X-ray and optical emission from Neutron Stars and Pulsar Wind Nebulae

Open Access
Kargaltsev, Oleg Y
Graduate Program:
Astronomy and Astrophysics
Doctor of Philosophy
Document Type:
Date of Defense:
October 01, 2004
Committee Members:
  • George Pavlov, Committee Chair
  • William N Brandt, Committee Member
  • John Andrew Nousek, Committee Member
  • Renee Denise Diehl, Committee Member
  • Gordon Paul Garmire, Committee Member
  • neutron stars
  • pulsars
  • X-rays
  • pulsar winds
This dissertation is devoted to X-ray and optical-UV observations of Neutron Stars (NSs) and Pulsar-Wind nebulae (PWNe). Part I of the dissertation describes the UV and X-ray observations of the famous Vela pulsar and its spectacular PWN. The observations were carried out with the {sl Chandra X-ray Observatory} and {sl Hubble Space Telescope}. I begin by presenting the spectrum and lightcurves of the pulsar as they are seen in different bands of electromagnetic radiation. I then turn to imaging observations of the Vela PWN. Thirteen observations of the Vela PWN with {sl Chandra}, spanning a period of 3 years, reveal its complex and variable structure which consists of arcs, jets, knots and diffuse emission. Especially interesting is the long external jet which changes its shape on a timescale of weeks and contains blobs moving at speeds of (0.5-0.6)c. In addition to the fine structure of the inner PWN, a much larger and fainter asymmetric X-ray nebula emerges in the deep summed images. The shape of this outer PWN is similar to that of the radio PWN. I present the high-resolution spectral map of the Vela PWN and compare its X-ray properties with those of other PWNe. To see if other PWNe are alike and to study the connection between the pulsar and the PWN properties, I retrieved data on rotation-powered pulsars and PWNe from the {sl Chandra} archive. Using these data, I performed a uniform statistical analysis of the PSR/PWN X-ray properties. These analysis can potentially provide powerful diagnostic of the energetics and emission mechanisms of neutron stars. Part II focuses on the individual observations of two middle-aged pulsars (Gemiga and B0656+14), very old millisecond pulsar J0437$-$4715, and the enigmatic central source in the Supernova Remnant G266.2$-$1.2. The observations were carried out with {sl HST} and {sl Chandra}. For each of these objects, I describe the observation setups, data reduction, quantitative results (e.g., fluxes, spectra, light curves) and their astrophysical implications (e.g., origin of the observed radiation, NS surface temperature, connection between the X-ray and optical radiation).