Toward understanding reionization and Lyman-alpha emitter from green pea galaxies

Lyman-alpha emitter (LAE) is one of the most important probe of cosmic reionization. LAEs also contribute a significant amount of ionizing photons during reionization. This motivates us to understand the physics of LAEs. We have shown that low redshift green pea galaxies are strong Lyman-alpha emitters. These nearby LAEs enable us to do detailed multiwavelength studies. From green peas, we have gained deep understanding about how Lyman-alpha and Lyman-continuum escape from galaxy, and how to better diagnose HI in IGM with Lyman-alpha.

Demystifying the Diverse IR Continuum SED Shapes among Type-1 AGNs

In the classical unification scheme, type-1 (broad-line) AGNs are depicted as unobscured accreting supermassive black holes with similar face-on viewings of the circumnuclear optically thick tori. However, the dust SEDs of these systems can have significant variations, as seen among, e.g., the hot-dust-obscured galaxies, extremely red quasars, and hot-dust-free quasars, that cannot be easily explained in a uniform picture. In this talk, I will introduce a semi-empirical framework that has successfully reconciled the IR SEDs of type-1 AGNs seen at z~0 to z~6.

Highly magnified stars in lensing clusters and a probe for dark matter substructure

Observations have uncovered a new type of gravitational lensing phenomenon that can be utilized to address fundamental physics questions: in galaxy cluster strong lensing systems, background galaxies straddle the lensing caustic and stars near the caustic can be individually detectable to optical/IR telescopes (as in the case of a recent detection by the HST) thanks to the extreme magnification.

Binary Neutron Star Mergers: Learning from the Afterglow of the > August 17th 2017 Event

On August 17 2017, gravitational waves from the inspiral
phase of a binary neutron star merger were detected. Then, with a slight
delay, a weak short gamma-ray burst GRB170817A was observed. These two
historical detections triggered a hitherto unseen series of astronomical
observations. First, follow-up ground-based searches inside the
uncertainty region inferred by the gravitational wave signal promptly
found an optical transient--the first observed kilonova--in the
spheroidal galaxy NGC4993. Then, at the position of this optical

Electron scattering wings on lines in interacting supernovae

Interacting supernovae, including type IIn and Ia-CSM, are supernovaethat show evidence of strong shock interaction between their ejectaand pre-existing circumstellar material (CSM), which may be ejectedfrom the unstable progenitor star before the explosion. After thesupernova shock wave has broken out of the progenitor star, theionizing radiation from the shock region is able to ionize thesurroundings. The CSM can have substantial optical depth to electronscattering and the continuum photosphere is in the unshocked CSM dueto the electron scattering opacity.

Highlights of DAMPE experiment

The dark matter particle explorer (DAMPE) is a space-borne high energy cosmic ray and gamma-ray detector dedicated to searching for dark matter indirectly in space. The wide energy range coverage, high energy resolution, and high particle identification capability of DAMPE successfully open a new window for the high energy Universe. Since its launch in the end of 2015, DAMPE has been operated smoothly for more than 2 years in space.

What can we learn about cosmic-ray sources from the isotropic gamma-ray background?

The isotropic gamma-ray background (IGRB) is the residual all-sky gamma-ray emission after subtracting the individual sources and diffuse gamma-ray emission in the Galactic plane. It contains the hadornic emission of cosmic ray via the interactions with gas and photon field in their propagation, and hence bring information of cosmic-ray sources. I will discuss the implication of the IGRB for the Galactic and extragalactic cosmic-ray sources based on my recent works.