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Title: THE VELOCITY WIDTH FUNCTION OF GALAXIES FROM THE 40% ALFALFA SURVEY: SHEDDING LIGHT ON THE COLD DARK MATTER OVERABUNDANCE PROBLEM

Abstract

The ongoing Arecibo Legacy Fast ALFA (ALFALFA) survey is a wide-area, extragalactic HI-line survey conducted at the Arecibo Observatory. Sources have so far been extracted over {approx}3000 deg{sup 2} of sky (40% of its final area), resulting in the largest HI-selected sample to date. We measure the space density of HI-bearing galaxies as a function of their observed velocity width (uncorrected for inclination) down to w = 20 km s{sup -1}, a factor of two lower than the previous generation HI Parkes All-Sky Survey. We confirm previous results that indicate a substantial discrepancy between the observational distribution and the theoretical one expected in a cold dark matter (CDM) universe, at low widths. In particular, a comparison with synthetic galaxy samples populating state-of-the-art CDM simulations imply a factor of {approx}8 difference in the abundance of galaxies with w = 50 km s{sup -1} (increasing to a factor of {approx}100 when extrapolated to the ALFALFA limit of w = 20 km s{sup -1}). We furthermore identify possible solutions, including a keV warm dark matter scenario and the fact that HI disks in low-mass galaxies are usually not extended enough to probe the full amplitude of the galactic rotation curve. In this lattermore » case, we can statistically infer the relationship between the measured HI rotational velocity of a galaxy and the mass of its host CDM halo. Observational verification of the presented relationship at low velocities would provide an important test of the validity of the established dark matter model.« less

Authors:
; ; ;  [1]
  1. Center for Radiophysics and Space Research, Space Sciences Building, Cornell University, Ithaca, NY 14853 (United States)
Publication Date:
OSTI Identifier:
21587499
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 739; Journal Issue: 1; Other Information: DOI: 10.1088/0004-637X/739/1/38; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DENSITY; FUNCTIONS; GALAXIES; NONLUMINOUS MATTER; ROTATION; VELOCITY; WIDTH; DIMENSIONS; MATTER; MOTION; PHYSICAL PROPERTIES

Citation Formats

Papastergis, Emmanouil, Martin, Ann M., Giovanelli, Riccardo, and Haynes, Martha P., E-mail: papastergis@astro.cornell.edu, E-mail: amartin@astro.cornell.edu, E-mail: riccardo@astro.cornell.edu, E-mail: haynes@astro.cornell.edu. THE VELOCITY WIDTH FUNCTION OF GALAXIES FROM THE 40% ALFALFA SURVEY: SHEDDING LIGHT ON THE COLD DARK MATTER OVERABUNDANCE PROBLEM. United States: N. p., 2011. Web. doi:10.1088/0004-637X/739/1/38; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Papastergis, Emmanouil, Martin, Ann M., Giovanelli, Riccardo, & Haynes, Martha P., E-mail: papastergis@astro.cornell.edu, E-mail: amartin@astro.cornell.edu, E-mail: riccardo@astro.cornell.edu, E-mail: haynes@astro.cornell.edu. THE VELOCITY WIDTH FUNCTION OF GALAXIES FROM THE 40% ALFALFA SURVEY: SHEDDING LIGHT ON THE COLD DARK MATTER OVERABUNDANCE PROBLEM. United States. doi:10.1088/0004-637X/739/1/38; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Papastergis, Emmanouil, Martin, Ann M., Giovanelli, Riccardo, and Haynes, Martha P., E-mail: papastergis@astro.cornell.edu, E-mail: amartin@astro.cornell.edu, E-mail: riccardo@astro.cornell.edu, E-mail: haynes@astro.cornell.edu. Tue . "THE VELOCITY WIDTH FUNCTION OF GALAXIES FROM THE 40% ALFALFA SURVEY: SHEDDING LIGHT ON THE COLD DARK MATTER OVERABUNDANCE PROBLEM". United States. doi:10.1088/0004-637X/739/1/38; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
@article{osti_21587499,
title = {THE VELOCITY WIDTH FUNCTION OF GALAXIES FROM THE 40% ALFALFA SURVEY: SHEDDING LIGHT ON THE COLD DARK MATTER OVERABUNDANCE PROBLEM},
author = {Papastergis, Emmanouil and Martin, Ann M. and Giovanelli, Riccardo and Haynes, Martha P., E-mail: papastergis@astro.cornell.edu, E-mail: amartin@astro.cornell.edu, E-mail: riccardo@astro.cornell.edu, E-mail: haynes@astro.cornell.edu},
abstractNote = {The ongoing Arecibo Legacy Fast ALFA (ALFALFA) survey is a wide-area, extragalactic HI-line survey conducted at the Arecibo Observatory. Sources have so far been extracted over {approx}3000 deg{sup 2} of sky (40% of its final area), resulting in the largest HI-selected sample to date. We measure the space density of HI-bearing galaxies as a function of their observed velocity width (uncorrected for inclination) down to w = 20 km s{sup -1}, a factor of two lower than the previous generation HI Parkes All-Sky Survey. We confirm previous results that indicate a substantial discrepancy between the observational distribution and the theoretical one expected in a cold dark matter (CDM) universe, at low widths. In particular, a comparison with synthetic galaxy samples populating state-of-the-art CDM simulations imply a factor of {approx}8 difference in the abundance of galaxies with w = 50 km s{sup -1} (increasing to a factor of {approx}100 when extrapolated to the ALFALFA limit of w = 20 km s{sup -1}). We furthermore identify possible solutions, including a keV warm dark matter scenario and the fact that HI disks in low-mass galaxies are usually not extended enough to probe the full amplitude of the galactic rotation curve. In this latter case, we can statistically infer the relationship between the measured HI rotational velocity of a galaxy and the mass of its host CDM halo. Observational verification of the presented relationship at low velocities would provide an important test of the validity of the established dark matter model.},
doi = {10.1088/0004-637X/739/1/38; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 739,
place = {United States},
year = {2011},
month = {9}
}