Wide angle and deep surveys, regardless of their primary purpose, always sample a large number of stars in the Galaxy and in its satellite system. Here we make a forecast of the expected stellar sample resulting from the Dark Energy Survey (DES) and the perspectives that it will open for studies of Galactic structure and resolved stellar populations in general. An estimated 1.2 × 108 stars will be sampled in DES grizY filters in the southern equatorial hemisphere. This roughly corresponds to 20% of all DES sources. Most of these stars belong to the stellar thick disk and halo of the Galaxy. DES will probe low-mass stellar and sub-stellar objects at depths from three to eight times larger than those in the Sloan Digital Sky Survey (SDSS). The faint end of the main sequence (MS) will be densely sampled beyond 10?kpc. The slope of the low mass end of the stellar initial mass function (IMF) will be constrained to within a few hundredths of dex, even in the thick disk and halo. In the sub-stellar mass regime, the IMF slope will be potentially constrained to within dlog (m)/dlog m 0.1. About 3 × 104 brown dwarf candidates and at least 7.6 × 105 white dwarf candidates will be selected, the latter embedded into the thick disk and halo, for future follow-up. The stellar halo flattening will also be constrained to within a few percent. DES will probe the MS of new Milky Way satellites and halo clusters for distances out to 120?kpc, therefore yielding stellar surface density contrasts 1.6-1.7 times larger than those attainable with SDSS. It will also allow detection of these objects in the far reaches of the stellar halo, substantially increasing the number and quality of probes to the Galactic potential. Combined with northern samples, such as the SDSS, the DES stellar sample will yield constraints on the structure and stellar populations of Galactic components in unprecedented detail. In particular, the combined sample from both hemispheres will allow detailed studies of halo and thick disk asymmetries and triaxiality.
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机译：不管其主要目的是什么，广角和深层勘测总是对银河系及其卫星系统中的大量恒星进行采样。在这里，我们对由暗能量调查（DES）产生的预期恒星样本进行了预测，并展望了它将为研究银河结构和一般恒星群体提供的前景。估计在赤道南半球的DES灰度滤镜中将采样到1.2×108颗恒星。这大约相当于所有DES来源的20％。这些恒星大部分属于银河系恒星的厚盘和光晕。 DES将探测低质量的恒星和亚星状物体，深度是斯隆数字天空测量（SDSS）的三到八倍。主序列（MS）的微弱末端将被密集采样超过10？kpc。恒星初始质量函数（IMF）的低质量端的斜率将被限制在dex的百分之几以内，即使在厚的圆盘和晕圈中也是如此。在星下质量状态下，IMF斜率可能会限制在dlog（m）/ dlog m 0.1以内。将选择大约3×104的棕色矮人候选者和至少7.6×105的白色矮人候选者，后者嵌入厚盘和光环中，以备将来之用。恒星晕平展度也将被限制在百分之几之内。 DES将探测新银河系卫星和晕圈星群的MS，其距离可达120？kpc，因此产生的恒星表面密度对比度是SDSS的1.6-1.7倍。它还可以在恒星晕的远处检测到这些物体，从而大大增加了银河系潜能的探测器的数量和质量。 DES恒星样本与北部样本（如SDSS）相结合，将以前所未有的细节限制银河系成分的结构和恒星种群。特别是，来自两个半球的组合样品将允许对晕圈和厚盘不对称性及三轴性进行详细研究。
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