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The Arecibo Pisces-Perseus Supercluster Survey (APPSS) aims to observationally measure the dark matter mass density of Pisces-Perseus by detecting the peculiar velocities of galaxies falling onto the supercluster. To do this, APPSS will measure galaxies' distances using the Baryonic Tully Fisher Relation (BTFR), which relates a galaxy's baryonic mass and rotational velocity. Recovering the signature of infall as robustly as possible requires a careful choice of rotational velocity measurement, as the use of various velocity definitions changes the scatter and systematics of the relation. We introduce and compare multiple automated methods for measuring a galaxy's rotational velocity using its unresolved line profile. The velocities discussed include global HI profile width measures commonly reported in large surveys, velocity widths derived from best-fit parametrizations to profiles, and velocity widths derived using more novel methods including the spectral line's curve of growth and neural network-derived velocities which incorporate information about the profile's width and shape. We compare these velocity measures by finding best-fit BTFR relations for two samples of galaxies - the SPARC sample and a selected sample of gas-dominated ALFALFA galaxies (Papastergis et al. 2016). With these best-fit BTFRs, we compare intrinsic scatters and residual correlations with source properties to investigate how velocity choice affects the absolute and systematic uncertainties of BTFR-derived galaxy distances. This research is supported by NSF/AST-1714828 and the Brinson Foundation. 

We present our work on constructing a template Baryonic Tully-Fisher Relation (BTFR) from galaxies in the local universe that have primary distances. We utilize HI 21 cm line data from the complete Arecibo Legacy Fast ALFA (ALFALFA) survey and the digital HI archive from Springob et al. 2005; we also use photometry from the Sloan Digital Sky Survey (SDSS) and the NASA Sloan Atlas (NSA) MANGA v1_0_2 database; lastly, we have also made use of the Extragalactic Distance Database (EDD) for identifying galaxies with primary distances. After cross-matching the galaxies in these catalogues, we identify some 144 galaxies which meet our requirements for having all the necessary HI and photometry data, having primary distances, residing within 30 Mpc, and having low enough uncertainties to be considered reliable data points. An important trait of this data set is the prominence of low-mass, low-luminosity dwarves. Notably, we find the values for the slope, intercept and intrinsic scatter of the relation to be around 2.3, 4.8, and 0.4, respectively. Further, while unresolved velocity widths have historically produced shallower slopes, and while the BTFR has been shown to have a higher intrinsic scatter for low-mass galaxies, these precedents are not enough to explain the deviation of our data from the “standard” values of the BTFR. This work therefore raises several questions about why this discrepancy exists, how it can be resolved, and what we can learn from it. The authors would like to acknowledge the support of NSF/AST-1714828 and the Brinson Foundation. 

We present an HI-optical catalog of ~ 30,000 galaxies based on the 100% complete Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) survey combined with data from the Sloan Digital Sky Survey (SDSS). Our goal is to facilitate public use of the completed ALFALFA catalog by providing carefully determined matches to SDSS counterparts, including matches for ~ 10,000 galaxies that do not have SDSS spectra. These identifications can provide a basis for further cross-matching with other surveys using SDSS photometric IDs as a reference point. We derive absolute magnitudes and stellar masses for each galaxy using optical colors combined with an internal reddening correction designed for small- and intermediate-mass galaxies with active star formation. We also provide measures of stellar masses and star formation rates based on infrared and/or ultraviolet photometry for galaxies that are detected by the Wide-field Infrared Survey Explorer (WISE) and/or the Galaxy Evolution Explorer (GALEX). Finally, we compare the galaxy population in the ALFALFA-SDSS sample with the populations in several other publicly-available galaxy catalogs, and confirm that ALFALFA galaxies typically have lower masses and bluer colors. 

The Arecibo Pisces-Perseus Supercluster Survey(APPSS) aims to measure the infall and mass density along the PPS filament using red-shift independent distances obtained from the Baryonic Tully-Fisher Relation (BTFR). We will combine photometric data from the Sloan Digital Sky Survey with HI line spectroscopy obtained with the Arecibo telescope to derive BTFR distances and peculiar velocities over the PPS volume and its immediate foreground and background. To supplement the ALFALFA detections in the PPS volume, we have conducted new HI line observations with the Arecibo L-band Wide receiver system of blue, low surface brightness galaxies identified by their photometric properties in the Sloan Digital Sky Survey (SDSS). These targets are predicted to lie in the PPS volume but with HI masses of 8.0 < log HI mass < 9.0, putting them below the ALFALFA detection limit at that distance. We compare a preliminary sample of 634 galaxies detected as part from the APPSS survey with the main ALFALFA survey and other public catalogs of local galaxies, confirming that the new APPSS HI line detections are rotation-dominated, HI bearing galaxies with low stellar mass. Nearly all are star-forming, bluer, and of lower surface brightness, extinction and metallicity than optically selected samples. Preliminary BTFRs were calculated for both APPSS and ALFALFA galaxies and compared with BTFRs of simulated galaxies similar to those found in APPSS and ALFALFA using simulations such as IllustrisTNG (see poster by J. Borden). This work has been supported by NSF/AST-1714828 and the Brinson Foundation. 

