Systematically Measuring Ultra-diffuse Galaxies (SMUDGes). III. The Southern SMUDGes Catalog
Systematically Measuring Ultra-diffuse Galaxies (SMUDGes). III. The Southern SMUDGes Catalog
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DOI：
10.3847/1538-4365/ac6ceb
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发表时间：
2022-05
期刊：
影响因子：
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通讯作者：
D. Zaritsky;R. Donnerstein;A. Karunakaran;C. E. Barbosa;A. Dey;J. Kadowaki;K. Spekkens;H. Zhang 张
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文献类型：
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作者：
D. Zaritsky;R. Donnerstein;A. Karunakaran;C. E. Barbosa;A. Dey;J. Kadowaki;K. Spekkens;H. Zhang 张
我们提出了一个目录的5598超扩散星系（UDG）的候选人与有效半径r e > 5.″3分布在整个南部的DESI遗产成像调查覆盖15,000 deg 2。对于红移范围为1800 cz/km s−1 <$7000的物理大（r e > 2.5 kpc）UDG，星表是最完整的，其中下限由天空中大天体的不完整性变得显著的地方定义，上限由我们的最小角尺寸选择标准定义。由于物理尺寸是不可或缺的UDG的定义，我们开发了一种方法，使用现有的红移调查的距离估计。使用三个不同的星系样本，其中两个包含具有光谱红移的UDG，我们估计当该方法收敛时，该方法的红移精度为1.75%，尽管需要更大，更有代表性的光谱UDG样本才能完全理解该方法的行为。我们能够估计1079个UDG候选人（19%）的距离。最后，为了说明一些使用的目录，我们提出了距离无关和距离相关的结果。在后一类中，我们建立的红色序列的UDG在于外推的红色序列关系的明亮的椭圆和环境颜色的关系是至少定性类似的高表面亮度星系。这两个结果都对UDG进化的一些模型提出了挑战。
We present a catalog of 5598 ultra-diffuse galaxy (UDG) candidates with effective radius r e > 5.″3 distributed throughout the southern portion of the DESI Legacy Imaging Survey covering ∼15,000 deg2. The catalog is most complete for physically large (r e > 2.5 kpc) UDGs lying in the redshift range 1800 ≲ cz/km s−1 ≲ 7000, where the lower bound is defined by where incompleteness becomes significant for large objects on the sky and the upper bound by our minimum angular size selection criterion. Because physical size is integral to the definition of a UDG, we develop a method of distance estimation using existing redshift surveys. With three different galaxy samples, two of which contain UDGs with spectroscopic redshifts, we estimate that the method has a redshift accuracy of ∼75% when the method converges, although larger, more representative spectroscopic UDG samples are needed in order to fully understand the behavior of the method. We are able to estimate distances for 1079 of our UDG candidates (19%). Finally, to illustrate some uses of the catalog, we present both distance-independent and distance-dependent results. In the latter category, we establish that the red sequence of UDGs lies on the extrapolation of the red sequence relation for bright ellipticals and that the environment–color relation is at least qualitatively similar to that of high surface brightness galaxies. Both of these results challenge some of the models proposed for UDG evolution.