The advancement of acoustic metamaterials enables the highly efficient absorption of low-frequency noise with a subwavelength structure thickness, but the complexity of these structures often hinders their large-scale practical applications. Here, we propose a straightforward and compact acoustic metamaterial structure composed of Helmholtz resonators with side slits (HRSS) for low-frequency noise absorption. The introduction of side slits not only simplifies the overall structure but also allows for easy adjustment of acoustic characteristics. By adjusting the depth of the resonator within the slit across 25 distinct units, an absorption coefficient above 0.8 is realized from 470 to 930 Hz. This work demonstrates the extensive low-frequency sound absorption capability of HRSS, providing valuable insights into the design of future practical acoustic materials.
{"title":"A compact acoustic metamaterial based on Helmholtz resonators with side slits for low-frequency sound absorption","authors":"Xingyu Chen, Feiyang Sun, Jing Zhang, Gaorui Chen, Liyue Xu, Li Fan, Liping Cheng, Xiaodong Xu, Yunteng Chen, Jiexin Zhou, Liangping Li, Shaoping Yang","doi":"10.1063/5.0212688","DOIUrl":"https://doi.org/10.1063/5.0212688","url":null,"abstract":"The advancement of acoustic metamaterials enables the highly efficient absorption of low-frequency noise with a subwavelength structure thickness, but the complexity of these structures often hinders their large-scale practical applications. Here, we propose a straightforward and compact acoustic metamaterial structure composed of Helmholtz resonators with side slits (HRSS) for low-frequency noise absorption. The introduction of side slits not only simplifies the overall structure but also allows for easy adjustment of acoustic characteristics. By adjusting the depth of the resonator within the slit across 25 distinct units, an absorption coefficient above 0.8 is realized from 470 to 930 Hz. This work demonstrates the extensive low-frequency sound absorption capability of HRSS, providing valuable insights into the design of future practical acoustic materials.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141521938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03DOI: 10.1007/s11182-024-03199-w
A. A. Eliseev, S. V. Fortuna, M. A. Khimich
In this paper, the effect of ultrasound on the microhardness and microstructure of friction stir welding joints is investigated. It has been found that the area with minimum microhardness is located in the thermomechanically affected zone on the retreating side. An ultrasonic impact resulted in an increase in the size of this area. The weakening of the region is attributed primarily to the low content of hardening particles due to overaging. It was also found that the ultrasonic impact during welding resulted in a 5 times reduction of residual stresses.
{"title":"Effect of Ultrasonic Impact on the Microhardness and Microstructure of Friction Stir Welded Aluminum Alloy 2024","authors":"A. A. Eliseev, S. V. Fortuna, M. A. Khimich","doi":"10.1007/s11182-024-03199-w","DOIUrl":"https://doi.org/10.1007/s11182-024-03199-w","url":null,"abstract":"<p>In this paper, the effect of ultrasound on the microhardness and microstructure of friction stir welding joints is investigated. It has been found that the area with minimum microhardness is located in the thermomechanically affected zone on the retreating side. An ultrasonic impact resulted in an increase in the size of this area. The weakening of the region is attributed primarily to the low content of hardening particles due to overaging. It was also found that the ultrasonic impact during welding resulted in a 5 times reduction of residual stresses.</p>","PeriodicalId":770,"journal":{"name":"Russian Physics Journal","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141522695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03DOI: 10.1007/s11182-024-03214-0
A. G. Aleksandrova, I. V. Tomilova, N. A. Kucheryavchenko, N. A. Popandopulo
Orbital evolution of model near-Earth space (NES) objects moving in orbits with semi-major axes in the range from 8 000 to 100 000 km is analyzed to reveal the dynamic structure features of this NES region to choose a disposal strategy for spent spacecrafts or deployment of new satellite systems. The areas possessing the greatest stability and keeping preset orbital elements and hence the most suitable for placing new satellites and disposal of spent satellites are shown. The areas in which the deployment of satellites is inexpedient are highlighted.