The Pisces-Perseus Supercluster (PPS) offers a convenient, accessible environment for the study of large scale structure in the local universe. The Arecibo Pisces-Perseus Supercluster Survey (APPSS) seeks to observe the infall of galaxies toward the main filament of the PPS which is nearly perpendicular to our line of sight. Tracing such infall reveals valuable information about the gravitational field - and thus mass distribution - of the PPS. However, obtaining accurate measurements of such deviation from smooth Hubble flow requires redshift-independent distance measurements. The baryonic Tully-Fisher relation (BTFR) offers an appealing solution in the distance regime of the PPS, but while the high-mass end of this relation boasts a tight correlation, the low-mass end - where the APPSS sample lies - shows considerably more scatter. We use the magnetohydrodynamical simulations of IllustrisTNG to examine a template BTFR in an attempt to better understand the error budget of, and identify systematic scatter within, the BTFR as it corresponds to the APPSS sample of galaxies. We find the low mass scatter of the simulated BTFR to be populated predominantly by highly gas dominated, low surface brightness galaxies with colors less blue than typical. This unusually quiescent subset of galaxies appears to share systematically inefficient star formation, with very high gas depletion timescales that deviate rapidly from an otherwise gradual trend apparent throughout the rest of the galaxy population. This subset of inefficiently star forming galaxies tends to decrease the slope of the BTFR at low masses, an effect that lies in contrast to the steepening of the BTFR generally expected in this mass regime. Further work is needed to determine if this collection of galaxies is physically motivated or is instead a finite resolution effect of the simulation. This work is supported by NSF/AST-1714828 to MPH. 

The Pisces-Perseus Supercluster is one of the most massive and cosmologically significant structures in the local universe. The Arecibo Pisces-Perseus Supercluster Survey (APPSS) will provide observational constraints as to the mass-infall rate onto the main filament of the Supercluster through a detailed analysis of the mass and motion of galaxies within and around the cluster. The APPSS galaxy sample consists of over 2,000 galaxies detected during the ALFALFA survey (a blind, HI 21-cm emission line survey of the local universe) combined with galaxies identified through our recent targeted observing campaign - designed to probe below the HI mass cutoff of the ALFALFA survey. These APPSS-candidates were observed using the L-band Wide receiver at the Arecibo Observatory over the last 4 years; to date the APPSS targeted observing has led to an HI 21-cm emission line detection rate of ~70% - corresponding to ~500 galaxies with cz < 9,000 km/s. Combining these new observations with the ALFALFA galaxies gives a total of ~2,500 galaxies in the current APPSS sample. Here, we describe and demonstrate the methods used by the APPSS team to reduce and analyze these targeted observations and explore the properties of the entire APPSS galaxy sample (while comparing the properties of the ALFALFA galaxies with the detections from the APPSS targeted observing campaign). This work has been supported by NSF AST-1637339. 

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 (Bralts-Kelly et al.) presents 3D kinematic modeling of selected sources. Here, we show the imaging products and discuss the morphological and kinematic properties of the six chosen sources: AGC 198606, AGC 215417, AGC219656, AGC 249525, AGC 258237, and AGC 268069. 

We present new Spitzer 3.6 µm images of the 82 galaxies in the "Survey of HI in Extremely Low-mass Dwarfs" (SHIELD). Selected from the ALFALFA blind HI survey, SHIELD is a volumetrically complete sample of galaxies with HI mass reservoirs smaller than 2x107 M☉. These galaxies populate extreme portions of parameter space and they offer unique opportunities to explore the physical properties of very low-mass halos in the local Universe. The new Spitzer images allow us to measure the stellar masses of the SHIELD galaxies. We discuss methods used to remove image artifacts and to excise foreground and background contaminants. We then measure the total 3.6 µm fluxes of the systems and apply a mass to light ratio in order to derive their stellar masses. We discuss the application of this technique to the Leoncino dwarf (AGC198691, one of the most extremely metal-poor galaxies known), resulting in a stellar mass of 7.3x107 M☉. This work has been supported by NSF AST-1637339 and by Macalester College. 

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.