Not that simple: the metallicity dependence of the wide binary fraction
  changes with separation and stellar mass
  The metallicity dependence of the wide binary fraction (WBF) is critical for
studying the formation of wide binaries. While controversial results have been
found in recent years. Here we combine the wide binary catalog recognized from
Gaia EDR3 and stellar parameters from LAMOST to investigate this topic. Taking
bias of the stellar temperature at given separations into account, we find that
the relationship between the WBF and metallicity depends on temperature for the
thin-disk at s > 200 AU. It changes from negative to positive as the
temperature increases from 4000 K to 7500 K. This temperature/mass dependence
is not seen for the thick-disk. Besides, the general tendency between the WBF
and metallicity varies with the separation, consistent with previous results.
It shows anti-correlation at small separations, s < 200 AU for the thin-disk
and s < 600 AU for the thick-disk. Then it becomes an "arcuate" shape at larger
separations (hundreds to thousands of AU), peaking at [Fe/H] ~ 0.1 for the
thin-disk and [Fe/H] ~ -0.5 for the thick disk. Finally it becomes roughly flat
for the thin-disk at 1000 < s < 10000 AU. Our work provides new observational
evidences for theoretical studies on binary formation and evolution.
