Observations of a Magellanic Corona

Dhanesh Krishnarao; Andrew J Fox; Elena D'Onghia; Bart P Wakker; Frances H Cashman; J Christopher Howk; Scott Lucchini; David M French; Nicolas Lehner

doi:10.1038/s41586-022-05090-5

Observations of a Magellanic Corona

Nature. 2022 Sep;609(7929):915-918. doi: 10.1038/s41586-022-05090-5. Epub 2022 Sep 28.

Authors

Dhanesh Krishnarao^{1

2

3}, Andrew J Fox⁴, Elena D'Onghia⁵, Bart P Wakker⁵, Frances H Cashman⁶, J Christopher Howk⁷, Scott Lucchini⁸, David M French⁶, Nicolas Lehner⁷

Affiliations

¹ Space Telescope Science Institute, Baltimore, MD, USA. dkrishnarao@coloradocollege.edu.
² William H. Miller III Department of Physics & Astronomy, Johns Hopkins University, Baltimore, MD, USA. dkrishnarao@coloradocollege.edu.
³ Department of Physics, Colorado College, Colorado Springs, CO, USA. dkrishnarao@coloradocollege.edu.
⁴ AURA for ESA, Space Telescope Science Institute, Baltimore, MD, USA.
⁵ Department of Astronomy, University of Wisconsin-Madison, Madison, WI, USA.
⁶ Space Telescope Science Institute, Baltimore, MD, USA.
⁷ Department of Physics and Astronomy, University of Notre Dame, Notre Dame, IN, USA.
⁸ Department of Physics, University of Wisconsin-Madison, Madison, WI, USA.

Abstract

The Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC) are the closest massive satellite galaxies of the Milky Way. They are probably on their first passage on an infalling orbit towards our Galaxy¹ and trace the continuing dynamics of the Local Group². Recent measurements of a high mass for the LMC (M_halo ≈ 10^11.1-11.4 M_⊙)^3-6 imply that the LMC should host a Magellanic Corona: a collisionally ionized, warm-hot gaseous halo at the virial temperature (10^5.3-5.5 K) initially extending out to the virial radius (100-130 kiloparsecs (kpc)). Such a corona would have shaped the formation of the Magellanic Stream⁷, a tidal gas structure extending over 200° across the sky^2,8,9 that is bringing in metal-poor gas to the Milky Way¹⁰. Here we show evidence for this Magellanic Corona with a potential direct detection in highly ionized oxygen (O⁺⁵) and indirectly by means of triply ionized carbon and silicon, seen in ultraviolet (UV) absorption towards background quasars. We find that the Magellanic Corona is part of a pervasive multiphase Magellanic circumgalactic medium (CGM) seen in many ionization states with a declining projected radial profile out to at least 35 kpc from the LMC and a total ionized CGM mass of log₁₀(M_{H II,CGM}/M_⊙) ≈ 9.1 ± 0.2. The evidence for the Magellanic Corona is a crucial step forward in characterizing the Magellanic group and its nested evolution with the Local Group.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.