20 research outputs found
The AMIGA sample of isolated galaxies. XIII. The HI content of an almost "nurture free" sample
We present the largest catalogue of HI single dish observations of isolated
galaxies to date and the corresponding HI scaling relations, as part of the
multi-wavelength project AMIGA (Analysis of the interstellar Medium in Isolated
GAlaxies). Despite numerous studies of the HI content of galaxies, no revision
has been made for the most isolated L* galaxies since 1984. In total we have
measurements or constraints on the HI masses of 844 galaxies from the Catalogue
of Isolated Galaxies (CIG), obtained with our own observations at Arecibo,
Effelsberg, Nancay and GBT, and spectra from the literature. Cuts are made to
this sample to ensure isolation and a high level of completeness. We then fit
HI scaling relations based on luminosity, optical diameter and morphology. Our
regression model incorporates all the data, including upper limits, and
accounts for uncertainties in both variables, as well as distance
uncertainties. The scaling relation of HI mass with optical diameter is in good
agreement with that of Haynes & Giovanelli 1984, but our relation with
luminosity is considerably steeper. This is attributed to the large
uncertainties in the luminosities, which introduce a bias when using OLS
regression (used previously), and the different morphology distributions of the
samples. We find that the main effect of morphology on the relations is to
increase the intercept and flatten the slope towards later types. These trends
were not evident in previous works due to the small number of detected
early-type galaxies. The HI scaling relations of the AMIGA sample define an
up-to-date metric of the HI content of almost "nurture free" galaxies. These
relations allow the expected HI mass, in the absence of interactions, of a
galaxy to be predicted to within 0.25 dex, and are thus suitable for use as
statistical measures of the impact of interactions on the neutral gas content
of galaxies. (Abridged)Comment: 29 pages, 14 figures, 16 tables. Accepted for publication in A&A.
Full data tables will be main available with the final publicatio
Infall Profiles for Supercluster-scale Filaments
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 rate V max and the distance ρ max between 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 max is positively correlated with the halo mass per length along the filament, and ρ max is negatively correlated with the degree to which the halos are concentrated along the principal axis. We also assess an alternative, single-parameter method using V 25, the infall rate at a distance of 25 Mpc from the axis of the filament. Filaments similar to the PPS have V max = 612 ± 116 km s−1, ρ max = 8.9 ± 2.1 Mpc, and V 25 = 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. © 2022. The Author(s). Published by the American Astronomical Society.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]