SFI++ I: A New I-band Tully-Fisher Template, the Cluster Peculiar Velocity Dispersion and H0

The SFI++ consists of ~5000 spiral galaxies which have measurements suitable for the application of the I-band Tully-Fisher (TF) relation. This sample builds on the SCI and SFI samples published in the 1990s but includes significant amounts of new data as well as improved methods for parameter determination. We derive a new I-band TF relation from a subset of this sample which consists of 807 galaxies in the fields of 31 nearby clusters and groups. This sample constitutes the largest ever available for the calibration of the TF template and extends the range of line-widths over which the template is reliably measured. Careful accounting is made of observational and sample biases such as incompleteness, finite cluster size, galaxy morphology and environment. We find evidence for a type-dependent TF slope which is shallower for early type than for late type spirals. The line-of-sight cluster peculiar velocity dispersion is measured for the sample of 31 clusters. This value is directly related to the spectrum of initial density fluctuations and thus provides an independent verification of the best fit WMAP cosmology and an estimate of Omega^0.6 sigma_8 = 0.52+/-0.06. We also provide an independent measure of the TF zeropoint using 17 galaxies in the SFI++ sample for which Cepheid distances are available. In combination with the ``basket of clusters'' template relation these calibrator galaxies provide a measure of H0 = 74+/-2 (random) +/-6 (systematic) km/s/Mpc.Comment: Accepted by ApJ (scheduled for 20 Dec 2006, issue 653). 21 pages (2 column emulateapj) including 12 figures. Version 2 corrects typos and other small errors noticed in proof

Maximum likelihood method for fitting the Fundamental Plane of the 6dF Galaxy Survey

We have used over 10,000 early-type galaxies from the 6dF Galaxy Survey (6dFGS) to construct the Fundamental Plane across the optical and near-infrared passbands. We demonstrate that a maximum likelihood fit to a multivariate Gaussian model for the distribution of galaxies in size, surface brightness and velocity dispersion can properly account for selection effects, censoring and observational errors, leading to precise and unbiased parameters for the Fundamental Plane and its intrinsic scatter. This method allows an accurate and robust determination of the dependencies of the Fundamental Plane on variations in the stellar populations and environment of early-type galaxies.Comment: 3 pages, 1 figure, to appear in the proceedings of the IAU Symposium 262 "Stellar Populations: Planning for the Next Decade", Charlot and Bruzual ed

The 2MASS Tully-Fisher Survey : Mapping the Mass in the Universe

The 2MASS Tully-Fisher Survey (2MTF) aims to measure Tully-Fisher (TF) distances for all bright inclined spirals in the 2MASS Redshift Survey (2MRS) using high quality HI widths and 2MASS photometry. Compared with previous peculiar velocity surveys, the 2MTF survey provides more accurate width measurements and more uniform sky coverage, combining observations with the Green Bank, Arecibo and Parkes telescopes. With this new redshift-independent distance database, we will significantly improve our understanding of the mass distribution in the local universe.Comment: 4 pages, 3 figures, IAU Symposium 289 proceedin

Cosmicflows-2: I-band Luminosity - HI Linewidth Calibration

In order to measure distances with minimal systematics using the correlation between galaxy luminosities and rotation rates it is necessary to adhere to a strict and tested recipe. We now derive a measure of rotation from a new characterization of the width of a neutral Hydrogen line profile. Additionally, new photometry and zero point calibration data are available. Particularly the introduction of a new linewidth parameter necessitates the reconstruction and absolute calibration of the luminosity-linewidth template. The slope of the new template is set by 267 galaxies in 13 clusters. The zero point is set by 36 galaxies with Cepheid or Tip of the Red Giant Branch distances. Tentatively, we determine H0 = 75 km s-1 Mpc-1. Distances determined using the luminosity-linewidth calibration will contribute to the distance compendium Cosmicflows-2.Comment: Accepted for publication in The Astrophysical Journal, 27 pages, 18 figure

The Arecibo Legacy Fast ALFA Survey: X. The HI Mass Function and Omega_HI From the 40% ALFALFA Survey

The Arecibo Legacy Fast ALFA (ALFALFA) survey has completed source extraction for 40% of its total sky area, resulting in the largest sample of HI-selected galaxies to date. We measure the HI mass function from a sample of 10,119 galaxies with 6.2 < log (M_HI/M_Sun) < 11.0 and with well-described mass errors that accurately reflect our knowledge of low-mass systems. We characterize the survey sensitivity and its dependence on profile velocity width, the effect of large-scale structure, and the impact of radio frequency interference in order to calculate the HIMF with both the 1/Vmax and 2DSWML methods. We also assess a flux-limited sample to test the robustness of the methods applied to the full sample. These measurements are in excellent agreement with one another; the derived Schechter function parameters are phi* = 4.8 (+/- 0.3) * 10^-3, log (M*/M_Sun) + 2 log(h_70) = 9.96 (+/- 0.2), and alpha = -1.33 (+/- 0.02). We find Omega_HI = 4.3 (+/- 0.3) * 10^-4, 16% larger than the 2005 HIPASS result, and our Schechter function fit extrapolated to log (M_HI/M_Sun) = 11.0 predicts an order of magnitude more galaxies than HIPASS. The larger values of Omega_HI and of M* imply an upward adjustment for estimates of the detection rate of future large-scale HI line surveys with, e.g., the Square Kilometer Array. A comparison with simulated galaxies from the Millennium Run and a treatment of photoheating as a method of baryon removal from HI-selected halos indicates that the disagreement between dark matter mass functions and baryonic mass functions may soon be resolved.Comment: 21 pages, 13 figures, submitted to Ap

