Kinematics of the Magellanic Stream and Implications for Its Ionization*

Frazer, Elaine M.; Bland-Hawthorn, Joss; Wakker, Bart P.; Barger, Kat; Richter, Philipp

doi:10.3847/1538-4357/ab92a3

Cited by 23 publications

(25 citation statements)

References 77 publications

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“…However, this increased radiation still cannot explain the extremely high Hα emission seen in the region of the Stream under the South Galactic Pole, which may indicate a recent Seyfert flare from the Galactic Center (Bland-Hawthorn et al 2019). The enhanced radiation field intensity at d=20 kpc would also affect the ionization level inferred from UV metal-line studies of the Stream (Fox et al 2014(Fox et al , 2020; however, the ionized/neutral ratio of ∼3:1 is distance-independent since both the neutral and ionized masses scale as d 2 .…”

Section: Resultsmentioning

confidence: 95%

The Magellanic Stream at 20 kpc: A New Orbital History for the Magellanic Clouds

Lucchini,

D'Onghia,

Fox

2021

Preprint

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We present new simulations of the formation of the Magellanic Stream based on an updated firstpassage interaction history for the Magellanic Clouds, including both the Galactic and Magellanic Coronae and a live dark matter halo for the Milky Way. This new interaction history is needed because previously successful orbits need updating to account for the Magellanic Corona and the loosely bound nature of the Magellanic Group. These orbits involve two tidal interactions over the last 3.5 Gyrs and reproduce the Stream's position and appearance on the sky, mass distribution, and velocity profile. Most importantly, our simulated Stream is only ∼20 kpc away from the Sun at its closest point, whereas previous first-infall models predicted a distance of 100 − 200 kpc. This dramatic paradigm shift in the Stream's 3D position would have several important implications. First, estimates of the observed neutral and ionized masses would be reduced by a factor of ∼5. Second, the stellar component of the Stream is also predicted to be <20 kpc away. Third, the enhanced interactions with the MW's hot corona at this small distance would substantially shorten the Stream's lifetime. Finally, the MW's UV radiation field would be much stronger, potentially explaining the Hα emission observed along most of the Stream. Our prediction of a 20 kpc Stream could be tested by searching for UV absorption lines towards distant MW halo stars projected onto the Stream.

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Section: Resultsmentioning

confidence: 95%

The Magellanic Stream at 20 kpc: A New Orbital History for the Magellanic Clouds

Lucchini,

D'Onghia,

Fox

2021

Preprint

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“…The most plausible explanation for this, so far, is recent ac-tivity from the Galactic Center. A bipolar, radiative ionization cone from a Seyfert nucleus associated with SGR A* can not only explain the elevated Hα emission but also higher hydrogen ionization fraction, higher C IV/ CII and Si IV/ Si II ratios, and high C IV and Si IV column densities along that segment of the Stream (Bland-Hawthorn et al 2013Fox et al 2020).…”

Section: Hα Emissionmentioning

confidence: 99%

Radiative Turbulent Mixing Layers and the Survival of Magellanic Debris

Bustard,

Gronke

2021

Preprint

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The Magellanic Stream is sculpted by its infall through the Milky Way's circumgalactic medium, but the rates and directions of mass, momentum, and energy exchange through the Stream-halo interface are relative unknowns critical for determining the origin and fate of the Stream. Complementary to large-scale simulations of LMC-SMC interactions, we apply new insights derived from idealized, highresolution "cloud-crushing" and radiative turbulent mixing layer simulations to the Leading Arm and Trailing Stream. Contrary to classical expectations of fast cloud breakup, we predict that the Leading Arm and much of the Trailing Stream should be surviving infall and even gaining mass due to strong radiative cooling. Provided a sufficiently supersonic tidal swing-out from the Clouds, the present-day Leading Arm could be a series of high-density clumps in the cooling tail behind the progenitor cloud. We back up our analytic framework with a suite of converged wind-tunnel simulations, finding that previous results on cloud survival and mass growth can be extended to high Mach number (M) flows with a modified drag time t drag ∝ 1 + M and longer growth time. We also simulate the Trailing Stream; we find that the growth time is long (∼ Gyrs) compared to the infall time, and approximate Hα emission is low on average (∼few mR) but can be up to tens of mR in bright spots. Our findings also have broader extragalactic implications for e.g. galactic winds, which we discuss.

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“…Due to this parameter degeneracy, the predicted gas temperature within the Fermi bubbles should be considered uncertain as it depends on the amount of injected thermal energy assumed in the model. Additional observational constraints such as X-ray, UV, and radio emission/absorption lines 33,34,46,47 may be used to break the parameter degeneracy.…”

Section: Simulation Setup and Parametersmentioning

confidence: 99%

Fermi and eRosita bubbles as relics of the past activity of the Galactic black hole

Yang,

Ruszkowski,

Zweibel

2022

Preprint

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The newly launched X-ray satellite, eRosita, has recently revealed two gigantic bubbles extending to ∼ 80 • above and below the Galactic center. The morphology of these "eRosita bubbles" bears a remarkable resemblance to the Fermi bubbles previously discovered by the Fermi Gamma-ray Space Telescope and its counterpart, the microwave haze. The physical origin of these striking structures has been intensely debated; however, because of their symmetry about the Galactic center, they likely originate from some energetic outbursts from the Galactic center in the past. Here we propose a theoretical model in which the eRosita bubbles, Fermi bubbles, and the microwave haze could be simultaneously explained by a single event of jet activity from the central supermassive black hole a few million years ago. Using numerical simulations, we show that this model could successfully reproduce the morphology and multi-wavelength spectra of the observed bubbles and haze, which allows us to derive critical constraints on the energetics and timescales of the outburst. This study serves as an important step forward in our understanding of the past Galactic center activity of our Milky Way Galaxy, and may bring valuable insights into the broader picture of supermassive black hole-galaxy co-evolution in the context of galaxy formation.Recent data taken by the eRosita satellite has revealed striking images of two giant X-ray bubbles extending ∼ 80 • (which corresponds to ∼ 15 kpc assuming a distance to the Galactic Center (GC) of 8.5kpc) above and below the GC 1 . Despite the larger extent, the morphology of the "eRosita bubbles" is remarkably similar to the Fermi bubbles, the two gamma-ray bubbles detected by the Fermi Gamma-ray Space Telescope in 2010 2 . It was also shown previously that the gamma-ray bubbles have counterparts in the microwave band, known as the microwave/WMAP/Planck haze 3,4 , as well as polarized lobes in radio 5 . The

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Kinematics of the Magellanic Stream and Implications for Its Ionization*

Cited by 23 publications

References 77 publications

The Magellanic Stream at 20 kpc: A New Orbital History for the Magellanic Clouds

The Magellanic Stream at 20 kpc: A New Orbital History for the Magellanic Clouds

Radiative Turbulent Mixing Layers and the Survival of Magellanic Debris

Fermi and eRosita bubbles as relics of the past activity of the Galactic black hole

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