First Identification of 10 kpc [C ii] 158 μm Halos around Star-forming Galaxies at z = 5–7

Fujimoto, Seiji; Ouchi, Masami; Ferrara, Andrea; Pallottini, Andrea; Ivison, R. J.; Behrens, Christoph; Gallerani, S.; Arata, Shohei; Yajima, Hidenobu; Nagamine, Kentaro

doi:10.3847/1538-4357/ab480f

Cited by 142 publications

(189 citation statements)

References 101 publications

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“…This compact UV-continuum emission would rule out a significant contribution from unresolved dwarf satellite galaxies (scenario 2). Recently, stacked ALMA data reveal that SFGs at z ∼ 5 − 7 have a 10 pkpc-scale extended carbon [Cii]158µm emission whose SB profile shape is very similar to the one of the Lyα emission (Fujimoto et al 2019). The existence of the extended emission of [Cii] similar to Lyα might suggest that LAHs are originated from the neutral gas expelled by outflows that are carbon enriched (scenario 3).…”

Section: Circum-galactic Medium (Cgm) and The Large-scale Structures mentioning

confidence: 99%

Observations of the Lyman-α Universe

Ouchi

Ono²,

Shibuya³

2020

Annu. Rev. Astron. Astrophys.

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160

124

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Hydrogen Lyman-α (Lyα) emission has been one of the major observational probes for the high-redshift Universe since the first discoveries of high- z Lyα-emitting galaxies in the late 1990s. Due to the strong Lyα emission originated by resonant scattering and recombination of the most abundant element, Lyα observations witness not only Hii regions of star formation and active galactic nuclei (AGNs) but also diffuse Hi gas in the circumgalactic medium (CGM) and the intergalactic medium (IGM). Here, we review Lyα sources and present theoretical interpretations reached to date. We conclude the following: ▪ A typical Lyα emitter (LAE) at z ≳ 2 with a L* Lyα luminosity is a high- z counterpart of a local dwarf galaxy, a compact metal-poor star-forming galaxy (SFG) with an approximate stellar (dark matter halo) mass and star-formation rate of 108−9M⊙ (1010−11M⊙) and 1–10 M⊙ year−1, respectively. ▪ High- z SFGs ubiquitously have a diffuse Lyα-emitting halo in the CGM extending to the halo virial radius and beyond. ▪ Remaining neutral hydrogen at the epoch of cosmic reionization makes a strong dimming of Lyα emission for galaxies at z > 6 that suggests the late reionization history. The next-generation large-telescope projects will combine Lyα emission data with Hi Lyα absorptions and 21-cm radio data that map out the majority of hydrogen (Hi+Hii) gas, uncovering the exchanges of ( a) matter by outflow and inflow and ( b) radiation, relevant to cosmic reionization, between galaxies and the CGM/IGM.

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Section: Circum-galactic Medium (Cgm) and The Large-scale Structures mentioning

confidence: 99%

Observations of the Lyman-α Universe

Ouchi

Ono²,

Shibuya³

2020

Annu. Rev. Astron. Astrophys.

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160

124

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“…Carniani et al 2018a). High-z galaxies are characterised by large surface star formation rates (> 1M yr −1 kpc −2 ); their [CII] emission appears to be considerably more extended than the UV (Carniani et al 2018a;Fujimoto et al 2019). As a result their [CII] surface brightness is much lower than expected from the relation derived from spatially resolved local galaxies.…”

