High Energy Astrophysics in Tsinghua Astrophysics Center _THAC_ by pengxiuhui

VIEWS: 6 PAGES: 54

									Review of High Energy Astrophysics
    Research in Mainland China
                 Zhang, Shuang Nan
    Tsinghua Center for Astrophysics (THCA)
            and Physics Department
       Tsinghua University, Beijing, China
        Key Lab for Particle Astrophysics
        Institute of High Energy Physics
         Chinese Academy of Sciences
 National Space Science Technology Center (NSSTC)
              and Physics Department
   University of Alabama in Huntsville, AL, USA
Institutions involved in high energy astrophysics (I)
   • Beijing
         –   Institute of High Energy Physics, Chinese Academy of Sciences
         –   Tsinghua University
         –   Peking University
         –   National Astronomical Observatories, Chinese Academy of Sciences
         –   Beijing Normal University
   • Nanjing
         – Nanjing University
         – Nanjing Purple Mountain Observatory, Chinese Academy of Sciences
   • Shanghai
         – Shanghai Observatory, Chinese Academy of Sciences
         – Shanghai Jiao-Tong University


  July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   2
Institutions involved in high energy astrophysics (II)
   • Hefei: University of Science and Technology of China,
     Chinese Academy of Sciences
   • Kunming
         – Yunnan University
         – Yunnan Observatory, Chinese Academy of Sciences
   • Guangzhou: Guangzhou University
   • Wuhan
         – Central China Normal University
         – Central China University of Science and Technology
   • Urumqi: Radio Astronomy Station
   • Xiamen: Xiamen University


  July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   3
Urumqi     Kunming Guangzhou Wuhan Beijing Hefei Nanjing Xiamen                                      Shanghai




   July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan              4
Urumqi     Kunming Guangzhou Wuhan Beijing Hefei Nanjing Xiamen                                      Shanghai




   July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan              5
   High energy astrophysics research in Beijing
       – Institute of High Energy Physics, Chinese Academy of Sciences
       – Tsinghua University
       – Peking University
       – National Astronomical Observatories, Chinese Academy of Sciences
           - AGN, clusters of galaxies, gamma-ray bursts, pulsars, accretion
             disks
       – Beijing Normal University
           - Accretion disks, X-ray binaries




July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   6
          Institute of High Energy Physics, CAS
• Key Lab and Center for Particle Astrophysics
      – Ground-based high energy gamma-ray astronomy
         - Tibet AS-gamma experiment
         - Tibet ARGO-YBJ array
      – Space-borne high energy astrophysics
         - Instrumentation
             • Hard X-ray Modulation Telescope (future satellite mission)
             • Gamma-ray burst monitor aboard the Shen-Zhou-II space lab.
             • Balloon-borne hard X-ray telescope
             • Small satellite R&D
         - Observations and data analysis
             • black hole and X-ray binaries, AGNs, gamma-ray bursts,
                supernova remnants, pulsars
         - Theoretical astrophysics
             • Accretion disks, gamma-ray bursts
July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   7
    YBJ International Cosmic Ray Observatory


Tibet -Lhasa: 4300 m asl
  China-Japan: AS-
  China-Italy: ARGO
Cosmic-ray
High Energy Gamma-ray




  July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   8
                                          ARGO-YBJ
• China-Italy
• @4300 m above sea level, 606 g/cm2
• 71x74 m2 full coverage of single layer RPC (resistive Plate
  Counters)
   – 100x100 m2 partial (~50%) coverage
   – 0.5 cm lead converter
• gamma-ray threshold ~100 GeV
   – field of view: -100 to 700
   – sensitivity: 0.1 Crab @ 100 GeV
       - 2.5 sigma detection of 30% flux variation of Crab within 20 days
• status:
   – detectors and electronics being assembled
   – partial data taking in late 2002 or early 2003

  July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   9
July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   10
                                       Morphology




July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   11
         Model: Close Cousin to the Crab Nebula




July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   12
            Doppler boosting model for the ring




