The Diffuse Ionized Gas of the Large Magellanic Cloud

Abstract

The Large Magellanic Cloud (LMC) has an extensive H${}_{\alpha }$ emission halo that traces an extended, warm ionized component of its interstellar medium. Using the Wisconsin H${}_{\alpha }$ Mapper (WHAM) telescope, we present the first kinematic \ha\ survey of an extensive region around the LMC, from $l,b=(264°.5,-45°.5)$ to $(295°.5,-19°.5)$, covering $+150\le v_{lsr}\le +390km{s}^{-1}$. We find that ionized hydrogen exists throughout the galaxy and extends several degrees beyond detected neutral hydrogen emission $(\log \left(N_{{\mathrm{H}}_{\mathrm{I}}/\mathrm{c}{\mathrm{m}}^{-2}}\right)\approx 18.3)$ as traced by 21-cm in current surveys. Using the column density structure of the neutral gas and stellar line-of-sight depths as a guide, we estimate the upper limit mass of the ionized component of the LMC to be roughly $M_{\mathrm{ionized}}\approx (0.6-1.8)\times 10^9{\mathrm{M}}_{sun}$, which is comparable to the total neutral atomic gas mass in the same region ($M_{\mathrm{neutral}}\approx 0.75-0.85\times 10^9{\mathrm{M}}_{sun}$). Considering only the atomic phases, we find $M_{\mathrm{ionized}}/M_{\mathrm{ionized}+\mathrm{neutral}}$, to be 46\%--68\% throughout the LMC and its extended halo. Additionally, we find an ionized gas cloud that extends off of the LMC at $l,b\approx (285°,-28°)$ into a region previously identified as the Leading Arm complex. This gas is moving at a similar line-of-sight velocity as the LMC and has $M_{\mathrm{ionized}}/M_{\mathrm{ionized}+\mathrm{neutral}}=$ 13\%--51\%. This study, combined with previous studies of the SMC and extended structures of the Magellanic Clouds, continues to suggest that warm, ionized gas is as massive and dynamically-important as the neutral gas in the Magellanic System.$

20 pages, 12 figures, 4 tables

References in corpus (13)

• HI4PI: A full-sky HI survey based on EBHIS and GASS
• An eclipsing binary distance to the Large Magellanic Cloud accurate to 2 per cent
• Are the Magellanic Clouds on their First Passage about the Milky Way?
• The Origin of the Magellanic Stream and Its Leading Arm
• The COS/UVES Absorption Survey of the Magellanic Stream. III: Ionization, Total Mass, and Inflow Rate onto the Milky Way
• Reproducing properties of MW dSphs as descendants of DM-free TDGs
• The Magellanic Corona and the formation of the Magellanic Stream
• Ionized Gas in the Smith Cloud
• Revealing the Ionization Properties of the Magellanic Stream using Optical Emission
• The Diffuse Ionized Gas Halo of the Small Magellanic Cloud
• H$\alpha$ Distances to the Leading Arm of the Magellanic Stream
• Mapping the Supernovae Driven Winds of the Large Magellanic Cloud in H$\alpha$ Emission I
• The Evolution of Magellanic-like Galaxy Pairs and The Production of Magellanic Stream Analogues in Simulations with Tides, Ram Pressure, and Stellar Feedback