AI 中文总结
该研究利用DES和DESI数据，通过交叉示踪聚类比测量椭圆星系和旋涡星系的偏差及相对偏差，发现椭圆星系聚类更强且偏差与尺度有关，新发现为星系形态影响偏差提供证据，确立CTCR可用于测试相关模型。
AI 中文摘要
我们利用暗能量调查（DES）和暗能量光谱巡天遗产成像调查（DESI）DR8的角自功率谱和交叉功率谱，对椭圆星系和旋涡星系的星系偏差及尺度依赖相对偏差进行了数据驱动测量。我们引入交叉示踪聚类比（CTCR），通过自功率谱与交叉功率谱之比来分离形态示踪的相对聚类作为角多极$\ell$的函数。在两项调查中，椭圆星系比旋涡星系聚类更强；DESI给出了最清晰的CTCR限制。差异与尺度有关：在大角尺度$\ell \lesssim 50$时相对偏差接近1，但向小尺度增加，在$\ell \sim 150 - 200$时平均分离达到$2.6\sigma$。线性偏差分析证实椭圆星系相对于物质场正偏差，旋涡星系与弱偏差或反偏差一致。椭圆星系样本红移演化小，与更广泛的晕质量分布一致。结果对两种协方差估计器、污染测试、光度划分以及与两个N体模拟目录的比较都很稳健。这些新发现为星系形态对星系偏差的幅度和尺度依赖性产生影响提供了经验证据，并确立CTCR作为未来成像调查测试晕占据和组装偏差模型的有用可观测量。
英文摘要
We present a data-driven measurement of galaxy bias and scale-dependent relative bias for elliptical and spiral galaxies using angular auto- and cross-power spectra from DES and DESI Legacy Imaging Surveys DR8. We introduce the cross-tracer clustering ratio (CTCR), which uses the ratio of auto- to cross-power spectra to isolate the relative clustering of morphological tracers as a function of angular multipole $\ell$. Across both surveys, ellipticals are more strongly clustered than spirals; the cleanest CTCR constraints come from DESI, where the two morphological samples have better-matched redshift distributions. The difference is scale dependent: the relative bias is close to unity on large angular scales, $\ell \lesssim 50$, but increases toward smaller scales, reaching an average separation of $2.6σ$ at $\ell \sim 150-200$. A complementary linear-bias analysis confirms that ellipticals are positively biased relative to the matter field, while spirals are consistent with weak bias or anti-bias. Unlike narrowly selected LRG samples, our morphologically selected elliptical samples show little redshift evolution, consistent with a broader halo-mass distribution. The results are robust to two covariance estimators, contamination tests, luminosity splits, and comparisons with two N-body mock catalogs. These new findings provide empirical evidence that galaxy morphology imprints both the amplitude and scale dependence of galaxy bias, and establish CTCR as a useful observable for testing halo occupation and assembly-bias models with future imaging surveys.
