期刊
ASTROPHYSICAL JOURNAL
卷 692, 期 2, 页码 1447-1463出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/692/2/1447
关键词
dark matter; galaxies: individual (NGC 2903); galaxies: formation; galaxies: spiral; radio lines: ISM
资金
- Alfred P. Sloan Foundation
- NSF
- U. S. Department of Energy
- National Aeronautics and Space Administration
- Japanese Monbukagakusho
- Max Planck Society
- Higher Education Funding Council for England
- STFC [PP/D000920/1, ST/G002630/1] Funding Source: UKRI
- Science and Technology Facilities Council [PP/D000920/1, ST/G002630/1] Funding Source: researchfish
We have conducted a deep, complete H I survey, using Arecibo/Arecibo L-band Feed Array (ALFA), of a field centered on the nearby, isolated galaxy, NGC 2903, which is similar to the Milky Way in its properties. The field size was 150 kpc x 260 kpc and the final velocity range spanned from 100 to 1133 km s(-1). The ALFA beams have been mapped as a function of azimuth and cleaned from each azimuth-specific cube prior to forming final cubes. The final H I data are sensitive down to an H I mass of 2x10(5) M-circle dot and column density of 2 x 10(17) cm(-2) at the 3 sigma 2 delta V level, where sigma is the rms noise level and delta V is the velocity resolution. NGC 2903 is found to have an H I envelope that is larger than previously known, extending to at least three times the optical diameter of the galaxy. Our search for ;companions yields one new discovery with an H I mass of 2.6x10(6) M-circle dot. The companion is 64 kpc from NGC2903 in projection, is likely associated with a small optical galaxy of similar total stellar mass, and is dark matter dominated, with a total mass > 10(8) M-circle dot. In the region surveyed, there are now two known companions: our new discovery and a previously known system that is likely a dwarf spheroidal, lacking H I content. If H I constitutes 1% of the total mass in all possible companions, then we should have detected 230 companions, according to Lambda cold dark matter (Lambda CDM) predictions. Consequently, if this number of dark-matter clumps are indeed present, then they contain less than 1% H I content, possibly existing as very faint dwarf spheroidals or as starless, gasless dark-matter clumps.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据