It is widely accepted that black holes (BHs) with masses greater than a million solar masses (M ⊙ ) lurk at the centres of massive galaxies. The origins of such 'supermassive' black holes (SMBHs) remain unknown 1 , while those of stellar-mass BHs are well-understood. One possible scenario is that intermediate-mass black holes (IMBHs), which are formed by the runaway coalescence of stars in young compact star clusters 2 , merge at the centre of a galaxy to form an SMBH 3 . Although many candidates for IMBHs have been proposed to date, none of them are accepted as definitive. Recently we discovered a peculiar molecular cloud, CO-0.40-0.22, with an extremely broad velocity width near the centre of our Milky Way galaxy.Based on the careful analysis of gas kinematics, we concluded that a compact object with a mass of ∼ 10 5 M ⊙ is lurking in this cloud 4 . Here we report the detection of a point-like continuum source as well as a compact gas clump near the center of CO-0.40-0.22. This point-like continuum source (CO-0.40-0.22 * ) has a wide-band spectrum consistent with 1/500 of the Galactic SMBH (Sgr A * ) in luminosity. Numerical simulations around a point-like massive object reproduce the kinematics of dense molecular gas well, which suggests that CO-0.40-0.22 * is the most promising candidate for an intermediate-mass black hole.CO-0.40-0.22 is a compact cloud (∼ 5 pc) with an extremely broad velocity width (∼ 100 km s −1 ) and very high CO J=3-2/J=1-0 intensity ratio (≥ 1.5) detected at a projected distance of ∼ 60 pc away from the galactic nucleus 5 . It belongs to a peculiar category of molecular clouds called high-velocity compact clouds (HVCCs) that were originally identified in the CO J=1-0 survey data 6-8 . CO-0.40-0.22 is only a dense cloud with a negative velocity detected in HCN J=4-3 line within the 0.3 • ×0.3 • area including it 4 . It has a continuous and roughly straight entity in the position-velocity maps, seeming not to be an aggregate of unrelated clouds with less broad velocity widths. The kinematical structure of CO-0.40-0.22 can be explained as being due to a gravitational kick experienced by the molecular cloud caused by an invisible compact object with a mass of ∼ 10 5 M ⊙ . The compactness and absence of a counterpart at other wavelengths suggest that this massive object is an inactive IMBH, which is not currently accreting matter. This is the second-largest black hole candidate in the Milky Way galaxy affter Sgr A * , as well as the second IMBH candidate in the Galaxy after that in the nuclear subcluster IRS13E (M BH ≃ 1300 M ⊙ ) 9,10 .ALMA band 6 observations towards CO-0.40-0.22 have provided high-resolution HCN J=3-2 (265.9 GHz) and CO J=2-1 (230.5 GHz) images. Dense molecular gas traced by HCN J=3-2 emission seems to concentrate near the centre of CO-0.40-0.22 as previously determined by the coarse-resolution ASTE HCN J=4-3 map (Fig. 1a). The displacement of 0.2 pc from the centre is within the ASTE beamwidth (22 ′′ = 0.9 pc). This dense gas clump is very compact (∼ 0.3

The synchrotron radiation system may be useful for evaluating microcirculatory disorders and early-stage malignant tumors in various human organs.

We report the discovery of molecular gas streams orbiting around an invisible massive object in the central region of our Galaxy, based on the high-resolution molecular line observations with the Atacama Large Millimeter/submillimeter Array (ALMA). The morphology and kinematics of these streams can be reproduced well through two Keplerian orbits around a single point mass of (3.2±0.6)×10 4 M . We also found ionized gas toward the inner part of the orbiting gas, indicating dissociative shock and/or photoionization. Our results provide new circumstantial evidences for a wandering intermediate-mass black hole in the Galactic center, suggesting also that high-velocity compact clouds can be probes of quiescent black holes abound in our Galaxy.

The lactonamycin model aglycon 4 was synthesized from the trihalogenated benzene derivative 10. Ethynyltetraol 6 was prepared from 10 via carbon elongations, oxidative demethylation, a cycloaddition reaction with the diene derived from homophthalic anhydride, and dihydroxylation. Final E- and F-ring constructions from 6 were realized via a palladium-catalyzed cyclization-methoxycarbonylation, a stereoselective methanol addition, and lactonization, leading to the production of 4.

Scheme 1. Lactonamycin (1), lactonamycin Z (2), lactonamycinone (3), and model BCDEF aglycon (AE)-4. Scheme 2. Intermediates 5 and 6 synthesized by other research groups.Scheme 6. Synthesis of (AE)-lactonamycinone ((AE)-3) through a Bischler-Napieralski-type cyclization. a) PdCl 2 , 1,4-benzoquinone, CO, MeOH, RT, 69 %; b) CSA, MeOH, 80 8C, then evaporation, benzene, 80 8C, 100 %; c) AcCl, pyridine, CH 2 Cl 2 , RT, 95 %; d) P 2 O 5 , CH 2 Cl 2 , RT, 71 %; e) ClCH 2 COCl, pyridine, CH 2 Cl 2 , RT, 99 %; f) P 2 O 5 , CH 2 Cl 2 , RT, 75 %; g) Et 3 N, MeOH/CH 2 Cl 2 (1:3 v/v), 40 8C; h) MgI 2 ·OEt 2 , benzene, 80 8C, 2 steps 56 %. CSA = camphorsulfonic acid, CA = chloroacetyl. Angewandte Chemie 2089

We report the results of high-resolution molecular line observations of the high-velocity compact cloud HCN-0.085-0.094 with the Atacama Large Millimeter/submillimeter Array. The HCN J=4-3, HCO + J=4-3, and CS J=7-6 line images reveal that HCN-0.085-0.094 consists mainly of three small clumps with extremely broad velocity widths. Each of the three clumps has a 5.5 GHz radio continuum counterpart in its periphery toward Sgr A * . The positional relationship indicates that their surfaces have been ionized by ultraviolet photons from young stars in the central cluster, suggesting the clumps are in close proximity to the Galactic nucleus. One of the three clumps has a ring-like structure with a very steep velocity gradient. This kinematical structure suggests an orbit around a point-like object with a mass of ∼ 10 4 M . The absence of stellar counterparts indicates that the point-like object may be a quiescent black hole. This discovery adds another intermediate-mass black hole candidate in the central region of our Galaxy.

A radio source at the Galactic center Sgr A* is a prime supermassive black hole candidate and therefore key to developing our understanding of them. Time variations in the 230 GHz band flux of Sgr A* have been found with the Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 5 observations. Measuring the flux density of Sgr A* in 1 min snapshots at 217.5, 219.5, and 234.0 GHz, we obtained light curves for ten 70 min periods. The light curves show variations at a few tens of minutes and hourly scales. The shorter timescale is similar to the orbital period of the innermost stable circular orbit around a 4 × 10 6 M ⊙ black hole, suggesting that the variation originates from the immediate vicinity of Sgr A*. We also detected no time lag between 217.5 and 234.0 GHz and a dependence of the spectral index on the flux density.

We discovered two small high-velocity compact clouds (HVCCs) in the HCN J = 4–3 and J = 3–2 maps of the central 20 pc of our Galaxy. Both HVCCs have broad velocity widths ( km s−1) and compact sizes ( ), and originate from the dense molecular clouds in the position–velocity space. One of them has a faint counterpart in a Paschen-α image. Their spatial structure, kinematics, and absence of luminous stellar object are compatible with the notion that each of the small HVCCs is driven by the plunge of an invisible compact object into a molecular cloud. Such objects are most likely inactive, isolated black holes.