July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   13
        Tsinghua University: Hard X-ray Modulation
                       Telescope
• ~1000 kg satellite mission
   – Survey of stellar mass and supermassive black holes
   – Broad band (15 - 200 keV) and high precision X-ray timing studies
• Current 973 project: Phase-A (40 million CNY = $5M)
   – full mission cost ~ $100M
• Main participating institutions:
   – CAS: Institute of High Energy Physics and Center for Space Science and
     Application Research
   – Tsinghua University: Astrophysics Center, Physics Department, Engineering
     Physics Department, Space Center
• Possible international collaborations
   – Institute of TeSRE/CNR (Italy): to provide focusing X-ray optics and wide-
     field X-ray camera
   – Tubingen University (Germany): to provide electronics, data acquisition
   – University of Southampton (UK): mission optimization, space environments
   July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   14
        Tsinghua University: Multiwavelength Small
                    Satellite Mission
• 100 kg satellite mission: wide field X-ray telescope + optical
  telescopes + gamma-ray monitor
   – Formation of black holes: gamma-ray bursts and supernovae
   – Evolution of black holes: broad band (0.5 - 30 keV) high precision spectral
     study (150-300 eV)
• Being proposed by Tsinghua, Nanjing University, National
  Astronomical Observatoroies and Institute of High Energy Physics
  (CAS)
   – Full mission cost ~ $8M
   – Satellite to be build by Tsinghua Space Center
• Possible international collaborations:
   – U.K., Italy, Germany, H.K.


   July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   15
   Tsinghua University: Theoretical Astrophysics
• Compact objects:
   –   Neutron stars: pulsars and pulsar wind
   –   Strange stars: state of equation, surface properties
   –   Black holes: formation and evolution
   –   Gamma-ray bursts: origin and properties
• Magnetohydrodynamics:
   –   Solar g-modes
   –   MHD density waves and tidal waves
   –   Quasi-periodic burst activities of Jupiter
   –   Circumnuclear starburst rings
• Accretion disks and outflows
   – Global disk solutions
   – Non-thermal particle energy distributions
   – General relativistic effects and high-energy particle interactions

  July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   16
     Tsinghua University: Observational Astrophysics
• Direct Demodulation technique for non-focusing imaging
   – The Hard X-ray Modulation Telescope
• New timing analysis technique in the time domain
   – Power density, Variability,Time-lag
   – Sometimes more advantageous than FFT based timing analysis methods
• New spectral-correlation technique
   – Detection of relativistic outflows without imaging or line identifications
• New technique for distance determination of binary sources
   – Chandra imaging + FFT analysis
• Data analysis with international space missions
   – Chandra, XMM-Newton, XTE, ASCA, BATSE, etc
   – X-ray binaries, galaxies, gamma-ray bursts, AGNs, jets/outflows
• Virtual Observatories
   – Data archiving and data mining
• Network optical telescope:
   – multiwavelength monitoring of transient high energy sources
   July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   17
July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   18
                PDS in time domain and with FFT




July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   19
           Neutron star low mass X-ray binaries




July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   20
                    Cygnus X-1: black hole binary




July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   21
July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   22
            Burst light curve in different bands




July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   23
             Theoretical Projects on High Energy
              Astrophysics at Peking University

1. Inverse Compton Scattering
Model for Pulsar Radiation
(lead by Prof. G.J. Qiao): The
proposed beams and cones can
naturally explain the observed
pulse profile & polarization
properties of pulsars
2. Bared Strange Stars (lead by
Dr. R.X. Xu): Discussing the
possibility, related physics and
consequences of the idea if some
pulsars are stars consisting of
strange matters
 July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   24
             Theoretical Projects on High Energy
              Astrophysics at Peking University

3. Accretion Disk Physics (lead by Prof.
   X.-B. Wu): Stability of the advection-
                                                                              Standard thin disk
   dominated accretion flow naturally
   explains the inactive feature of nearby
   galaxies and X-ray binaries in low state.                                ADAF + thin disk
4. Binary Black Hole Model in AGNs
   (lead by Dr. F.K. Liu): The interaction
   of secondary black hole with accretion
   disk around the primary black hole may
   explain the observed periodic variations
   and discontinuity of jet formation in
   radio-loud AGNs

 July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   25
                                            Nanjing
   • Nanjing University
   • Nanjing Purple Mountain Observatory, Chinese Academy
     of Sciences
         – gamma-ray bursts
         – solar flares




July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   26
             High Energy Astrophysics Research at
                      Nanjing University
•   Non-thermal emission of supernova remnants and their evolution
•   Morphology, structure and composition of supernova remnants
•   Identification of historical supernova remnants
•   Supernovae and binary evolution
•   High energy radiation from compact stars
•   Gamma-ray bursts




    July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   27
                   The Lx             
                                     E Relation for SNRs


By analyzing Einstein data for
SNRs, Zhen-Ru Wang at NJU,
cooperating with F. Seward at
CfA, found an important
empirical relation between the
X-ray luminosity of SNRs and
the rotational energy loss rate
of the pulsars inside.




 July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   28
    This relation, sometimes called “Seward-Wang relation”, is
    widely recognized and confirmed by observations with
    various X-ray satellites.




