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Register a new userA comprehensive study of H$alpha$ emitters at $z sim$ 0.62 in the DAWN survey: the need for deep and wide regions
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We present new estimates of the luminosity function (LF) and star formation rate density (SFRD) for an H$alpha$ selected sample at $zsim0.62$ from the Deep And Wide Narrow-band (DAWN) survey. Our results are based on a new H$alpha$ sample in the extended COSMOS region (compared to Coughlin et al. 2018) with the inclusion of flanking fields, resulting in a total area coverage of $sim$1.5 deg$^2$. A total of 241 H$alpha$ emitters were selected based on robust selection criteria using spectro-photometric redshifts and broadband color-color classification. We explore the effect of different dust correction prescriptions by calculating the LF and SFRD using a constant dust extinction correction, A{$_{textrm{H}alpha}=1$} mag, a luminosity-dependent correction, and a stellar-mass dependent correction. The resulting H$alpha$ LFs are well fitted using Schechter functions with best-fit parameters: L$^*=10^{42.24}$ erg s$^{-1}$, $phi^*=10^{-2.85}$ Mpc$^{-3}$, $alpha = -1.62$ for constant dust correction, L$^*=10^{42.31}$ erg s$^{-1}$, $phi^*=10^{-2.8}$ Mpc$^{-3}$, $alpha=-1.39$ for luminosity-dependent dust correction, and L$^*=10^{42.36}$ erg s$^{-1}$, $phi^*=10^{-2.91}$ Mpc$^{-3}$, $alpha = -1.48$, for stellar mass-dependent dust correction. The deep and wide nature of the DAWN survey effectively samples H$alpha$ emitters over a wide range of luminosities, thereby providing better constraints on both the faint and bright end of the LF. Also, the SFRD estimates $rho_{textrm{SFR}}=10^{-1.39}$ M$_{odot}$yr$^{-1}$Mpc$^{-3}$ (constant dust correction), $rho_{textrm{SFR}}=10^{-1.47}$ M$_{odot}$yr$^{-1}$Mpc$^{-3}$ (luminosity-dependent dust correction), and $rho_{textrm{SFR}}=10^{-1.49}$ M$_{odot}$yr$^{-1}$Mpc$^{-3}$ (stellar mass-dependent dust correction) are in good agreement with the evolution of SFRD across redshifts ($0 < z < 2$) seen from previous H$alpha$ surveys.
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FastSound is a galaxy redshift survey using the near-infrared Fiber Multi-Object Spectrograph (FMOS) mounted on the Subaru Telescope, targeting H$alpha$ emitters at $z sim 1.18$--$1.54$ down to the sensitivity limit of H$alpha$ flux $sim 2 times 10^{-16} rm erg cm^{-2} s^{-1}$. The primary goal of the survey is to detect redshift space distortions (RSD), to test General Relativity by measuring the growth rate of large scale structure and to constrain modified gravity models for the origin of the accelerated expansion of the universe. The target galaxies were selected based on photometric redshifts and H$alpha$ flux estimates calculated by fitting spectral energy distribution (SED) models to the five optical magnitudes of the Canada France Hawaii Telescope Legacy Survey (CFHTLS) Wide catalog. The survey started in March 2012, and all the observations were completed in July 2014. In total, we achieved $121$ pointings of FMOS (each pointing has a $30$ arcmin diameter circular footprint) covering $20.6$ deg$^2$ by tiling the four fields of the CFHTLS Wide in a hexagonal pattern. Emission lines were detected from $sim 4,000$ star forming galaxies by an automatic line detection algorithm applied to 2D spectral images. This is the first in a series of papers based on FastSound data, and we describe the details of the survey design, target selection, observations, data reduction, and emission line detections.
We present a clustering analysis of a sample of 238 Ly{$alpha$}-emitters at redshift 3<z<6 from the MUSE-Wide survey. This survey mosaics extragalactic legacy fields with 1h MUSE pointings to detect statistically relevant samples of emission line galaxies. We analysed the first year observations from MUSE-Wide making use of the clustering signal in the line-of-sight direction. This method relies on comparing pair-counts at close redshifts for a fixed transverse distance and thus exploits the full potential of the redshift range covered by our sample. A clear clustering signal with a correlation length of r0 = 2.9(+1.0/-1.1) Mpc (comoving) is detected. Whilst this result is based on only about a quarter of the full survey size, it already shows the immense potential of MUSE for efficiently observing and studying the clustering of Ly{$alpha$}-emitters.
