A strong negative correlation between radio loudness RUVR_{\rm UV} and optical-to-X-ray spectral index αox\alpha_{\rm ox} in low-luminosity AGNs

It has been argued for years that the accretion mode changes from bright active galactic nuclei (AGNs) to low-luminosity AGNs (LLAGNs) at a rough dividing point of bolometric Eddington ratio $\lambda \sim 10^{-2}$. In this work, we strengthen this scenario through investigation of the relationship between the radio loudness $R_{\rm UV}$ and the optical-to-X-ray spectral index $\alpha_{\rm ox}$ in LLAGNs with $10^{-6} \lesssim \lambda \lesssim 10^{-3}$. We compile from literature a sample of 32 LLAGNs, consisting 18 LINERs and 14 low Eddington ratio Seyfert galaxies, and observe a strong negative $R_{\rm UV}$--$\alpha_{\rm ox}$ relationship, with large scatter in both $R_{\rm UV}$ and $\alpha_{\rm ox}$. We further demonstrate that this negative correlation, and the additional two negative relationships reported in literature ($R_{\rm UV}$--$\lambda$ and $\alpha_{\rm ox}$--$\lambda$ correlations), can be understood consistently and comprehensively under the truncated accretion--jet model, the model that has been applied successfully applied to LLAGNs. We argue that the scatter in the observations are (mainly) due to the spread in the viscosity parameter $\alpha$ of a hot accretion flow, a parameter that potentially can serve as a diagnose of the strength and/or configuration of magnetic fields in accretion flows.Comment: 8 pages, 3 figures, 2 tables. Accepted by MNRA

Hexyl (E)-3-(3,4-dihy­droxy­phen­yl)acrylate

The title mol­ecule, C15H20O4, has an E conformation about its C=C bond and is almost planar (r.m.s. deviation of all non-H atoms = 0.04 Å). The crystal structurere features O—H⋯O and C—H⋯O hydrogen bonds

(E)-Isopentyl 3-(3,4-dihy­droxy­phen­yl)­acrylate

The title compound, C14H18O4, a derivative of caffeic acid, has an E configuration about the C=C bond. The benzene ring is almost coplanar with the C=C—C(O)—O—C linker [maximum deviation = 0.050 (2) Å], making a dihedral angle of only 4.53 (2)°. In the mol­ecule, the adjacent hy­droxy groups form an O—H⋯O inter­action. In the crystal, mol­ecules are linked by O—H⋯O hydrogen bonds, generating a chain propagating in the [110] direction

2,2-Dichloro-1-(2-phenyl-1,3-oxazolidin-3-yl)ethanone

In the title mol­ecule, C11H11Cl2NO2, the oxazolidine ring is in an envelope conformation with the O atom forming the flap; the other four essentially planar ring atoms (r.m.s. deviation = 0.012 Å) form a dihedral angle of 91.1 (3)° with the phenyl ring. In the crystal structure, mol­ecules are linked by weak inter­molecular C—H⋯O hydrogen bonds, forming one-dimensional chains

Observation of Zeeman effect in topological surface state with distinct material dependence

The helical Dirac fermions on the surface of topological insulators host novel relativistic quantum phenomena in solids. Manipulating spins of topological surface state (TSS) represents an essential step towards exploring the theoretically predicted exotic states related to time reversal symmetry (TRS) breaking via magnetism or magnetic field. Understanding Zeeman effect of TSS and determining its g-factor are pivotal for such manipulations in the latter form of TRS breaking. Here, we report those direct experimental observations in Bi2Se3 and Sb2Te2Se by spectroscopic imaging scanning tunneling microscopy. The Zeeman shifting of zero mode Landau level is identified unambiguously by judiciously excluding the extrinsic influences associated with the non-linearity in the TSS band dispersion and the spatially varying potential. The g-factors of TSS in Bi2Se3 and Sb2Te2Se are determined to be 18 and -6, respectively. This remarkable material dependence opens a new route to control the spins in the TSS.Comment: main text: 17 pages, 4 figures; supplementary: 15 pages, 7 figure