  As the plausible central engine of gamma-ray bursts (GRBs), a black hole (BH)
hyperaccretion disk should be in a state of neutrino-dominated accretion flow
(NDAF) if the accretion rate is larger than the ignition rate of an NDAF. A
rotating stellar-mass BH surrounded by a hyperaccretion disk might be born in
the center of a massive core collapsar. In the initial hundreds of seconds of
the accretion process, the mass supply rate of the massive progenitor is
generally higher than the ignition accretion rate, but the jets are generally
choked in the envelope. Thus, neutrinos can be emitted from the center of a
core collapsar. In this paper, we study the effects of the masses and
metallicities of progenitor stars on the time-integrated spectra of electron
neutrinos from NDAFs. The peak energies of the calculated spectra are
approximately 10-20 MeV. The mass of a collapsar has little influence on the
neutrino spectrum, and a low metallicity is beneficial to the production of
low-energy ($\lesssim$ 1 MeV) neutrinos. We also investigate the differences in
the electron neutrino spectra between NDAFs and proto-neutron stars. Combining
with the electromagnetic counterparts and multi-messenger astronomy, one may
verify the possible remnants of the core collapse of massive stars with future
neutrino detectors.
