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Neutron Stars

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Questions

  • What are the properties of the superdense matter in the interiors of neutron stars?
  • Are neutron stars indeed made of neutrons or they are composed of more exotic matter, such as quark-gluon plasma?
  • What is the equation of state of the superdense matter?
  • What are the properties of surface layers (atmospheres) of neutron stars?
  • What are the effects of the superstrong magnetic fields of neutron stars on the properties of their surface layers and radiation?
  • How are the relativistic particles, responsible for pulsar wind nebulae, created and accelerated?
  • What are the mechanisms of the pulsar wind interaction with the ambient medium?

Discoveries and Milestones

  • George Pavlov has developed new methods to determine the chemical composition, temperature and magnetic fields of the surface layers of neutron stars and the masses and radii of these objects. He also has detected the first spectral lines from an isolated neutron star and has discovered a large number of X-ray pulsar wind nebulae with the Chandra X-ray Observatory.

Current Projects

  • George Pavlov is using multi-epoch observations with Chandra to measure the variability of the nebula generated by the wind of the Vela pulsar. These data should provide insight into the generation of pulsar winds and their interaction with the ambient medium.
  • George Pavlov has observed the middle-aged pulsar B0656+14 at far-UV wavelengths with the Hubble Space Telescope. He is using these data to separate the thermal emission produced by the neutron star surface from the nonthermal emission from the pulsar magnetosphere by measuring the pulsar spectrum at different phase of its pulsations.
  • George Pavlov is collecting all available information on multiwavelength emission of isolated (nonaccreting) pulsars and pulsar wind nebulae for inclusion in publicly accessible on-line catalogs of these objects.
  • George Pavlov is planning to search for polarized optical emission from the Vela pulsar wind nebula using the Hubble Space Telescope. These observations could provide the first detection of this nebula at optical wavelengths, which would enable the measurement of the the energy spectrum of ultrarelativistic wind particles and establish the geometry of the magnetic field.

Student Highlights

  • Oleg Kargaltsev detected a millisecond pulsar at UV wavelengths for the first time.
  • Oleg Kargaltsev discovered the long, strongly collimated and variable jet of the Vela pulsar.

Participants

  • Faculty
  • Postdocs and Research Associates
Chulhoon Chang
  • Students

Prakash Arumugasamy

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