The SAURON project - XIII. SAURON-GALEX study of early-type galaxies

The ultraviolet colour-magnitude relations and Fundamental Planes

Hyunjin Jeong, Sukyoung Yi, Martin Bureau, Roger L. Davies, Jesús Falcón-Barroso, Glenn Van De Ven, Reynier F. Peletier, Roland Bacon, Michele Cappellari, Tim De Zeeuw, Eric Emsellem, Davor Krajnović, Harald Kuntschner, Richard M. McDermid, Marc Sarzi, Remco C.E. Van Den Bosch

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Abstract

We present Galaxy Evolution Explorer far-ultraviolet (FUV) and near-ultraviolet (NUV) imaging of 34 nearby early-type galaxies from the SAURON representative sample of 48 E/S0 galaxies, all of which have ground-based optical imaging from the MDM Observatory. The surface brightness profiles of nine galaxies (≈26 per cent) show regions with blue UV-optical colours suggesting RSF. Five of these (≈15 per cent) show blue integrated UV-optical colours that set them aside in the NUV integrated colour-magnitude relation. These are objects with either exceptionally intense and localized NUV fluxes or blue UV-optical colours throughout. They also have other properties confirming they have had RSF, in particular Hβ absorption higher than expected for a quiescent population and a higher CO detection rate. This suggests that residual star formation is more common in early-type galaxies than we are used to believe. NUV blue galaxies are generally drawn from the lower stellar velocity dispersion (σe < 200 km s-1) and thus lower dynamical mass part of the sample. We have also constructed the first UV Fundamental Planes and show that NUV blue galaxies bias the slopes and increase the scatters. If they are eliminated, the fits get closer to expectations from the virial theorem. Although our analysis is based on a limited sample, it seems that a dominant fraction of the tilt and scatter of the UV Fundamental Planes is due to the presence of young stars in preferentially low-mass early-type galaxies. Interestingly, the UV-optical radial colour profiles reveal a variety of behaviours, with many galaxies showing signs of RSF, a central UV-upturn phenomenon, smooth but large-scale age and metallicity gradients and in many cases a combination of these. In addition, FUV-NUV and FUV-V colours even bluer than those normally associated with UV-upturn galaxies are observed at the centre of some quiescent galaxies. Four out of the five UV-upturn galaxies are slow rotators. These objects should thus pose interesting challenges to stellar evolutionary models of the UV upturn.

Original languageEnglish
Pages (from-to)2028-2048
Number of pages21
JournalMonthly Notices of the Royal Astronomical Society
Volume398
Issue number4
DOIs
Publication statusPublished - 2009 Jan 1

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galaxies
color
set-aside
tilt
project
observatory
virial theorem
stellar models
profiles
metallicity
star formation
observatories
brightness
slopes
stars
gradients

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Jeong, Hyunjin ; Yi, Sukyoung ; Bureau, Martin ; Davies, Roger L. ; Falcón-Barroso, Jesús ; Van De Ven, Glenn ; Peletier, Reynier F. ; Bacon, Roland ; Cappellari, Michele ; De Zeeuw, Tim ; Emsellem, Eric ; Krajnović, Davor ; Kuntschner, Harald ; McDermid, Richard M. ; Sarzi, Marc ; Van Den Bosch, Remco C.E. / The SAURON project - XIII. SAURON-GALEX study of early-type galaxies : The ultraviolet colour-magnitude relations and Fundamental Planes. In: Monthly Notices of the Royal Astronomical Society. 2009 ; Vol. 398, No. 4. pp. 2028-2048.
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Jeong, H, Yi, S, Bureau, M, Davies, RL, Falcón-Barroso, J, Van De Ven, G, Peletier, RF, Bacon, R, Cappellari, M, De Zeeuw, T, Emsellem, E, Krajnović, D, Kuntschner, H, McDermid, RM, Sarzi, M & Van Den Bosch, RCE 2009, 'The SAURON project - XIII. SAURON-GALEX study of early-type galaxies: The ultraviolet colour-magnitude relations and Fundamental Planes', Monthly Notices of the Royal Astronomical Society, vol. 398, no. 4, pp. 2028-2048. https://doi.org/10.1111/j.1365-2966.2009.15238.x

The SAURON project - XIII. SAURON-GALEX study of early-type galaxies : The ultraviolet colour-magnitude relations and Fundamental Planes. / Jeong, Hyunjin; Yi, Sukyoung; Bureau, Martin; Davies, Roger L.; Falcón-Barroso, Jesús; Van De Ven, Glenn; Peletier, Reynier F.; Bacon, Roland; Cappellari, Michele; De Zeeuw, Tim; Emsellem, Eric; Krajnović, Davor; Kuntschner, Harald; McDermid, Richard M.; Sarzi, Marc; Van Den Bosch, Remco C.E.

In: Monthly Notices of the Royal Astronomical Society, Vol. 398, No. 4, 01.01.2009, p. 2028-2048.

Research output: Contribution to journalArticle

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T2 - The ultraviolet colour-magnitude relations and Fundamental Planes

AU - Jeong, Hyunjin

AU - Yi, Sukyoung

AU - Bureau, Martin

AU - Davies, Roger L.

AU - Falcón-Barroso, Jesús

AU - Van De Ven, Glenn

AU - Peletier, Reynier F.

AU - Bacon, Roland

AU - Cappellari, Michele

AU - De Zeeuw, Tim

AU - Emsellem, Eric

AU - Krajnović, Davor

AU - Kuntschner, Harald

AU - McDermid, Richard M.

AU - Sarzi, Marc

AU - Van Den Bosch, Remco C.E.

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N2 - We present Galaxy Evolution Explorer far-ultraviolet (FUV) and near-ultraviolet (NUV) imaging of 34 nearby early-type galaxies from the SAURON representative sample of 48 E/S0 galaxies, all of which have ground-based optical imaging from the MDM Observatory. The surface brightness profiles of nine galaxies (≈26 per cent) show regions with blue UV-optical colours suggesting RSF. Five of these (≈15 per cent) show blue integrated UV-optical colours that set them aside in the NUV integrated colour-magnitude relation. These are objects with either exceptionally intense and localized NUV fluxes or blue UV-optical colours throughout. They also have other properties confirming they have had RSF, in particular Hβ absorption higher than expected for a quiescent population and a higher CO detection rate. This suggests that residual star formation is more common in early-type galaxies than we are used to believe. NUV blue galaxies are generally drawn from the lower stellar velocity dispersion (σe < 200 km s-1) and thus lower dynamical mass part of the sample. We have also constructed the first UV Fundamental Planes and show that NUV blue galaxies bias the slopes and increase the scatters. If they are eliminated, the fits get closer to expectations from the virial theorem. Although our analysis is based on a limited sample, it seems that a dominant fraction of the tilt and scatter of the UV Fundamental Planes is due to the presence of young stars in preferentially low-mass early-type galaxies. Interestingly, the UV-optical radial colour profiles reveal a variety of behaviours, with many galaxies showing signs of RSF, a central UV-upturn phenomenon, smooth but large-scale age and metallicity gradients and in many cases a combination of these. In addition, FUV-NUV and FUV-V colours even bluer than those normally associated with UV-upturn galaxies are observed at the centre of some quiescent galaxies. Four out of the five UV-upturn galaxies are slow rotators. These objects should thus pose interesting challenges to stellar evolutionary models of the UV upturn.

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