Observations of a Magellanic Corona

Krishnarao, Dhanesh; Zweibel, E.; Wakker, Bart P.; Cashman, Frances H.; Howk, J. Christopher; Lucchini, Scott; French, David M.; Lehner, Nicolas

doi:10.1038/s41586-022-05090-5

Cited by 15 publications

(15 citation statements)

References 60 publications

(105 reference statements)

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“…This shows that our models require an LMC whose dark matter halo extends out to at least ∼ 53 kpc at the 2𝜎 level. Such an extended dark matter halo is in agreement with the recently observed extent of the LMC hot corona (Krishnarao et al 2022) and is consistent with the LMC being on its first approach to the Milky Way (e.g. Besla et al 2007).…”

Section: Lmc Mass Measurementsupporting

confidence: 90%

$S^5$: Probing the Milky Way and Magellanic Clouds potentials with the 6-D map of the Orphan-Chenab stream

Koposov¹,

Erkal²,

Li³

et al. 2022

Preprint

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We present a 6-D map of the Orphan-Chenab (OC) stream by combining the data from 5 years of Southern Stellar Stream Spectroscopic Survey (𝑆 5 ) observations with Gaia EDR3 data. We reconstruct the proper motion, radial velocity, distance and on-sky track of stream stars with spline models and extract the stellar density along the stream. The stream has a total luminosity of 𝑀 𝑉 = −8.2 and an average metallicity of [Fe/H] = −1.9, similar to classical MW satellites like Draco. The stream shows drastic changes in its physical width varying from 200 pc to 1 kpc, a constant line of sight velocity dispersion of 5 km s −1 , but an increase in the velocity dispersion along the stream near pericenter to ∼ 10 km s −1 . Despite the large apparent variation in the stellar number density along the stream, the flow rate of stars along the stream is remarkably constant. We model the 6-D stream track by a Lagrange-point stripping method with a flexible MW potential in the presence of a moving extended LMC potential. This allows us to constrain the mass profile of the MW within the distance range 15.6 < r < 55.5 kpc, with the best measured enclosed mass of (2.85 ± 0.1) × 10 11 M within 32.4 kpc. With the OC stream's closest approach distance to the LMC of ∼ 21 kpc, our stream measurements are highly sensitive to the LMC mass profile with the most precise measurement of the LMC's enclosed mass being at 32.8 kpc with 𝑀 = (7.02 ± 0.9) × 10 10 M . We confidently detect that the LMC DM halo extends to at least 53 kpc. The fitting of the OC stream allows us to constrain the past LMC trajectory and the degree of dynamical friction it experienced. We demonstrate that the stars on the OC stream show large energy and angular momentum spreads caused by the LMC perturbation and revealing the limitations of orbital invariants for substructure identification in the MW halo.

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Section: Lmc Mass Measurementsupporting

confidence: 90%

$S^5$: Probing the Milky Way and Magellanic Clouds potentials with the 6-D map of the Orphan-Chenab stream

Koposov¹,

Erkal²,

Li³

et al. 2022

Preprint

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show abstract

“…This means that the bow shock could explain a significant portion of the ionized gas observed surrounding the LMC without appealing to an existing LMC CGM that resists dispersal by ram pressure (Section 5), providing an alternative explanation for the ionized gas observed at high ionization states associated with a Magellanic Corona. Indeed, the predicted enhancement in column density along the lines of sight through the shock (see Figure 1 and Section 5) are within ∼a factor of 2-3 of the inferred coronal columns from Figure 3 in Krishnarao et al (2022), indicating that a bow shock provides a plausible explanation for a significant amount of the excess material observed around the LMC.…”

Section: Implications For the Origin Of Ionized Gas Associated With T...supporting

confidence: 54%

“…This would be true regardless of the LMC halo mass, although the removed CGM may still be retained at large distances in a more massive LMC model. As a result, we propose here instead that the ionized gas within 20-30 kpc of the LMC observed by Krishnarao et al (2022) is not the primordial LMC CGM (i.e., CGM the LMC possessed at infall). Rather, this gas is likely a combination of new outflows from ongoing star formation in the LMC's disk and shocked CGM gas from the LMC's bow shock.…”

