We present the star-forming properties of 378 satellite galaxies around 101 Milky Way analogs in the Satellites Around Galactic Analogs (SAGA) Survey, focusing on the environmental processes that suppress or quench star formation. In the SAGA stellar mass range of 106−10M⊙, we present quenched fractions, star-forming rates, gas-phase metallicities, and gas content. The fraction of SAGA satellites that are quenched increases with decreasing stellar mass and shows significant system-to-system scatter. SAGA satellite quenched fractions are highest in the central 100 kpc of their hosts and decline out to the virial radius. Splitting by specific star formation rate (sSFR), the least star-forming satellite quartile follows the radial trend of the quenched population. The median sSFR of star-forming satellites increases with decreasing stellar mass and is roughly constant with projected radius. Star-forming SAGA satellites are consistent with the star formation rate–stellar mass relationship determined in the Local Volume, while the median gas-phase metallicity is higher and median H i gas mass is lower at all stellar masses. We investigate the dependence of the satellite quenched fraction on host properties. Quenched fractions are higher in systems with larger host halo mass, but this trend is only seen in the inner 100 kpc; we do not see significant trends with host color or star formation rate. Our results suggest that lower-mass satellites and satellites inside 100 kpc are more efficiently quenched in a Milky Way–like environment, with these processes acting sufficiently slowly to preserve a population of star-forming satellites at all stellar masses and projected radii.

中文翻译：

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SAGA 调查。IV. 围绕银河系质量星系的 101 个卫星系统的恒星形成特性


我们在银河系类似物卫星 （SAGA） 巡天中介绍了围绕 101 个银河系类似物的 378 个卫星星系的恒星形成特性，重点关注抑制或淬灭恒星形成的环境过程。在 106-10M⊙ 的 SAGA 恒星质量范围内，我们给出了淬灭分数、恒星形成速率、气相金属丰度和气体含量。被淬灭的 SAGA 卫星的比例随着恒星质量的减小而增加，并显示出显着的系统间散射。SAGA 卫星猝灭部分在其宿主的中心 100 kpc 中最高，并下降到维里半径。按特定恒星形成速率 （sSFR） 划分，恒星形成最少的卫星四分位数遵循猝灭种群的径向趋势。恒星形成卫星的中位 sSFR 随着恒星质量的减小而增加，并且与投影半径大致相同。形成恒星的 SAGA 卫星与本体积中确定的恒星形成速率-恒星质量关系一致，而在所有恒星质量下，气相金属丰度的中位数较高，而 H i 气体质量的中位数较低。我们研究了卫星猝灭分数对宿主特性的依赖性。在具有较大主晕质量的系统中，淬灭馏分较高，但这种趋势仅在内部 100 kpc 中出现;我们没有看到宿主颜色或恒星形成速率的显著趋势。我们的结果表明，在类似银河系的环境中，低质量卫星和 100 kpc 以内的卫星被更有效地淬灭，这些过程作用得足够慢，可以保存所有恒星质量和投影半径的恒星形成卫星群。