The MOSDEF Survey: No Significant Enhancement in Star Formation or
  Deficit in Metallicity in Merging Galaxy Pairs at 1.5<=z<=3.5
  We study the properties of 30 spectroscopically-identified pairs of galaxies
observed during the peak epoch of star formation in the universe. These systems
are drawn from the MOSFIRE Deep Evolution Field (MOSDEF) Survey at $1.4 \leq z
\leq 3.8$, and are interpreted as early-stage galaxy mergers. Galaxy pairs in
our sample are identified as two objects whose spectra were collected on the
same Keck/MOSFIRE spectroscopic slit. Accordingly, all pairs in the sample have
projected separations $R_{{\rm proj}}\leq 60$ kpc. The velocity separation for
pairs was required to be $\Delta v \leq 500 \mbox{ km s}^{-1}$, which is a
standard threshold for defining interacting galaxy pairs at low redshift.
Stellar mass ratios in our sample range from 1.1 to 550, with 12 ratios closer
than or equal to 3:1, the common definition of a "major merger." Studies of
merging pairs in the local universe indicate anenhancement in star-formation
activity and deficit in gas-phase oxygen abundance relative to isolated
galaxies of the same mass. We compare the MOSDEF pairs sample to a control
sample of isolated galaxies at the same redshift, finding no measurable SFR
enhancement or metallicity deficit at fixed stellar mass for the pairs sample.
The lack of significant difference between the average properties of pairs and
control samples appears in contrast to results from low-redshift studies,
although the small sample size and lower signal-to-noise of the high-redshift
data limit definitive conclusions on redshift evolution. These results are
consistent with some theoretical works suggesting a reduced differential effect
of pre-coalescence mergers on galaxy properties at high redshift --
specifically that pre-coalescence mergers do not drive strong starbursts.
