High-redshift cosmology with oxygen lines from H$alpha$ surveys. (arXiv:2001.04473v1 [astro-ph.CO])

High-redshift cosmology with oxygen lines from H$alpha$ surveys. (arXiv:2001.04473v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Fonseca_J/0/1/0/all/0/1">Jos&#xe9; Fonseca</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Camera_S/0/1/0/all/0/1">Stefano Camera</a>

A new generation of cosmological experiments will spectroscopically detect
the H$alpha$ line from emission-line galaxies (ELGs) at optical/near-infrared
frequencies. Other emission lines will also be present, which may come from the
same H$alpha$ sample or constitute a new galaxy sample altogether. Our goal is
to assess the value, for cosmological investigation, of galaxies at $zgtrsim2$
present in H$alpha$ galaxy surveys and identifiable by the highly redshifted
ultra-violet and optical lines – namely the OII line and the OIII doublet in
combination with the H$beta$ line. We use state-of-the-art models of
luminosity functions of astrophysical spectral lines to estimate the volumetric
number density of OIII+H$beta$ and OII ELGs. We focus on a wavelength range
which will be covered by planned cosmological surveys. We study the
constraining power of these high-redshift galaxy samples on cosmological
parameters such as the amplitude of baryon acoustic oscillations, $H(z)$,
$D_A(z)$, $fsigma_8(z)$, and $bsigma_8(z)$ for different survey designs. We
present a strong science case for extracting the OIII+H$beta$ sample, which we
consider as an independent probe of the Universe in the redshift range 2 to 3.
Moreover, we show that the OII sample can be used to measure the baryon
acoustic oscillations and the growth of structures above $z=3$; albeit it may
be shot-noise dominated, it will nonetheless provide valuable tomographic
information. Summarising, we discuss the scientific potential of a sample of
galaxies which, so far, has been mainly considered as a contaminant in
H$alpha$ galaxy surveys. Our findings indicate that planed H$alpha$ surveys
should include the extraction of these oxygen-line samples in their pipeline,
to enhance their scientific impact on cosmology.

A new generation of cosmological experiments will spectroscopically detect
the H$alpha$ line from emission-line galaxies (ELGs) at optical/near-infrared
frequencies. Other emission lines will also be present, which may come from the
same H$alpha$ sample or constitute a new galaxy sample altogether. Our goal is
to assess the value, for cosmological investigation, of galaxies at $zgtrsim2$
present in H$alpha$ galaxy surveys and identifiable by the highly redshifted
ultra-violet and optical lines – namely the OII line and the OIII doublet in
combination with the H$beta$ line. We use state-of-the-art models of
luminosity functions of astrophysical spectral lines to estimate the volumetric
number density of OIII+H$beta$ and OII ELGs. We focus on a wavelength range
which will be covered by planned cosmological surveys. We study the
constraining power of these high-redshift galaxy samples on cosmological
parameters such as the amplitude of baryon acoustic oscillations, $H(z)$,
$D_A(z)$, $fsigma_8(z)$, and $bsigma_8(z)$ for different survey designs. We
present a strong science case for extracting the OIII+H$beta$ sample, which we
consider as an independent probe of the Universe in the redshift range 2 to 3.
Moreover, we show that the OII sample can be used to measure the baryon
acoustic oscillations and the growth of structures above $z=3$; albeit it may
be shot-noise dominated, it will nonetheless provide valuable tomographic
information. Summarising, we discuss the scientific potential of a sample of
galaxies which, so far, has been mainly considered as a contaminant in
H$alpha$ galaxy surveys. Our findings indicate that planed H$alpha$ surveys
should include the extraction of these oxygen-line samples in their pipeline,
to enhance their scientific impact on cosmology.

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