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SMASHing the LMC: Mapping a Ring-like Stellar Overdensity in the LMC Disk

Choi, Yumi, Nidever, David L., Olsen, Knut, Besla, Gurtina, Blum, Robert D., Zaritsky, Dennis, Cioni, Maria-Rosa L., van der Marel, Roeland P., Bell, Eric F., Johnson, L. Clifton , Vivas, A. Katherina, Walker, Alistair R., de Boer, Thomas J. L., Noel, Noelia E. D., Monachesi, Antonela, Gallart, Carme, Monelli, Matteo, Stringfellow, Guy S., Massana, Pol, Martinez-Delgado, David and Muñoz, Ricardo R. (2018) SMASHing the LMC: Mapping a Ring-like Stellar Overdensity in the LMC Disk The Astrophysical Journal, 869 (2), 125.

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We explore the stellar structure of the Large Magellanic Cloud (LMC) disk using data from the Survey of the MAgellanic Stellar History and the Dark Energy Survey. We detect a ring-like stellar overdensity in the red clump star count map at a radius of ~6° (~5.2 kpc at the LMC distance) that is continuous over ~270° in position angle and is only limited by the current data coverage. The overdensity shows an amplitude up to 2.5 times higher than that of the underlying smooth disk. This structure might be related to the multiple arms found by de Vaucouleurs. We find that the overdensity shows spatial correlation with intermediate-age star clusters, but not with young (<1 Gyr) main-sequence stars, indicating the stellar populations associated with the overdensity are intermediate in age or older. Our findings on the LMC overdensity can be explained by either of two distinct formation mechanisms of a ring-like overdensity: (1) the overdensity formed out of an asymmetric one-armed spiral wrapping around the LMC main body, which is induced by repeated encounters with the Small Magellanic Cloud (SMC) over the last Gyr, or (2) the overdensity formed very recently as a tidal response to a direct collision with the SMC. Although the measured properties of the overdensity alone cannot distinguish between the two candidate scenarios, the consistency with both scenarios suggests that the ring-like overdensity is likely a product of tidal interaction with the SMC, but not with the Milky Way halo.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Physics
Authors :
Choi, Yumi
Nidever, David L.
Olsen, Knut
Besla, Gurtina
Blum, Robert D.
Zaritsky, Dennis
Cioni, Maria-Rosa L.
van der Marel, Roeland P.
Bell, Eric F.
Johnson, L. Clifton
Vivas, A. Katherina
Walker, Alistair R.
de Boer, Thomas J. L.
Noel, Noelia E.
Monachesi, Antonela
Gallart, Carme
Monelli, Matteo
Stringfellow, Guy S.
Massana, Pol
Martinez-Delgado, David
Muñoz, Ricardo R.
Date : 18 December 2018
Funders : NSF, European Union’s Horizon 2020, European Research Council (ERC), CONICYTFONDECYT
DOI : 10.3847/1538-4357/aaed1f
Grant Title : NSF Grant
Copyright Disclaimer : © 2018. The American Astronomical Society. All rights reserved
Uncontrolled Keywords : galaxies: dwarf–galaxies: interactions–galaxies: structure–Magellanic Clouds
Additional Information : Embargo OK Metadata OK No Further Action
Depositing User : James Marshall
Date Deposited : 21 Aug 2020 08:51
Last Modified : 21 Aug 2020 08:51

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