{"title":"Analysis of Near-Earth Space for the Search of Optimal Orbits for Placement of Satellites","authors":"A. G. Aleksandrova, I. V. Tomilova, N. A. Kucheryavchenko, N. A. Popandopulo","doi":"10.1007/s11182-024-03214-0","DOIUrl":"https://doi.org/10.1007/s11182-024-03214-0","url":null,"abstract":"<p>Orbital evolution of model near-Earth space (NES) objects moving in orbits with semi-major axes in the range from 8 000 to 100 000 km is analyzed to reveal the dynamic structure features of this NES region to choose a disposal strategy for spent spacecrafts or deployment of new satellite systems. The areas possessing the greatest stability and keeping preset orbital elements and hence the most suitable for placing new satellites and disposal of spent satellites are shown. The areas in which the deployment of satellites is inexpedient are highlighted.</p>","PeriodicalId":770,"journal":{"name":"Russian Physics Journal","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141522758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03DOI: 10.1103/physreva.110.013502
Zhe Gao, Wei-Min Wang
Many studies have shown that high-energy -photon beams can be efficiently generated via nonlinear Compton scattering driven by laser pulses with intensities greater than recently available in laboratories. Here we propose a laserless scheme to efficiently generate high-energy polarized -photon beams by collision of two ultrarelativistic electron beams. The self-generated field of a dense driving electron beam provides a strong deflection field for the other ultrarelativistic seeding electron beam. A QED Monte Carlo code based on the locally constant field approximation is employed to simulate the collision process, and the polarization properties of the photons produced are investigated. The simulation results and theoretical analysis indicate that the photon polarization, including both linear and circular polarizations, can be tuned by changing the initial polarization of the seeding beam. If an unpolarized seeding beam is used, linearly polarized photons with an average polarization of 55% can be obtained. If the seeding beam is transversely (longitudinally) polarized, the linear (circular) polarization of photons above 3 GeV can reach 90% (67%), which is favorable for highly polarized, high-energy -photon sources.
{"title":"Polarized γ-photon beams produced by collision of two ultrarelativistic electron beams","authors":"Zhe Gao, Wei-Min Wang","doi":"10.1103/physreva.110.013502","DOIUrl":"https://doi.org/10.1103/physreva.110.013502","url":null,"abstract":"Many studies have shown that high-energy <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>γ</mi></math>-photon beams can be efficiently generated via nonlinear Compton scattering driven by laser pulses with intensities greater than <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msup><mn>10</mn><mn>22</mn></msup><mspace width=\"0.28em\"></mspace><mrow><mi mathvariant=\"normal\">W</mi><mo>/</mo><msup><mi>cm</mi><mn>2</mn></msup></mrow></mrow></math> recently available in laboratories. Here we propose a laserless scheme to efficiently generate high-energy polarized <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>γ</mi></math>-photon beams by collision of two ultrarelativistic electron beams. The self-generated field of a dense driving electron beam provides a strong deflection field for the other ultrarelativistic seeding electron beam. A QED Monte Carlo code based on the locally constant field approximation is employed to simulate the collision process, and the polarization properties of the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>γ</mi></math> photons produced are investigated. The simulation results and theoretical analysis indicate that the photon polarization, including both linear and circular polarizations, can be tuned by changing the initial polarization of the seeding beam. If an unpolarized seeding beam is used, linearly polarized photons with an average polarization of 55% can be obtained. If the seeding beam is transversely (longitudinally) polarized, the linear (circular) polarization of photons above 3 GeV can reach 90% (67%), which is favorable for highly polarized, high-energy <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>γ</mi></math>-photon sources.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141514200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03DOI: 10.1103/physreva.110.l010401
Ranendu Adhikary, Abhishek Mishra, Ramij Rahaman
We study the self-testing problem of quantum correlations in the context of a multipartite scenario, a task that becomes increasingly complex compared to the bipartite systems. Recently, [Šupić et al., Nat. Phys.19, 670 (2023)] introduced a novel self-testing method for pure multipartite entangled states, which leverages network assistance and relies on bipartite entangled measurements. Hence, their scheme loses the ideal device-independent nature of self-testing. To address this, we provide a self-testing scheme for genuine multipartite entanglement in the true sense. Our approach utilizes a generalized Hardy-type nonlocality argument and requires only local operations, eliminating the need for network assistance or bipartite entangled measurements. Furthermore, we establish a device-independent bound for the maximum probability of success for a generalized Hardy-type argument. This paves the way for reliable and efficient self-testing of quantum correlations without relying on additional resources.
