Outflows and extended [C ii] haloes in high-redshift galaxies

Pizzati, E.; Ferrara, Andrea; Pallottini, Andrea; Gallerani, S.; Vallini, L.; Decataldo, D.; Fujimoto, Seiji

doi:10.1093/mnras/staa1163

Cited by 52 publications

(46 citation statements)

References 76 publications

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“…This result is in line with other works showing the effective radius of [CII] is in general larger than the radius of UV region by a factor 2-3 (Carniani et al 2018a;Fujimoto et al 2020). The origin of such extended component is yet unknown; an appealing explanation is that it may be associated to either inflowing or outflowing material (Maiolino et al 2015;Carniani et al 2017Carniani et al , 2018aGallerani et al 2018;Pizzati et al 2020;Fujimoto et al 2020;Ginolfi et al 2020).…”

Section: Discussionmentioning

confidence: 99%

“…The origin of a such extended [CII] structure is still debated. The diffuse emission can be ascribed to: (a) circumgalactic gas which is illuminated by the strong radiation field produced by the galaxy (Carniani et al 2017(Carniani et al , 2018aFujimoto et al 2020); (b) satellites in the process of accreting (Pallottini et al 2017a;Carniani et al 2018b,a;Matthee et al 2019); (c) outflow remnants, which enriched the circum-galactic medium (Maiolino et al 2015;Vallini et al 2015;Gallerani et al 2018;Fujimoto et al 2019Fujimoto et al , 2020Pizzati et al 2020;Ginolfi et al 2020). Despite its debated origin, it is clear that [CII] is tracing gas on galactic scales different from those of rest-frame UV and [OIII] emission.…”

Section: Comparing Mock Data With Observationsmentioning

confidence: 99%

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Missing [C ii] emission from early galaxies

Carniani

Ferrara

Maiolino

et al. 2020

Monthly Notices of the Royal Astronomical Society

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155

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ALMA observations have revealed that [C$\scriptstyle \rm II$]158μm line emission in high-z galaxies is ≈2 − 3 × more extended than the UV continuum emission. Here we explore whether surface brightness dimming (SBD) of the [C$\scriptstyle \rm II$] line is responsible for the reported [C$\scriptstyle \rm II$] deficit, and the large L[OIII]/L[CII] luminosity ratio measured in early galaxies. We first analyse archival ALMA images of nine z > 6 galaxies observed in both [C$\scriptstyle \rm II$] and [O$\scriptstyle \rm III$]. After performing several uv-tapering experiments to optimize the identification of extended line emission, we detect [C$\scriptstyle \rm II$] emission in the whole sample, with an extent systematically larger than the [O$\scriptstyle \rm III$] emission. Next, we use interferometric simulations to study the effect of SBD on the line luminosity estimate. About 40% of the extended [C$\scriptstyle \rm II$] component might be missed at an angular resolution of 0.8″, implying that L[CII] is underestimated by a factor ≈2 in data at low (<7) signal-to-noise ratio. By combining these results, we conclude that L[CII] of z > 6 galaxies lies, on average, slightly below the local L[CII] − SFR relation (Δz = 6 − 9 = −0.07 ± 0.3), but within the intrinsic dispersion of the relation. SBD correction also yields L[OIII]/L[CII] < 10, i.e. more in line with current hydrodynamical simulations.

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Section: Discussionmentioning

confidence: 99%

Section: Comparing Mock Data With Observationsmentioning

confidence: 99%

Missing [C ii] emission from early galaxies

Carniani

Ferrara

Maiolino

et al. 2020

Monthly Notices of the Royal Astronomical Society

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155

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“…In addition to these agreements with the observational results, the recent theoretical results also support the SF-driven outflow. Pizzati et al (2020) model the [C II] line emission produced from the supernova-driven cooling outflow with two key parameters of the outflow mass loading factor η and circular velocity of the parent galaxy dark matter halo v circ that depends on the gravitational potential of the system. The authors find that the 10 kpc scale [C II] halo is well reproduced with the best-fit parameters of η= 3.20±0.10 and v circ =170±10 km s −1 around a galaxy with a dynamical mass of ;10 11 M e .…”

