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|Title:||MegaMorph: classifying galaxy morphology using multi-wavelength Sérsic profile fits||Authors:||Vika, Marina
Bamford, Steven P.
Rojas, Alex L.
|Issue Date:||2015||Journal:||ASTRONOMY & ASTROPHYSICS||Number:||577||First Page:||A97||Abstract:||Aims: This work investigates the potential of using the wavelength-dependence of galaxy structural parameters (Sérsic index, n, and effective radius, R<SUB>e</SUB>) to separate galaxies into distinct types. Methods: A sample of nearby galaxies with reliable visual morphologies is considered, for which we measure structural parameters by fitting multi-wavelength single-Sérsic models. Additionally, we use a set of artificially redshifted galaxies to test how these classifiers behave when the signal-to-noise ratio decreases. <BR /> Results: We show that the wavelength-dependence of n may be employed to separate visually-classified early- and late-type galaxies in a manner similar to the use of colour and n. Furthermore, we find that the wavelength variation of n can recover galaxies that are misclassified by these other morphological proxies. Roughly half of the spiral galaxies that contaminate an early-type sample selected using (u - r) versus n can be correctly identified as late-types by N, the ratio of n measured in two different bands. Using a set of artificially redshifted images, we show that this technique remains effective up to z ~ 0.1. Therefore, N can be used to achieve purer samples of early-types and more complete samples of late-types than using a colour-n cut alone. We also study the suitability of ℛ, the ratio of R<SUB>e</SUB> in two different bands, as a morphological classifier, but find that the average sizes of both early- and late-type galaxies do not change substantially over optical wavelengths.||Acknowledgments:||This publication was made possible by NPRP grant # 08-643-1-112 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors. B.H. and M.V. are supported by this NPRP grant. S.P.B. gratefully acknowledges an STFC Advanced Fellowship. B.V. was supported by the World Premier International Research Center Initiative (WPI), MEXT, Japan and by the Kakenhi Grant-in-Aid for Young Scientists (B)(26870140) from the Japan Society for the Promotion of Science (JSPS). We would like to thank Carnegie Mellon University in Qatar and The University of Nottingham for their hospitality. We also thank the referee for helpful suggestions and clarifications. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web Site is http://www.sdss.org/ . The SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions.||URI:||http://hdl.handle.net/20.500.12386/23115||URL:||https://www.aanda.org/articles/aa/abs/2015/05/aa25174-14/aa25174-14.html||ISSN:||0004-6361||DOI:||10.1051/0004-6361/201425174||Bibcode ADS:||2015A&A...577A..97V||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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