A COMPREHENSIVE ARCHIVAL SEARCH for COUNTERPARTS to ULTRA-COMPACT HIGH-VELOCITY CLOUDS: FIVE LOCAL VOLUME DWARF GALAXIES

D. J. Sand, D. Crnojević, P. Bennet, B. Willman, J. Hargis, J. Strader, Edward W Olszewski, E. J. Tollerud, J. D. Simon, N. Caldwell, P. Guhathakurta, B. L. James, S. Koposov, B. McLeod, N. Morrell, M. Peacock, R. Salinas, A. C. Seth, Daniel P Stark, E. Toloba

Research output: Contribution to journalArticle

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Abstract

We report five Local Volume dwarf galaxies (two of which are presented here for the first time) uncovered during a comprehensive archival search for optical counterparts to ultra-compact high-velocity clouds (UCHVCs). The UCHVC population of HI clouds are thought to be candidate gas-rich, low-mass halos at the edge of the Local Group and beyond, but no comprehensive search for stellar counterparts to these systems has been presented. Careful visual inspection of all publicly available optical and ultraviolet imaging at the position of the UCHVCs revealed six blue, diffuse counterparts with a morphology consistent with a faint dwarf galaxy beyond the Local Group. Optical spectroscopy of all six candidate dwarf counterparts show that five have an H-derived velocity consistent with the coincident HI cloud, confirming their association; the sixth diffuse counterpart is likely a background object. The size and luminosity of the UCHVC dwarfs is consistent with other known Local Volume dwarf irregular galaxies. The gas fraction () of the five dwarfs are generally consistent with that of dwarf irregular galaxies in the Local Volume, although ALFALFA-Dw1 (associated with ALFALFA UCHVC HVC274.68+74.70-123) has a very high ∼ 40. Despite the heterogenous nature of our search, we demonstrate that the current dwarf companions to UCHVCs are at the edge of detectability due to their low surface brightness, and that deeper searches are likely to find more stellar systems. If more sensitive searches do not reveal further stellar counterparts to UCHVCs, then the dearth of such systems around the Local Group may be in conflict with ΛCDM simulations.

Original languageEnglish (US)
Article number95
JournalAstrophysical Journal
Volume806
Issue number1
DOIs
StatePublished - Jun 10 2015

Fingerprint

dwarf galaxies
irregular galaxies
stellar systems
gases
gas
inspection
halos
brightness
spectroscopy
luminosity

Keywords

  • galaxies: dwarf
  • galaxies: individual (ALFALFA-Dw1, GALFA-Dw1, GALFA-Dw2, GALFA-Dw3, GALFA-Dw4)
  • radio lines: galaxies

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

A COMPREHENSIVE ARCHIVAL SEARCH for COUNTERPARTS to ULTRA-COMPACT HIGH-VELOCITY CLOUDS : FIVE LOCAL VOLUME DWARF GALAXIES. / Sand, D. J.; Crnojević, D.; Bennet, P.; Willman, B.; Hargis, J.; Strader, J.; Olszewski, Edward W; Tollerud, E. J.; Simon, J. D.; Caldwell, N.; Guhathakurta, P.; James, B. L.; Koposov, S.; McLeod, B.; Morrell, N.; Peacock, M.; Salinas, R.; Seth, A. C.; Stark, Daniel P; Toloba, E.

In: Astrophysical Journal, Vol. 806, No. 1, 95, 10.06.2015.

Research output: Contribution to journalArticle

Sand, DJ, Crnojević, D, Bennet, P, Willman, B, Hargis, J, Strader, J, Olszewski, EW, Tollerud, EJ, Simon, JD, Caldwell, N, Guhathakurta, P, James, BL, Koposov, S, McLeod, B, Morrell, N, Peacock, M, Salinas, R, Seth, AC, Stark, DP & Toloba, E 2015, 'A COMPREHENSIVE ARCHIVAL SEARCH for COUNTERPARTS to ULTRA-COMPACT HIGH-VELOCITY CLOUDS: FIVE LOCAL VOLUME DWARF GALAXIES', Astrophysical Journal, vol. 806, no. 1, 95. https://doi.org/10.1088/0004-637X/806/1/95
Sand, D. J. ; Crnojević, D. ; Bennet, P. ; Willman, B. ; Hargis, J. ; Strader, J. ; Olszewski, Edward W ; Tollerud, E. J. ; Simon, J. D. ; Caldwell, N. ; Guhathakurta, P. ; James, B. L. ; Koposov, S. ; McLeod, B. ; Morrell, N. ; Peacock, M. ; Salinas, R. ; Seth, A. C. ; Stark, Daniel P ; Toloba, E. / A COMPREHENSIVE ARCHIVAL SEARCH for COUNTERPARTS to ULTRA-COMPACT HIGH-VELOCITY CLOUDS : FIVE LOCAL VOLUME DWARF GALAXIES. In: Astrophysical Journal. 2015 ; Vol. 806, No. 1.
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AU - Hargis, J.

AU - Strader, J.

AU - Olszewski, Edward W

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