Journal article
The ALFALFA Almost Dark Galaxy AGC 229101: A 2 Billion Solar Mass HI Cloud with a Very Low Surface Brightness Optical Counterpart
The Astronomical journal, Vol.162(6), 274
12/01/2021
DOI: 10.3847/1538-3881/ac2a38
Abstract
We present results from deep H I and optical imaging of AGC 229101, an unusual H I source detected at nu(helio) =7116 km s(-1) in the Arecibo Legacy Fast ALFA (ALFALFA) blind H I survey. Initially classified as a candidate "dark" source because it lacks a clear optical counterpart in Sloan Digital Sky Survey (SDSS) or Digitized Sky Survey 2 (DSS2) imaging, AGC 229101 has 10(9.31 +/- 0.05) M-circle dot of H I, but an H I line width of only 43 +/- 9 km s(-1). Low-resolution Westerbork Synthesis Radio Telescope (WSRT) imaging and higher-resolution Very Large Array (VLA) B-array imaging show that the source is significantly elongated, stretching over a projected length of similar to 80 kpc. The H I imaging resolves the source into two parts of roughly equal mass. WIYN partially populated One Degree Imager (pODI) optical imaging reveals a faint, blue optical counterpart coincident with the northern portion of the H I. The peak surface brightness of the optical source is only mu(g) similar to 26.6 mag arcsec(-2), well below the typical cutoff that defines the isophotal edge of a galaxy, and its estimated stellar mass is only 10(7.32 +/- 0.33) M-circle dot, yielding an overall neutral gas-to-stellar mass ratio of M/M-* = 98(-52)(+111). We demonstrate the extreme nature of this object by comparing its properties with those of other H I-rich sources in ALFALFA and the literature. We also explore potential scenarios that might explain the existence of AGC 229101, including a tidal encounter with neighboring objects and a merger of two dark H I clouds.
Details
- Title: Subtitle
- The ALFALFA Almost Dark Galaxy AGC 229101: A 2 Billion Solar Mass HI Cloud with a Very Low Surface Brightness Optical Counterpart
- Creators
- Lukas Leisman - Valparaiso UniversityKatherine L. Rhode - Indiana University BloomingtonCatherine Ball - Macalester CollegeHannah J. Pagel - Indiana University BloomingtonJohn M. Cannon - Macalester CollegeJohn J. Salzer - Indiana University BloomingtonSteven Janowiecki - Univ Texas, McDonald Observ, Hobby Eberly Telescope, Ft Davis, TX 79734 USAWilliam F. Janesh - Case Western Reserve UniversityGyula I. G. Jozsa - Rhodes UniversityRiccardo Giovanelli - Cornell UniversityMartha P. Haynes - Cornell UniversityElizabeth A. K. Adams - University of GroningenLaurin Gray - Indiana University BloomingtonNicholas J. Smith - Indiana University Bloomington
- Resource Type
- Journal article
- Publication Details
- The Astronomical journal, Vol.162(6), 274
- Publisher
- IOP Publishing Ltd
- DOI
- 10.3847/1538-3881/ac2a38
- ISSN
- 0004-6256
- eISSN
- 1538-3881
- Number of pages
- 14
- Grant note
- Max Planck Society U.S. Department of Energy; United States Department of Energy (DOE) National Aeronautics and Space Administration; National Aeronautics & Space Administration (NASA) Brinson Foundation University of Illinois College of Arts & Sciences at Indiana University (IU) 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) Valparaiso University AST-2009894; AST-0607007; AST-1107390; AST-2045371; AST-1615483; AST-1100968 / NSF; National Science Foundation (NSF) WISE research programme - Dutch Research Council (NWO) National Science Foundation; National Science Foundation (NSF) DP150101734 / Australian Research Councils; Australian Research Council Macalester College Alfred P. Sloan Foundation
- Language
- English
- Date published
- 12/01/2021
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984627282202771
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