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1. Density and Velocity Profiles for Large-scale Cosmological Filaments

   Viscardi, T.; Graham, L.; Young, B.; Crone-Odekon, M.; Halstead, E.; Jones, M.; Team, APPSS; Team, Undergraduate ALFALFA; Team, ALFALFA (January 2020, American Astronomical Society meeting)

   In preparation for comparison with the Arecibo Pisces-Perseus Supercluster Survey (APPSS), we present the theoretically expected density and velocity profiles for large-scale (~ 50 Mpc) filaments from the Millennium simulation. We use an observationally-friendly method to identify filaments using the positions of large groups of galaxies, and average filaments together to find the typical structure of a filament in terms of cylindrical density profile and velocity infall profile. Both profiles can be fit by simple functions, but show a large scatter across the population of filaments. We are in the process of categorizing filaments to facilitate comparison with observations of specific filaments, like the Pisces-Perseus Supercluster filament. This work has been supported by NSF grant AST-1637339. 

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2. Infall Profiles for Supercluster-scale Filaments

   https://doi.org/10.3847/1538-4357/ac815b  

   Odekon, Mary Crone; Jones, Michael G.; Graham, Lucas; Kelley-Derzon, Jessica; Halstead, Evan (August 2022, The Astrophysical Journal)

   Abstract We present theoretical expectations for infall toward supercluster-scale cosmological filaments, motivated by the Arecibo Pisces–Perseus Supercluster Survey (APPSS) to map the velocity field around the Pisces–Perseus Supercluster (PPS) filament. We use a minimum spanning tree applied to dark matter halos the size of galaxy clusters to identify 236 large filaments within the Millennium simulation. Stacking the filaments along their principal axes, we determine a well-defined, sharp-peaked velocity profile function that can be expressed in terms of the maximum infall rateV_maxand the distanceρ_maxbetween the location of maximum infall and the principal axis of the filament. This simple, two-parameter functional form is surprisingly universal across a wide range of linear mass densities.V_maxis positively correlated with the halo mass per length along the filament, andρ_maxis negatively correlated with the degree to which the halos are concentrated along the principal axis. We also assess an alternative, single-parameter method usingV₂₅, the infall rate at a distance of 25 Mpc from the axis of the filament. Filaments similar to the PPS have $V_{\max }=612\pm$116 km s⁻¹, ${\rho }_{\max }=8.9\pm 2.1$Mpc, andV₂₅= 329 ± 68 km s⁻¹. We create mock observations to model uncertainties associated with viewing angle, lack of three-dimensional velocity information, limited sample size, and distance uncertainties. Our results suggest that it would be especially useful to measure infall for a larger sample of filaments to test our predictions for the shape of the infall profile and the relationships among infall rates and filament properties. 

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3. The Arecibo Pisces-Perseus Supercluster Survey: Declination Strips 27 and 29, and Comparison to Cosmological Simulations

   Cane, Thomas; Mierzejewski, Veronica; Gartenstein, Sam; Kelley-Derzon, Jesse; Odekon, Mary C.; Viscardi, Trevor; Koopmann, Rebecca; Haynes, Martha P.; Jones, Michael (January 2019, American Astronomical Society, AAS Meeting)

   The Arecibo Pisces-Perseus Supercluster Survey (APPSS) will provide strong observational constraints on the infall rate onto the main filament of the Pisces-Perseus Supercluster. The survey data consist of HI emission-line galaxies in the PPS region, obtained primarily at the Arecibo Observatory. Here we present data from Declination strips 27 and 29, which include 308 target galaxies, and describe our method for deducing the dark matter distribution in the filament from galaxy peculiar velocities by comparison to similar filaments in the Millennium simulation. This work has been supported by NSF grants AST-1211005 and AST-1637339. 

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4. Targeted HI Line Observations of Low Mass Galaxies in the Pisces-Perseus Supercluster: Results for the Declination Strip 30° < Dec < 32°

   Kumagai, Samuel F. (January 2019, American Astronomical Society, AAS Meeting)

   The Arecibo Pisces-Perseus Supercluster Survey (APPSS) is an observing project undertaken by the Undergraduate ALFALFA Team that aims to detect HI in galaxies in the Pisces-Perseus neighborhood and analyze the dynamics and the properties of the galaxies. The galaxies targeted in APPSS are suspected from their optical properties (color, morphology, surface brightness) to lie in the Pisces-Perseus Supercluster (PPS) but are below the detection threshold of the ALFALFA blind HI survey. Here we present results for galaxies targeted in a strip across the PPS region in declination from 30o to 32o. This region is along the main filament of the supercluster and includes objects such as the Pisces Cluster. The data was recorded by the L-Band Wide receiver of the Arecibo Observatory. Data reduction was done using routines derived for the APPSS in IDL. After baselining the spectra and sifting out radio interference, we fit either a gaussian or two-horned profile to their 21-centimeter line to measure the HI line flux density, velocity, and velocity width. From these parameters we calculate distances, hydrogen gas mass, and rotational velocities. As expected, the galaxies analyzed in this slice of declination have consistently lower mass than the ALFALFA detections thus extending the sampling of galaxies within the PPS. The combined ALFALFA and APPSS HI line detections will be used for future applications of the Baryonic Tully-Fisher Relation in this region. This research has been supported by NSF grant NSF/AST-1714828 to M.P. Haynes and by the Brinson Foundation for the Arecibo Pisces-Perseus Supercluster Survey (APPSS). 

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5. The Arecibo Pisces-Perseus Supercluster Survey: Declination Strip 35

   McMichael, Chelsey; Ribaudo, Joseph; Koopmann, Rebecca A.; Haynes, Martha P.; APPSS Team, Undergraduate ALFALFA (January 2018, American Astronomical Society, AAS Meeting)

   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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