Browsing by Author "Debattista, Victor P."

Now showing 1 - 5 of 5
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    Chemically Dissected Rotation Curves of the Galactic Bulge from Main-sequence Proper Motions
    (2018) Clarkson, William I.; Calamida, Annalisa; Sahu, Kailash C.; Brown, Thomas M.; Gennaro, Mario; Avila, Roberto J.; Valenti, Jeff; Debattista, Victor P.; Rich, R. Michael; Minniti, D.; Zoccali, Manuela; Aufdemberge, Emily R.
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    Separation of stellar populations by an evolving bar: implications for the bulge of the Milky Way
    (2017) Debattista, Victor P.; Ness, Melissa; Gonzalez, Oscar A.; Freeman, K.; Zoccali, Manuela; Minniti, D.
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    The binary nucleus in VCC 128: A candidate supermassive black hole in a dwarf elliptical galaxy
    (2006) Debattista, Victor P.; Ferreras, Ignacio; Pasquali, Anna; Seth, Anil; De Rijcke, Sven; Morelli, Lorenzo
    Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) images of the Virgo Cluster dwarf elliptical galaxy VCC 128 reveal an apparently double nucleus. The two components, which are separated by similar to 32 pc in projection, have the same magnitude and color. We present a spectrum of this double nucleus and show that it is inconsistent with one or both components being emission-line background objects or foreground stars. The most likely interpretation is that, as suggested by Lauer et al. for the double nucleus in NGC 4486B, we are seeing a nuclear disk surrounding a supermassive black hole. This is only the second time an early-type dwarf (dE/dSph) galaxy has been suggested to host a supermassive black hole.
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    The Imprint of Clump Formation at High Redshift. II. The Chemistry of the Bulge
    (2023) Debattista, Victor P.; Liddicott, David J.; Gonzalez, Oscar A.; Beraldo e Silva, Leandro; Amarante, Joao A. S.; Lazar, Ilin; Zoccali, Manuela; Valenti, Elena; Fisher, Deanne B.; Khachaturyants, Tigran; Nidever, David L.; Quinn, Thomas R.; Du, Min; Kassin, Susan
    In Paper I, we showed that clumps in high-redshift galaxies, having a high star formation rate density (sigma(SFR)), produce disks with two tracks in the [Fe/H]-[alpha/Fe] chemical space, similar to that of the Milky Way's (MW's) thin+thick disks. Here we investigate the effect of clumps on the bulge's chemistry. The chemistry of the MW's bulge is comprised of a single track with two density peaks separated by a trough. We show that the bulge chemistry of an N-body + smoothed particle hydrodynamics clumpy simulation also has a single track. Star formation within the bulge is itself in the high-sigma(SFR) clumpy mode, which ensures that the bulge's chemical track follows that of the thick disk at low [Fe/H] and then extends to high [Fe/H], where it peaks. The peak at low metallicity instead is comprised of a mixture of in situ stars and stars accreted via clumps. As a result, the trough between the peaks occurs at the end of the thick disk track. We find that the high-metallicity peak dominates near the mid-plane and declines in relative importance with height, as in the MW. The bulge is already rapidly rotating by the end of the clump epoch, with higher rotation at low [alpha/Fe]. Thus clumpy star formation is able to simultaneously explain the chemodynamic trends of the MW's bulge, thin+thick disks, and the splash.
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    The structure behind the galactic bar traced by red clump stars in the VVV survey
    (2018) Gonzalez, Oscar A.; Minniti, D.; Valenti, Elena; Alonso-Garcia, Javier; Debattista, Victor P.; Zoccali, Manuela; Rejkuba, Marina; Dias, Bruno; Surot, Bruno; Hempel, Maren