Intensity mapping of [C ii] emission from early galaxies

Abstract

The intensity mapping of the [C II] 157.7 µm fine-structure emission line represents an ideal experiment to probe star formation activity in galaxies, especially in those that are too faint to be individually detected. Here, we investigate the feasibility of such an experiment for z > 5 galaxies. We construct the L CII − M h relation from observations and simulations, then generate mock [C II] intensity maps by applying this relation to halo catalogs built from large scale N-body simulations. Maps of the extragalactic farinfrared (FIR) continuum, referred to as "foreground", and CO rotational transition lines and [C I] fine-structure lines referred to as "contamination", are produced as well. We find that, at 316 GHz (corresponding to z CII = 5), the mean intensities of the extragalactic FIR continuum, [C II] signal, all CO lines from J = 1 to 13 and two [C I] lines are ∼ 3 × 10 5 Jy sr −1 , ∼ 1200 Jy sr −1 , ∼ 800 Jy sr −1 and ∼ 100 Jy sr −1 , respectively. We discuss a method that allows us to subtract the FIR continuum foreground by removing a spectrally smooth component from each line of sight, and to suppress the CO/[C I] contamination by discarding pixels that are bright in contamination emission. The z > 5 [C II] signal comes mainly from halos in the mass range 10 11−12 M ⊙ ; as this mass range is narrow, intensity mapping is an ideal experiment to investigate these early galaxies. In principle such signal is accessible to a ground-based telescope with a 6 m aperture, 150 K system temperature, a 128 × 128 pixels FIR camera in 5000 hr total integration time, however it is difficult to perform such an experiment by using currently available telescopes.

ALMA suggests outflows in z ∼ 5.5 galaxies

“…2). The UV magnitude limit of the C15 sample (MUV > −19.94) converts into an upper limit for the [CII] emission line peak (F sat peak < 0.4 mJy; see also Yue et al 2015;Vallini et al 2015). We note that this UV magnitude roughly corresponds to satellites with SF R sat ∼ 1 M yr −1 and M sat * ∼ 10 9 M .…”

Data Analysis for Precision 21 cm Cosmology

“…Several solutions to the problem of interloper lines have been proposed. One is to mask strong point sources, which can be substantial contributors to the interloper problem (Breysse et al 2015;Yue et al 2015;Silva et al 2015). Another possibility is to match putative detections of a line with companion lines that are also expected to be present at the same redshift, given reasonable assumptions about the physics of galaxies (Kogut et al 2015).…”

Detecting high-zgalaxies in the near-infrared background

“…We collectively refer to these two components as contamination, since in this work the targeted signal is 19.5), the values of β −19.5 and dβ dM UV at z = 4, 5, 6 and 7 could be found in Bouwens et al (2014). For convenience of using this form at in-between redshifts, we fit z-dependent forms (Yue et al 2015): β −19.5 = −1.97 − 0.06(z − 6) and dβ dM UV = −0.18 − 0.03(z − 6). We use these fittings anyway when 5 < z < 10.…”