ALMA Deep Field in SSA22: Blindly Detected CO Emitters and [CII] Emitter
  Candidates
  We report the identification of four millimeter line emitting galaxies with
the Atacama Large Milli/submillimeter Array (ALMA) in SSA22 Field (ADF22). We
analyze the ALMA 1.1 mm survey data, with an effective survey area of 5
arcmin$^2$, a frequency range of 253.1--256.8 and 269.1--272.8 GHz, angular
resolution of 0".7 and RMS noise of 0.8 mJy beam$^{-1}$ at 36 km s$^{-1}$
velocity resolution. We detect four line emitter candidates with significance
levels above $6 \sigma$. We identify one of the four sources as a CO(9-8)
emitter at $z = 3.1$ in a member of the proto-cluster known in this field.
Another line emitter with an optical counterpart is likely a CO(4-3) emitter at
$z = 0.7$. The other two sources without any millimeter continuum or
optical/near-infrared counterpart are likely to be [CII] emitter candidates at
$z = 6.0$ and $6.5$. The equivalent widths of the [CII] candidates are
consistent with those of confirmed high-redshift [CII] emitters and candidates,
and are a factor of 10 times larger than that of the CO(9-8) emitter detected
in this search. The [CII] luminosity of the candidates are $4-7 \times 10^8~\rm
L_\odot$. The star formation rates (SFRs) of these sources are estimated to be
$10-20~\rm M_{\odot}~yr^{-1}$ if we adopt an empirical [CII] luminosity - SFR
relation. One of them has a relatively low-S/N ratio, but shows features
characteristic of emission lines. Assuming that at least one of the two
candidates is a [CII] emitter, we derive a lower limit of [CII]-based star
formation rate density (SFRD) at $z~\sim~6$. The resulting value of $> 10^{-2}$
$\rm M_\odot yr^{-1} Mpc^{-3}$ is consistent with the dust-uncorrected UV-based
SFRD. Future millimeter/submillimeter surveys can be used to detect a number of
high redshift line emitters, with which to study the star formation history in
the early Universe.
