A Herschel*-ATLAS study of dusty spheroids: Probing the minor-merger process in the local Universe

S. Kaviraj, K. Rowlands, M. Alpaslan, L. Dunne, Y.S. Ting, M. Bureau, S. Shabala, C.J. Lintott, D.J.B. Smith, N. Agius, R. Auld, M. Baes, N. Bourne, A. Cava, D.L. Clements, A. Cooray, A. Dariush, G. De Zotti, Simon Driver, S. EalesR. Hopwood, C. Hoyos, E. Ibar, S. Maddox, M.J. Michałowski, A.E. Sansom, M. Smith, E. Valiante

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    Abstract

    We use multiwavelength (0.12-500 μm) photometry from Herschel-ATLAS, WISE, UKIDSS, SDSS and GALEX to study 23 nearby spheroidal galaxies with prominent dust lanes (DLSGs). DLSGs are considered to be remnants of recent minor mergers, making them ideal laboratories for studying both the interstellar medium (ISM) of spheroids and minor-merger-driven star formation in thenearby Universe. The DLSGs exhibit star formation rates (SFRs) between 0.01and 10M⊙ yr-1 with a median of 0.26M⊙ yr-1 (a factor of 3.5 greater thanthe average SG). The median dust mass, dust-to-stellar mass ratio and dust temperature in these galaxies are around 107.6M⊙, ≈0.05 per cent and ≈19.5K, respectively. The dust masses are at least a factor of 50 greater than that expected from stellar mass loss and, like the SFRs, show no correlationwith galaxy luminosity, suggesting that both the ISM and the star formationhave external drivers. Adopting literature gas-to-dust ratios and star formation histories derived from fits to the panchromatic photometry, we estimate that the median current and initial gasto- stellar mass ratios in these systems are ≈4 and ≈7 per cent, respectively. If, as indicated by recent work, minor mergers that drive star formation in spheroids with (NUV - r) > 3.8 (the colour range of our DLSGs) have stellar mass ratios between 1:6 and 1:10, then the satellite gas fractions are likely =50 per cent. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
    Original languageEnglish
    Pages (from-to)1463-1468
    JournalMonthly Notices of the Royal Astronomical Society
    Volume435
    Issue number2
    DOIs
    Publication statusPublished - 2013

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    Kaviraj, S., Rowlands, K., Alpaslan, M., Dunne, L., Ting, Y. S., Bureau, M., Shabala, S., Lintott, C. J., Smith, D. J. B., Agius, N., Auld, R., Baes, M., Bourne, N., Cava, A., Clements, D. L., Cooray, A., Dariush, A., De Zotti, G., Driver, S., ... Valiante, E. (2013). A Herschel*-ATLAS study of dusty spheroids: Probing the minor-merger process in the local Universe. Monthly Notices of the Royal Astronomical Society, 435(2), 1463-1468. https://doi.org/10.1093/mnras/stt1629