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  1. Abstract

    The baryonic Tully–Fisher relation (BTFR) has applications in galaxy evolution as a test bed for the galaxy–halo connection and in observational cosmology as a redshift-independent secondary distance indicator. This analysis leverages the 31,000+ galaxy Arecibo Legacy Fast ALFA (AreciboL-band Feed Array) Survey (ALFALFA) sample—which provides redshifts, velocity widths, and Hicontent for a large number of gas-bearing galaxies in the local universe—to fit and test an extensive local universe BTFR. The fiducial relation is fit using a 3000-galaxy subsample of ALFALFA, and is shown to be consistent with the full sample. This BTFR is designed to be as inclusive of ALFALFA and comparable samples as possible. Velocity widths measured via an automated method andMbproxies extracted from survey data can be uniformly and efficiently measured for other samples, giving this analysis broad applicability. We also investigate the role of sample demographics in determining the best-fit relation. We find that the best-fit relations are changed significantly by changes to the sample mass range and to second order by changes to mass sampling, gas fraction, different stellar mass and velocity width measurements. We use a subset of ALFALFA with demographics that reflect the full sample to measure a robust BTFR slope of 3.30 ± 0.06. We apply this relation and estimate source distances, finding general agreement with flow-model distances as well as average distance uncertainties of ∼0.17 dex for the full ALFALFA sample. We demonstrate the utility of these distance estimates by applying them to a sample of sources in the Virgo vicinity, recovering signatures of infall consistent with previous work.

     
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  2. Abstract

    The bimodal absorption system imaging campaign (BASIC) aims to characterize the galaxy environments of a sample of 36 Hi-selected partial Lyman limit systems (pLLSs) and Lyman limit systems (LLSs) in 23 QSO fields atz≲ 1. These pLLSs/LLSs provide a unique sample of absorbers with unbiased and well-constrained metallicities, allowing us to explore the origins of metal-rich and low-metallicity circumgalactic medium (CGM) atz< 1. Here we present Keck/KCWI and Very Large Telescope/MUSE observations of 11 of these QSO fields (19 pLLSs) that we combine with Hubble Space Telescope/Advanced Camera for Surveys imaging to identify and characterize the absorber-associated galaxies at 0.16 ≲z≲ 0.84. We find 23 unique absorber-associated galaxies, with an average of one associated galaxy per absorber. For seven absorbers, all with <10% solar metallicities, we find no associated galaxies withlogM9.0withinρ/Rvirand ∣Δv∣/vesc≤ 1.5 with respect to the absorber. We do not find any strong correlations between the metallicities or Hicolumn densities of the gas and most of the galaxy properties, except for the stellar mass of the galaxies: the low-metallicity ([X/H] ≤ −1.4) systems have a probability of0.390.15+0.16for having a host galaxy withlogM9.0withinρ/Rvir≤ 1.5, while the higher metallicity absorbers have a probability of0.780.13+0.10. This implies metal-enriched pLLSs/LLSs atz< 1 are typically associated with the CGM of galaxies withlogM>9.0, whereas low-metallicity pLLSs/LLSs are found in more diverse locations, with one population arising in the CGM of galaxies and another more broadly distributed in overdense regions of the universe. Using absorbers not associated with galaxies, we estimate the unweighted geometric mean metallicity of the intergalactic medium to be [X/H] ≲ −2.1 atz< 1, which is lower than previously estimated.