{"title":"Self-testing of genuine multipartite entangled states without network assistance","authors":"Ranendu Adhikary, Abhishek Mishra, Ramij Rahaman","doi":"10.1103/physreva.110.l010401","DOIUrl":"https://doi.org/10.1103/physreva.110.l010401","url":null,"abstract":" We study the self-testing problem of quantum correlations in the context of a multipartite scenario, a task that becomes increasingly complex compared to the bipartite systems. Recently, [Šupić <i>et al.</i>, <span>Nat. Phys.</span> <b>19</b>, 670 (2023)] introduced a novel self-testing method for pure multipartite entangled states, which leverages network assistance and relies on bipartite entangled measurements. Hence, their scheme loses the ideal device-independent nature of self-testing. To address this, we provide a self-testing scheme for genuine multipartite entanglement in the true sense. Our approach utilizes a generalized Hardy-type nonlocality argument and requires only local operations, eliminating the need for network assistance or bipartite entangled measurements. Furthermore, we establish a device-independent bound for the maximum probability of success for a generalized Hardy-type argument. This paves the way for reliable and efficient self-testing of quantum correlations without relying on additional resources.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141514201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03DOI: 10.1103/physreva.110.l010801
A. Boeschoten, V. R. Marshall, T. B. Meijknecht, A. Touwen, H. L. Bethlem, A. Borschevsky, S. Hoekstra, J. W. F. van Hofslot, K. Jungmann, M. C. Mooij, R. G. E. Timmermans, W. Ubachs, L. Willmann (NL-eEDM Collaboration)
We demonstrate a spin-precession method to observe and analyze multilevel coherence between all hyperfine levels in the ground state of barium monofluoride (). The signal is sensitive to the state-preparation Rabi frequency and external electric and magnetic fields applied in searches for a permanent electric dipole moment (EDM). In the obtained interference spectrum, the electric field and Rabi frequency become observable simultaneously with the EDM. This method reduces systematic biases and the number of auxiliary measurements for such precision measurements.
{"title":"Spin-precession method for sensitive electric dipole moment searches","authors":"A. Boeschoten, V. R. Marshall, T. B. Meijknecht, A. Touwen, H. L. Bethlem, A. Borschevsky, S. Hoekstra, J. W. F. van Hofslot, K. Jungmann, M. C. Mooij, R. G. E. Timmermans, W. Ubachs, L. Willmann (NL-eEDM Collaboration)","doi":"10.1103/physreva.110.l010801","DOIUrl":"https://doi.org/10.1103/physreva.110.l010801","url":null,"abstract":"We demonstrate a spin-precession method to observe and analyze multilevel coherence between all hyperfine levels in the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>X</mi><msup><mspace width=\"0.16em\"></mspace><mn>2</mn></msup><msup><mi mathvariant=\"normal\">Σ</mi><mo>+</mo></msup><mo>,</mo><mi>N</mi><mo>=</mo><mn>0</mn></mrow></math> ground state of barium monofluoride (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mmultiscripts><mi>Ba</mi><mprescripts></mprescripts><none></none><mn>138</mn></mmultiscripts><mmultiscripts><mi mathvariant=\"normal\">F</mi><mprescripts></mprescripts><none></none><mn>19</mn></mmultiscripts></mrow></math>). The signal is sensitive to the state-preparation Rabi frequency and external electric and magnetic fields applied in searches for a permanent electric dipole moment (EDM). In the obtained interference spectrum, the electric field and Rabi frequency become observable simultaneously with the EDM. This method reduces systematic biases and the number of auxiliary measurements for such precision measurements.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141514203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shufeng Song, Zongyuan Chen, Shengxian Wang, Fengkun Wei, Serguei V. Savilov, Anji Reddy Polu, Pramod K. Singh, Zhaoqin Liu, Ning Hu