Section: Kinematics Of [C Ii] Halomentioning

confidence: 99%

“…We note that this is a simplified picture. A realistic picture might have a transition from hot to cold through a catastrophic cooling in the outflow process (Li & Tonnesen 2019;Pizzati et al 2020). The study of these multiphase (cold and hot) gas structures will be useful to understand which is the dominant mode and to constrain the feedback mechanisms in the high-z star-forming galaxies.…”

Section: Kinematics Of [C Ii] Halomentioning

confidence: 99%

The ALPINE–ALMA [C ii] Survey: Size of Individual Star-forming Galaxies at z = 4–6 and Their Extended Halo Structure

Fujimoto

Silverman

Béthermin

et al. 2020

ApJ

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114

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We present the physical extent of [C II] 158 μm line-emitting gas from 46 star-forming galaxies at z=4-6 from the ALMA Large Program to INvestigate C II at Early Times (ALPINE). Using exponential profile fits, we measure the effective radius of the [C II] line ( [ ] r e, C II ) for individual galaxies and compare them with the rest-frame ultraviolet (UV) continuum (r e,UV ) from Hubble Space Telescope images. The effective radius [ ] r e, C II exceeds r e,UV by factors of ∼2-3, and the ratio of [ ] r r e, C e,UV II increases as a function of M star . We do not find strong evidence that the [C II] line, rest-frame UV, and far-infrared (FIR) continuum are always displaced over ;1 kpc scale from each other. We identify 30% of isolated ALPINE sources as having an extended [C II] component over 10 kpc scales detected at 4.1σ-10.9σ beyond the size of rest-frame UV and FIR continuum. One object has tentative rotating features up to ∼10 kpc, where the 3D model fit shows the rotating [C II]-gas disk spread over 4 times larger than the rest-frame UV-emitting region. Galaxies with the extended [C II] line structure have high star formation rate, high stellar mass (M star ), low Lyα equivalent width, and more blueshifted (redshifted) rest-frame UV metal absorption (Lyα line), as compared to galaxies without such extended [C II] structures. Although we cannot rule out the possibility that a selection bias toward luminous objects may be responsible for such trends, the star-formation-driven outflow also explains all these trends. Deeper observations are essential to test whether the extended [C II] line structures are ubiquitous to high-z star-forming galaxies.

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“…[CII] emission is also reported to be significantly more extended than the UV continuum (e.g. Fujimoto et al 2019;Ginolfi et al 2020), possibly tracing past outflow activity (Pizzati et al 2020).…”

Section: Introductionmentioning

confidence: 99%

The nature of CR7 revealed with MUSE: a young starburst powering extended Ly α emission at z = 6.6

Matthee

Pezzulli

Mackenzie

et al. 2020

Monthly Notices of the Royal Astronomical Society

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CR7 is among the most luminous Lyman-α emitters (LAEs) known at z = 6.6 and consists of at least three UV components that are surrounded by Lyman-α (Lyα) emission. Previous studies have suggested that it may host an extreme ionising source. Here, we present deep integral field spectroscopy of CR7 with VLT/MUSE. We measure extended emission with a similar halo scale length as typical LAEs at z ≈ 5. CR7’s Lyα halo is clearly elongated along the direction connecting the multiple components, likely tracing the underlying gas distribution. The Lyα emission originates almost exclusively from the brightest UV component, but we also identify a faint kinematically distinct Lyα emitting region nearby a fainter component. Combined with new near-infrared data, the MUSE data show that the rest-frame Lyα equivalent width (EW) is ≈100 Å. This is a factor four higher than the EW measured in low-redshift analogues with carefully matched Lyα profiles (and thus arguably HI column density), but this EW can plausibly be explained by star formation. Alternative scenarios requiring AGN powering are also disfavoured by the narrower and steeper Lyα spectrum and much smaller IR to UV ratio compared to obscured AGN in other Lyα blobs. CR7’s Lyα emission, while extremely luminous, resembles the emission in more common LAEs at lower redshifts very well and is likely powered by a young metal poor starburst.

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Outflows and extended [C ii] haloes in high-redshift galaxies

Cited by 52 publications

References 76 publications

Missing [C ii] emission from early galaxies

Missing [C ii] emission from early galaxies

The ALPINE–ALMA [C ii] Survey: Size of Individual Star-forming Galaxies at z = 4–6 and Their Extended Halo Structure

The nature of CR7 revealed with MUSE: a young starburst powering extended Ly α emission at z = 6.6

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