The nature of [S III]{\lambda}{\lambda}9096, 9532 emitters at z = 1.34
  and 1.23
  A study of [S III]$\lambda\lambda9096,9532$ emitters at $z$ = 1.34 and 1.23
is presented using our deep narrow-band $H_2S1$ (centered at 2.13 $\mu$m)
imaging survey of the Extended Chandra Deep Field South (ECDFS). We combine our
data with multi-wavelength data of ECDFS to build up spectral energy
distributions (SEDs) from the $U$ to the $K_{s}$-band for emitter candidates
selected with strong excess in $H_2S1 - K_{s}$ and derive photometric
redshifts, line luminosities, stellar masses and extinction. A sample of 14 [S
III] emitters are identified with $H_2S1<22.8$ and $K_{\rm s}<24.8$ (AB) over
381 arcmin$^{2}$ area, having [S III] line luminosity $L_{[SIII]}= \sim
10^{41.5-42.6}$erg s$^{-1}$. None of the [S III] emitters is found to have
X-ray counterpart in the deepest Chandra 4 Ms observation, suggesting that they
are unlikely powered by AGN. HST/ACS F606W and HST/WFC3 F160W images show their
rest-frame UV and optical morphologies. About half of the [S III] emitters are
mergers and at least one third are disk-type galaxies. Nearly all [S III]
emitters exhibit a prominent Balmer break in their SEDs, indicating the
presence of a significant post-starburst component. Taken together, our results
imply that both shock heating in post-starburst and photoionization caused by
young massive stars are likely to excite strong [S III] emission lines. We
conclude that the emitters in our sample are dominated by star-forming galaxies
with stellar mass $8.7<\log (M/M_{sun})<9.9$.
