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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Galaxy Zoo
T2 - finding offset discs and bars in SDSS galaxies
AU - Kruk, Sandor J.
AU - Lintott, Chris J.
AU - Simmons, Brooke D.
AU - Bamford, Steven P.
AU - Cardamone, Carolin N.
AU - Fortson, Lucy
AU - Hart, Ross E.
AU - Häußler, Boris
AU - Masters, Karen L.
AU - Nichol, Robert C.
AU - Schawinski, Kevin
AU - Smethurst, Rebecca J.
N1 - This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review
PY - 2017/8/11
Y1 - 2017/8/11
N2 - We use multiwavelength Sloan Digital Sky Survey (SDSS) images and Galaxy Zoo morphologies to identify a sample of ∼270 late-type galaxies with an off-centre bar. We measure offsets in the range 0.2–2.5 kpc between the photometric centres of the stellar disc and stellar bar. The measured offsets correlate with global asymmetries of the galaxies, with those with largest offsets showing higher lopsidedness. These findings are in good agreement with predictions from simulations of dwarf–dwarf tidal interactions producing off-centre bars. We find that the majority of galaxies with off-centre bars are of Magellanic type, with a median mass of 109.6 M⊙, and 91 per cent of them having M⋆ < 3 × 1010 M⊙, the characteristic mass at which galaxies start having higher central concentrations attributed to the presence of bulges. We conduct a search for companions to test the hypothesis of tidal interactions, but find that a similar fraction of galaxies with offset bars have companions within 100 kpc as galaxies with centred bars. Although this may be due to the incompleteness of the SDSS spectroscopic survey at the faint end, alternative scenarios that give rise to offset bars such as interactions with dark companions or the effect of lopsided halo potentials should be considered. Future observations are needed to confirm possible low-mass companion candidates and to determine the shape of the dark matter halo, in order to find the explanation for the off-centre bars in these galaxies.
AB - We use multiwavelength Sloan Digital Sky Survey (SDSS) images and Galaxy Zoo morphologies to identify a sample of ∼270 late-type galaxies with an off-centre bar. We measure offsets in the range 0.2–2.5 kpc between the photometric centres of the stellar disc and stellar bar. The measured offsets correlate with global asymmetries of the galaxies, with those with largest offsets showing higher lopsidedness. These findings are in good agreement with predictions from simulations of dwarf–dwarf tidal interactions producing off-centre bars. We find that the majority of galaxies with off-centre bars are of Magellanic type, with a median mass of 109.6 M⊙, and 91 per cent of them having M⋆ < 3 × 1010 M⊙, the characteristic mass at which galaxies start having higher central concentrations attributed to the presence of bulges. We conduct a search for companions to test the hypothesis of tidal interactions, but find that a similar fraction of galaxies with offset bars have companions within 100 kpc as galaxies with centred bars. Although this may be due to the incompleteness of the SDSS spectroscopic survey at the faint end, alternative scenarios that give rise to offset bars such as interactions with dark companions or the effect of lopsided halo potentials should be considered. Future observations are needed to confirm possible low-mass companion candidates and to determine the shape of the dark matter halo, in order to find the explanation for the off-centre bars in these galaxies.
U2 - 10.1093/mnras/stx1026
DO - 10.1093/mnras/stx1026
M3 - Journal article
VL - 469
SP - 3363
EP - 3373
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 3
ER -