CaltechAUTHORS
Published December 2007 | Version Published
Journal Article Open

A Search for Extended Ultraviolet Disk (XUV-Disk) Galaxies in the Local Universe

Creators

  • 1. ROR icon Johns Hopkins University
  • 2. ROR icon Complutense University of Madrid
  • 3. ROR icon Laboratoire d'Astrophysique de Marseille
  • 4. ROR icon Carnegie Observatories
  • 5. ROR icon University of Edinburgh
  • 6. ROR icon University of Sydney
  • 7. ROR icon Hampshire College
  • 8. ROR icon California Institute of Technology
  • 9. ROR icon Goddard Space Flight Center
  • 10. ROR icon Columbia University
  • 11. ROR icon Yonsei University
  • 12. ROR icon University of California, Los Angeles
  • 13. ROR icon University of California, Berkeley

Abstract

We have initiated a search for extended ultraviolet disk (XUV-disk) galaxies in the local universe. Here we compare GALEX UV and visible-NIR images of 189 nearby (D < 40 Mpc) S0-Sm galaxies included in the GALEX Atlas of Nearby Galaxies and present the first catalog of XUV-disk galaxies. We find that XUV-disk galaxies are surprisingly common but have varied relative (UV/optical) extent and morphology. Type 1 objects (≳20% incidence) have structured, UV-bright/optically faint emission features in the outer disk, beyond the traditional star formation threshold. Type 2 XUV-disk galaxies (~10% incidence) exhibit an exceptionally large, UV-bright/optically low surface brightness (LSB) zone having blue UV–K_s outside the effective extent of the inner, older stellar population, but not reaching extreme galactocentric distance. If the activity occurring in XUV-disks is episodic, a higher fraction of present-day spirals could be influenced by such outer disk star formation. Type 1 disks are associated with spirals of all types, whereas Type 2 XUV-disks are predominantly found in late-type spirals. Type 2 XUV-disks are forming stars quickly enough to double their (currently low) stellar mass in the next Gyr (assuming a constant star formation rate). XUV-disk galaxies of both types are systematically more gas-rich than the general galaxy population. Minor external perturbation may stimulate XUV-disk incidence, at least for Type 1 objects. XUV-disks are the most actively evolving galaxies growing via inside-out disk formation in the current epoch, and may constitute a segment of the galaxy population experiencing significant, continued gas accretion from the intergalactic medium or neighboring objects.

Additional Information

© 2007 American Astronomical Society. Print publication: Issue 2 (2007 December); received 2007 April 30; accepted for publication 2007 September 11. GALEX (Galaxy Evolution Explorer) is a NASA Small Explorer, launched in 2003April.We gratefully acknowledgeNASA's support for construction, operation, and science analysis for the GALEX mission, developed in cooperation with the Centre National d'Etudes Spatiales of France and the Korean Ministry of Science and Technology. A. G. d. P. is financed by the MAGPOP EU Marie Curie Research Training Network and partially by the Spanish Programma Nacional de Astronomı´a y Astrofı´sica under grants AYA2003-01676 and AYA2006-02358. This research has made use of the NASA/IPAC Extragalactic Database (NED). We acknowledge the use of the HyperLeda database ( http:// leda.univ-lyon1.fr). The Digitized Sky Surveys were produced at the Space Telescope Science Institute under US Government grant NAGW-2166. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the US Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. Some images presented in this paper were obtained from the Multimission Archive at the Space Telescope Science Institute (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5- 26555. Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NAG5-7584 and by other grants and contracts. This research has made use of the NASA/IPAC Infrared Science Archive. This publication makes use of data products from the Two Micron All Sky Survey. Facilities: GALEX, CTIO:2MASS, FLWO:2MASS, Sloan, PO:1.2m, UKST

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Additional details

Identifiers

Eprint ID
16870
Resolver ID
CaltechAUTHORS:20091203-140520449

Funding

Alfred P. Sloan Foundation
Participating Institutions
NSF
Department of Energy (DOE)
NASA
Japanese Monbukagakusho
Max Planck Society
Higher Education Funding Council for England

Dates

Created
2010-01-04
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Updated
2021-11-08
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Caltech groups
Space Radiation Laboratory , Space Astrophysics Laboratory