Journal article
THE SURVEY OF H I IN EXTREMELY LOW-MASS DWARFS (SHIELD)
Astrophysical journal. Letters, Vol.739(1), pp.L22-jQuery1323915814083='48'
09/20/2011
DOI: 10.1088/2041-8205/739/1/L22
Abstract
We present first results from the Survey of H I in Extremely Low-mass Dwarfs (SHIELD), a multi-configuration Expanded Very Large Array (EVLA) study of the neutral gas contents and dynamics of galaxies with H I masses in the 10(6)-10(7) M(circle dot) range detected by the Arecibo Legacy Fast ALFA (ALFALFA) survey. We describe the survey motivation and concept demonstration using Very Large Array imaging of six low-mass galaxies detected in early ALFALFA data products. We then describe the primary scientific goals of SHIELD and present preliminary EVLA and WIYN 3.5 m imaging of the 12 SHIELD galaxies. With only a few exceptions, the neutral gas distributions of these extremely low-mass galaxies are centrally concentrated. In only one system have we detected H I column densities higher than 10(21) cm(-2). Despite this, the stellar populations of all of these systems are dominated by blue stars. Further, we find ongoing star formation as traced by H alpha emission in 10 of the 11 galaxies with H alpha imaging obtained to date. Taken together these results suggest that extremely low-mass galaxies are forming stars in conditions different from those found in more massive systems. While detailed dynamical analysis requires the completion of data acquisition, the most well-resolved system is amenable to meaningful position-velocity analysis. For AGC 749237, we find well-ordered rotation of 30 km s(-1) at similar to 40 '' distance from the dynamical center. At the adopted distance of 3.2 Mpc, this implies the presence of a greater than or similar to 1 x 10(8) M(circle dot) dark matter halo and a baryon fraction less than or similar to 0.1.
Details
- Title: Subtitle
- THE SURVEY OF H I IN EXTREMELY LOW-MASS DWARFS (SHIELD)
- Creators
- John M. Cannon - Macalester CollegeRiccardo Giovanelli - Cornell UniversityMartha P. Haynes - Cornell UniversitySteven Janowiecki - Indiana University BloomingtonAngela Parker - Indiana University BloomingtonJohn J. Salzer - Indiana University BloomingtonElizabeth A. K. Adams - Cornell UniversityEric Engstrom - Macalester CollegeShan Huang - Cornell UniversityKristen B. W. McQuinn - University of MinnesotaJuergen Ott - National Radio Astronomy ObservatoryAmelie Saintonge - Max Planck Institute for AstrophysicsEvan D. Skillman - University of MinnesotaJohn Allan - Macalester CollegeGrace Erny - Macalester CollegePalmer Fliss - Macalester CollegeAnnaLeigh Smith - Macalester College
- Resource Type
- Journal article
- Publication Details
- Astrophysical journal. Letters, Vol.739(1), pp.L22-jQuery1323915814083='48'
- DOI
- 10.1088/2041-8205/739/1/L22
- ISSN
- 2041-8205
- eISSN
- 2041-8213
- Publisher
- Iop Publishing Ltd
- Number of pages
- 7
- Grant note
- Max Planck Society Participating Institutions National Science Foundation; National Science Foundation (NSF) U.S. Department of Energy; United States Department of Energy (DOE) National Aeronautics and Space Administration; National Aeronautics & Space Administration (NASA) Alfred P. Sloan Foundation Higher Education Funding Council for England; UK Research & Innovation (UKRI); Higher Education Funding Council for England (HEFCE) Japanese Monbukagakusho; Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT)
- Language
- English
- Date published
- 09/20/2011
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984627237002771
Metrics
10 Record Views