Ionogels, which are being considered as quasi-solid electrolytes for energy-storage devices, exhibited technical superiority in terms of nonflammability, negligible vapor pressure, remarkable thermostability, high ionic conductivity, and broad electrochemical stability window. However, their applications in lithium metal batteries (LMBs) have been hindered by several issues: poor compatibility with Li-metal anodes and high-voltage cathodes, high viscosity, and inadequate wettability. Little attention has been paid to ionogel-based low-concentration electrolytes, despite their potential advantages in terms of Li+ mobility, viscosity, electrode wettability, and cost. Here, we demonstrate the surprising capabilities of localized high-concentration ionogel (LHCI) and dilutedly localized high-concentration ionogel (DLHCI) electrolytes, utilizing the non-solvating fluorinated ether 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, to realize high-voltage quasi-solid-state lithium metal batteries (QSLMBs). Notably, the DLHCI electrolyte not only delivers superior ionic conductivity of 3.93 × 10−3 S cm−1 but also provides a high Li plating/stripping Coulombic efficiency exceeding 99%. Moreover, it significantly enhances anodic stability when paired with 4.4 V LiNi0.8Co0.1Mn0.1O2 (NCM811) and 4.8 V LiNi0.5Mn1.5O4 (LNMO). Consequently, substantial improvement in cycling performance of QSLMBs has been realized with the DLHCI electrolyte.
离子凝胶被认为是储能设备的准固体电解质，在不可燃性、可忽略的蒸汽压、显著的热稳定性、高离子电导率和宽电化学稳定性窗口等方面具有技术优势。然而，它们在锂金属电池（LMB）中的应用却受到几个问题的阻碍：与锂金属阳极和高压阴极的兼容性差、粘度高和润湿性不足。基于离子凝胶的低浓度电解质虽然在锂+迁移率、粘度、电极润湿性和成本方面具有潜在优势，但却很少受到关注。在这里，我们展示了局部高浓度离子凝胶（LHCI）和稀释局部高浓度离子凝胶（DLHCI）电解质的惊人能力，它们利用非溶解性氟化醚 1,1,2,2-四氟乙基-2,2,3,3-四氟丙基醚实现了高压准固态锂金属电池（QSLMB）。值得注意的是，DLHCI 电解液不仅离子电导率高达 3.93 × 10-3 S cm-1，而且锂镀层/剥离库仑效率超过 99%。此外，当与 4.4 V LiNi0.8Co0.1Mn0.1O2 (NCM811) 和 4.8 V LiNi0.5Mn1.5O4 (LNMO) 搭配使用时，它还能大大提高阳极稳定性。因此，在使用 DLHCI 电解液时，QSLMB 的循环性能得到了显著改善。
{"title":"Dilutedly localized high-concentration ionogel electrolyte enabling high-voltage quasi-solid-state lithium metal batteries","authors":"Shufeng Song, Zongyuan Chen, Shengxian Wang, Fengkun Wei, Serguei V. Savilov, Anji Reddy Polu, Pramod K. Singh, Zhaoqin Liu, Ning Hu","doi":"10.1063/5.0221854","DOIUrl":"https://doi.org/10.1063/5.0221854","url":null,"abstract":"Ionogels, which are being considered as quasi-solid electrolytes for energy-storage devices, exhibited technical superiority in terms of nonflammability, negligible vapor pressure, remarkable thermostability, high ionic conductivity, and broad electrochemical stability window. However, their applications in lithium metal batteries (LMBs) have been hindered by several issues: poor compatibility with Li-metal anodes and high-voltage cathodes, high viscosity, and inadequate wettability. Little attention has been paid to ionogel-based low-concentration electrolytes, despite their potential advantages in terms of Li+ mobility, viscosity, electrode wettability, and cost. Here, we demonstrate the surprising capabilities of localized high-concentration ionogel (LHCI) and dilutedly localized high-concentration ionogel (DLHCI) electrolytes, utilizing the non-solvating fluorinated ether 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, to realize high-voltage quasi-solid-state lithium metal batteries (QSLMBs). Notably, the DLHCI electrolyte not only delivers superior ionic conductivity of 3.93 × 10−3 S cm−1 but also provides a high Li plating/stripping Coulombic efficiency exceeding 99%. Moreover, it significantly enhances anodic stability when paired with 4.4 V LiNi0.8Co0.1Mn0.1O2 (NCM811) and 4.8 V LiNi0.5Mn1.5O4 (LNMO). Consequently, substantial improvement in cycling performance of QSLMBs has been realized with the DLHCI electrolyte.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":null,"pages":null},"PeriodicalIF":4.0,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141521404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03DOI: 10.1103/physrevb.110.l020402
