Do spirals and ellipticals trace the same velocity field?

Abstract

view Abstract Citations (12) References (41) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Do Spirals and Ellipticals Trace the Same Velocity Field? Kolatt, Tsafrir ; Dekel, Avishai Abstract We test the hypothesis that the velocity field derived from Tully- Fisher measurements of spiral galaxies, and the one derived independently from D_n_-σ measurements of ellipticals and S0s, are noisy versions of the same underlying velocity field. The radial velocity fields are derived using tensor Gaussian smoothing of radius 1200 km s^-1^. They are compared at grid points near which the sampling by both types of galaxies is adequate. This requirement defines a volume of ~(50 h-^-1^ Mpc)^3^, containing ~10 independent subvolumes, mostly limited by the available ellipticals. The two fields are compared using a correlation statistic, whose distribution is determined via Monte Carlo simulations. We find that the data is consistent with the hypothesis, at the 10% level. We demonstrate that the failure to reject the correlation is not just a result of the errors being big by using the same method to rule out complete independence between the fields at the 99.8% level. The zero points of the two distance indicators are matched by maximizing the correlation between the two velocity fields. There is a marginal hint that the ellipticals tend to stream slower than the spirals by ~8%. The correlation reinforced here is consistent with the common working hypotheses that (1) the derived large-scale velocity field is real, (2) it has a gravitational origin, and (3) the large-scale velocities of spirals and ellipticals are hardly biased relative to each other. On the other hand, it does not rule out any alternative to gravity where objects of all types obtain similar large-scale velocities. Publication: The Astrophysical Journal Pub Date: June 1994 DOI: 10.1086/174217 arXiv: arXiv:astro-ph/9309038 Bibcode: 1994ApJ...428...35K Keywords: Correlation Coefficients; Cosmology; Elliptical Galaxies; Galactic Rotation; Radial Velocity; Spiral Galaxies; Density Distribution; Distance; Galactic Clusters; Monte Carlo Method; Radial Distribution; Red Shift; Astrophysics; COSMOLOGY: LARGE-SCALE STRUCTURE OF UNIVERSE; COSMOLOGY: OBSERVATIONS; GALAXIES: DISTANCES AND REDSHIFTS; GALAXIES: ELLIPTICAL AND LENTICULAR; CD; GALAXIES: SPIRAL; Astrophysics E-Print: 16 pages, compressed and uuencoded PostScript 0.6Mbyte, (Also anonymous ftp venus.huji.ac.il pub/dekel/es/es.ps.Z of 0.43Mbyte) full text sources arXiv | ADS | data products SIMBAD (3)