http://arxiv.org/abs/1907.09680
In this work, we perform a simulation with Galacticus, a semi-analytical galaxy formation model, to predict the number counts of H$\alpha$ and [OIII] emitting galaxies. With a state-of-the-art N-body simulation, UNIT, we first calibrate Galacticus with the current observation of H$\alpha$ luminosity function. The resulting model coupled with a redshift-dependent dust attenuation model, can reproduce the current observations, including the H$\alpha$ luminosity function from HiZELS and number density from WISP. We extrapolate the model prediction to higher redshift and the result is consistent with previous investigations. We then use the same galaxy formation model to predict the number counts for [OIII] emitting galaxies. The consistency of these predictions with current observation of [OIII] number density and luminosity function provides further validatation of our galaxy formation model and dust model. We present number counts of H$\alpha$ and [OIII] emission line galaxies for three different line flux limits: $5\times10^{-17}$erg/s/cm$^{2}$, $1\times10^{-16}$erg/s/cm$^{2}$ (6.5$\sigma$ norminal depth for WFIRST GRS), and $2\times10^{-16}$erg/s/cm$^{2}$ (3.5$\sigma$ depth of Euclid GRS). At redshift $2<z<3$, our model predicts that WFIRST can observe 1685$\pm92$ [OIII] emission line galaxies per square degree with a line flux limit of $1\times10^{-16}$erg/s/cm$^{2}$. This will provide accurate measurement of large scale structure to probe dark energy over a huge cosmic volume to an unprecedented high redshift. Finally, we compare the flux ratio of H$\alpha$/[OIII] within the redshift range of $0<z<3$. Our results show the known trend of increasing H$\alpha$/[OIII] flux ratio with H$\alpha$ flux at low redshift, which becomes a weaker trend at higher redshifts.
Z. Zhai, A. Benson, Y. Wang, et. al.
Wed, 24 Jul 19
43/60
Comments: 10 pages, 7 figures, 2 table; Comments welcome
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