Astronomy and Astrophysics

Very Large Array Radio Telescope
Very Large Array Radio Telescope

People

Academic staff

Research staff

Students

Dr. Ivan BOJICIC
Prof. Kwong Sang CHENG
Prof. Allan Shi-Chung
CHEUNG (Chemistry)

Dr. David John FREW
Dr. Kai Ming LEE

Dr. Man Hoi LEE
(Adjunct with Department of Earth Sciences)

Dr. Jeremy J.L. LIM
Dr. Stephen Chi Yung NG
Prof. Quentin A. PARKER
Dr. Jason C.S. PUN
Dr. Pablo, SAZ PARKINSON
Dr. Meng SU

Dr. Yong ZHANG

Ms. Yuk Ying CHAN
Dr. Chin-Ping HU
Dr. Foteini LYKOU
Ms. Wai Emily WONG
Dr. Shuxu YI



 

Mr. Ming Yan CHAN (MPhil)
Ms. Cuncheng CHEN (MPhil)
Ms. Vasiliki FRAGKOU (PhD)
Mr. Yuan GAO (MPhil)
Mr. Wai Yan LEUNG (PhD)
Mr. Yi Lok Enoch LEUNG (MPhil)
Mr. Junhao LI (MPhil)
Mr. Yik Lun MONG (MPhil)
Ms. Cho Wing NG (PhD)
Ms. Kris Akira STERN (PhD)
Mr. Jun TIAN (MPhil)
Mr. Wenchao WANG (MPhil)
Ms. Run WEN (MPhil)

 

Research Activities

1.  Theoretical Astrophysics

The major research areas are related to neutron stars and pulsars, which are rapidly spinning and magnetized neutron stars, including X-ray and gamma-ray emission mechanisms, stellar structure, stellar cooling and heating mechanisms and the internal activities, e.g. sudden unpinning of superfluid vortices.  In addition to topics related to pulsars and neutron stars, we also study topics related to gamma-ray bursts, in particular the central engine problem, and high energy phenomena resulting from the stellar capture processes by supermassive black holes in the galactic center.

2.  Observational Astrophysics

(1) Dr. Lim's research has spanned a broad range of topics in astrophysics, encompassing magnetic activity on the Sun and nearby stars, formation and evolution of stars in our Galaxy, star formation in and dynamics of nearby galaxies, and most lately astrophysical applications of gravitational lensing. In the field of star formation, Dr. Lim’s goal is to elucidate how binary and multiple star systems form – the majority of stars having masses comparable to and higher than that of the Sun are born as members of binary or multiple star systems. For this study, Dr. Lim uses radio interferometers such as the VLA, SMA, and ALMA to study how material in molecular clouds accumulates onto binary or multiple protostellar systems. He and his collaborators have shown, for the first time, that some of these systems form through the rotationally driven fragmentation of molecular cloud cores. Dr. Lim uses radio and optical telescopes to study the interstellar medium and formation of star clusters in the central giant elliptical galaxies of nearby galaxy clusters. Cool gas in these galaxies may originate from the cooling of X-ray-emitting gas in the intracluster medium that flows into the cluster center, a process analogous to that believed to help fuel star formation at high redshifts. Finally, over the last few years, in collaboration with overseas experts in particular Prof. Thomas Broadhurst and Dr. Jose Diego who pay frequent visits to HKU. Dr. Lim has assembled a group at HKU working on gravitational. The goal of this group is to construct robust lens models for galaxy clusters observed by the Hubble Space Telescope for the purpose of: (i) studying the distribution of dark matter on cluster scales, so as to test and constrain different forms of dark matter (e.g., cold vs. wave dark matter); and (ii) finding and studying distant galaxies magnified (through gravitational lensing) by the foreground galaxy cluster, so as to study the formation and early evolution of galaxies.

(2) Dr. Ng studies extreme objects in our Galaxy, including magnetars, energetic pulsars, pulsar wind nebulae (PWNe), and supernova remnants. He has led observational projects using world-class telescopes in X-rays and radio, such as the Chandra X-ray Observatory, XMM-Newton, the Expanded Very Large Array, and the Australia Telescope Compact Array. He has identified a pulsar moving at an enormous velocity over 2,000 km/s. He has also developed a powerful 3D modeling technique to capture the X-ray torus and jet morphology of PWNe and to measure the structure and evolution of the supernova remnant 1987A.

Dr. Ng's latest research focuses on the magnetic fields of neutron stars and their environments. Employing X-ray observations, he measures the surface temperature of magnetars, which are stars with the strongest magnetic fields in the Universe, to understand their extreme properties and their connection with ordinary radio pulsars. In addition, he maps the magnetic field configurations of PWNe using radio telescopes, in order to probe the cosmic ray production and transport in these systems. Further information can be found at the webpage http://www.physics.hku.hk/~ncy/.

