ALFA pulsar surveys: Searching for fundamental laboratories of extreme physics

The pulsar-ALFA (PALFA) consortium\footnote{See http://alfa.naic.edu/pulsars} is conducting large-area pulsar surveys at the Arecibo telescope using a new 7-beam receiver operating at 20-cm wavelengths. The high sensitivity of the telescope allows unprecedented survey sensitivities with relatively small integration times. In this talk, we show that these short integration times remove observational biases against the detection of pulsars in tight binary systems. Also, because of their high spectral and time resolution, the PALFA surveys are uniquely sensitive to fast-spinning objects with very sharp pulse profiles, i.e., pulsars with potentially excellent timing precision. We then show, by presenting specific examples, that pulsars in tight binary systems, fast spin periods and excellent timing precision are the most useful to test gravitational theories and study the behavior of matter under extreme densities. This implies that the PALFA surveys will very likely have a major scientific impact in the study of gravitation and the study of matter at supranuclear densities.