SFI++ II: A New I-band Tully-Fisher Catalog, Derivation of Peculiar Velocities and Dataset Properties

We present the SFI++ dataset, a homogeneously derived catalog of photometric and rotational properties and the Tully-Fisher distances and peculiar velocities derived from them. We make use of digital optical images, optical long-slit spectra, and global HI line profiles to extract parameters of relevance to disk scaling relations, incorporating several previously published datasets as well as a new photometric sample of some 2000 objects. According to the completeness of available redshift samples over the sky area, we exploit both a modified percolation algorithm and the Voronoi-Delaunay method to assign individual galaxies to groups as well as clusters, thereby reducing scatter introduced by local orbital motions. We also provide corrections to the peculiar velocities for both homogeneous and inhomogeneous Malmquist bias, making use of the 2MASS Redshift Survey density field to approximate large scale structure. We summarize the sample selection criteria, corrections made to raw observational parameters, the grouping techniques, and our procedure for deriving peculiar velocities. The final SFI++ peculiar velocity catalog of 4861 field and cluster galaxies is large enough to permit the study not just of the global statistics of large scale flows but also of the {\it details} of the local velocity field.Comment: 14 pages, 6 figures, 4 external online tables, accepted for publication in ApJ

The growth of the disk galaxy UGC8802

The disk galaxy UGC8802 has high neutral gas content and a flat profile of star formation rate compared to other disk galaxies with similar stellar mass. It also shows a steep metallicity gradient. We construct a chemical evolution model to explore its growth history by assuming its disk grows gradually from continuous gas infall, which is shaped by a free parameter -- the infall-peak time. By adopting the recently observed molecular surface density related star formation law, we show that a late infall-peak time can naturally explain the observed high neutral gas content, while an inside-out disk formation scenario can fairly reproduce the steep oxygen abundance gradient. Our results show that most of the observed features of UGC8802 can be well reproduced by simply `turning the knob' on gas inflow with one single parameter, which implies that the observed properties of gas-rich galaxies could also be modelled in a similar way.Comment: 6 pages, 2 figures, accepted by ApJ

The observed infall of galaxies towards the Virgo cluster

We examine the velocity field of galaxies around the Virgo cluster induced by its overdensity. A sample of 1792 galaxies with distances from the Tip of the Red Giant Branch, the Cepheid luminosity, the SNIa luminosity, the surface brightness fluctuation method, and the Tully-Fisher relation has been used to study the velocity-distance relation in the Virgocentric coordinates. Attention was paid to some observational biases affected the Hubble flow around Virgo. We estimate the radius of the zero-velocity surface for the Virgo cluster to be within (5.0 - 7.5) Mpc corresponding to (17 - 26)^\circ at the mean cluster distance of 17.0 Mpc. In the case of spherical symmetry with cosmological parameter \Omega_m=0.24 and the age of the Universe T_0= 13.7 Gyr, it yields the total mass of the Virgo cluster to be within M_T=(2.7 - 8.9) * 10^{14} M_\sun in reasonable agreement with the existing virial mass estimates for the cluster.Comment: 22 pages, 11 figures, 2 tables. Accepted for publication in MNRA

Is the far border of the Local Void expanding?

According to models of evolution in the hierarchical structure formation scenarios, voids of galaxies are expected to expand. The Local Void (LV) is the closest large void, and it provides a unique opportunity to test observationally such an expansion. It has been found that the Local Group, which is on the border of the LV, is running away from the void center at ~260 km/s. In this study we investigate the motion of the galaxies at the far-side border of the LV to examine the presence of a possible expansion. We selected late-type, edge-on spiral galaxies with radial velocities between 3000 km/s and 5000 km/s, and carried out HI 21 cm line and H-band imaging observations. The near-infrared Tully-Fisher relation was calibrated with a large sample of galaxies and carefully corrected for Malmquist bias. It was used to compute the distances and the peculiar velocities of the LV sample galaxies. Among the 36 sample LV galaxies with good quality HI line width measurements, only 15 galaxies were selected for measuring their distances and peculiar velocities, in order to avoid the effect of Malmquist bias. The average peculiar velocity of these 15 galaxies is found to be -419+208-251 km/s, which is not significantly different from zero. Due to the intrinsically large scatter of Tully-Fisher relation, we cannot conclude whether there is a systematic motion against the center of the LV for the galaxies at the far-side boundary of the void. However, our result is consistent with the hypothesis that those galaxies at the far-side boundary have an average velocity of ~260 km/s equivalent to what is found at the position of the Local Group.Comment: 15 pages, 6 figures, and 4 tables. Accepted for publication in A&