(3) Prof. Q.A. Parker arrived at HKU in March 2015 and is intent on establishing a world-leading group in late-stage stellar evolution that includes post-AGB stars, planetary nebulae and massive star ejecta including Wolf-Rayet shells and supernova remnants. This is assisted by i) the new 5-year appointment of Prof. Albert Zijlstra as a Hung Hing Ying Distinguished visiting professor to HKU who is a world leader in planetary nebula;, ii) the appointment of two Research Assistant Professors (Dr. D.J. Frew and Dr. I. Boijicic); iii) a new postdoctoral research fellow (Dr F. Lykou) and iv) several new PhD students. Significant contributions to this research field have been made by this strong team including two recent HKU press releases (see https://www.ras.org.uk/news-and-press/2741-planetary-nebulae and http://www.scifac.hku.hk/news/any/planebulae). Exciting research opportunities exist for additional research postgraduate students to join the group. This group also has strong synergies to existing departmental expertise in late stage stellar evolution (including supernova remnants), to the very active group of Prof Sun. Kwok, and to the newly established Laboratory for Space research (http://www.lsr.hku.hk).

Some Representative Publications

(For the complete publication list of the department, please go back to Research.)


Prof. K.S. Cheng

  1. "Probing gamma-ray emissions of Fermi-LAT pulsars with a non-stationary outer gap model", Takata, J., Ng, C. W., Cheng, K. S., MNRAS, 455, 4249-4266 (2016)
  2. "Origin of the Fermi Bubble", K.S. Cheng, D. Chernyshov, V. Dogel, C.M. Ko and W.H. Ip, The Astrophysical Journal Letters, 731, L17: 1-4 (2011) 
  3. "A Three-Dimensional Outer Magnetospheric Gap Model for Gamma-Ray Pulsars: Geometry, Pair Production, Emission Morphologies, and Phase-Resolved Spectra", K.S. Cheng, M. Ruderman and L. Zhang, The Astrophysical Journal, 537, 964-976 (2000). 
  4. "High-energy Radiation from Rapidly Spinning Pulsars with Think Outer Gaps", L. Zhang and K.S. Cheng, The Astrophysical Journal, 487, 370-379 (1997)
  5. "Energetic Radiation from Rapidly Spinning pulsars. I: Outermagnetosphere Gaps", Cheng, K.S., Ho, C. & Ruderman, M., The Astrophysical Journal, 300, 500-521 (1986)
     

Dr. J.J.L. Lim

  1. “Rotationally-Driven Fragmentation for the Formation of the Binary Protostellar System L1551 IRS 5”, J. Lim, P. K. H. Yeung, T. Hanawa, S. Takakuwa, M. Matsumoto, & K. Saigo,The Astrophysical Journal, 826, 153 (2016)
  2. “The High-Velocity System: Infall of a Giant Low-Surface-Brightness Galaxy towards the center of the Perseus Cluster”, A. Yu, J. Lim, Y. Ohyama, J. C. C. Chan, & T. Broadhurst, The Astrophysical Journal, 814, 101 (2015)
  3. “Free-form lensing implications for the collision of dark matter and gas in the frontier fields cluster MACS J0416.1-2403”, J.M. Diego, T. Broadhurst, S.M. Molnar, D. Lam, J.J.L. Lim, et al., Monthly Notices of the Royal Astronomical Society, 447, 3130 (2015)
  4. “A Rigorous Free-form Lens Model of A2744 to Meet the Hubble Frontier Fields Challenge”, D. Lam, T. Broadhurst, J.M. Diego, J.J.L. Lim, D. Coe, H.C. Ford and Z. Wei, The Astrophysical Journal, 697, 98 (2014)
  5. “A Geometrically Supported z ~ 10 Candidate Multiply Imaged by the Hubble Frontier Fields Cluster A2744”, A. Zitrin,  W. Zheng, T. Broadhurst, J. Moustakas, C.C. Lam, X.W. Shu , X.X. Huang, J.M. Diego , H. Ford, J.J.L. Lim, F.E. Bauer, L. Infante, D.D. Kelson and A. Molino, The Astrophysical Journal, 793, L12 (2014)
  6. “Angular Momentum Exchange by Gravitational Torques and Infall in the Circumbinary Disk of the Protostellar System L1551 NE”, S. Takakuwa, M. Saito, K. Saigo, T. Matsumoto, J.J.L. Lim, T. Hanawa and P.T.P. Ho,The Astrophysical Journal, 796, 1 (2014)
  7. “Molecular Gas in the X-Ray Bright Group NGC 5044 as Revealed by ALMA”, L.P. David, J.J.L. Lim, et al., The Astrophysical Journal, 792, 94 (2014)
  8. "A Molecular Hydrogen Nebula in the Central cD Galaxy of the Perseus Cluster", J.J.L. Lim, Y. Ohyama, C.H. Yan, D.V. Trung and S.Y. Wang, The Astrophysical Journal, 744, 112 (2012)
     

