The centers of our Galaxy and the nearby Messier 87 are known to contain supermassive black holes, which support accretion flows that radiate across the electromagnetic spectrum. Although the composition of the accreting gas is unknown, it is likely a mix of ionized hydrogen and helium. We use a simple analytic model and a suite of numerical general relativistic magnetohydrodynamic accretion simulations to study how polarimetric images and spectral energy distributions of the source are influenced by the hydrogen/helium content of the accreting matter. We aim to identify general trends rather than make quantitatively precise predictions, since it is not possible to fully explore the parameter space of accretion models. If the ion-to-electron temperature ratio is fixed, then increasing the helium fraction increases the gas temperature; to match the observational flux density constraints, the number density of electrons and magnetic field strengths must therefore decrease. In our numerical simulations, emission shifts from regions of low to high plasma
- Award ID(s):
- 1842643
- NSF-PAR ID:
- 10325723
- Date Published:
- Journal Name:
- Plasma
- Volume:
- 4
- Issue:
- 3
- ISSN:
- 2571-6182
- Page Range / eLocation ID:
- 435 to 449
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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null (Ed.)ABSTRACT Coherent bipolar electric field structures, ubiquitously found in various space and astrophysical plasma environments, play an important role in plasma transport and particle acceleration. Most of the studies found in the literature about them pertain to bipolar structures with positive potentials interpreted in terms of electron holes. Magnetospheric Multiscale spacecraft have recently observed a series of coherent electric field structures with negative potential in the Earth’s bow shock region, which are interpreted as ion holes. The existing theoretical models of ion holes are inadequate because they entail stringent conditions on the ratio of ion to electron temperature. This letter presents a new theory that provides a satisfactory explanation to these observations. A salient point is that this letter incorporates the electron dynamics in the theoretical formalism, which removes ambiguities associated with existing theories, thus showing that the new theory for ion holes may be widely applicable for space and astrophysical plasmas.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/plasma4030032
