MUSEQuBES：低红移星系内部及周围含OVI气体的柱密度、覆盖比例与质量
MUSEQuBES: The column density, covering fraction, and mass of OVI-bearing gas in and around low-redshift galaxies
AI总结：
基于MUSEQuBES巡天，本研究分析了低红移星系周围的含OVI气体，发现OVI柱密度与覆盖比例在log(M*/Msun)~9.5处达峰，并指出碰撞电离主导该峰值而矮星系需光致电离等过程，同时证实矮星系维里半径外存在高度电离金属底限。
摘要：
作为MUSE类星体场盲发射体巡天（MUSEQuBES）的一部分，我们利用背景类星体，对247个低红移（0.1 < z < 0.7）低质量（中位数 log(M*/Msun)~8.7）星系周围的含OVI气体进行了研究。我们发现，在样本的维里半径内测得的平均OVI柱密度 ${\rm log}_{10}<N({\rm OVI})/{\rm cm}^{-2}>$ = $14.14^{+0.09}_{-0.10}$，显著低于L_*星系。将文献中的253个恒星形成星系（质量通常更大）与MUSEQuBES的176个恒星形成星系结合，我们发现<N(OVI)>和平均覆盖比例均在 log(M*/Msun)~9.5 处达到峰值。与该恒星质量对应的维里温度非常适合通过碰撞电离产生OVI。然而，我们认为光致电离和/或非平衡过程是产生与低质量矮星系（log(M*/Msun)<9）相关的OVI所必需的。矮星系维里半径内的平均OVI质量测得为 $10^{5.2_{-0.1}^{+0.1}}$ Msun。对于恒星质量为 log(M*/Msun)~9.5 的星系，其OVI覆盖比例降至峰值一半时的特征归一化撞击参数最大（~1.1）。基于中值光谱叠加，我们发现在矮星系维里半径之外存在一个高度电离的金属底限，其 ${\rm log}_{10}(N({\rm OVI})/{\rm cm}^{-2}) = 13.2$。
英文摘要：
We present a study of OVI-bearing gas around 247 low-mass (median log(M*/Msun)~8.7) galaxies at low redshifts (0.1 < z < 0.7) using background quasars as part of the MUSE Quasar-fields Blind Emitters Survey (MUSEQuBES). We find that the average OVI column density, ${\rm log}_{10}<N({\rm OVI})/{\rm cm}^{-2}>$ = $14.14^{+0.09}_{-0.10}$, measured within the virial radius for our sample, is significantly lower than for L_* galaxies. Combining 253 star-forming galaxies (mostly more massive) from the literature with 176 star-forming galaxies from MUSEQuBES, we find that both <N(OVI)> and the average covering fraction peak at log(M*/Msun)~9.5. The virial temperature corresponding to this stellar mass is ideal for OVI production via collisional ionization. However, we argue that photoionization and/or non-equilibrium processes are necessary to produce the OVI associated with low-mass, dwarf galaxies (log(M*/Msun)<9). The average OVI mass within the virial radius of dwarf galaxies is measured to be $10^{5.2_{-0.1}^{+0.1}}$ Msun. The characteristic normalized impact parameter at which the OVI covering fraction drops to half of its peak value is the largest (~1.1) for galaxies with stellar mass log(M*/Msun)~9.5. We report the presence of a highly ionized metal floor with ${\rm log}_{10}(N({\rm OVI})/{\rm cm}^{-2}) = 13.2$ outside the virial radius of dwarf galaxies inferred from median spectral stacking.
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