Dr. C.Y. Ng

  1. "Radio Polarization Observations of the Snail: A Crushed Pulsar Wind Nebula in G327.1-1.1 with a Highly Ordered Magnetic Field",Y. K. Ma, C.-Y. Ng, N. Bucciantini, P. O. Slane, B. M. Gaensler, & T. Temim, The Astrophysical Journal, 820, 100 (2016)
  2. "Hunting for Orphaned Central Compact Objects among Radio Pulsars", J. Luo, C.-Y. Ng, W. C. G. Ho, S. Bogdanov, V. M. Kaspi, & C. He, The Astrophysical Journal, 808, 130 (2015)
  3. “High-energy Emission of the First Millisecond Pulsar”, C. Y. Ng, J. Takata, G.C.K. Leung, K.S. Cheng, P. Philippopoulos, The Astrophysical Journal, 787, 167, 1-10 (2014)
  4. "An anti-glitch in a magnetar", R.F. Archibald , S.C.Y. Ng, K.N. Gourgouliatos, D. Tsang, P. Scholz, A.P. Beardmore, N. Gehrels, J.A. Kennea, Nature, 497, 7451, 591-593 (2013)
  5. "The Correlation between Dispersion Measure and X-Ray Column Density from Radio Pulsars", C. He, S.C.Y. Ng, V.M. Kaspi, The Astrophysical Journal, 768, 1, 64 (2013)

 

Prof. Q.A. Parker

  1. “HASH: The Hong Kong/AAO/Strasbourg H-alpha planetary nebula database” Q.A. Parker, I. Bojcic & D.J. Frew, 11th Pacific Rim Conference held in Hong-Kong in Dec 2015, JPhCS, 728 (2016)
  2. “Fast, Low-ionization Emission Regions of the Planetary Nebula M2-42” A. Danehkar, Q.A. Parker, W. Steffen, The Astrophysical Journal, 151, 38 (2016)
  3. “The H-Alpha Surface Brightness - Radius Relation: A Robust Statistical Distance Indicator for Planetary Nebulae” D.J. Frew, Q.A. Parker and I. Bojicic, MNRAS, 455, 1459 (2016)
  4. “New light on Galactic post-asymptotic giant branch stars - I. First distance catalogue” S. Vickers, D.J. Frew, Q.A. Parker and I.S. Bojičić, MNRAS, 447, 1673 (2015)
  5. “Kathryn’s Wheel: A Spectacular Galaxy Collision Discovered in the Galactic Neighbourhood” Q.A. Parker, A.A. Zijlstra, M. Stupar, M. Cluver, D.J. Frew, G. Bendo and I. Bojici, MNRAS, 452, 3759 (2015)
  6. “Four New Planetary Nebulae Towards the Small Magellanic Cloud”, D. Draskovic, Q.A. Parker, W.A. Reid and M. Stupar, MNRAS, 425, 1402 (2015)
  7. “Spatially resolved kinematic observations of the planetary nebulae Hen 3-1333”, A. Danehkar, Q.A. Parker, MNRAS, 449, 56 (2015)
  8. “New light on Galactic post-asymptotic giant branch stars - I. First distance catalogue”, S.B.Vickers, D.J.Frew, Q.A.Parker and I.S. Bojicic, MNRAS, 447, 1673 (2015)

 

Dr. J.C.S. Pun

  1. "Measurement of cosmic-ray muons and muon-induced neutrons in the Aberdeen Tunnel Underground Laboratory" S. Blyth, et al. (Aberdeen Tunnel Underground Experiment collaboration), Physical Review D, 93, 072005 (2016)
  2. "The destruction of the circumstellar ring of SN1987A," C. Fransson, J. Larsson,... C.S.J. Pun, G. Sonneborn and B. Sugerman, The Astrophysical Journal Letters, 806, L19 (2015)
  3. "Contributions of artificial lighting sources on light pollution in Hong Kong measured through a night sky brightness monitoring network", C.S.J. Pun, C.W. So, W.Y. Leung and C.F. Wong, Journal of Quantitative Spectroscopy & Radiative Transfer, 139, 90-108 (2014)
  4. "The discovery of an X-ray / UV stellar flare from the late-K/early-M dwarf LMC 335," B.T.H. Tsang, C.S.J. Pun,R. DiStefano, K.L. Li and A.K.H. Kong, The Astrophysical Journal, 754, 107 (2012)
  5. "Observation of Electron-Antielectron Disappearance at Daya Bay" F.P. An, et al. (Daya Bay Reactor Neutrino Experiment collaboration) Physical Review Letters, 108, 171803 (2012)

 

For details, please refer to Astrophysics Group Homepage.

Last updated on 03 August 2017