发表机构
Pontificia Universidad Católica de Valparaíso; Universidad Técnica Federico Santa María; Leibniz-Institut for Astrophysik Potsdam (AIP); The University of Tokyo; University of California, Santa Cruz; New Mexico State University; University of Edinburgh; University of Washington; CONICET-Universidad Nacional de Córdoba（智利天主教瓦帕莱索大学; 费德里科·圣塔玛丽亚理工大学; 波茨坦阿基米德天体物理研究所; 东京大学; 加州大学圣克鲁兹分校; 新墨西哥州立大学; 爱丁堡大学; 华盛顿大学; 阿根廷国家科学研究委员会-科尔多瓦国立大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究通过HST/COS的远紫外吸收光谱，分析连接大质量星系团的宇宙网纤维附近HI、OVI等WHIM示踪物的发生率，发现其超额与覆盖分数显著高于冷气体示踪物，为探测星系团间纤维的WHIM提供了潜在信号。
AI 中文摘要
在红移z<1时，ΛCDM范式预测约40-50%的重子物质以温热星系际介质（WHIM）的形式存在于宇宙网纤维中。表征这一主导重子成分的物理状态与分布，对于完整认识低红移宇宙中的重子演化至关重要。然而，由于WHIM密度低、温度高且电离状态特殊，直接观测它颇具挑战。吸收线光谱学提供了一种有前景的方法，尤其通过对宽Ly-α吸收体（BLAs；多普勒参数b>40 km/s）和OVI吸收体的分析。本研究聚焦于探测WHIM信号，分析这些示踪物在连接大质量星系团的推定宇宙网纤维内部及周围的发生率。我们利用HST/COS获取的远紫外（FUV）吸收光谱，覆盖10条红移z<1的类星体（QSO）视线，这些视线因与星系团对在投影距离和速度上接近而被选中。我们重点研究WHIM示踪物（BLAs和OVI）以及冷气体示踪物（窄Ly-α吸收体，即NLAs；b<40 km/s）的吸收特征，其中NLAs用作冷气体的对照样本。我们测量了在静止帧Δv=±1000 km/s且 impact参数Δd<3 Mpc范围内，总HI、NLAs、BLAs和OVI相对于场预期的超额发生率，发现BLAs和OVI的超额约为NLAs的两倍。此外，BLAs和OVI的覆盖分数分别比随机场对照样本大约1.7倍和1.8倍，而NLA的覆盖分数与随机预期一致。在独立星系团对附近，WHIM示踪物相对于冷气体示踪物的更大相对超额，表明温热气体在这些环境中普遍存在，这代表了在星系团间纤维中探测WHIM的潜在信号。
英文摘要
At redshift z<1, the $Λ$CDM paradigm predicts that $\sim$40-50\% of baryons reside in the warm-hot intergalactic medium (WHIM) within cosmic web filaments. Characterizing the physical state and distribution of this dominant baryonic component is crucial for a complete picture of baryon evolution in the low-redshift Universe. However, directly observing the WHIM has been challenging due to its low density and high temperature and ionization state. Absorption-line spectroscopy offers a promising approach, particularly through analyses of broad Ly-$α$ absorbers (BLAs; Doppler parameter b>40 km/s) and OVI absorbers. This work focuses on probing WHIM signatures by analyzing the incidence rates of these tracers in and around putative cosmic web filaments connecting massive galaxy clusters. We use far-ultraviolet (FUV) absorption spectroscopy from HST/COS along ten QSO sightlines at z<1, selected for their proximity in projected distance and velocity to cluster pairs. We focus on absorption features of WHIM tracers (BLAs and OVI) and cold-gas tracers (narrow Ly-$α$ absorbers, or NLAs; b<40 km/s), which are used as a control sample for colder gas. We measure excess incidence rates for total HI, NLAs, BLAs, and OVI within a rest-frame $Δv=\pm1000$ km/s and an impact parameter $Δd<3$ Mpc relative to the field expectation, and find that the excesses of BLAs and OVI are about twice those of NLAs. Additionally, the covering fractions of BLAs and OVI appear larger by factors of $\sim$1.7 and 1.8, respectively, than in a random field control sample, whereas the NLA covering fraction is consistent with the random expectation. The larger relative excess of WHIM tracers compared to cold-gas tracers near independent cluster pairs indicates the prevalence of warm-hot gas in these environments, representing a potential signature of WHIM detection in inter-cluster filaments.
