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Session 50 - Pulsars in the UV and Visible.
Topical, Oral session, Wednesday, June 10
New observational capabilities have recently provided rapid progress in measurement of rotation-powered pulsars in the near-IR through UV. We now have optical detections of \sim a dozen young pulsars, color information on over half of these objects, and a few low resolution spectra. Optical pulse profiles are now available for five pulsars, and phase-resolved color changes have been seen in the spectrum of the Crab. Coupled with recent \gamma- and X-ray data, we are now assembling a good general picture of the non-thermal magnetospheric emission. Optical/UV emission, while energetically insignificant, plays an important role since (as in the soft X-rays) the spectrum can also contain a significant thermal component in this band.
At present, theory lags the data. We summarize the general constraints that have been deduced from the observations, arguing that the IR-UV emission is dominated by synchrotron emission from the magnetosphere above a single magnetic pole. We then describe some recent attempts to model optical pulse profiles and spectra. These models suggest that optical data are a keen diagnostic of the particle production in the magnetosphere, and show that phase-resolved spectra and polarimetry will be particularly powerful at probing the pulsar physics and connecting with other wavebands. Intriguing results are already available for the brightest pulsar, the Crab; but sensitive measurements of a typical young pulsar at m_V > 25 require new detector technology along with modern large telescopes.
Program listing for Wednesday