The Void Galaxy Survey: Optical Properties and H I Morphology and Kinematics
Abstract
We have carefully selected a sample of 60 galaxies that reside in the deepest underdensities of geometrically identified voids within the Sloan Digital Sky Survey. H I imaging of 55 galaxies with the Westerbork Synthesis Radio Telescope reveals morphological and kinematic signatures of ongoing interactions and gas accretion. We probe a total volume of 485 Mpc3 within the voids, with an angular resolution of 8 kpc at an average distance of 85 Mpc. We reach column density sensitivities of 5 × 1019 cm-2, corresponding to an H I mass limit of 3 × 108 M ⊙. We detect H I in 41 galaxies, with total masses ranging from 1.7 × 108 to 5.5 × 109 M ⊙. The upper limits on the 14 non-detections are not inconsistent with their luminosities, given their expected H I mass-to-light ratios. We find that the void galaxies are generally gas-rich, low-luminosity, blue disk galaxies, with optical and H I properties that are not unusual for their luminosity and morphology. The sample spans a range of absolute magnitudes (-16.1 > Mr > -20.4) and colors (0.06 <g - r < 0.87), and includes disk and irregular galaxies. We also identify three as early-type galaxies, all of which are not detected in H I. All galaxies have stellar masses less than 3 × 1010 M ⊙, and many have kinematic and morphological signs of ongoing gas accretion, suggesting that the void galaxy population is still in the process of assembling. The small-scale clustering in the void, within 600 kpc and 200 km s-1, is similar to that in higher density regions, and we identify 18 H I-rich neighboring galaxies in the voids. Most are within 100 kpc and 100 km s-1 of the targeted galaxy, and we find no significant population of H I-rich low-luminosity galaxies filling the voids, contrary to what is predicted by simulations.
- Publication:
-
The Astronomical Journal
- Pub Date:
- July 2012
- DOI:
- 10.1088/0004-6256/144/1/16
- arXiv:
- arXiv:1204.5185
- Bibcode:
- 2012AJ....144...16K
- Keywords:
-
- galaxies: evolution;
- galaxies: formation;
- galaxies: kinematics and dynamics;
- galaxies: structure;
- large-scale structure of Universe;
- radio lines: galaxies;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 34 pages, 33 figures (including Atlas in Appendix), accepted for publication in AJ