PULSAR STATISTICS .2. THE LOCAL LOW-MASS BINARY PULSAR POPULATION

Using a fully self-consistent approach to account for known survey sel ection effects, we constrain the number and scale height of low-mass b inary pulsars (LMBPs) in the local solar neighbourhood. Our results sh ow that the local surface density of LMBPs with luminosities above 2.5 mJy kpc(2) is similar to 20 kpc(-2). Models in which the scale height of LMBPs above the galactic plane is greater than or similar to 500 p c are found to be most consistent with the data. The mean space veloci ty at birth required to produce scale heights of this order is found t o be greater than or similar to 80 km s(-1). Assuming that LMBPs are l ong-lived (less than or similar to 10(10) yr) objects, their local bir th rate is at least 2 x 10(-9) kpc(-2) yr(-1). Whilst this is in excel lent agreement with the birth rate of their proposed progenitors, the low-mass X-ray binaries, there are several uncertainties involved whic h could significantly increase this limit on the birth rate, perhaps b y an order of magnitude. We should not discount the possibility that s ome of these pulsars are formed via a different process, such as the a ccretion-induced collapse of a white dwarf.