Redshift-distance survey of early-type galaxies: Dipole of the velocity field

L. N. Da Costa, M. Bernardi, M. V. Alonso, G. Wegner, C. N.A. Willmer, P. S. Pellegrini, M. A.G. Maia, S. Zaroubi

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

We use the recently completed redshift-distance survey of nearby early-type galaxies (ENEAR) to measure the dipole component of the peculiar velocity field to a depth of cz ∼ 6000 km s-1. The sample consists of 1145 galaxies brighter than mB, = 14.5 and with cz ≤ 7000 km s-1, uniformly distributed over the whole sky, and 129 fainter cluster galaxies within the same volume. Most of the Dn,-σ distances were obtained from new spectroscopic and photometric observations conducted by this project, ensuring the homogeneity of the data over the whole sky. These 1274 galaxies are objectively assigned to 696 objects - 282 groups/clusters and 414 isolated galaxies. We find that within a volume of radius ∼6000 km s-1, the best-fitting bulk flow has an amplitude of |vb| = 220 ± 60 ± 50 km s-1 in the cosmic microwave background rest frame pointing toward l = 304° ± 16°, b = 25° ± 11°. The error in the amplitude includes statistical, sampling, and possible systematic errors. This solution is in excellent agreement with that obtained by the SFI (I-band field spiral) Tully-Fisher survey. Our results suggest that most of the motion of the Local Group is due to fluctuations within 6000 km s-1, in contrast to recent claims of large-amplitude bulk motions on larger scales.

Original languageEnglish (US)
Pages (from-to)L81-L84
JournalAstrophysical Journal
Volume537
Issue number2 PART 2
DOIs
StatePublished - Jul 10 2000
Externally publishedYes

Keywords

  • Cosmology: observations
  • Galaxies: distances and redshifts
  • Large-scale structure of universe

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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