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

被引：42

作者：

Sand, D. J. ^{[1
]}

Crnojevic, D. ^{[1
]}

Bennet, P. ^{[1
]}

Willman, B. ^{[2
]}

Hargis, J. ^{[2
]}

Strader, J. ^{[3
]}

Olszewski, E. ^{[4
]}

Tollerud, E. J. ^{[5
]}

Simon, J. D. ^{[6
]}

Caldwell, N. ^{[8
]}

Guhathakurta, P. ^{[10
]}

James, B. L. ^{[7
]}

Koposov, S. ^{[7
]}

McLeod, B. ^{[8
]}

Morrell, N. ^{[9
]}

Peacock, M. ^{[3
]}

Salinas, R. ^{[3
]}

Seth, A. C. ^{[11
]}

Stark, D. P. ^{[4
]}

Toloba, E. ^{[1
]}

机构：

[1] Texas Tech Univ, Dept Phys, Lubbock, TX 79409 USA

[2] Haverford Coll, Dept Phys, Haverford, PA 19041 USA

[3] Michigan State Univ, Dept Phys & Astron, E Lansing, MI 48824 USA

[4] Univ Arizona, Tucson, AZ 85721 USA

[5] Yale Univ, Dept Astron, New Haven, CT 06510 USA

[6] Observ Carnegie Inst Sci, Pasadena, CA 91101 USA

[7] Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England

[8] Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA

[9] Carnegie Observ, Las Campanas Observ, La Serena, Chile

[10] Univ Calif Santa Cruz, Lick Observ, UCO, Santa Cruz, CA 95064 USA

[11] Univ Utah, Dept Phys & Astron, Salt Lake City, UT 84112 USA

来源：

ASTROPHYSICAL JOURNAL | 2015年 / 806卷 / 01期

基金：

美国国家科学基金会;

关键词：

galaxies: dwarf; galaxies:; individual; (ALFALFA-Dw1; GALFA-Dw1; GALFA-Dw2; GALFA-Dw3; GALFA-Dw4); radio lines: galaxies; DIGITAL SKY SURVEY; FAST ALPHA SURVEY; ALFALFA DISCOVERY; H I; VIRGO CLUSTER; STRUCTURAL-PROPERTIES; DATA RELEASE; DEEP SURVEY; LEO-T; GAS;

D O I：

10.1088/0004-637X/806/1/95

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

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 alpha-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 (M-HI/M-star) 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 M-HI/M-star similar to 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 Lambda CDM simulations.

引用

页数：13

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