Retrieving the True Masses of Gravitational-wave Sources

Gravitational waves (GWs) encode important information about the mass of the source. For binary black holes (BBHs), the templates that are used to retrieve the masses normally are developed under the assumption of a vacuum environment. However, theories suggest that some BBHs form in gas-rich environments. Here we study the effect of hydrodynamic drag on the chirp signal of a stellar-mass BBH and the impact on the measurement of the mass. Based on theoretical arguments, we show that the waveform of a BBH in gas resembles that of a more massive BBH residing in a vacuum. The effect is important for LISA sources but negligible for LIGO/Virgo binaries. Furthermore, we carry out a matched-filtering search of the best fitting parameters. We find that the best-fit chirp mass could be significantly greater than the real mass if the gas effect is not appropriately accounted for. Our results have important implications for the future joint observation of BBHs using both ground- and space-based detectors.Comment: 5 pages, 1 figure. This is a contribution to the conference proceedings: Recent Progress in Relativistic Astrophysics, Fudan University, Chin

Selective attachment of benzonitrile on Si(111)-7×7: Configuration, selectivity, and mechanism

The cycloaddition of benzonitrile with Si(111)-7×7 has been investigated as a model system for understanding the interaction of conjugated π-electron systems with Si(111)-7×7 using high-resolution electron energy loss spectroscopy, x-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy, scanning-tunneling microscopy (STM), and density-functional-theory calculation (perturbative Beck-Perdew functional in conjugation with a basis set of DN**). Vibrational features of chemisorbed benzonitrile unambiguously demonstrate that the cyano group directly interacts with Si surface dangling bonds, evidenced in the disappearance of C≡N stretching mode around 2256 cm-1 coupled with the appearance of C=N stretching mode at 1623 cm-1 and the retention of all vibrational signatures of phenyl ring. XPS shows that both C 1s and N 1s core levels of the cyano groups display large down-shifts by 2.5 and 1.5 eV, respectively, after chemisorption. A smaller down-shift of ∼0.8 eV is observed for the C 1s core level of phenyl group due to the weaker inductive effect of the formed C=N groups in chemisorbed benzonitrile than that of C≡N groups in physisorbed molecules. Compared with physisorbed molecules, the photoemission from πCN orbitals of chemisorbed benzonitrile is significantly reduced, suggesting the direct involvement of πCN in the surface binding. These experimental results show that the covalent attachment of benzonitrile on Si(111)-7×7 occurs in a selective manner through the (2+2) cycloaddition between the cyano group and the adjacent adatom-rest atom pair. The cycloadduct formed contains an intact phenyl ring protruding into vacuum, retaining aromaticity. This functionalized Si surface may serve as a substrate for further modification or act as an intermediate for fabrication of multilayer organic thin films or materials syntheses in vacuum

Spatial effect of digital financial inclusion on the urban–rural income gap in China—analysis based on path dependence

Digital financial inclusion (DFI) helps to narrow the income gap between urban and rural areas, but path dependence may lead to spatial agglomeration in the development of DFI, causing the spatial effect on the urban–rural income gap. This study mainly examines the mechanism and effect of DFI on the urban–rural income gap in China, including its spatial effect issues. Results show that China’s DFI has different impacts on the urban–rural income gap in the east, central, and western regions, showing evident spatial heterogeneity. In addition, the development of DFI has spatial agglomeration, and its impact on China’s urban–rural income gap also has a spatial spillover effect. Moreover, the spatial effect of DFI is mainly because of the path dependence on the development of traditional finance and digital technology. The spatial correlation between them is transmitted to DFI, and the impact of digital technology development is greater. Finally, corresponding policy recommendations are proposed based on the conclusions

2-[(2-Carboxy­phen­yl)sulfan­yl]acetic acid

The title compound, C9H8O4S, affords a zigzig chain in the crystal structure by inter­molecular O—H⋯O hydrogen bonds. The molecular geometry suggests that extensive but not uniform π-electron delocalization is present in the benzene ring and extends over the exocyclic C—S and C—C bonds