天体物理学以及天体化学Astrophysics Astrochemistry

Spatial variations in aromatic hydrocarbon emission in a dust-rich galaxy

富灰尘星系中芬芳烃排放的空间变迁

▲ 作者：Justin S. Spilker, Kedar A. Phadke, Manuel Aravena, Melanie Archipley, Matthew B. Bayliss, Jack E. Birkin, Matthieu B thermin, James Burgoyne, Jared Cathey, Scott C. Chapman, H?kon Dahle, Anthony H. Gonzalez, Gayathri Gururajan, Christopher C. Hayward, Yashar D. Hezaveh, Ryley Hill, Taylor A. Hutchison, Keunho J. Kim, Seonwoo Kim, David Law, Ronan Legin, Matthew A. Malkan, Daniel P. Marrone, Eric J. Murphy, Katherine E. Whitaker Show authors

▲ 链接：

https://www.nature.com/articles/s41586-023-05998-6

▲ 择要：

于整个宇宙汗青中，灰尘颗粒接收了恒星发出的一半辐射，并以红外波长从头发射这些能量。多环芳烃（PAHs）是一种年夜型无机份子，可追踪毫米巨细的灰尘颗粒，并调治星系内星际气体的冷却。因为之前的红外千里镜的敏捷度以及波长笼罩规模有限，于很是遥远的星系中不雅测多环芳烃的特性始终很坚苦。研究者展示了詹姆斯韦伯太空千里镜于年夜爆炸后不到15亿年不雅测到的星系中探测到3.3 m多环芬芳烷特性的不雅测成果。多环芳烃特性的高档效宽度注解，整个星系的红外发射重要是恒星造成，而不是黑洞吸积。

多环芳烃份子、热灰尘、年夜灰尘颗粒以及恒星发出的光于空间上相互差别，致使多环芳烃等效宽度以及多环芳烃与整个星系的总红外光度之比发生了数目级的变迁。研究者不雅察到的空间变迁注解，多环芳烃与年夜灰尘颗粒之间存于物理偏移，或者者于局部紫外线辐射场中存于较年夜差异。咱们的不雅察注解，多环芳烃份子以及年夜灰尘颗粒的发射差异是初期星系局部历程的繁杂成果。

▲ Abstract：

Dust grains absorb half of the radiation emitted by stars throughout the history of the universe, re-emitting this energy at infrared wavelengths. Polycyclic aromatic hydrocarbons (PAHs) are large organic molecules that trace millimetre-size dust grains and regulate the cooling of interstellar gas within galaxies. Observations of PAH features in very distant galaxies have been difficult owing to the limited sensitivity and wavelength coverage of previous infrared telescopes. Here we present James Webb Space Telescope observations that detect the 3.3? m PAH feature in a galaxy observed less than 1.5?billion years after the Big Bang. The high equivalent width of the PAH feature indicates that star formation, rather than black hole accretion, dominates infrared emission throughout the galaxy. The light from PAH molecules, hot dust and large dust grains and stars are spatially distinct from one another, leading to order-of-magnitude variations in PAH equivalent width and ratio of PAH to total infrared luminosity across the galaxy. The spatial variations we observe suggest either a physical offset between PAHs and large dust grains or wide variations in the local ultraviolet radiation field. Our observations demonstrate that differences in emission from PAH molecules and large dust grains are a complex result of localized processes within early galaxies.

A metal-poor star with abundances from a pair-instability supernova

贫金属恒星金属品貌来自一对于不不变的超新星

▲ 作者：Qian-Fan Xing, Gang Zhao, Zheng-Wei Liu, Alexander Heger, Zhan-Wen Han, Wako Aoki, Yu-Qin Chen, Miho N. Ishigaki, Hai-Ning Li Jing-Kun Zhao

▲ 链接：

https://www.nature.com/articles/s41586-023-06028-1

▲ 择要：

品质最年夜、寿命最短的恒星主导着前星河系时代的化学演化。于数值模仿的根蒂根基上，人们早就猜度这种第一代恒星的品质可达数百个太阳品质。

超年夜品质的第一代恒星的品质规模于140到260太阳品质之间，估计会经由过程对于不不变超新星富厚初期星际介质。然而，颠末几十年的不雅测起劲，还没有能怪异辨认出云云伟大的恒星于星河系中最缺少金属的恒星上留下的印记。

