Formation of S0 galaxies through mergers. Bulge-disc structural coupling resulting from major mergers



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Querejeta, M. and Eliche Moral, María del Carmen and Tapia, T. and Borlaff, A. and Rodríguez Pérez, C. and Zamorano Calvo, Jaime and Gallego Maestro, Jesús (2015) Formation of S0 galaxies through mergers. Bulge-disc structural coupling resulting from major mergers. Astronomy & Astrophysics, 573 . ISSN 0004-6361

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Context. Observations reveal a strong structural coupling between bulge and disc in S0 galaxies, which seems difficult to explain if they have formed from supposedly catastrophic events such as major mergers. Aims. We face this question by quantifying the bulge-disc coupling in dissipative simulations of major and minor mergers that result in realistic S0s. Methods. We have studied the dissipative N-body binary merger simulations from the GalMer database that give rise to realistic, relaxed E/S0 and S0 remnants (67 major and 29 minor mergers). We simulate surface brightness profiles of these S0-like remnants in the K band, mimicking typical observational conditions, to perform bulge-disc decompositions analogous to those carried out in real S0s. Additional components have been included when needed. The global bulge-disc structure of these remnants has been compared with real data. Results. The S0-like remnants distribute in the B/T - r(e) - h(d) parameter space consistently with real bright S0s, where B/T is the bulge-to- total luminosity ratio, r(e) is the bulge effective radius, and h(d) is the disc scalelength. Major mergers can rebuild a bulge-disc coupling in the remnants after having destroyed the structures of the progenitors, whereas minor mergers directly preserve them. Remnants exhibit B/T and r(e)/h(d) spanning a wide range of values, and their distribution is consistent with observations. Many remnants have bulge Sersic indices ranging 1 < n < 2, flat appearance, and contain residual star formation in embedded discs, a result which agrees with the presence of pseudobulges in real S0s. Conclusions. Contrary to the popular view, mergers (and in particular, major events) can result in S0 remnants with realistically coupled bulge-disc structures in less than similar to 3 Gyr. The bulge-disc coupling and the presence of pseudobulges in real S0s cannot be used as an argument against the possible major-merger origin of these galaxies.

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© ESO 2014. The authors would like to thank the anonymous reviewer for a very helpful and constructive referee report. We would also like to acknowledge I. Chilingarian, P. Di Matteo, F. Combes, A.-L. Melchior, and B. Semelin for creating the GalMer database. We also appreciate valuable comments by P.G. Pérez González and E. Laurikainen, as well as the GALFIT code made publicly available by his author C. Peng. We also acknowledge the usage of the HyperLeda database ( This research has made use of the NASA's Astrophysics Data System and NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. M.Q. acknowledges financial support to the DAGAL network from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007-2013/ under REA grant agreement number PITN-GA-2011-289313. Supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under projects AYA2006-12955, AYA2009-10368, AYA2012-30717, and AYA2012-31277, and by the Madrid Regional Government through the AstroMadrid Project (CAM S2009/ESP-1496, php). Funded by the Spanish MICINN under the Consolider-Ingenio 2010 Programme grant CSD2006-0070: "First Science with the GTC" (, and by the Spanish programme of International Campus of Excellence Moncloa (CEI).

Uncontrolled Keywords:Dry minor mergers; Telescope nicmos observations; Similar-to 2; Spiral galaxies; Star-formation; Secular evolution; Galactic bulges; E/S0 galaxies; Virgo cluster; Stellar discs
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
Sciences > Physics > Atmospheric physics
ID Code:29449
Deposited On:14 Apr 2015 12:24
Last Modified:10 Dec 2018 15:05

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