LATEST NEWS

Mining for Candidates of Galactic Stellar-mass Black Hole Binaries with LAMOST

Abstract: We study the prospects of searching for black hole (BH) binary systems with a stellar-mass BH and a non-compact visible companion, by utilizing the spectroscopic data of Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). We simulate the Galactic BH binary population and determine its optical visibility by considering the stellar synthetic population model and the dist...

Searching for Black Hole Candidates by LAMOST and ASAS-SN

ABSTRACT:Most dynamically confirmed stellar-mass black holes and the candidates were originally selected from X-ray outbursts. In the present work, we search for black hole candidates in the LAMOST survey by using the spectra along with photometry from the ASAS-SN survey, where the orbital period of the binary may be revealed by the periodic light curve, such as the ellipsoidal modulation type...

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...

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