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abstract: |
    The possibility and the implications of the idea, that pulsars are born as strange stars, are explored. Strange stars are very likely to have atmospheres with typical mass of $\sim 5\times 10^{-15}M_\odot$ but bare polar caps almost throughout their lifetimes, if they are produced during supernova explosions. A direct consequence of the bare polar cap is that the binding energies of both positively and negatively charged particles at the bare quark surface are nearly infinity, so that the vacuum polar gap sparking scenario as proposed by Ruderman & Sutherland should operate above the cap, regardless of the sense of the magnetic pole with respect to the rotational pole. Heat can not accumulate on the polar cap region due to the large thermal conductivity on the bare quark surface. We test this “bare polar cap strange star” (BPCSS) idea with the present broad band emission data of pulsars, and propose several possible criteria to distinguish BPCSSs from neutron stars.

    [*PACS codes:*]{} 97.60.G, 97.60.J
address:
- 'CAS-PKU Beijing Astrophysical Center and Astronomy Department, Peking University, Beijing 100871, China'
- 'Laboratory of High Energy Astrophysics, NASA Golddard Space Flight Center, Greenbelt, MD 20771'
author:
- 'R.X. Xu'
- Bing Zhang
