  In this work, we look for evidence of a non-unity mass ratio binary dwarf
galaxy merger in the Sagittarius stream. Simulations of such a merger show
that, upon merging with a host, particles from the less-massive galaxy will
often mostly be found in the extended stream and less-so in the central
remnant. Motivated by these simulations, we use APOGEE DR17 chemical data from
approximately 1100 stars in both the Sagittarius remnant and stream to look for
evidence of contamination from a second dwarf galaxy. This search is initially
justified by the idea that disrupted binary dwarf galaxies provide a possible
explanation of the Sagittarius bifurcation, and the location of the massive,
chemically peculiar globular cluster NGC 2419 found within the stream of
Sagittarius. We separate the Sagittarius data into its remnant and stream and
compare the [Mg/Fe] content of the two populations. In particular, we select
[Mg/Fe] to search for hints of unique star formation histories among our sample
stars. Comparing the stream and remnant populations, we find regions have
distinct [Mg/Fe] distributions for fixed [Fe/H], in addition to distinct
chemical tracks in [Mg/Fe] -- [Fe/H] abundance space. We show that there are
large regions of the tracks for which the probability of the two samples being
drawn from the same distribution is very low (p < 0.05). Furthermore, we show
that the two tracks can be fit with unique star formation histories using
simple, one zone galactic chemical evolution models. While more work must be
done to discern whether the hypothesis presented here is true, our work hints
at the possibility that Sagittarius may consist of two dwarf galaxy
progenitors.

Astrophysics of Galaxies