Han Yan (闫寒), Owen Benton, Roderich Moessner, Andriy H. Nevidomskyy
Classical spin liquids (CSL) lack long-range magnetic order and are characterized by an extensive ground-state degeneracy. We propose a classification scheme of CSLs based on the structure of the flat bands of their Hamiltonians. Depending on absence or presence of the gap from the flat band, the CSL are classified as algebraic or fragile topological, respectively. Each category is further classified: the algebraic case by the nature of the emergent Gauss's law at the gap-closing point(s), and the fragile topological case by the homotopy of the eigenvector winding around the Brillouin zone. Previously identified models of CSLs fit snugly into our scheme, on a landscape where algebraic CSLs are located at transitions between fragile topological ones. It also allows us to present new families of models illustrating this landscape, which hosts both fragile topological and algebraic CSLs, as well as transitions between them.
{"title":"Classification of classical spin liquids: Typology and resulting landscape","authors":"Han Yan (闫寒), Owen Benton, Roderich Moessner, Andriy H. Nevidomskyy","doi":"10.1103/physrevb.110.l020402","DOIUrl":"https://doi.org/10.1103/physrevb.110.l020402","url":null,"abstract":"Classical spin liquids (CSL) lack long-range magnetic order and are characterized by an extensive ground-state degeneracy. We propose a classification scheme of CSLs based on the structure of the flat bands of their Hamiltonians. Depending on absence or presence of the gap from the flat band, the CSL are classified as algebraic or fragile topological, respectively. Each category is further classified: the algebraic case by the nature of the emergent Gauss's law at the gap-closing point(s), and the fragile topological case by the homotopy of the eigenvector winding around the Brillouin zone. Previously identified models of CSLs fit snugly into our scheme, on a landscape where algebraic CSLs are located at transitions between fragile topological ones. It also allows us to present new families of models illustrating this landscape, which hosts both fragile topological and algebraic CSLs, as well as transitions between them.","PeriodicalId":20082,"journal":{"name":"Physical Review B","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141521407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03DOI: 10.1146/annurev-astro-071221-052651
E. Schinnerer, A.K. Leroy
Observations that resolve nearby galaxies into individual regions across multiple phases of the gas–star formation feedback “matter cycle” have provided a sharp new view of molecular clouds, star-formation efficiencies, timescales for region evolution, and stellar feedback. We synthesize these results, covering aspects relevant to the interpretation of observables, and conclude the following: ▪ The observed cloud-scale molecular gas surface density, line width, and internal pressure all reflect the large-scale galactic environment while also appearing mostly consistent with properties of a turbulent medium strongly affected by self-gravity. ▪ Cloud-scale data allow for statistical inference of both evolutionary and physical timescales. These suggest a period of cloud collapse on the order of the free-fall or turbulent crossing time (∼10–30 Myr) followed by forming massive stars and subsequent rapid (≲5 Myr) gas clearing after the onset of star formation. The star-formation efficiency per free-fall time is well determined over thousands of individual regions at εff ≈ 0.5−0.3+0.7%. ▪ The role of stellar feedback is now measured using multiple observational approaches. The net yield is constrained by the requirement to support the vertical weight of the galaxy disk. Meanwhile, the short gas-clearing timescales suggest a large role for presupernova feedback in cloud disruption. This leaves the supernovae free to exert a large influence on the larger galaxy, including stirring turbulence, launching galactic-scale winds, and carving superbubbles.