Section: Implications For the Origin Of Ionized Gas Associated With T...mentioning

confidence: 69%

“…This is the case in the simulations of Salem et al (2015), who initialize their LMC with a low-mass CGM (5 × 10 6 M e ) that is almost immediately swept into an ionized tail owing to ram pressure. Given that the truncated H I disk of the LMC provides clear evidence of a direct impact from ram pressure (Salem et al 2015), our simulation suggests that the ionized gas at high ionization states within 20-30 kpc of the LMC observed by Krishnarao et al (2022) is unlikely to be the primordial CGM gas that the LMC possessed at infall.…”

Section: Implications For the Origin Of Ionized Gas Associated With T...mentioning

confidence: 84%

“…There is also, however, a significant ionized gas component associated spatially and kinematically with the Magellanic Stream (∼2 × 10 9 M e (d/55 kpc) 2 ; Fox et al 2014) and Magellanic Bridge (0.7-1.7 × 10 8 M e ; Barger et al 2013) and surrounding the LMC (0.6-1.8 × 10 9 M e ; Smart et al 2023). It has been posited that much of this gas originates in a "Magellanic Corona" (Krishnarao et al 2022) that is being removed through a combination of ram pressure and tidal stripping (Lucchini et al 2020).…”

Section: Implications For the Origin Of Ionized Gas Associated With T...mentioning

confidence: 99%

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The Large Magellanic Cloud’s ∼30 kpc Bow Shock and Its Impact on the Circumgalactic Medium

Setton,

Besla,

Patel

et al. 2023

ApJL

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The interaction between the supersonic motion of the Large Magellanic Cloud (LMC) and the circumgalactic medium (CGM) is expected to result in a bow shock that leads the LMC’s gaseous disk. In this letter, we use hydrodynamic simulations of the LMC’s recent infall to predict the extent of this shock and its effect on the Milky Way’s (MW) CGM. The simulations clearly predict the existence of an asymmetric shock with a present-day standoff radius of ∼6.7 kpc and a transverse diameter of ∼30 kpc. Over the past 500 Myr, ∼8% of the MW’s CGM in the southern hemisphere should have interacted with the shock front. This interaction may have had the effect of smoothing over inhomogeneities and increasing mixing in the MW CGM. We find observational evidence of the existence of the bow shock in recent Hα maps of the LMC, providing a potential explanation for the envelope of ionized gas surrounding the LMC. Furthermore, the interaction of the bow shock with the MW CGM may also explain the observations of ionized gas surrounding the Magellanic Stream. Using recent orbital histories of MW satellites, we find that many satellites have likely interacted with the LMC shock. Additionally, the dwarf galaxy Ret2 is currently sitting inside the shock, which may impact the interpretation of the reported gamma-ray excess in Ret2. This work highlights how bow shocks associated with infalling satellites are an underexplored yet potentially very important dynamical mixing process in the circumgalactic and intracluster media.

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The Magellanic Corona as the key to the formation of the Magellanic Stream

Lucchini

D’Onghia

Bustard

et al. 2020

Nature

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We characterize the Magellanic Corona model of the formation of the Magellanic Stream, which we introduced in Lucchini et al. (2020, 2021). Using high-resolution hydrodynamic simulations, we constrain the properties of the primordial Magellanic Clouds, including the Magellanic Corona -the gaseous halo around the Large Magellanic Cloud (LMC). With an LMC mass of 1.75 × 10 11 M ⊙ , a Magellanic Corona of > 5 × 10 9 M ⊙ at 3 × 10 5 K, a total Small Magellanic Cloud mass < 10 10 M ⊙ , and a Milky Way corona of 2 × 10 10 M ⊙ , we can reproduce the observed total mass of the neutral and ionized components of the Trailing Stream, ionization fractions along the Stream, morphology of the neutral gas, and on-sky extent of the ionized gas. The inclusion of advanced physical routines in the simulations allow the first direct comparison of a hydrodynamical model with UV absorption-line spectroscopic data. Our model reproduces O I, O VI, and C IV observations from HST/COS and FUSE. The stripped material is also nearby (< 50 kpc from the Sun), as found in our prior models including a Magellanic Corona.

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Observations of a Magellanic Corona

Cited by 15 publications

References 60 publications

$S^5$: Probing the Milky Way and Magellanic Clouds potentials with the 6-D map of the Orphan-Chenab stream

$S^5$: Probing the Milky Way and Magellanic Clouds potentials with the 6-D map of the Orphan-Chenab stream

The Large Magellanic Cloud’s ∼30 kpc Bow Shock and Its Impact on the Circumgalactic Medium

The Magellanic Corona as the key to the formation of the Magellanic Stream

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