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Probing the low surface brightness outskirts of Milky Way dSphs: Sextans

Published online by Cambridge University Press:  21 March 2017

Luis Cicuéndez ,
Giuseppina Battaglia ,
Mike Irwin ,
Brendan McMonigal ,
Geraint Lewis  and
Nick Bate
Luis Cicuéndez
Affiliation:
Instituto de Astrofísica de Canarias, University of La Laguna, C/Vía Láctea, s/n, 38205, San Cristóbal de la Laguna, Spain emails: [email protected] & [email protected]
Giuseppina Battaglia
Affiliation:
Instituto de Astrofísica de Canarias, University of La Laguna, C/Vía Láctea, s/n, 38205, San Cristóbal de la Laguna, Spain emails: [email protected] & [email protected]
Mike Irwin
Affiliation:
Institute of Astronomy, University of Cambridge, Madingley Road, CB3 0HA, Cambridge, United Kingdom
Brendan McMonigal
Affiliation:
Sydney Institute for Astronomy, School of Physics A28, The University of Sydney, NSW 2006, Sydney, Australia
Geraint Lewis
Affiliation:
Sydney Institute for Astronomy, School of Physics A28, The University of Sydney, NSW 2006, Sydney, Australia
Nick Bate
Affiliation:
Institute of Astronomy, University of Cambridge, Madingley Road, CB3 0HA, Cambridge, United Kingdom
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Abstract

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Faint dwarf galaxies such as those found around the Milky Way (MW) display the largest known dynamical mass-to-light ratios (up to several 100s M⊙/L⊙). However, tidal interaction with the MW may impact the dynamical equilibrium in the outer parts of some of these objects, and partly affect the derived dynamical M/L. Assessing this is crucial for the study of the dark matter content of these galaxies. A clear sign of ongoing tidal disturbance would be the presence of tidal tails. These are expected to be low surface brightness features, hence difficult to detect from star counts in systems where contamination is also present, e.g. from foreground MW stars. At present we have searched for these sorts of tidal features in the Sextans dwarf spheroidal galaxy (dSph), by adopting the Matched Filter Method (e.g. Rockosi et al. 2002), a very efficient technique to decontaminate stellar density maps with a high ratio of contamination versus source density (dwarf galaxies outer regions or ultra faint dwarf galaxies). We also calculate structural parameters from the position of stars without requiring spatial binning (Richardson et al. 2011), through a Bayesian MCMC (Foreman-Mackey et al. 2013).

Keywords

galaxies: individual (Sextans)galaxies: dwarfLocal Groupdark mattergalaxies: photometryHertzsprung-Russell diagram
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 11 , Symposium S321: Formation and Evolution of Galaxy Outskirts , March 2016 , pp. 45
Copyright
Copyright © International Astronomical Union 2017 

References

Rockosi, C. M. et al. 2002, AJ, 124, 349 Google Scholar
Richardson, J. C. et al. 2011, ApJ, 732, 76 Google Scholar
Foreman-Mackey, D., Hogg, D. W., Lang, D., & Goodman, J. 2013, PASP, 125, 306 Google Scholar
Irwin, M. & Hatzidimitriou, D. 1995, MNRAS, 277, 1354 Google Scholar