thus this object would not be classified as an Ly$\alpha$ emitter according to the traditional criterion of EW(Ly$\alpha$) $>$ 20 Å. This value is also below the cutoff of EW(Ly$\alpha$) $>$ 25 Å [@stark11] often adopted in the study of the evolution of the Ly$\alpha$ fraction at high redshift.

Low-z interpretations {#sec:lowz}
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We examined the possibility that the object is a foreground [\[O[ii]{}\]]{}$\lambda\lambda$3726, 3729, H$\beta$, [\[O[iii]{}\]]{}$\lambda\lambda$4959, 5007, or H$\alpha$ emitter. First, if the detected line is H$\beta$ or one of the [\[O[iii]{}\]]{} doublet, the other two lines would have been detected within our spectral coverage in regions free from sky lines. We did not find any signal at the expected wavelengths of these lines.

Practically, the strong break observed between the [*z$_{850}$*]{} and [*Y$_{105}$*]{} bands (see Figure \[fig:sed\]) rules out the possibility that the detected emission is H$\beta$, [\[O[iii]{}\]]{}, or H$\alpha$, and leaves the only alternative possibility of the detected line being the [\[O[ii]{}\]]{} doublet. If the detected emission line is an [\[O[ii]{}\]]{} doublet at $z=1.83$, the spectral resolution of MOSFIRE $Y$-band grating ($\sim$3 Å) is sufficient to resolve the doublet. The possibility of the detected line being one of the two peaks, however, cannot be entirely ruled out. 