July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   29
               Gamma-Ray Sources and Guest Stars


On the basis of the fact that
the youngest neutron stars
emit strong gamma-ray
radiation, Zhen-Ru Wang at
NJU suggested that a few
gamma-ray sources may be
identified with young
compact sources formed in
the events of guest stars. One
of such sources, 2CG 353 +
16 was identified with guest
stars observed in the 14th
century B.C.

    July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   30
Chandra Observation of the Crab like SNR G21.5-0.9
   Yang Chen at NJU presents the first evidence for the presence
   of an X-ray extended halo surrounding the Crab-like core
   G21.5-0.9.




  July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   31
Supersoft X-ray Sources and Progenitors of SN Ia


Calculations of the evolution
of white dwarfs in binaries by
Xiang-Dong Li at NJU lend
support to the connection
between supersoft X-ray
sources, first observed with
ROSAT, and the progenitors
of SN Ia, and suggest possible
distributions of the latter.




  July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   32
                 Is 4U 1728-34 a Strange Star?
 With the RXTE observations of the kilo-Hertz QPOs in
 4U1728-34, Xiang-Dong Li at NJU suggested that the
 equation of state of the compact star is more compatible with
 a strange star rather a neutron star.




 Allowed
 region



July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   33
         Generic Dynamic Model for
                            GRB afterglow
       d     2 1
          
       dm      M                    
                        d             2 1
                           
                        dm    M ej  m  2(1   )m
                                          (Y.F. Huang, Z.G. Dai, T. Lu, 1999)
       It gives the overall description from ultra-relativistic and
       highly radiative phase to non-relativistic and adiabatic phase,
       especially leads to the correct Sedov limit:
                                         β∝ R-3/2,
       as the fireball getting into the non-relativistic and adiabatic
       phase.

July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   34
  Generic Model: v-R                              Dynamical Evolution



• Solid:
  generic model
• Dash-dotted:
  ultra-relativistic
• Dashed:
  Newtonian




   July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   35
GRB Environments
           Non-uniform Environment of GRB
        GRB970616                                                    n ~ r-k
                                                                  
                                              n ~ r-2
                                     (wind environment)
                                                      (Dai, Lu, 1998)

        Support the view of massive star origin for GRBs.
                                                     (Chevaliar, Li, 1999)




July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   37
               Dense Environment
·     Break in optical light curve of GRB990123:
                                            n~106 cm-3
     (Relativistic to non-relativistic transition  break)
                                                 Dai-Lu, ApJL, 1999


· Rapidly declining optical to X-ray afterglow of GRB980519
     can be explained well by dense medium, and its radio
     afterglow can also be excellently explained.
                                    Wang-Dai-Lu, MNRAS, 2000




  July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   38
             Meaning of Environmental Effects



                      •1st:Wind Effects Wind environments
                   were provided by the progenitor of the GRB
                    •2nd:Density Effects Dense environments
                          were probably molecular clouds
                   GRB is associated with stellar forming region




             The existence of two kinds of environmental
              effects both support the view: GRBs were
             originated from the collapse of massive stars
July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   39
GRB Energy Source
                             Energy Source Models
• Merger of NS-NS, NS-BH (Eichler et al., 1989; Paczynski, 1991)
      ► ~ 108 yr                (Gravitational radiation timescale)
• Massive star collapse         (Woosley, 1993; Paczynski, 1998)
      ►Association with Star Forming Regions
      ►Association with supernovae
• Phase Transition of NS⇨SS
  (Cheng-Dai, PRL, 1996; Dai-Lu, PRL, 1998)

Natural ways to avoid baryon contamination:
      ►A strange star
      ►A rapidly rotating          Black Hole + Disk
                                                                 
          Maximum available energy      29% MBHc2     42% Mdiskc2
   (through Blandford-Znajek mechanism)    spin energy binding energy


     July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   41
           Phase Transition of NS  SS
                                                (one way avoiding baryon-contamination)



 Energy: Phase Transition        ~ 20 MeV/baryon
           Rotation Energy       ~ 5×1051 ergs I44Ω4
 Baryon only in thin Crust      ~ 10-5 M⊙
 Multi-sub-bursts --- Differential Rotations
 Rate of Accreting NS in LMXB to SS ~ 10-6/yr per galaxy

                                              (Dai, Lu, PRL, 1998; Cheng, Dai, PRL, 1996)




  July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   42
                                          Shanghai
       – Shanghai Jiao-Tong University
       – Shanghai Observatory, Chinese Academy of Sciences
          - Bl Lac objects (VLBI observations)
          - Accretion disk and outflows
          - High energy radiation mechanisms




July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   43
                  Shanghai Jiao-Tong University

