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1. SHIELD: Observations of Three Candidate Interacting Systems

   Ruvolo, Elizabeth ; Miazzo, Masao ; Cannon, John M. ; McNichols, Andrew ; Teich, Yaron ; Adams, Elizabeth A. ; Giovanelli, Riccardo ; Haynes, Martha P. ; McQuinn, Kristen B. ; Salzer, John Joseph ; et al ( January 2017 , American Astronomical Society ... meeting)

   The “Survey of HI in Extremely Low-mass Dwarfs” (SHIELD) is a multiwavelength study of local volume low-mass galaxies. Using the now-complete Arecibo Legacy Fast ALFA (ALFALFA) source catalog, 82 systems are identified that meet distance, line width, and HI flux criteria for being gas-rich, low-mass galaxies. These systems harbor neutral gas reservoirs smaller than 3x10^7 M_sun, thus populating the faint end of the HI mass function with statistical confidence for the first time. In a companion poster, we present new Karl G. Jansky Very Large Array D-configuration HI spectral line observations of 32 previously unobserved galaxies. Three galaxies in that study have been discovered to lie in close angular proximity to more massive galaxies. Here we present VLA HI imaging of these candidate interacting systems. We compare the neutral gas morphology and kinematics with optical images from SDSS. We discuss the frequency of low-mass galaxies undergoing tidal interaction in the complete SHIELD sample.Support for this work was provided by NSF grant 1211683 to JMC at Macalester College. 

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2. SHIELD: EVLA HI Spectral Line Observations of Low-mass Dwarfs

   Miazzo, Masao ; Ruvolo, Elizabeth ; Cannon, John M. ; McNichols, Andrew ; Teich, Yaron ; Adams, Elizabeth A. ; Giovanelli, Riccardo ; Haynes, Martha P. ; McQuinn, Kristen B. ; Salzer, John Joseph ; et al ( January 2017 , American Astronomical Society ... meeting)

   The “Survey of HI in Extremely Low-mass Dwarfs” (SHIELD) is a multiwavelength study of local volume low-mass galaxies. Using the now-complete Arecibo Legacy Fast ALFA (ALFALFA) source catalog, 82 systems are identified that meet distance, line width, and HI flux criteria for being gas-rich, low-mass galaxies. These systems harbor neutral gas reservoirs smaller than 3x10^7 M_sun, thus populating the faint end of the HI mass function with statistical confidence for the first time. Here we present new Karl G. Jansky Very Large Array D-configuration HI spectral line observations of 32 previously unobserved galaxies. These low angular resolution (~40" beam) images localize the HI gas; with a few exceptions, the HI gas is co-spatial with the optical centers of the galaxies. These images provide the first glimpse of the neutral interstellar medium in these systems.Support for this work was provided by NSF grant 1211683 to JMC at Macalester College. 

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3. The Neutral ISM of the Extremely Metal­Deficient Galaxy Leoncino

   Bartz, Josh ; Page, Tylyn ; Cannon, John M. ; Adams, Elizabeth ; Berg, Danielle ; Dolphin, Andrew ; Giovanelli, Riccardo ; Gordon, Alex J. ; Haynes, Martha P. ; Hirschauer, Alec S. ; et al ( January 2019 , American Astronomical Society, AAS Meeting)

   We present new multi-configuration VLA HI spectral line imaging of the dwarf galaxies AGC 198691 (hereafter, Leoncino) and UGC 5186. Leoncino is one of 82 galaxies in the "Survey of HI in Extremely Low-mass Dwarfs" ("SHIELD"), a multi-wavelength investigation of low-mass galaxies that were cataloged by the Arecibo Legacy Fast ALFA (ALFALFA) survey. Leoncino is one of the lowest metallicity galaxies known in the local universe (Hirschauer et al. 2016). A single pointing with the VLA allows us to study the HI morphology and dynamics of both galaxies simultaneously. We present HI images at a variety of angular resolutions in order to explore both the global and the resolved properties of the neutral ISM. 

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4. HI Spectral Line Imaging of Three SHIELD Galaxies

   Hetrick, Jacob ; Cannon, John M. ; Adams, Elizabeth ; Giovanelli, Riccardo ; Haynes, Martha P. ; Janewiecki, Steven ; Jones, Michael ; Leisman, Lukas ; McQuinn, Kristen B. ; Rhode, Katherine ; et al ( January 2019 , American Astronomical Society, AAS Meeting)

   The ALFALFA blind HI survey has populated the low-mass end of the HI mass function for the first time, allowing an unprecedented opportunity to explore the physical properties of the galaxies that inhabit this extreme portion of parameter space. Using the now-complete ALFALFA dataset, we have constructed the "Survey of HI in Extremely Low-mass Dwarfs" ("SHIELD"), a complete sample of 82 galaxies that provides a unique opportunity to further our understanding of these cosmologically important systems. Here we present new VLA imaging of the final 3 of the 82 sources to be observed at low angular resolution in the HI spectral line: AGC215284, AGC731448, and AGC732041 (program VLA/18A-177). We compare the HI images to ground-based H-alpha imaging in order to examine the star formation properties of each system. 

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5. ALFALFA Harvest: 3D Modeling of HI-Rich Candidate Local Group Dwarf Galaxies

   Bralts-Kelly, L. ; Paine, S. ; Adams, E. A. ; Cannon, J. M. ; Giovanelli, R. ; Haynes, M. P. ; Janesh, W. ; Janowiecki, S. ; Oosterloo, T. ; Rhode, K. L. ; et al ( January 2020 , American Astronomical Society meeting)

   The ALFALFA blind extragalactic survey has populated the faint end of the neutral hydrogen (HI) mass function with statistical confidence for the first time. Of particular interest is a subset of the ALFALFA detections, termed "ultra-compact high-velocity clouds" (UCHVCs). These systems, if located within ~1 Mpc, would populate the lowest-mass end of the HI mass function. Subsequent optical imaging has revealed that some of these UCHVCs harbor associated (though sparse) stellar populations, revealing that they may be some of the most extreme galaxies known in the Local Volume, with optical properties akin to ultra-faint dwarf galaxies but with significant neutral gas reservoirs. In this campaign, we investigate the neutral hydrogen properties of six UCHVC candidate galaxies using deep VLA HI spectral line imaging. A companion poster (Paine et al.) presents details on the data reduction, imaging, and resulting products. Here, we examine the morphological and kinematic properties of selected sources. We apply the modeling software 3D-Barolo to our deep HI images in order to derive the rotation curve and constrain the inclination angle for each source. Successful modeling allows us to determine the dynamical masses of these objects and thus to consider them in the context of various fundamental scaling relations defined by more massive galaxies. 

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