M. V. Alonso

Redshift-Distance Survey of Early-Type Galaxies. I. Sample Selection, Properties, and Completeness*

This is the first in a series of papers describing the recently completed all-sky redshift-distance survey of nearby early-type galaxies (ENEAR) carried out for peculiar velocity analysis. The sample is divided into two parts and consists of 1607 elliptical and lenticular galaxies with cz < 7000 km/s and with blue magnitudes brighter than m_B=14.5 (ENEARm), and of galaxies in clusters (ENEARc). Galaxy distances based on the Dn-sigma and Fundamental Plane (FP) relations are now available for 1359 and 1107 ENEARm galaxies, respectively, with roughly 80% based on new data gathered by our group. The Dn-sigma and FP template distance relations are derived by combining 569 and 431 galaxies in 28 clusters, respectively, of which about 60% are based on our new measurements. The ENEARm redshift-distance survey extends the earlier work of the 7S and the recent Tully-Fisher surveys sampling a comparable volume. In subsequent papers of this series we intend to use the ENEAR sample by itself or in combination with the SFI Tully-Fisher survey to analyze the properties of the local peculiar velocity field and to test how sensitive the results are to different sampling and to the distance indicators. We also anticipate that the homogeneous database assembled will be used for a variety of other applications and serve as a benchmark for similar studies at high-redshift.

Redshift-Distance Survey of Early-Type Galaxies: Dipole of the Velocity Field

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 = 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.

Comparison of the ENEAR peculiar velocities with the PSCz gravity field

We present a comparison between the peculiar velocity field measured from the ENEAR all-sky D-n-sigma catalogue and that derived from the galaxy distribution of the IRAS Point Source Catalog Redshift Survey (PSCz). The analysis is based on a modal expansion of these data in redshift space by means of spherical harmonics and Bessel functions. The effective smoothing scale of the expansion is almost linear with redshift reaching 1500 km s(-1) at 3000 km s(-1). The general flow patterns in the filtered ENEAR and PSCz velocity fields agree well within 6000 km s(-1), assuming a linear biasing relation between the mass and the PSCz galaxies. The comparison allows us to determine the parameter beta=Omega (0.6)b, where Omega is the cosmological density parameter and b is the linear biasing factor. A likelihood analysis of the ENEAR and PSCz modes yields beta =0.5 +/-0.1, in good agreement with values obtained from Tully-Fisher surveys.

Large‐scale power spectrum and structures from the ENEAR galaxy peculiar velocity catalogue

We estimate the mass density fluctuations power spectrum (PS) on large scales by applying a maximum likelihood technique to the peculiarvelocity data of the recently completed redshift-distance survey of early-type galaxies (ENEAR). The general results are in agreement with the high amplitude power spectra found from similar analysis of other independent all-sky catalogs of peculiar velocity data such as MARK III and SFI. For Lambda & Open CDM COBE normalized PS models, the best-fit parameters are confined by a contour approximately defined by Omega h^{1.3}=0.377+-0.08 and Omega h^{0.88}=0.517+-0.083, respectively. Gamma-shape models, free of COBE normalization, resultsin the weak constraint of

Redshift-Distance Survey of Early-Type Galaxies. II. The Dn-σ Relation*

\Gamma \geq 0.17

ENEAR REDSHIFT-DISTANCE SURVEY: COSMOLOGICAL CONSTRAINTS

and in the rather stringent constraint of sigma_8 Omega^{0.6}=1.0+-0.25. All quoted uncertainties refer to 3-sigma confidence-level. The calculated PS is used as a prior for Wiener reconstruction of the density field at different resolutions and the three-dimensional velocity field within a volume of radius ~80 Mpc/h. All major structures in the nearby universe are recovered and are well matched to those predicted from all-sky redshift surveys.

