"GiGa": the Billion Galaxy HI Survey -- Tracing Galaxy Assembly from Reionization to the Present

In this paper, we review the Billion Galaxy Survey that will be carried out at radio--optical wavelengths to micro--nanoJansky levels with the telescopes of the next decades. These are the Low-Frequency Array, the Square Kilometer Array and the Large Synoptic Survey Telescope as survey telescopes, and the Thirty Meter class Telescopes for high spectral resolution+AO, and the James Webb Space Telescope (JWST) for high spatial resolution near--mid IR follow-up. With these facilities, we will be addressing fundamental questions like how galaxies assemble with super-massive black-holes inside from the epoch of First Light until the present, how these objects started and finished the reionization of the universe, and how the processes of star-formation, stellar evolution, and metal enrichment of the IGM proceeded over cosmic time. We also summarize the high-resolution science that has been done thus far on high redshift galaxies with the Hubble Space Telescope (HST). Faint galaxies have steadily decreasing sizes at fainter fluxes and higher redshifts, reflecting the hierarchical formation of galaxies over cosmic time. HST has imaged this process in great structural detail to z<~6. We show that ultradeep radio-optical surveys may slowly approach the natural confusion limit, where objects start to unavoidably overlap because of their own sizes, which only SKA can remedy with HI redshifts for individual sub-clumps. Finally, we summarize how the 6.5 meter James Webb Space Telescope (JWST) will measure first light, reionization, and galaxy assembly in the near--mid-IR.Comment: 8 pages, LaTeX2e requires 'aip' style (included), 8 postscript figures. To appear in the proceedings of the `The Evolution of Galaxies through the Neutral Hydrogen Window' conference, Arecibo Observatory Feb 1-3, 2008; Eds. R. Minchin & E. Momjian, AIP Conf Pro

The Arecibo Galaxy Environments survey IV: the NGC7448 region and the HI mass function

In this paper we describe results from the Arecibo Galaxy Environments Survey (AGES). The survey reaches column densities of ~3x10^18 cm^-2 and masses of ~10^7 M_O, over individual regions of order 10 sq deg in size, out to a maximum velocity of 18,000 km s^-1. Each surveyed region is centred on a nearby galaxy, group or cluster, in this instance the NGC7448 group. Galaxy interactions in the NGC7448 group reveal themselves through the identification of tidal tails and bridges. We find ~2.5 times more atomic gas in the inter-galactic medium than in the group galaxies. We identify five new dwarf galaxies, two of which appear to be members of the NGC7448 group. This is too few, by roughly an order of magnitude, dwarf galaxies to reconcile observation with theoretical predictions of galaxy formation models. If they had observed this region of sky previous wide area blind HI surveys, HIPASS and ALFALFA, would have detected only 5% and 43% respectively of the galaxies we detect, missing a large fraction of the atomic gas in this volume. We combine the data from this paper with that from our other AGES papers (370 galaxies) to derive a HI mass function with the following Schechter function parameters alpha=-1.52+/-0.05, M^*=5.1+/-0.3x10^9 h_72^-2 M_O, phi=8.6+/-1.1x10-3 h_72^3 Mpc^-3 dex-1. Integrating the mass function leads to a cosmic mass density of atomic hydrogen of Omega_HI=5.3+/-0.8x10^-4 h_72^-1. Our mass function is steeper than that found by both HIPASS and ALFALFA (alpha=1.37 and 1.33 respectively), while our cosmic mass density is consistent with ALFALFA, but 1.7 times larger than found by HIPASS

Mapping Hydrogen in the Galaxy, Galactic Halo, and Local Group with ALFA: The GALFA-HI Survey Starting with TOGS

Radio observations of gas in the Milky Way and Local Group are vital for understanding how galaxies function as systems. The unique sensitivity of Arecibo's 305m dish, coupled with the 7-beam Arecibo L-Band Feed Array (ALFA), provides an unparalleled tool for investigating the full range of interstellar phenomena traced by the HI 21cm line. The GALFA (Galactic ALFA) HI Survey is mapping the entire Arecibo sky over a velocity range of -700 to +700 km/s with 0.2 km/s velocity channels and an angular resolution of 3.4 arcminutes. We present highlights from the TOGS (Turn on GALFA Survey) portion of GALFA-HI, which is covering thousands of square degrees in commensal drift scan observations with the ALFALFA and AGES extragalactic ALFA surveys. This work is supported in part by the National Astronomy and Ionosphere Center, operated by Cornell University under cooperative agreement with the National Science Foundation.Comment: 3 pages, including 2 figure pages; figure image quality significantly reduced; for full resolution version, please see http://www.naic.edu/~gibson/cv/ao08_writeup.pdf ; to be published in AIP conference proceedings for ``The Evolution of Galaxies through the Neutral Hydrogen Window'', eds. R. Minchin & E. Momjia