研究者陈诉了一颗极低钠以及钴品貌的金属极贫恒星的化学身分。这颗恒星中钠与铁的比值比太阳低两个数目级以上。这颗恒星的奇电荷数以及偶电荷数元素的品貌差异很是年夜，好比钠/镁以及钴/镍。

这类奇异的奇偶效应，加之钠以及 元素的缺少，与对证量跨越140个太阳品质的恒星孕育发生的原始对于不不变超新星的猜测相一致。这提供了一个清楚的化学特性，注解初期宇宙中存于很是年夜品质的恒星。

▲ Abstract：

The most massive and shortest-lived stars dominate the chemical evolution of the pre-galactic era. On the basis of numerical simulations, it has long been speculated that the mass of such first-generation stars was up to several hundred solar masses1,2,3,4. The very massive first-generation stars with a mass range from 140 to 260 solar masses are predicted to enrich the early interstellar medium through pair-instability supernovae (PISNe). Decades of observational efforts, however, have not been able to uniquely identify the imprints of such very massive stars on the most metal-poor stars in the Milky Way. Here we report the chemical composition of a very metal-poor (VMP) star with extremely low sodium and cobalt abundances. The sodium with respect to iron in this star is more than two orders of magnitude lower than that of the Sun. This star exhibits very large abundance variance between the odd- and even-charge-number elements, such as sodium/magnesium and cobalt/nickel. Such peculiar odd even effect, along with deficiencies of sodium and elements, are consistent with the prediction of primordial pair-instability supernova (PISN) from stars more massive than 140 solar masses. This provides a clear chemical signature indicating the existence of very massive stars in the early universe.

物理学Physics

Density-wave ordering in a unitary Fermi gas with photon-mediated interactions

具备光子介导彼此作用的单一费米气体中的密度波有序

▲ 作者：Victor Helson, Timo Zwettler, Farokh Mivehvar, Elvia Colella, Kevin Roux, Hideki Konishi, Helmut Ritsch Jean-Philippe Brantut

▲ 链接：

https://www.nature.com/articles/s41586-023-06018-3

▲ 择要：

密度波（DW）是量子物资中一种基本的长程秩序，与晶体布局的自构造有关。DW阶与超流动性的彼此作用会致使繁杂的环境，这对于理论阐发提出了很年夜的应战。

已往几十年，可调谐量子费米气体已经经成为摸索强彼此作用费米子物理学的模子体系，包孕最闻名的磁有序、配对于以及超流动性，和从巴丁-库珀-施里弗超流体到博色-爱因斯坦凝结体的交织。

研究者于横向驱动的高邃密光学����APP腔中实现了具备强的、可调谐的接触彼此作用以及光子介导的、空间布局的长途彼此作用的费米气体。

于一个临界的长途彼此作用强度之上，DW阶于体系中是不变的，研究者经由过程其超辐射光散射特征来辨认。他们定量地丈量了接触彼此作用于巴丁-库珀-徐瑞弗超流体以及博色-爱因斯坦凝结交织中发生变迁时DW阶的最先变迁，定性地与平均场理论一致。将远距彼此作用的强度以及符号调解到低在自排序阈值时，原子DW磁化率变迁跨越一个数目级，注解对于接触以及远距彼此作用的自力以及同时节制。研究者暗示，该试验装配为超流体与DW阶序彼此作用的试验研究提供了一个彻底可和谐微不雅可控的平台。

▲ Abstract：

A density wave (DW) is a fundamental type of long-range order in quantum matter tied to self-organization into a crystalline structure. The interplay of DW order with superfluidity can lead to complex scenarios that pose a great challenge to theoretical analysis. In the past decades, tunable quantum Fermi gases have served as model systems for exploring the physics of strongly interacting fermions, including most notably magnetic ordering, pairing and superfluidity, and the crossover from a Bardeen Cooper Schrieffer superfluid to a Bose Einstein condensate. Here, we realize a Fermi gas featuring both strong, tunable contact interactions and photon-mediated, spatially structured long-range interactions in a transversely driven high-finesse optical cavity. Above a critical long-range interaction strength, DW order is stabilized in the system, which we identify via its superradiant light-scattering properties. We quantitatively measure the variation of the onset of DW order as the contact interaction is varied across the Bardeen Cooper Schrieffer superfluid and Bose Einstein condensate crossover, in qualitative agreement with a mean-field theory. The atomic DW susceptibility varies over an order of magnitude upon tuning the strength and the sign of the long-range interactions below the self-ordering threshold, demonstrating independent and simultaneous control over the contact and long-range interactions. Therefore, our experimental setup provides a fully tunable and microscopically controllable platform for the experimental study of the interplay of superfluidity and DW order.

