THE WEAK CARBON MONOXIDE EMISSION IN AN EXTREMELY METAL-POOR GALAXY, SEXTANS A
THE WEAK CARBON MONOXIDE EMISSION IN AN EXTREMELY METAL-POOR GALAXY, SEXTANS A
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金属极度贫乏的星系中微弱的一氧化碳排放，六分星
DOI：
10.1088/2041-8205/804/1/l11
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发表时间：
2015-05-01
影响因子：
7.9
通讯作者：
Stierwalt, Sabrina
中科院分区：
文献类型：
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作者：
Shi, Yong;Wang, Junzhi;Stierwalt, Sabrina
一氧化碳（CO）是气体的主要冷却剂之一，也是螺旋星系中容易获得的分子气体示踪剂，但目前尚不清楚CO是否在缺乏金属的矮星中起着类似的作用。我们利用IRAM 30 m进行了深度观测，以附近一个金属含量为7%的极贫星系六分星a中最亮的远红外峰为目标，寻找CO发射。观测到CO J = 1−0发射的边缘信号，该信号已经足够微弱，足以对转换因子(&agr; CO ？>)从CO亮度到分子气体质量，这是由空间分辨的尘埃质量图得出的。agr;有限公司?>至少是银河系的700倍。这表明六分星A的CO排放非常微弱，挑战了它在金属极度缺乏的星系中作为冷却剂的作用。
Carbon monoxide (CO) is one of the primary coolants of gas and an easily accessible tracer of molecular gas in spiral galaxies, but it is unclear if CO plays a similar role in metal-poor dwarfs. We carried out a deep observation with IRAM 30 m to search for CO emission by targeting the brightest far-IR peak in a nearby extremely metal-poor galaxy, Sextans A, with 7% solar metallicity. A marginal signal of CO J = 1 − 0 emission is seen, which is already faint enough to place a strong constraint on the conversion factor ( &agr; CO ?> ) from the CO luminosity to the molecular gas mass that is derived from the spatially resolved dust-mass map. The &agr; CO ?> is at least seven hundred times the Milky Way value. This indicates that CO emission is exceedingly weak in Sextans A, challenging its role as a coolant in extremely metal-poor galaxies.