  We show that in the presence of a pseudogap, the spectral function in the
superconducting state of the underdoped cuprates exhibits additional Bogoliubov
quasiparticle peaks at both positive and negative energy which are revealed by
the particle-hole asymmetry of the pseudogapped energy bands. This provides
direct information on the unoccupied band via measurement of the occupied
states. When sufficiently close, these Bogoliubov peaks will appear to merge
with existing peaks leading to the anomalous observation, seen in experiment,
that the carrier spectral density broadens with reduced temperature in the
superconducting state. Using the resonating valence bond (RVB) spin liquid
model in conjunction with recent angle-resolved photoemission spectroscopy
(ARPES) data allows for an empirical determination of the temperature
dependence of the pseudogap suggesting that it opens only very gradually below
the pseudogap onset temperature $T^*$.
