SHAO Astrophysics Colloquia

Title: Testing Einstein’s Equivalent Principle with Fast Radio Bursts and the Problem of Detecting Electromagnetic Waves from Merging Black Holes

Speaker: Prof.  Shuang-Nan Zhang (张双南研究员 IHEP/CAS)

Time: 3 PM, Dec. 22 (Thursday)

Location: Lecture Hall, 3rd floor

Abstract: Fast Radio Bursts (FRBs) are extremely short, but intensive radio bursts, believed to originate at cosmological distances. Wei et al (2015) used FRBs to make the so far most stringent tests on Einstein’s Equivalent Principle (EEP). I propose to use FRBs to be found behind clusters of galaxies to provide significant improvement on testing EEP. On a totally different topic, I will discuss the problem of detecting electromagnetic waves from merging black holes. Based on self-consistent calculations of general relativity, we proved that matter cannot accumulate outside the event horizon of a black hole, even clocked by an external observer, contrary to the original claim by Oppenheimer and Snyder (1939) in their classical and seminal paper on black hole formation. We thus predicted (Liu and Zhang 2009) that merging BHs can only produce gravitation waves, but no electromagnetic waves, as proved by recent LIGO results. Finally, I will present the status of the POLAR gamma-ray burst polarimetry onboard China’s Tiang-Gong 2 spacelab, launched on Sept.14, 2016, as well as the prospect of detecting gamma-ray bursts with the Hard X-ray Modulation Telescope, to be launched in June 2017.

 Galaxy Seminar

Location: 1714

Time: 10:30, Dec.21( Wednesday)

Title: The galactic orbital distribution and dark matter distribution in the local universe

Speaker: 朱玲 (MPIA, Heidelberg)

Contact: Jian Fu, Fangting Yuan, Chunyan Jiang, Zhaoyu Li, Ting Xiao

Group meetings

Galactic Dynamics Group Journal Club

Location：1608

Time：9:30-11:00, Dec. 22 (Thursday)

Speaker: Man I Lam

Title: SDSS-IV MaNGA: The Impact of Diffuse Ionized Gas on Emission Lines Ratios and Gas metallicity Measurements from face-on galaxies and stacked spectra

Abstract:

Diffuse Ionized Gas (DIG) is prevalent in star-forming galaxies. The first paper studied the emission-line ratios and gas metallicities by using 365 nearly face-on sample galaxies in MaNGA. They found that DIG shows LI(N)ERs ratios rather than the HII region in the line ratios diagnostic diagrams. The second paper is presented the stacked results of eDIG around the late-type galaxies

References:

(1) SDSS-IV MaNGA: The Impact of Diffuse Ionized Gas on Emission-line Ratios, Interpretation of Diagnostic Diagrams, and Gas Metallicity Measurements, Zhang et al., 2016, MNRAS accepted. arxiv: 1612.02000

(2) SDSS IV MaNGA: Deep observations of extra-planar, diffuse ionized gas around late-type galaxies from stacked IFU spectra, Jones et al., 2016, A&A accepted: arxiv: 1612.03920