CCD calibration of the magnitude scale for the Southern Sky Redshift Survey Extension galaxy sample

R-band photometric and velocity dispersion measurements for a sample of 452 elliptical and S0 galaxies in 28 clusters are used to construct a template Dn-� relation. This template relation is constructed by combining the data from the 28 clusters, under the assumption that galaxies in different clusters have similar properties. The photometric and spectroscopic data used consist of new as well as published measurements, converted to a common system, as presented in an accompanying paper. The resulting direct relation, corrected for incompleteness bias, is logDn ¼ 1:203 log � þ 1:406; the zero point has been defined by requiring distant clusters to be at rest relative to the cosmic microwave background. This zero point is consistent with the value obtained by using the distance to Virgo as determined by the Cepheid period-luminosity relation. This new Dn-�relation leads to a peculiar velocity of � 72 � 189 km s � 1 for the Coma Cluster. The scatter in the distance relation corresponds to a distance error of about 20%, comparable to the values obtained for the fundamental plane relation. Correlations between the scatter and residuals of the Dn-� relation with other parameters that characterize the cluster and/or the galaxy stellar population are also analyzed. The direct and inverse relations presented here have been used in recent studies of the peculiar velocity field mapped by the ENEAR all-sky sample.

Redshift-distance Survey of Early-type Galaxies: The D_n-sigma Relation

We present an analysis of the ENEAR sample of peculiar velocities of field and cluster elliptical galaxies, obtained with Dn-σ distances. We use the velocity correlation function ψ1(r) to analyze the statistics of the field objects velocities, while the analysis of the cluster data is based on the estimate of their rms peculiar velocity Vrms. The results are compared with predictions from cosmological models using linear theory. The statistics of the model velocity field is parameterized by the amplitude η8 = σ8Ω and by the shape parameter Γ of the cold dark matter-like power spectrum. This analysis is performed in redshift space, so as to circumvent the need to address corrections due to inhomogeneous Malmquist bias and to the redshift cutoff adopted in the sample selection. From the velocity correlation statistics, we obtain η8 = 0.51 for Γ = 0.25 at the 2 σ level for one interesting fitting parameter. This result agrees with that obtained from a similar analysis of the SFI I-band Tully-Fisher (TF) survey of field Sc galaxies. Even though less constraining, a consistent result is obtained by comparing the measured Vrms of clusters with linear theory predictions. For Γ = 0.25, we find η8 = 0.63 at 1 σ. Again, this result agrees, within the uncertainties, with that obtained from the SCI cluster sample based on TF distances. Overall, our results point toward a statistical concordance of the cosmic flows traced by spiral and early-type galaxies, with galaxy distances estimated using TF and Dn-σ distance indicators, respectively.

Redshift-Distance Survey of Early-Type Galaxies. I. The ENEAR[CLC]c[/CLC] Cluster Sample

In this paper we use new CCD observations to examine the accuracy of the magnitude system we have adopted to define the galaxy sample being used to conduct the Southern Sky Redshift Survey Extension hereafter referred to as (SSRS2). The magnitude scale of the SSRS2 is based on the instrumental magnitudes of the nonstellar objects listed in the ST ScI Guide Star Catalog, converted to the B(0) (Zwicky) system. This was done using a linear relation derived from the comparison of objects in common with the photometric catalogue of Lauberts & Valentijn [The Surface Photometry Catalogue of the ESO-Uppsala Galaxies (European Southern Observatory, Munchen) (1989)]

Redshift-Distance Survey of Early-Type Galaxies: Circular-Aperture Photometry*

R-band photometric and velocity dispersion measurements for a sample of 452 elliptical and S0 galaxies in 28 clusters are used to construct a template Dn-� relation. This template relation is constructed by combining the data from the 28 clusters, under the assumption that galaxies in different clusters have similar properties. The photometric and spectroscopic data used consist of new as well as published measurements, converted to a common system, as presented in an accompanying paper. The resulting direct relation, corrected for incompleteness bias, is logDn ¼ 1:203 log � þ 1:406; the zero point has been defined by requiring distant clusters to be at rest relative to the cosmic microwave background. This zero point is consistent with the value obtained by using the distance to Virgo as determined by the Cepheid period-luminosity relation. This new Dn-�relation leads to a peculiar velocity of � 72 � 189 km s � 1 for the Coma Cluster. The scatter in the distance relation corresponds to a distance error of about 20%, comparable to the values obtained for the fundamental plane relation. Correlations between the scatter and residuals of the Dn-� relation with other parameters that characterize the cluster and/or the galaxy stellar population are also analyzed. The direct and inverse relations presented here have been used in recent studies of the peculiar velocity field mapped by the ENEAR all-sky sample.