The OTELO survey: Revealing a population of low-luminosity
  current/active star-forming galaxies at z$\sim0.9$
  We study a sample of H$\beta$ emission line sources at $z\sim$0.9 to identify
the star-forming (SF) galaxies sample and characterise them in terms of line
luminosity, stellar mass, SFR, and morphology. The final aim is to obtain the
H$\beta$ luminosity function (LF) of the SF galaxies at this redshift.
  We used the instrument OSIRIS at GTC to obtain the pseudo spectra of emission
line sources in the OTELO field. From these pseudo spectra, we identified the
objects with H$\beta$ emission. As the resolution of the pseudo spectra allowed
us to separate H$\beta$ from O[III], we derive the H$\beta$ flux without
contamination. Using data from the extended OTELO catalogue, we discriminated
AGNs and studied the SFR, the stellar mass, and the morphology of the SF
galaxies.
  We find that our sample is located on the main sequence of SF galaxies. The
sources are morphologically classified, mostly as disc-like galaxies (76%), and
90% of the sample are low-mass galaxies ($M_*<10^{10}\;\mathrm{M}_\odot$). The
low-mass SF galaxies at $z \sim 0.9$ that were detected by OTELO present
similar properties as low-mass SF galaxies in the local universe, suggesting
that these kinds of objects do not have a favorite epoch of formation and star
formation enhancement from $z \sim 1$ to now. Our sample of 40 H$\beta$ SF
galaxies includes the faintest H$\beta$ emitters detected so far. This allows
us to constrain the faint end of the LF for the H$\beta$ line alone with a
minimum luminosity of $\log L = 39 \;\mathrm{erg\,s}^{-1}$, which is a hundred
times fainter than previous surveys. The dust-corrected OTELO H$\beta$ LF
established the faint-end slope as $\alpha =-1.36\pm 0.15$. We increased the
scope of the analysis to the bright end by adding ancillary data from the
literature, which was not dust-corrected in this case. The obtained slope for
this extended LF is $\alpha = -1.43\pm 0.12$.