Quantum-limited optical time transfer for future geosynchronous links

将来地球同步链路的量子限定光时间传输

▲ 作者：Emily D. Caldwell, Jean-Daniel Deschenes, Jennifer Ellis, William C. Swann, Benjamin K. Stuhl, Hugo Bergeron, Nathan R. Newbury Laura C. Sinclair

▲ 链接：

https://www.nature.com/articles/s41586-023-06032-5

▲ 择要：

光时间传输以及光时钟的联合，为毗连地面光时钟以及将来天基光时钟的年夜范围自由空间收集斥地了可能性。如许的收集无望更好地测试广义相对于论、暗物资搜刮以及引力波探测。

将光学时钟毗连到长途卫星的威力可以实现天基超长基线干预干与丈量、进步前辈的卫星导航、基在时钟的年夜地丈量和洲际时间流传的数千倍革新。

到今朝为止，只要光学时钟朝着量子限定机能的标的目的成长。比拟之下，光时间通报没有于由吸收光子数目设定的近似量子极限下运转。研究者展示了时间传输与近量子限定的收罗以及按时比之前的要领低10000倍的吸收功率。

夏威夷山顶之间的间隔跨越300千米，发射功率低至40微瓦，远间隔站点同步到320阿秒。这类近乎量子限定的操尴尬刁难在光子少且放年夜成本高的长间隔自由空间链路至关主要：于4.0 mW的发射功率下，这类要领可以撑持102 dB的链路损耗，足以于将来将时间传输到地球同步轨道。

▲ Abstract：

The combination of optical time transfer and optical clocks opens up the possibility of large-scale free-space networks that connect both ground-based optical clocks and future space-based optical clocks. Such networks promise better tests of general relativity, dark-matter searches and gravitational-wave detection. The ability to connect optical clocks to a distant satellite could enable space-based very long baseline interferometry, advanced satellite navigation, clock-based geodesy and thousandfold improvements in intercontinental time dissemination. Thus far, only optical clocks have pushed towards quantum-limited performance. By contrast, optical time transfer has not operated at the analogous quantum limit set by the number of received photons. Here we demonstrate time transfer with near quantum-limited acquisition and timing at 10,000 times lower received power than previous approaches. Over 300?km between mountaintops in Hawaii with launched powers as low as 40 W, distant sites are synchronized to 320 attoseconds. This nearly quantum-limited operation is critical for long-distance free-space links in which photons are few and amplification costly: at 4.0mW transmit power, this approach can support 102?dB link loss, more than sufficient for future time transfer to geosynchronous orbits.

地球物理学Geophysics

Increasingly negative tropical water interannual CO2 growth rate coupling

束热带水-年际二氧化碳日趋增长的富增加率耦合

▲ 作者：Laibao Liu, Philippe Ciais, Mengxi Wu, Ryan S. Padr n, Pierre Friedlingstein, Jonas Schwaab, Lukas Gudmundsson Sonia I. Seneviratne

▲ 链接：

https://www.nature.com/articles/s41586-023-06056-x

▲ 择要：

已往60年，陆地生态体系已经经接收了约32%的报酬二氧化碳（CO2）排放总量。然而，陆地碳-天气反馈的伟大不确定性使患上猜测陆地碳汇怎样相应将来的天气变迁变患上坚苦。

热带地域年夜气CO2增加率（CGR）的年际变迁重要由陆地-年夜气碳通量主导，这为摸索陆地-天气彼此作用提供了时机。

科学家以为CGR的变迁于很年夜水平上受温度节制，但也有证据注解，水的可用性以及CGR11之间存于慎密耦合。研究者哄骗全世界年夜气CO2记载、陆地储水量以及降水数据，研究了天气变迁下热带陆地天气前提与CGR的年际瓜葛变迁。