{"title":"Molecular Gas and the Star-Formation Process on Cloud Scales in Nearby Galaxies","authors":"E. Schinnerer, A.K. Leroy","doi":"10.1146/annurev-astro-071221-052651","DOIUrl":"https://doi.org/10.1146/annurev-astro-071221-052651","url":null,"abstract":"Observations that resolve nearby galaxies into individual regions across multiple phases of the gas–star formation feedback “matter cycle” have provided a sharp new view of molecular clouds, star-formation efficiencies, timescales for region evolution, and stellar feedback. We synthesize these results, covering aspects relevant to the interpretation of observables, and conclude the following: <jats:list list-type=\"bullet\"> <jats:list-item> <jats:label>▪</jats:label> The observed cloud-scale molecular gas surface density, line width, and internal pressure all reflect the large-scale galactic environment while also appearing mostly consistent with properties of a turbulent medium strongly affected by self-gravity. </jats:list-item> <jats:list-item> <jats:label>▪</jats:label> Cloud-scale data allow for statistical inference of both evolutionary and physical timescales. These suggest a period of cloud collapse on the order of the free-fall or turbulent crossing time (∼10–30 Myr) followed by forming massive stars and subsequent rapid (≲5 Myr) gas clearing after the onset of star formation. The star-formation efficiency per free-fall time is well determined over thousands of individual regions at ε<jats:sub>ff</jats:sub> ≈ 0.5<jats:sub>−0.3</jats:sub> <jats:sup>+0.7</jats:sup>%. </jats:list-item> <jats:list-item> <jats:label>▪</jats:label> The role of stellar feedback is now measured using multiple observational approaches. The net yield is constrained by the requirement to support the vertical weight of the galaxy disk. Meanwhile, the short gas-clearing timescales suggest a large role for presupernova feedback in cloud disruption. This leaves the supernovae free to exert a large influence on the larger galaxy, including stirring turbulence, launching galactic-scale winds, and carving superbubbles. </jats:list-item> </jats:list>","PeriodicalId":8138,"journal":{"name":"Annual Review of Astronomy and Astrophysics","volume":null,"pages":null},"PeriodicalIF":33.3,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141521946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03DOI: 10.1103/physrevb.110.045107
Axel Fünfhaus, Marius Möller, Thilo Kopp, Roser Valentí
Motivated by recently reported magnetic-field-induced topological phases in ultracold atoms and correlated Moiré materials, we investigate topological phase transitions in a minimal model consisting of interacting spinless fermions described by the Hofstadter model with Coulomb interaction on a square lattice. For interacting lattice Hamiltonians in the presence of a commensurate magnetic flux it has been demonstrated that the quantized Hall conductivity is constrained by a Lieb-Schultz-Mattis (LSM) type theorem due to magnetic translation symmetry. In this work, we revisit the validity of the theorem for such models and establish that a topological phase transition from a topological to a trivial insulating phase can be realized but must be accompanied by spontaneous magnetic translation symmetry breaking caused by charge ordering of the spinless fermions. To support our findings, the topological phase diagram for varying interaction strength is mapped out numerically with exact diagonalization for different flux quantum ratios and band fillings using symmetry indicators. We discuss our results in the context of the LSM-type theorem.
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