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3.2 Formation rate

UpdateJump To The Next Update Information Type II/Ib/Ic supernovae are observed to occur in only spiral and irregular galaxies. The most thorough computation of SN rates is that of Cappellaro et al. [46]. Their sample includes 137 SNe from five different SN searches. They determined that the core collapse SN rate in the Galaxy is -3 -2 -1 6× 10 - 1.6× 10 yr. Thus, a reasonable occurrence rate can be found for an observation distance of 10 Mpc. (Note that a infrared survey estimates that the rate may actually be an order of magnitude higher [161].) What this rate might exclude are those stars that collapse to form neutron stars, but have sufficiently weak explosions that they eject very little nickel and hence are not very bright. Including these systems as well will increase the total number of stellar collapses initially into neutron stars by less than 5 - 40% [89Jump To The Next Citation Point]. However, it does include those stars that collapse to black holes directly and form GRBs (producing supernova-like outbursts). We will discuss the GWs from such collapses in Section 4. Excluding them from this sample will not change the above numbers.
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