  The mass function of hydrogen-rich atmosphere white dwarfs has been
frequently found to reveal a distinctive high-mass excess near 1Msun. However,
a significant excess of massive white dwarfs has not been detected in the mass
function of the largest white dwarf catalogue to date from the Sloan Digital
Sky Survey. Hence, whether a high-mass excess exists or not has remained an
open question. In this work we build the mass function of the latest catalogue
of data release 10 SDSS hydrogen-rich white dwarfs, including the cool and
faint population (i.e. effective temperatures 6,000 <~ Teff <~ 12,000 K,
equivalent to 12 mag <~ Mbol <~ 13 mag). We show that the high-mass excess is
clearly present in our mass function, and that it disappears only if the
hottest (brightest) white dwarfs (those with Teff >~ 12,000 K, Mbol <~ 12 mag)
are considered. This naturally explains why previous SDSS mass functions failed
at detecting a significant excess of high-mass white dwarfs. Thus, our results
provide additional and robust observational evidence for the existence of a
distinctive high-mass excess near 1Msun. We investigate possible origins of
this feature and argue that the most plausible scenario that may lead to an
observed excess of massive white dwarfs is the merger of the degenerate core of
a giant star with a main sequence or a white dwarf companion during or shortly
after a common envelope event.