Trajectories of Vegetation Response to Water Management in Taylor Slough, Everglades National Park, Florida

Ecosystem management practices that modify the major drivers and stressors of an ecosystem often lead to changes in plant community composition. This paper examines how closely the trajectory of vegetation change in seasonally-flooded wetlands tracks management-induced alterations in hydrology and soil characteristics. We used trajectory analysis, a multivariate method designed to test hypotheses about rates and directions of community change, to examine vegetation shifts in response to changes in water management practices within the Taylor Slough basin of Everglades National Park. We summarized vegetation data by non-metric multidimensional scaling ordination, and examined the time trajectory of each site along environmental vectors representing hydrology and soil phosphorus gradients. In the Taylor Slough basin, vegetation change trajectories closely followed the hydrologic changes caused by the operation of water pumps and detention ponds adjacent to the canals. We also observed a shift in vegetation composition along a vector of increasing soil phosphorus, which suggests the need for implementing measures to avoid P-enrichment in southern Everglades marl prairies. This study indicates that shifts in vegetation composition in response to changes in hydrologic conditions and associated parameters may be detected through trajectory analysis, thereby providing feedback for adaptive management of wetland ecosystems

An equatorial wind from the massive young stellar object S140 IRS 1

The discovery of the second equatorial ionized stellar wind from a massive young stellar object is reported. High resolution radio continuum maps of S140 IRS 1 reveal a highly elongated source that is perpendicular to the larger scale bipolar molecular outflow. This picture is confirmed by location of a small scale monopolar near-IR reflection nebula at the base of the blueshifted lobe. A second epoch of observations over a five year baseline show little ordered outward proper motion of clumps as would have been expected for a jet. A third epoch, taken only 50 days after the second, did show significant changes in the radio morphology. These radio properties can all be understood in the context of an equatorial wind driven by radiation pressure from the central star and inner disc acting on the gas in the surface layers of the disc as proposed by Drew et al. (1998). This equatorial wind system is briefly compared with the one in S106IR, and contrasted with other massive young stellar objects that drive ionized jets.Comment: 19 pages, 5 figures, accepted by ApJ, minor changes in light of referees repor

A multi-beam HI survey of the Virgo Cluster - two isolated HI clouds ?

We have carried out a fully sampled large area ($4^{\circ} \times 8^{\circ}$) 21cm \HI line survey of part of the Virgo cluster using the Jodrell Bank multi-beam instrument. The survey has a sensitivity some 3 times better than the standard HIJASS and HIPASS surveys. We detect 31 galaxies, 27 of which are well known cluster members. The four new detections have been confirmed in the HIPASS data and by follow up Jodrell Bank pointed observations. One object lies behind M86, but the other 3 have no obvious optical counter parts upon inspection of the digital sky survey fields. These 3 objects were mapped at Arecibo with a smaller \am{3}{6} HPBW and a 4 times better sensitivity than the Jodrell Bank data, which allow an improved determination of the dimensions and location of two of the objects, but surprisingly failed to detect the third. The two objects are resolved by the Arecibo beam giving them a size far larger than any optical images in the nearby field. To our mass limit of $5 \times 10^{7}$ $\frac{\Delta v}{50 km s^{-1}}$ $M_{\odot}$ and column density limit of $3 \times 10^{18}$ $\frac{\Delta v}{50 km s^{-1}}$ atoms cm$^{-2}$ these new detections represent only about 2% of the cluster atomic hydrogen mass. Our observations indicate that the \HI mass function of the cluster turns down at the low mass end making it very different to the field galaxy \HI mass function. This is quite different to the Virgo cluster optical luminosity function which is much steeper than that in the general field. Many of the sample galaxies are relatively gas poor compared to \HI selected samples of field galaxies, confirming the 'anaemic spirals' view of Virgo cluster late type galaxies.Comment: Accepted for publication in MNRA