The Effect of the Remnant Mass in Estimating Stellar Mass of Galaxies
  The definition of the galactic stellar mass estimated from the spectral
energy distribution is ambiguous in the literature; whether the stellar mass
includes the mass of the stellar remnants, i.e. white dwarfs, neutron stars,
and black holes, is not well described. The remnant mass fraction in the total
(living+remnant) stellar mass of a simple stellar population monotonically
increases with the age of the population, and the initial mass function and
metallicity affect the increasing rate. Since galaxies are composed of a number
of stellar populations, the remnant mass fraction may depend on the total
stellar mass of galaxies in a complex way. As a result, the shape of the
stellar mass function of galaxies may change, depending on the definition of
the stellar mass. In order to explore this issue, we ran a cosmological
hydrodynamical simulation, and then, we have found that the remnant mass
fraction indeed correlates with the total stellar mass of galaxies. However,
this correlation is weak and the remnant fraction can be regarded as a constant
which depends only on the redshift. Therefore, the shape of the stellar mass
function is almost unchanged, but it simply shifts horizontally if the remnant
mass includes or not. The shift is larger at lower redshift and it reaches
0.2-dex at z=0 for a Chabrier IMF. Since this causes a systematic difference,
we should take care of the definition of the `stellar' mass, when comparing
one's result with others.
