Discovery of An Active Intermediate-Mass Black Hole Candidate in the Barred Bulgeless Galaxy NGC 3319

We report the discovery of an active intermediate-mass black hole (IMBH) candidate in the center of nearby barred bulgeless galaxy $\rm NGC~3319$. The point X-ray source revealed by archival Chandra and XMM-Newton observations is spatially coincident with the optical and UV galactic nuclei from Hubble Space Telescope observations. The spectral energy distribution derived from the unresolved X-ray and UV-optical flux is comparable with active galactic nuclei (AGNs) rather than ultra-luminous X-ray sources, although its bolometric luminosity is only $3.6\times10^{40}~\rm erg~s^{-1}$. Assuming an Eddington ratio range between 0.001 and 1, the black hole mass (M_\rm{BH}) will be located at $3\times10^2-3\times10^5~M_{\odot}$, placing it in the so-called IMBH regime and could be the one of the lowest reported so far. Estimates from other approaches (e.g., fundamental plane, X-ray variability) also suggest M_\rm{BH}\lesssim10^5~M_{\odot}.Similar to other BHs in bulgeless galaxies, the discovered IMBH resides in a nuclear star cluster with mass of $\sim6\times10^6~M_{\odot}$. The detection of such a low-mass BH offers us an ideal chance to study the formation and early growth of SMBH seeds, which may result from the bar-driven inflow in late-type galaxies with a prominent bar such as $\rm NGC~3319$.Comment: ApJ accepted, 2 tables, 6 figure

Coordination Behavior of Bis-Imidazole and Various Carboxylate Ligands towards Zn(II) and Cd(II) Ions: Synthesis, Structure, and Photoluminescence Study

Four coordination polymers (CPs) based on bis-imidazole ligands (1,2-bimb and 1,2-bmimb), namely, {[Zn(1,2-bimb)(2,5-dtpa)] H2O}n (1), {[Cd2(1,2-bimb)2(5-hipa)2] 2H2O} (2), {Zn2(1,2-bimb)(L)(CH3COO) DMF·2H2O}n (3) and {Cd(1,2-bmimb)(3-npa)}n (4), have been synthesized by solvothermal reactions (1,2-bimb = 1,2-bis((1H-imidazol-1-yl)methyl)benzene, 1,2-bmimb = 1,2-bis((2-methyl-1H-imidazol-1-yl)methyl)benzene, 2,5-H2dtpa = 2,5-diaminoterephthalic acid, 5-H2hipa = 5-hydroxyisophthalic acid, H3L= 3,3′,3′′-(2,4,6-trioxo-1,3,5-triazinane-1,3,5-triyl)tripropanoic acid, 3-H2npa = 3-nitrophthalic acid) and structurally verified by single-crystal X-ray diffraction analyses and further characterized by powder X-ray diffraction (PXRD), elemental analyses and infrared spectroscopy (IR). Complex 1 and 2 show a dinuclear 2D layered structure. Complex 4 exhibits a two-dimensional network consisting of [Cd(3-npa)]n and [Cd(1,2-bmimb)]n chains. Both 1,2 and 4 display a 4-connected sql topology sheet, which can be further expanded into a 3D supramolecular network through π···π interaction between layers. Complex 3 features a 3D (3,6)-connected {42·6}·{44·610·8}-3,6T24 topology structure consisting of 2D bilayers. Structural comparison reveals that it is not only the substituents at different positions of ancillary ligands and the primary bis(imidazole) linkers that play crucial roles in the control of the final structures. Besides, the photoluminescence properties of 1–4 have been investigated in the solid state at room temperature

Synthesis, Structure, and Properties of Coordination Polymers Based on 1,4-Bis((2-methyl-1H-imidazol-1-yl)methyl)benzene and Different Carboxylate Ligands

Three novel coordination polymers, formulated as {[Zn(1,4-bmimb)(PhAA)2]·H2O}n (1), [Cu(1,4-bmimb)0.5(2,6-PyDC)]n (2), and {[Cu(1,4-bmimb)0.5(2-PAC)(HCOO)]·2H2O}n (3) (1,4-bmimb = 1,4-bis((2-methyl-1H-imidazol-1-yl)methyl)benzene; PhAA = phenylacetic acid; 2,6-PyDC = pyridine-2,6-dicarboxylic acid; 2-PAC = 2-pyrazinecarboxylic acid), were synthesized by the self-assembly of mixed ligands with Zn(II) and Cu(II) under solvothermal conditions and characterized by means of single-crystal X-ray diffraction, X-ray powder diffraction, infrared spectra, thermogravimetric analysis, fluorescence spectra and UV-vis absorption spectra. 1 is shown as a Z-shaped chain, which is formed by Zn2+, PhAA ligands, and 1,4-bmimb ligands, and is assembled into a 3D structure by hydrogen bonding and π···π interaction. Similarly, 2 displays a single chain, which is built by Cu2+, 2,6-PyDC ligands, and 1,4-bmimb ligands, and is assembled into a 3D structure by hydrogen bonding and π···π interaction. 3 possesses a 1D ladder structure, which is formed by Cu2+, 2,6-PyDC ligands, and 1,4-bmimb ligands, and is assembled into a 3D structure by hydrogen bonding. The luminescence properties (for 1) and UV-vis spectrum (for 2 and 3) were also studied and discussed