• X-ray Imaging Study of Elliptical Galaxies with Chandra
    1. Distributions of gas and gravitating mass
       Constraint on the ellipticity and the mass profile of dark halos
    2. Mass-to-light ratio & baryon fraction
       Comparison with theories & N-body simulations
    3. Comparison with clusters of galaxies
          Xu et al. (ongoing)
• Cerenkov Radiation as the Origin of the
  Iron K Line in AGNs
           You et al. 2002
• Resonant Inverse Compton Scattering of Fast
  Electrons in an Intense Magnetic Field
           You et al. 2002


July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   44
                                  Kunming, Yunnan
     • Yunnan Observatory, Chinese Academy of Sciences
     • Yunnan University




July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   45
         High Energy Astrophysics Activity in
                 Yunnan Observatory

• Periodic brightness minima and implications for binary
  pair of supermassive black holes in GeV QSO PKS1510-
  089.
• Searches for optical short timescale variations in gamma-
  ray loud blazars.
• Supermassive black holes in gamma-ray loud blazars:
  masses, rotations, and emission regions.
• Development of AGN model




 July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   46
            Astrophysical Center in Yunnan
                      University

        The Astrophysical Center in Yunnan University was formally
         established in December 1998. The current research interests are high-
         energy radiation from both pulsars and Active Galactic Nuclei (AGNs).




July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   47
     Gamma-Ray Pulsars

        Dr. Zhang and his collaborator, Prof. K.S. Cheng (HKU),
         have made a detailed study in high-energy emission from
         rotation-powered pulsars. They proposed a self-consistent
         outer gap model (Zhang & Cheng, 1997, ApJ, 487, 370), and
         developed a three-dimensional outer gap model (Cheng,
         Ruderman & Zhang, 2000) for explaining the observed features
         of gamma-ray pulsars.




July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   48
      AGNs

      High-energy radiation from blazars (Zhang &Cheng 1997, ApJ,
         475, 534; Zhang &Cheng 1997, ApJ, 488,94; Fan, Cheng & Zhang ,1999,
         A&A, 352, 32)
      Gamma-ray and multi-waveband emission from blazars
         (Cheng, Zhang, &Zhang, 2000, ApJ, 537, 80; Zhang, Cheng & Fan, 2001,
         PASJ, 53, 207; 2002, PASJ, 54, 159; Mei, Zhang & Jiang, 2002, A&A)
      Polarization and variations (Fan, Cheng, Zhang, et al. 1997, A&A,
         327, 947; Fan, Cheng &Zhang, 2001, PASJ, 53, 201; Fan et al. 2002, A&A,
         381,1)




July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   49
                              Introduction
                            Guangzhou University



         Center for Astrophysics
         Guangzhou University




July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   50
Summary:
1) Estimate the central black hole masses of high-energy gamma-ray
   loud blazars
2) Investigate the high-energy gamma-ray emission mechanism
3) The variability properties of blazars
4) The beaming model for blazars
5) The long-term variation periodicity analysis




  July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   51
   Central black hole masses of gamma-ray loud
                      blazars


1) Assumed the gamma-rays are from a 200R_g distance from the
  center black holes and used the short time scales in the gamma-ray
  regions, the intrinsic luminosities of the gamma-ray loud blazars,
  the black hole masses of (1-7)*107 M。




  July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   52
     Correlation Analysis for Gamma Ray Loud Blazars


1) The high frequency (230GHz) radio emissions are correlated with
  the GeV gamma-ray emissions with a chance probability of 5*10-3 ,
  but the lower frequency (5GHz) radio emissions do not show this
  kind of correlation, suggesting that the high frequency radio
  emissions are important for high energy GeV gamma-ray emissions.

2) From the available emission lines and gamma-ray emissions, we
   found that there is no clear correlation between the emission line
   emission and the high-energy GeV gamma-ray emissions. This
   analysis does not conflict with the synchrotron self-compton model
   for the gamma-ray emsissions.

    July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   53
                               Other Instututions
 • Hefei: University of Science and Technology of China,
   Chinese Academy of Sciences
       – AGN: multiwavelength studies
       – Accretion disk: theoretical modeling and X-ray data analysis
       – Jets/outflows
 • Wuhan
       – Central China Normal University
          - Accretion disk theories
       – Central China University of Science and Technology
          - B-Z mechanism and General relativity
 • Urumqi: Radio Astronomy Station: radio pulsars
 • Xiamen: Xiamen University
       – Accretion disk theories: ADAF

July 6, 2002, IAU Regional Meeting, Satellite Meeting on High Energy Astrophysics, Tokyo, Japan   54

								
To top