The Impact of Distance Uncertainties on Local Luminosity and Mass Functions

In order to investigate discrepancies between recent published estimates of the the HI mass function (HIMF), we explore the impact of distance uncertainties on the derivation of the faint end slope of mass and luminosity functions of galaxies in the local volume by deriving HIMFs from mock HI surveys. We consider various survey geometries and depths and compare the HIMFs measured when using ``real'' distances, distances derived by assuming pure Hubble flow and distances assigned from parametric models of the local velocity field. The effect is variable and dependent on the exact survey geometry, but can easily lead to incorrect estimates of the HIMF, particularly at the low mass end. We show that at least part of the discrepancies among recent derivations of the HIMF can be accounted for by the use of different methods to assign distances. We conclude that a better understanding of the local velocity field will be necessary for accurate determinations of the local galaxy luminosity and mass functions.Comment: 4 pages, accepted to ApJ

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

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

Artist in Residence Recital

Program listing performers and works performe

How do Teacher Evaluation Ratings on Kentucky\u27s Professional Growth and Effectiveness System Relate to Student Achievement?

A capstone submitted in partial fulfillment of the Requirements for the degree of Doctor of Education in the College of Education at Morehead State University by Martha Collins Jones, Jennifer R. Allen, and Jim Masters on January 23, 2017

Multi-wavelength Study of Galaxy Rotation Curves and its Application to Cosmology

Rotation information for spiral galaxies can be obtained through the observation of different spectral lines. While the Halpha(6563 A) line is often used for galaxies with low to moderate redshifts, it is redshifted into the near-infrared at z>0.4. This is why most high redshift surveys rely on the [OII](3727 A) line. Using a sample of 32 spiral galaxies at 0.155 < z < 0.25 observed simultaneously in both Halpha and [OII] with the Hale 200 inch telescope, the relation between velocity widths extracted from these two spectral lines is investigated, and we conclude that Halpha derived velocities can be reliably compared to high z [OII] measurements. The sample of galaxies is then used along with VIMOS-VLT Deep Survey observations to perform the angular diameter - redshift test to find constraints on cosmological parameters. The test makes it possible to discriminate between various cosmological models, given the upper limit of disc size evolution at the maximum redshift of the data set, no matter what the evolutionary scenario is.Comment: 2 pages, to be published in the proceedings of the Vth Marseille International Cosmology Conferenc

HIghMass - High HI Mass, HI-Rich Galaxies at z∼0z\sim0: Combined HI and H2_2 Observations

We present resolved HI and CO observations of three galaxies from the HIghMass sample, a sample of HI-massive ($M_{HI} > 10^{10} M_\odot$), gas-rich ($M_{HI}$ in top $5\%$ for their $M_*$) galaxies identified in the ALFALFA survey. Despite their high gas fractions, these are not low surface brightness galaxies, and have typical specific star formation rates (SFR$/M_*$) for their stellar masses. The three galaxies have normal star formation rates for their HI masses, but unusually short star formation efficiency scale lengths, indicating that the star formation bottleneck in these galaxies is in the conversion of HI to H$_2$, not in converting H$_2$ to stars. In addition, their dark matter spin parameters ($\lambda$) are above average, but not exceptionally high, suggesting that their star formation has been suppressed over cosmic time but are now becoming active, in agreement with prior H$\alpha$ observations.Comment: 20 pages, 13 figure

Faculty Recital

Program listing performers and works performe

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