Section: Introductionmentioning

confidence: 97%

A physical model for [C ii] line emission from galaxies

Ferrara

Vallini

Pallottini

et al. 2019

Monthly Notices of the Royal Astronomical Society

114

138

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A tight relation between the [C ii] 158 $\mu$m line luminosity and star formation rate is measured in local galaxies. At high redshift (z > 5), though, a much larger scatter is observed, with a considerable (15–20 per cent) fraction of the outliers being [C ii]-deficient. Moreover, the [C ii] surface brightness ($\Sigma_{\rm [C\, \small {II}]}$) of these sources is systematically lower than expected from the local relation. To clarify the origin of such [C ii]-deficiency, we have developed an analytical model that fits local [C ii] data and has been validated against radiative transfer simulations performed with cloudy. The model predicts an overall increase of $\Sigma_{\rm [C\, \small {II}]}$ with ΣSFR. However, for ΣSFR ${\gtrsim} 1 \, \mathrm{M}_\odot \,{\rm yr}^{-1}\,{\rm kpc}^{-2}$, $\Sigma_{\rm [C\, \small {II}]}$ saturates. We conclude that underluminous [C ii] systems can result from a combination of three factors: (a) large upward deviations from the Kennicutt–Schmidt relation (κs ≫ 1), parametrized by the ‘burstiness’ parameter κs; (b) low metallicity; (c) low gas density, at least for the most extreme sources (e.g. CR7). Observations of [C ii] emission alone cannot break the degeneracy among the above three parameters; this requires additional information coming from other emission lines (e.g. [O iii]88 $\mu$m, C iii]1909 Å, CO lines). Simple formulae are given to interpret available data for low- and high-z galaxies.

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“…This whole domain opened up at high redshift (z > 4) with the ALMA interferometer becoming fully operational when pilot observations took note that detecting [CII] for normal galaxies was ubiquitous even with short on-source exposure times (Capak et al 2015). Galaxies with star formation rates as low as a few M yr −1 have been detected in [CII] at z ∼ 5 (Riechers et al 2014;Capak et al 2015), and [CII] is now detected for galaxies well into the reionization epoch (e.g., Bradač et al 2017;Smit et al 2018;Harikane et al 2018;Fujimoto et al 2019;Sobral et al 2019;Hashimoto et al 2019).…”

Section: Introductionmentioning

confidence: 99%

The ALPINE-ALMA [CII] survey

Fèvre

Béthermin

Faisst

et al. 2020

A&A

171

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The ALMA-ALPINE [CII] survey is aimed at characterizing the properties of a sample of normal star-forming galaxies (SFGs). The ALMA Large Program to INvestigate (ALPINE) features 118 galaxies observed in the [CII]-158 μm line and far infrared (FIR) continuum emission during the period of rapid mass assembly, right after the end of the HI reionization, at redshifts of 4 < z < 6. We present the survey science goals, the observational strategy, and the sample selection of the 118 galaxies observed with ALMA, with an average beam minor axis of about 0.85″, or ∼5 kpc at the median redshift of the survey. The properties of the sample are described, including spectroscopic redshifts derived from the UV-rest frame, stellar masses, and star-formation rates obtained from a spectral energy distribution (SED) fitting. The observed properties derived from the ALMA data are presented and discussed in terms of the overall detection rate in [CII] and FIR continuum, with the observed signal-to-noise distribution. The sample is representative of the SFG population in the main sequence at these redshifts. The overall detection rate in [CII] is 64% for a signal-to-noise ratio (S/N) threshold larger than 3.5 corresponding to a 95% purity (40% detection rate for S/N > 5). Based on a visual inspection of the [CII] data cubes together with the large wealth of ancillary data, we find a surprisingly wide range of galaxy types, including 40% that are mergers, 20% extended and dispersion-dominated, 13% compact, and 11% rotating discs, with the remaining 16% too faint to be classified. This diversity indicates that a wide array of physical processes must be at work at this epoch, first and foremost, those of galaxy mergers. This paper sets a reference sample for the gas distribution in normal SFGs at 4 < z < 6, a key epoch in galaxy assembly, which is ideally suited for studies with future facilities, such as the James Webb Space Telescope (JWST) and the Extremely Large Telescopes (ELTs).

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First Identification of 10 kpc [C ii] 158 μm Halos around Star-forming Galaxies at z = 5–7

Cited by 142 publications

References 101 publications

Observations of the Lyman-α Universe

Observations of the Lyman-α Universe

A physical model for [C ii] line emission from galaxies

The ALPINE-ALMA [CII] survey

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