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Exploring the Mass Segregation Effect of X-ray Sources in Globular Clusters. II. The Case of Terzan 5

​Abstract: Using archival Chandra observations with a total effective exposure of 734 ks, we derive an updated catalog of point sources in the massive globular cluster Terzan 5. Our catalog covers an area of 58.1arcmin2 (R≤4.3arcmin) with 489 X-ray sources, and more than 75% of these sources are first detected in this cluster. We find significant dips in the radial distribution profiles of X...

Black hole hyperaccretion in collapsars. I. MeV neutrinos

Title:Black hole hyperaccretion in collapsars. I. MeV neutrinosAuthors:Wei, Yun-Feng; Liu, Tong; Song, C​ui-YingAs the plausible central engine of gamma-ray bursts (GRBs), a black hole (BH) hyperaccretion disk should be in a state of neutrino-dominated accretion flow (NDAF) if the accretion rate is larger than the ignition rate of an NDAF. A rotating stellar-mass BH surrounded by a hyper...

Thick-disc model to explain the spectral state transition in NGC 247

Abstract: We propose the thick-disc model of Gu et al. 2016 to interpret the transition between soft ultraluminous state (SUL) and supersoft ultraluminous state (SSUL) in NGC247. As accretion rate increases, the inner disc will puff up and act as shield to block the innermost X-ray emission regions and absorb both soft and hard X-ray photons. The absorbed X-ray emission will be re-radiated as a...

A method to search for black hole candidates with giant companions by LAMOST

Recently, by using the LAMOST spectra, Prof. Wei-Min Gu and his collaborators have published a paper in ApJ Letters (ApJL, 872, L20) on a new method to search for stellar-mass black hole candidates. Based on the stellar spectra of LAMOST Data Release 6, a sample of seven giants in binaries is obtained with large radial velocity variation (> 80 km/s). With the effective temperature, surface grav...

Quark mean-field model for nuclear matter with or without bag

Authors: Zhen-Yu Zhu, Ang Li*, Jin-Niu Hu, Hong Shen​ | Abstract: We propose the new quark mean-field bag (QMFB) model by incorporating the bag confinement mechanism in the original quark mean-field model. ..

Spectral Energy Distribution of the inner accretion flow around Sgr A* -- Clue for a weak outflow in the innermost region

Sgr A* represents a unique laboratory for the detailed study of accretion processes around a low-luminosity supermassive black hole (SMBH). Recent X-ray observations have allowed for spatially resolved modeling of the emission from the accretion flow around the SMBH, placing tight constraints on the flux and spectral shape of the accretion from the inner region with $r<10^3~r_g$, where $r_g$ is...

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