We take advantage of the capability of the OTELO survey to obtain the H$alpha$ luminosity function (LF) at ${rm z}sim0.40$. Because of the deepest coverage of OTELO, we are able to determine the faint end of the LF, and thus better constrain the star formation rate and the number of galaxies at low luminosities. The AGN contribution to this LF is estimated as well. We make use of the multi-wavelength catalogue of objects in the field compiled by the OTELO survey, which is unique in terms of minimum flux and equivalent width. We also take advantage of the pseudo-spectra built for each source, which allow the identification of emission lines and the discrimination of different types of objects. The H$alpha$ luminosity function at $zsim0.40$ is obtained, which extends the current faint end by almost 1 dex, reaching minimal luminosities of $log_{10}L_{rm lim}=38.5$ erg s$^{-1}$ (or $sim0.002, text{M}_odottext{ yr}^{-1})$. The AGN contribution to the total H$alpha$ luminosity is estimated. We find that no AGN should be expected below a luminosity of $log_{10}L=38.6$ erg s$^{-1}$. From the sample of non-AGN (presumably, pure SFG) at $zsim0.40$ we estimated a star formation rate density of $rho_{rm SFR}=0.012pm0.005 {rm text{M}_{odot} yr^{-1} Mpc^{-3}}$.
We present an analysis of the spatial clustering of 695 Ly$alpha$-emitting galaxies (LAE) in the MUSE-Wide survey. All objects have spectroscopically confirmed redshifts in the range $3.3<z<6$. We employ the K-estimator of Adelberger et al. (2005), adapted and optimized for our sample. We also explore the standard two-point correlation function approach, which is however less suited for a pencil-beam survey such as ours. The results from both approaches are consistent. We parametrize the clustering properties by, (i) modelling the clustering signal with a power law (PL), and (ii) adopting a Halo Occupation Distribution (HOD) model. Applying HOD modeling, we infer a large-scale bias of $b_{rm{HOD}}=2.80^{+0.38}_{-0.38}$ at a median redshift of the number of galaxy pairs $langle z_{rm pair}ranglesimeq3.82$, while the PL analysis results in $b_{rm{PL}}=3.03^{+1.51}_{-0.52}$ ($r_0=3.60^{+3.10}_{-0.90};h^{-1}$Mpc and $gamma=1.30^{+0.36}_{-0.45}$). The implied typical dark matter halo (DMH) mass is $log(M_{rm{DMH}}/[h^{-1}rm{M}_odot])=11.34^{+0.23}_{-0.27}$. We study possible dependencies of the clustering signal on object properties by bisecting the sample into disjoint subsets, considering Ly$alpha$ luminosity, UV absolute magnitude, Ly$alpha$ equivalent width, and redshift as variables. We find a suggestive trend of more luminous Ly$alpha$ emitters residing in more massive DMHs than their lower Ly$alpha$ luminosity counterparts. We also compare our results to mock LAE catalogs based on a semi-analytic model of galaxy formation and find a stronger clustering signal than in our observed sample. By adopting a galaxy-conserving model we estimate that the LAEs in the MUSE-Wide survey will typically evolve into galaxies hosted by halos of $log(M_{rm{DMH}}/[h^{-1}rm{M}_odot])approx13.5$ at redshift zero, suggesting that we observe the ancestors of present-day galaxy groups.
We report on a sensitive search for redshifted H$alpha$ line-emission from three high-metallicity damped Ly$alpha$ absorbers (DLAs) at $z approx 2.4$ with the Near-infrared Integral Field Spectrometer (NIFS) on the Gemini-North telescope, assisted by the ALTtitude conjugate Adaptive optics for the InfraRed (ALTAIR) system with a laser guide star. Within the NIFS field-of-view, $approx 3.22 times 2.92$ corresponding to $approx 25$ kpc $ times 23$ kpc at $z=2.4$, we detect no statistically significant line-emission at the expected redshifted H$alpha$ wavelengths. The measured root-mean-square noise fluctuations in $0.4$ apertures are $1-3times10^{-18}$ erg s$^{-1}$ cm$^{-2}$. Our analysis of simulated, compact, line-emitting sources yields stringent limits on the star-formation rates (SFRs) of the three DLAs, $< 2.2$~M$_{odot}$ yr$^{-1}$ ($3sigma$) for two absorbers, and $< 11$~M$_{odot}$ yr$^{-1}$ ($3sigma$) for the third, at all impact parameters within $approx 12.5$~kpc to the quasar sightline at the DLA redshift. For the third absorber, the SFR limit is $< 4.4$~M$_odot$ yr$^{-1}$ for locations away from the quasar sightline. These results demonstrate the potential of adaptive optics-assisted, integral field unit searches for galaxies associated with high-$z$ DLAs.
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