他们发明，与1960-1989年比拟，1989-2018年热带水资源可患上性与CGR的年际瓜葛变患上愈来愈负。这可能与厄尔尼诺/南边涛动遥相干变迁驱动的热带水可用性异样的时空变迁有关，包孕空间赔偿性水效应的削弱。

研究还证实，年夜大都开始进的地球体系以及陆地外貌耦合模子不克不及再现水-碳耦合的加重。研究成果注解，热带水份可患上性正日趋节制着陆地碳轮回的年际变迁，并调治着热带陆地碳-天气反馈。

▲ Abstract：

Terrestrial ecosystems have taken up about 32% of the total anthropogenic CO2 emissions in the past six decades. Large uncertainties in terrestrial carbon climate feedbacks, however, make it difficult to predict how the land carbon sink will respond to future climate change. Interannual variations in the atmospheric CO2 growth rate (CGR) are dominated by land atmosphere carbon fluxes in the tropics, providing an opportunity to explore land carbon climate interactions. It is thought that variations in CGR are largely controlled by temperature but there is also evidence for a tight coupling between water availability and CGR11. Here, we use a record of global atmospheric CO2, terrestrial water storage and precipitation data to investigate changes in the interannual relationship between tropical land climate conditions and CGR under a changing climate. We find that the interannual relationship between tropical water availability and CGR became increasingly negative during 1989 2018 compared to 1960 1989. This could be related to spatiotemporal changes in tropical water availability anomalies driven by shifts in El Ni?o/Southern Oscillation teleconnections, including declining spatial compensatory water effects. We also demonstrate that most state-of-the-art coupled Earth System and Land Surface models do not reproduce the intensifying water carbon coupling. Our results indicate that tropical water availability is increasingly controlling the interannual variability of the terrestrial carbon cycle and modulating tropical terrestrial carbon climate feedbacks.

Major southern San Andreas earthquakes modulated by lake-filling events

南部圣安地列斯地动由湖泊填充事务调制

▲ 作者：Ryley G. Hill, Matthew Weingarten, Thomas K. Rockwell Yuri Fialko

▲ 链接：

https://www.nature.com/articles/s41586-023-06058-9

▲ 择要：

水文荷载可以刺激地壳的地动勾当性。然而，激发年夜地动的证据仍旧难以捉摸。南加州的南圣安德烈亚斯断层（SSAF）邻接萨尔顿海，这是古卡韦拉湖的遗址，于已往一千年里，它周期性地布满并干枯。

本文哄骗新的地质以及古地动资料证实，已往6次年夜地动可能发生于卡韦拉湖的高点。为了研究可能的因果瓜葛，研究者计较了湖泊水位变迁惹起的库仑应力随时间的变迁。

哄骗黏弹性地幔上的孔弹性地壳的彻底耦合模子，研究者发明水文荷载使SSAF上的库仑应力增长了几百千帕斯卡，断层应力率增长了2倍以上，这可能足以激发地动。

非垂直断层倾角、断层粉碎带的存于以及侧向孔隙压力散布加强了湖泊沉没的不不变效应。咱们的模子可能合用在其他地域的水文负荷，不管是天然的照旧报酬的，都与年夜量的地动勾当有关。

▲ Abstract：

Hydrologic loads can stimulate seismicity in the Earth s crust. However, evidence for the triggering of large earthquakes remains elusive. The southern San Andreas Fault (SSAF) in Southern California lies next to the Salton Sea, a remnant of ancient Lake Cahuilla that periodically filled and desiccated over the past millennium. Here we use new geologic and palaeoseismic data to demonstrate that the past six major earthquakes on the SSAF probably occurred during highstands of Lake Cahuilla. To investigate possible causal relationships, we computed time-dependent Coulomb stress changes due to variations in the lake level. Using a fully coupled model of a poroelastic crust overlying a viscoelastic mantl, we find that hydrologic loads increased Coulomb stress on the SSAF by several hundred kilopascals and fault-stressing rates by more than a factor of 2, which is probably sufficient for earthquake triggering. The destabilizing effects of lake inundation are enhanced by a nonvertical fault dip, the presence of a fault damage zone and lateral pore-pressure diffusion. Our model may be applicable to other regions in which hydrologic loading, either natural or anthropogenic, was associated with substantial seismicity.

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