Structure and dynamics of giant low surface brightness galaxies

F. Lelli*, F. Fraternali, R. Sancisi

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Giant low surface brightness (GLSB) galaxies are commonly thought to be massive, dark matter dominated systems. However, this conclusion is based on highly uncertain rotation curves. We present here a new study of two prototypical GLSB galaxies: Malin 1 and NGC 7589. We re-analysed existing HI observations and derived new rotation curves, which were used to investigate the distributions of luminous and dark matter in these galaxies.

In contrast to previous findings, the rotation curves of both galaxies show a steep rise in the central parts, typical of high surface brightness (HSB) systems. Mass decompositions with a dark matter halo show that baryons may dominate the dynamics of the inner regions. Indeed, a "maximum disk" fit gives stellar mass-to-light ratios in the range of values typically found for HSB galaxies. These results, together with other recent studies, suggest that GLSB galaxies are systems with a double structure: an inner HSB early-type spiral galaxy and an outer extended LSB disk.

We also tested the predictions of MOND: the rotation curve of NGC 7589 is reproduced well, whereas Malin 1 represents a challenging test for the theory.

Original languageEnglish
Article numberA11
Number of pages11
JournalAstronomy & astrophysics
Volume516
DOIs
Publication statusPublished - Jun-2010

Keywords

  • dark matter
  • galaxies: structure
  • galaxies: kinematics and dynamics
  • galaxies: individual: Malin 1
  • galaxies: individual: NGC 7589
  • methods: data analysis
  • NEUTRAL HYDROGEN OBSERVATIONS
  • MODIFIED NEWTONIAN DYNAMICS
  • RESOLUTION ROTATION CURVES
  • ON SPIRAL GALAXIES
  • DISK GALAXIES
  • GALACTIC DISKS
  • DARK-MATTER
  • STAR-FORMATION
  • STELLAR MASS
  • NGC 5383

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