     
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  3. This White Paper highlights the role Primarily Undergraduate Institutions (PUIs) play within the astronomy profession, addressing issues related to employment, resources and support, research opportunities and productivity, and educational and societal impacts. 
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  4. As part of our Survey of the Circumgalactic Regions of the ALFALFA Galaxies (CRAG), we report on the analysis of QSO sightlines that pass within ~100 kpc of ALFALFA galaxies that show no discernable evidence of a circumgalactic medium (CGM) as probed by the presence of Lyα absorption. Many of these corresponding galaxies reside in group or cluster environments, in agreement with recent studies that indicate the nearby galaxy environment plays a significant role in determining the physical conditions of the CGM. However, we also identify a sample of isolated ALFALFA galaxies that show no evidence of HI within ~100 kpc - suggesting the physical distribution of the CGM around these galaxies is patchy and non-uniform, even within relatively small volumes around the galaxies. We explore photometric, spectroscopic, and imaging observations from the Sloan Digital Sky Survey in an attempt to characterize the properties these galaxies and the environments in which they reside. This work has been supported by NSF grant AST-1716569. 
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  5. We report the initial findings of our Survey of the Circumgalactic Regions of the ALFALFA Galaxies (CRAG). We combine the blindly detected 21-cm HI sources of the ALFALFA catalog with archival HST/COS G130M QSO spectroscopic observations taken from the HST Spectroscopic Legacy Archive to quantify and characterize the circumgalactic medium (CGM) around these local, HI-rich galaxies. We find the covering factor of HI, as probed by Lyα, to be near unity within 50 kpc of all ALFALFA galaxies, regardless of HI mass, MHI. However, we have identified a significant correlation between the extent of the HI-bearing CGM beyond 50 kpc and MHI of the ALFALFA galaxies. We find the galaxies with log(MHI/M☉) > 9.5 give rise to Lyα covering factors > 0.5 out to 300 kpc, indicating the CGM of the most HI-rich galaxies of the ALFALFA sample fills a significant volume. At the same time we find the galaxies with log(MHI/M☉) < 9.5 give rise to substantively lower Lyα covering factors beyond 50 kpc. Most notably, the log(MHI/M☉) < 7.5 galaxies give rise to a Lyα covering factor < 0.3 beyond 50 kpc and negligible covering factors beyond 150 kpc. This work has been supported by NSF grant AST-1716569. 
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  6. As part of our Survey of the Circumgalactic Regions of the ALFALFA Galaxies (CRAG), we report on the identification and analysis of strong HI absorption in the circumgalactic medium (CGM) of the ALFALFA galaxies as identified in archival HST/COS G130M QSO spectroscopic observations. We characterize the HI and metal content of these strong absorbers and explore the physical distribution of the CGM for these galaxies. Using photometric, spectroscopic, and imaging observations from the Sloan Digital Sky Survey, we analyze the environments of these galaxies. We also summarize the gas-galaxy connection for this sample of strong HI absorbers and HI-rich galaxies. This work has been supported by NSF grant AST-1716569. 
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  7. We present results from a highly successful model of faculty development and undergraduate research and education, the Undergraduate ALFALFA Team (UAT), an NSF-sponsored 23-institution collaboration. We recommend that granting agencies identify funding resources to support similar efforts for other large-scale scientific projects. 
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  8. The Arecibo Pisces-Perseus Supercluster Survey (APPSS) will provide strong observational constraints on the mass-infall rate onto the main filament of the Pisces-Perseus Supercluster. The survey data consist of HI emission-line spectra of cluster galaxy candidates, obtained primarily at the Arecibo Observatory (with ALFA as part of the ALFALFA Survey and with the L-Band Wide receiver as part of APPSS observations). Here we present the details of the data reduction process and spectral-analysis techniques used to determine if a galaxy candidate is at a velocity consistent with the Supercluster, as well as the detected HI-flux and rotational velocity of the galaxy, which will be used to estimate the corresponding HI-mass. We discuss the results of a preliminary analysis on a subset of the APPSS sample, corresponding to 98 galaxies located within ~1.5° of DEC = +35.0°, with 65 possible detections. We also highlight several interesting emission-line features and galaxies discovered during the reduction and analysis process and layout the future of the APPSS project. This work has been supported by NSF grants AST-1211005 and AST-1637339. 
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  9. The NSF-sponsored Undergraduate ALFALFA (Arecibo Legacy Fast ALFA) Team (UAT) is a consortium of 20 institutions across the US and Puerto Rico, founded to promote undergraduate research and faculty development within the extragalactic ALFALFA HI blind survey project and follow-up programs. The objective of the UAT is to provide opportunities for its members to develop expertise in the technical aspects of observational radio spectroscopy, its associated data analysis, and the motivating science. Partnering with Arecibo Observatory, the UAT has worked with more than 280 undergraduates and 26 faculty to date, offering 8 workshops onsite at Arecibo (148 undergraduates), observing runs at Arecibo (69 undergraduates), remote observing runs on campus, undergraduate research projects based on Arecibo science (120 academic year and 185 summer projects), and presentation of results at national meetings such as the AAS (at AAS229: Ball et al., Collova et al., Davis et al., Miazzo et al., Ruvolo et al, Singer et al., Cannon et al., Craig et al., Koopmann et al., O'Donoghue et al.). 40% of the students and 45% of the faculty participants have been women and members of underrepresented groups. More than 90% of student alumni are attending graduate school and/or pursuing a career in STEM. 42% of those pursuing graduate degrees in Physics or Astronomy are women.In this presentation, we summarize the UAT program and the current research efforts of UAT members based on Arecibo science, including multiwavelength followup observations of ALFALFA sources, the UAT Collaborative Groups Project, the Survey of HI in Extremely Low-mass Dwarfs (SHIELD), and the Arecibo Pisces-Perseus Supercluster Survey (APPSS). This work has been supported by NSF grants AST-0724918/0902211, AST-075267/0903394, AST-0725380, AST-121105, and AST-1637339. 
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