Empowering line intensity mapping to study early galaxies

Abstract

Line intensity mapping is a superb tool to study the collective radiation from early galaxies. However, the method is hampered by the presence of strong foregrounds, mostly produced by low-redshift interloping lines. We present here a general method to overcome this problem which is robust against foreground residual noise and based on the cross-correlation function ${\psi }_{\alpha L}(r)$ between diffuse line emission and Ly$\alpha$ emitters (LAE). We compute the diffuse line (Ly$\alpha$ is used as an example) emission from galaxies in a $(800\mathrm{Mpc}{)}^3$ box at $z=5.7$ and $6.6$. We divide the box in slices and populate them with $14000(5500)$ LAEs at $z=5.7(6.6)$, considering duty cycles from $10^{-3}$ to $1$. Both the LAE number density and slice volume are consistent with the expected outcome of the Subaru HSC survey. We add gaussian random noise with variance ${\sigma }_{\mathrm{N}}$ up to 100 times the variance of the Ly$\alpha$ emission, ${\sigma }_{\alpha }$, to simulate foregrounds and compute ${\psi }_{\alpha L}(r)$. We find that the signal-to-noise of the observed ${\psi }_{\alpha L}(r)$ does not change significantly if ${\sigma }_{\mathrm{N}}\le 10{\sigma }_{\alpha }$ and show that in these conditions the mean line intensity, $I_{Ly\alpha }$, can be precisely recovered independently of the LAE duty cycle. Even if ${\sigma }_{\mathrm{N}}=100{\sigma }_{\alpha }$, $I_{\alpha }$ can be constrained within a factor $2$. The method works equally well for any other line (e.g. HI 21 cm, [CII], HeII) used for the intensity mapping experiment.

5 pages, 4 figures

References in corpus (11)

• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• The Subaru/XMM-Newton Deep Survey (SXDS). IV. Evolution of Lya Emitters from z=3.1 to 5.7 in the 1 deg^2 Field: Luminosity Functions and AGN
• Efficient Simulations of Early Structure Formation and Reionization
• A Spectroscopic Redshift Measurement for a Luminous Lyman Break Galaxy at z=7.730 using Keck/MOSFIRE
• Identification of the brightest Lyα emitters at z=6.6: implications for the evolution of the luminosity function in the re-ionisation era
• Carbon monoxide line emission as a CMB foreground: tomography of the star-forming universe with different spectral resolutions
• Intensity mapping of [CII] from early galaxies
• Carbon Monoxide Intensity Mapping at Moderate Redshifts
• Looking for Population III stars with He II line intensity mapping
• Cross-correlation of the cosmic 21-cm signal and Lyman Alpha Emitters during reionization
• Prospects for detecting CII emission during the Epoch of Reionization

Cited by in corpus (6)

• Line-Intensity Mapping: 2017 Status Report
• Line-Intensity Mapping: Theory Review
• The contribution from stars stripped in binaries to cosmic reionization of hydrogen and helium
• Studying high-z galaxies with [CII] intensity mapping
• [CII] line intensity mapping the epoch of reionization with the Prime-Cam on FYST
• SILVERRUSH. XI. Intensity Mapping for Lya Emission Extending over $100-1000$ comoving kpc around $z\sim 2-7$ LAEs with Subaru HSC-SSP and CHORUS Data