AI 中文总结
本研究利用SDSS-V LVM对ω Cen的观测，绘制其自转并验证LVM数据精度，以高信噪比积分光谱测试SSP模板库，揭示古老多星族系统积分光研究的系统误差下限。
AI 中文摘要
SDSS-V本地体积测绘仪（LVM）是一项针对南银道面、麦哲伦云及近邻本星系群星系的大视场积分场光谱巡天项目。我们利用对最近的核星团半人马座ω星团（ω Cen）整体的早期科学观测，将LVM的应用范围扩展至其原有的星际介质科学研究范畴之外。LVM的大视场能力使我们能精确测绘ω Cen的视线方向自转，覆盖至约3倍半光半径（$r_{HL}$）或15角分，在$r \neq 4.7$角分处达到最大值$(8.4 \neq 0.8)$千米每秒。在中心区域，与现有VLT MUSE oMEGACat数据的对比明确显示，未分辨光信号由少量亮星主导，每个分辨率单元的有效样本量仅约12颗。我们以Gaia DR3为外部参考，验证了SDSS-V的LVM处理管线可在6个表面亮度星等范围内，将积分恒星光度恢复至1-4%的精度。我们得到的ω Cen总光谱是所有球状星团或核星团中最高信噪比（S/N）的积分光谱之一。利用该光谱，我们针对来自oMEGACat的已分辨年龄-金属丰度真值，测试了4种广泛使用的单星族（SSP）模板库。所有模板均恢复出古老、贫金属的星族，但即便在S/N约1300的情况下，不同模板库及波长范围内推断出的平均年龄和平均铁丰度([Fe/H])仍分别存在约7亿年和约0.4 dex的差异，这反映了古老多星族系统积分光研究的系统误差下限。
英文摘要
The SDSS-V Local Volume Mapper (LVM) is a wide-field integral field spectroscopic survey of the Southern Milky Way plane, the Magellanic Clouds, and nearby Local Group galaxies. We use Early Science observations of the whole body of the nearest nuclear cluster, Omega Centauri, to extend the LVM beyond its primary interstellar-medium science case. The wide LVM field allows us to precisely map $ω$ Cen's line-of-sight rotation out to $\sim 3r_{HL}$ or $15^\prime$, reaching a maximum value of $(8.4 \pm 0.8)$ km s$^{-1}$ at $r \approx 4.7^\prime$. Within the central region, comparisons with existing VLT MUSE oMEGACat data show explicitly that the unresolved-light signal is dominated by a small number of bright stars, with an effective sample size of only $\sim$12 per resolution element. Using Gaia DR3 as an external reference, we verify that the SDSS-V's LVM reduction pipeline recovers integrated stellar fluxes to 1-4 % across six magnitudes of surface brightness. Our resulting total spectrum of $ω$ Cen is one of the highest S/N integrated spectrum for any globular or nuclear star cluster. We use it to test four widely-used SSP template libraries against resolved age-metallicity ground truth from oMEGACat. All templates recover an old, metal-poor population. But, even at S/N $\sim$1300, the inferred mean ages and mean [Fe/H] vary by $\sim$7 Gyr and $\sim$0.4 dex, respectively, across libraries and wavelength ranges, reflecting a systematic floor for integrated-light studies of old multi-population systems.
Comments16 pages, 13 figures. Accepted for publication in Astronomy & Astrophysics
