Galaxies

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“…Several headline science projects are being developed, with the highest priority embodied in a large-area, deep, broadband survey for Faraday rotation measures (Johnston-Hollitt et al 2015). Additional science cases in-clude those focused on nearby galaxies Beck et al 2015), the Milky Way galaxy (Haverkorn et al 2015), detailed broadband studies of radio galaxies (Gaensler et al 2015), and intermediate-redshift normal and starforming galaxies (Taylor et al 2015). There clearly remain a great number of outstanding questions of fundamental importance that will be pursued in the coming decades of radio surveys.…”

Section: Future Prospectsmentioning

confidence: 99%

Magnetic fields on a wide range of scales in star-forming galaxies

Heald¹,

Williams²,

Sridhar³

2016

Proceedings of the Many Facets of Extragalactic Radio Surveys: Towards New Scientific Challenges — PoS(EXTRA-RADSUR2015)

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A key ingredient in the evolution of galaxies is the star formation cycle. Recent progress in the study of magnetic fields is revealing the close connection between star formation and its effect on the small-scale structure in the magnetized interstellar medium (ISM). In this contribution we describe how the modern generation of radio telescopes is being used to probe the physics of the ISM through sensitive multiwavelength surveys of gas and magnetic fields, from the inner star forming disk and outward into the galaxy outskirts where large-scale magnetic fields may also play a key role. We highlight unique pioneering efforts towards performing and scientifically exploiting large-scale surveys of the type that the SKA will undertake routinely. Looking to the future, we describe plans for using the Square Kilometre Array (SKA) and its pathfinders to gain important new insights into the cosmic history of galaxy evolution.

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“…For further information see the following chapters in the 2015 SKA Science Case: Beck et al (2015); Heald et al (2015).…”

Section: Magnetic Fields In Nearby Galaxiesmentioning

confidence: 99%

Using SKA Rotation Measures to Reveal the Mysteries of the Magnetised Universe

Johnston‐Hollitt¹,

Govoni²,

Beck³

et al. 2015

Proceedings of Advancing Astrophysics With the Square Kilometre Array — PoS(AASKA14)

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We know that magnetic fields are pervasive across all scales in the Universe and over all of cosmic time and yet our understanding of many of the properties of magnetic fields is still limited. We do not yet know when, where or how the first magnetic fields in the Universe were formed, nor do we fully understand their role in fundamental processes such as galaxy formation or cosmic ray acceleration or how they influence the evolution of astrophysical objects. The greatest challenge to addressing these issues has been a lack of deep, broad bandwidth polarimetric data over large areas of the sky. The Square Kilometre Array will radically improve this situation via an allsky polarisation survey that delivers both high quality polarisation imaging in combination with observations of 7-14 million extragalactic rotation measures. Here we summarise how this survey will improve our understanding of a range of astrophysical phenomena on scales from individual Galactic objects to the cosmic web.Advancing Astrophysics with the Square Kilometre Array

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Structure, dynamical impact and origin of magnetic fields in nearby galaxies in the SKA era

Cited by 15 publications

References 65 publications

Revisiting the Equipartition Assumption in Star-Forming Galaxies

Revisiting the Equipartition Assumption in Star-Forming Galaxies

Magnetic fields on a wide range of scales in star-forming galaxies

Using SKA Rotation Measures to Reveal the Mysteries of the Magnetised Universe

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