SHAO Astrophysics Colloquia

Title: Multi-wavelength Time Domain Astronomy: To Probe the Environs of Central Super Massive Black Hole of Blazars

Speaker: Alok C. Gupta (ARIES/SHAO)

Time: 3 PM, Mar. 23th (Thursday)

Location: Lecture Hall, 3rd floor

Abstract:

This is the age of multi-wavelenth time domain astronomy in which the transient astronomical sources are of great interest due to their rapid change in flux and polarization. Simultaneous multi-wavelength observation of a particular transient source on an extended period of time has importance to understand the emission mechanism in different electromagnetic bands. Blazars are among one of the most favorite astronomical transient objects, because they emit radiation in the complete electromagnetic spectrum, and their flux and polarization are highly variable.

In the present talk, I will summarize our recent results based on multi-wavelength observations taken with space and ground based telescopes.  The scientific projects involve are: multi-wavelength flux, polarization and cross-correlated variability of blazars on diverse timescales, and optical and X-ray QPOs in blazars.

Galaxy Seminar

Location: 1714

Time: 10:30, Mar.22 (Wednesday)

Title: Lighting up the Universe with the First Cosmic Explosions

Speaker: Ke-Jung (Ken) Chen（National Astronomical Observatory of Japan EACOA Postdoctoral Fellow）

Abstract:

One of the paramount problems in modern cosmology is to elucidate how the first generation of luminous objects, stars, supernovae, and galaxies shaped the early universe at the end of the cosmic dark ages. According to the modern theory of cosmological structure formation, the hierarchical assembly of dark matter halos provided the gravitational potential wells that allowed gas to form stars and galaxies inside them. Modern large telescopes have pushed the detection of galaxies up to a redshift of z ~ 10. However, models of the first luminous objects still require considerable effort to reach the level of sophistication necessary for meaningful predictions, Due to the complexity of involved physical phenomena, this physical understanding may only come by the proper use of numerical simulations. Therefore, I have used state-of-the-art simulations on some of largest supercomputers to study these objects. In my talk, I will discuss the possible physics behind the formation of these first luminous objects by presenting the results from our simulations. I will also give possible observational signatures of the cosmic dawn that will be the prime targets for the future telescopes such as the James Webb Space Telescope (JWST).

Group meetings

Black hole Accretion and High-energy Astrophysics /Black Hole Feedback and Cosmic Ray Astrophysics Seminar

Location: 1608

Time: 14:00-16:00, Wednesday (Mar. 22th)

Speaker: Yu Wang (王宇), Fudan University

Title：X-ray Multi-epoch and Multi-instrument Study of Galaxy MCG-05-23-16: the Accurate Measure of BH spin

Galactic Dynamics Group Journal Club

Time & Location: 9:30 AM, March 23th (Thursday), Room 1608

Title: Galaxy Outskirts

Speaker: Lin Lin

Abstract: Galaxy outskirts contain fundamental clues about the galaxy formation and evolution process. Hierarchical cosmological models predict halos to be ubiquitous, and to be (at least in part) the product of past merger and/or accretion events. The advent of deep wide-field surveys in the last two decades has enrich our view of galactic outskirts. Resolved stellar populations of galaxy haloes will enable the estimations of ages, metallicities and gradients. The valuable information collected for galaxies with a range of masses, morphologies and within diverse environments will test theoretical models and simulations.

Ref:

Crnojevic+16 (arXiv: 1612.05471)

Knapen+16 (arXiv: 1612.054051)

Wisnioski+14 (arXiv: 1409.6791)