Education and Experiences:
Sep. 2004 – Sep. 2007 : Ph.D., Max-Planck-Institute for Extraterrestrial Physics (MPE);
Observational High Energy Astrophysics
Now I am carrying out the hard X-ray (several keV) to gamma-ray (GeV to TeV) studies on Galactic sources with the INTEGRAL/IBIS and Fermi Gamma-ray Telescope observations. The main science aims to the pulsar physics, neutron stars and black holes in binary systems, supernova remnants. Using the high energy observational data, we will probe the unclear phenomena and intense physical processes in strong gravity, strong magnetic field, dense interstellar medium, relativistic accelerations by shock waves.
Gamma-ray Line Astronomy:
My work at Gamma-ray Group of MPE was concentrating on the data processing and software programming of the Spectrometer on the International Gamma-Ray Astrophysical Laboratory (SPI/INTEGRAL) in the energy range from 20 keV to 8 MeV. The scientific interest focuses on the detections of gamma-ray lines. Gamma-ray lines are our window into nuclear physics processes in the universe, e.g. nucleosythesis in the stellar interiors, supernovae, novae and so on. We can measure the electron-positron annihilation line (511 keV), the gamma-ray lines from radioactive isotopes such as 26Al (1809 keV), 60Fe (59 keV, 1173 keV, 1332 keV) and 44Ti (78 keV, 68 keV, 1157 keV). The accurate measurements of these gamma-ray line shape, intensity and all-sky map can provide a powerful tool to study the structure, dynamics and evolution of the Galaxy, and constrain the models of stellar evolution and nucleosynthesis.
Theoretical high energy astrophysics:
High energy astrophysics is an active research field in modern astronomy, studying the diffuse radiation, sources, and populations in the very wide energy range from X-rays (keV) to very high gamma-rays (TeV). My present interest is on the high energy physics and phenomena related to compact stars, e.g. neutron stars (NS) and black holes (BH), gamma-ray bursts (GRB).
1. Gamma-ray bursts are the most intense astrophysical processes known in the Universe at present. A typical GRB can release about 1053 ergs during 10 seconds if its radiation is isotropic. Though it has been discovered for 30 years, the nature is still a mystery. Nowadays, astronomers generally think the long duration GRBs are connected with supernovae, possibly originate from the collapse of massive stars. In the previous work, we have proposed that the merger of a NS and a massive BH as the possible progenitor for a GRB, and study the evolution and lightcurves of a fireball produced by a GRB with the central energy injection. In 2002, we suggested that the Cerenkov line emission can contribute to Fe Kα lines detected in X-ray afterglows of some GRBs. The Cerenkov line mechanism is quite different from the traditional line mechanisms, like fluorescence or recombination.
Pulsars and wind nebulae: We
study the radiation from pulsars and their wind nebulae from soft X-rays to TeV
gamma-rays. We first used generation order parameters to describe spin-powered
X-ray pulsars, found the correlation between the generation order parameters
and the photon index in X-ray band. Meanwhile, the emission properties of
pulsar wind nebulae are studied in a one-zone model, and we suggest that pulsar
wind nebulae component could be dominated in the X-rays of pulsars detected by
ASCA (2-10 keV), contributing to the X-ray luminosity-spin down power relation
(with a power-law index 3/2). In addition, the TeV photons through inverse
“Spectral and intensity variations of Galactic 26Al emission”, W. Wang, M.G. Lang, R. Diehl, H. Halloin, P, Jean, J. Kn\"odlseder, K. Kretschmer, P. Martin, J.P. Roques, A.W. Strong, C. Winkler, X.L. Zhang, 2009, Astron. Astrophys. in press (preprint, Arxiv:0902.0211)
“Study of Long-lived Radioactive Sources in the Galaxy with INTEGRAL/SPI”, W. Wang, 2008, PASP, 120, 118
“SPI observations of the diffuse 60Fe emission in the Galaxy”, W. Wang, M.J. Harris, R. Diehl, H. Halloin, B. Cordier, A.W. Strong, K. Kretschmer, J. Knoedlseder, P. Jean, G.G. Lichti, J.P. Roques, S. Schanne, A. von Kienlin, G. Weidenspointner, C. Wunderer, 2007, Astron. Astrophys., 469, 1005
“Radioactive 26Al and massive stars in the Galaxy”, R. Diehl, H. Halloin, K. Kretschmer, G.G. Lichti, V. Schonfelder, A.W. Strong, A. von Kienlin, W. Wang, P. Jean, J. Knodlseder, J. Roques, G. Weidenspointner, S. Schanne, D.H. Hartmann, C. Winkler, & C. Wunderer, 2006, Nature, 439, 45
“Could electron-positron annihilation lines in the Galactic center result from pulsar winds?”, W. Wang, C.S.J. Pun & K.S. Cheng, 2006, Astron. Astrophys., 446, 943
“Pulsar Wind Nebulae and the Non-thermal X-Ray Emission of Millisecond Pulsars”, K.S. Cheng, R.E. Taam & W. Wang, 2006, Astrophysical Journal, 641, 427
“Contribution to diffuse gamma-rays in the Galactic center region from unresolved millisecond pulsars”, W. Wang, Z.J. Jiang & K.S. Cheng, 2005, Mon. Not. Royal Astron. Society, 358, 263
“Possible TeV Source Candidates Among The Unidentified EGRET Sources”, W. Wang, Z.J. Jiang, C.S.J. Pun & K.S. Cheng, 2005, Mon. Not. Royal Astron. Society, 360, 646
“Pulsar Wind Nebulae and the X-Ray Emission of Non-Accreting Neutron Stars”, K.S. Cheng, R.E. Taam & W. Wang, 2004, Astrophysical Journal, 617, 480
“X-ray Lines in Gamma-ray Bursts and Cerenkov Line Mechanism”, W. Wang, 2005, Astrophysics & Space Science, 297, 415
“Spectral properties, generation order parameters and luminosities for spin-powered X-ray pulsars”, W. Wang & Y. Zhao, 2004, Astrophysical Journal, 601, 1038
“Cerenkov Line Emission as a Possible Mechanism of X-ray Lines in Gamma-ray Bursts”, W. Wang, Y. Zhao & J.H. You, 2002, Astrophysical Journal (Letters), 576, L37
“Early Tracking Behavior in Small-field Quintessence Models”, W. Wang, B. Feng, 2003, Chin. J. Astron. Astrophys., 3, 105
“Gamma-ray bursts: probe of a black holes”, W. Wang, Y. Zhao, 2001, Chin. J. Astron. Astrophys., 1, 487
“Gamma-Ray Burst Afterglows with Energy Injection: Homogeneous Versus Wind External Media”, W. Wang, Z.G. Dai, 2001, Chin. Phys. Lett., 18, 1153