Star-forming clumps in the Lyman Alpha Reference Sample of galaxies – I. Photometric analysis and clumpiness

Messa, Matteo; Adamo, Angela; Östlin, Göran; Melinder, Jens; Hayes, Matthew; Bridge, J.; Cannon, John

doi:10.1093/mnras/stz1337

Cited by 46 publications

(57 citation statements)

References 97 publications

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“…With increasing galactic distance the approximation of having a single cluster within the compact source becomes weaker and weaker (Randriamanakoto et al 2013) and eventually even the approximation of single stellar population fails. At distance beyond 80 Mpc starforming regions with the size of 30 Doradus become unresolved, we enter the domain of the so-called stellar clumps (e.g., Messa et al 2019) studied up to redshift z ∼ 6 (e.g., Shibuya et al 2016).…”

Section: Observational Constraintsmentioning

confidence: 99%

“…Indirect evidence of proto-GCs formation at high redshift is produced by the physical properties of stellar clumps. Stellar clumps dominate the UV rest-frame of their host systems (e.g., Elmegreen et al 2013;Shibuya et al 2016;Messa et al 2019) and have very high SRF surface densities, making them a natural sight for very massive cluster formation (Elmegreen 2018). Indeed, assuming that proto-GCs form in stellar clumps following a Schechter mass function distribution and accounting for cluster disruption, it produces a first order calculation of the surving GC populations at redshift z = 0 that are comparable to the number and mass functions of the GCs detected around galaxies like the Milky Way and M31 (e.g., Shapiro et al 2010;Adamo et al 2013).…”

Section: Current and Future Observations And Simulations Of Massive Cluster Formation Across Cosmic Timementioning

confidence: 99%

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Star Clusters Near and Far

et al. 2020

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Star clusters are fundamental units of stellar feedback and unique tracers of their host galactic properties. In this review, we will first focus on their constituents, i.e. detailed insight into their stellar populations and their surrounding ionised, warm, neutral, and molecular gas. We, then, move beyond the Local Group to review star cluster populations at various evolutionary stages, and in diverse galactic environmental conditions accessible in the local Universe. At high redshift, where conditions for cluster formation and evolution are more extreme, we are only able to observe the integrated light of a handful of objects that we believe will become globular clusters. We therefore discuss how numerical and analytical methods, informed by the observed properties of cluster populations in the local Universe, are used to develop sophisticated simulations potentially capable of disentangling the genetic map of galaxy formation and assembly that is carried by globular cluster populations.

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Section: Observational Constraintsmentioning

confidence: 99%

Section: Current and Future Observations And Simulations Of Massive Cluster Formation Across Cosmic Timementioning

confidence: 99%

Star Clusters Near and Far

et al. 2020

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“…The Lyman Alpha Reference Sample (LARS; Östlin et al 2014) provides a unique and complete z ∼ 0 benchmark sample of different galaxies displaying diverse Lyα properties, studied across the entire electromagnetic spectrum, from the UV to the 21 cm line, including Hα imaging and spectroscopy. Despite the large amount of information available, the authors identified many factors that can affect Lyα emission, however, such as dust, outflows, morphology, turbulence, and clumpiness of the ISM (Hayes 2015;Herenz et al 2016;Guaita et al 2015;Messa et al 2019). A recent multivariate analysis of the low-z dataset (Runnholm et al 2020) indicates that Lyα emission primarily correlates with the star formation rate (SFR; which sets the absolute scale), and then with the reddening of the stellar continuum E(B − V) * and the gas-covering fraction in decreasing order, with both governing the Lyα escape.…”

Section: Introductionmentioning

confidence: 99%

The ALPINE-ALMA [CII] survey

Cassata

Morselli

Faisst

et al. 2020

A&A

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Context. The Lyman-α line in the ultraviolet (UV) and the [CII] line in the far-infrared (FIR) are widely used tools to identify galaxies in the early Universe and to obtain insights into interstellar medium (ISM) properties in high-redshift galaxies. By combining data obtained with ALMA in band 7 at ∼320 GHz as part of the ALMA Large Program to INvestigate [CII] at Early Times (ALPINE) with spectroscopic data from DEIMOS at the Keck Observatory, VIMOS and FORS2 at the Very Large Telescope, we assembled a unique sample of 53 main-sequence star-forming galaxies at 4.4 < z < 6 in which we detect both the Lyman-α line in the UV and the [CII] line in the FIR. Aims. The goal of this paper is to constrain the properties of the Lyα emission in these galaxies in relation to other properties of the ISM. Methods. We used [CII], observed with ALMA, as a tracer of the systemic velocity of the galaxies, and we exploited the available optical spectroscopy to obtain the Lyα-[CII] and ISM-[CII] velocity offsets. Results. We find that 90% of the selected objects have Lyα-[CII] velocity offsets in the range 0 < ΔvLyα − [CII] < 400 km s−1, in line with the few measurements available so far in the early Universe, and significantly smaller than those observed at lower redshifts. At the same time, we observe ISM-[CII] offsets in the range −500 < ΔvISM−[CII] < 0 km s−1, in line with values at all redshifts, which we interpret as evidence for outflows in these galaxies. We find significant anticorrelations between ΔvLyα−[CII] and the Lyα rest-frame equivalent width EW0(Lyα) (or equivalently, the Lyα escape fraction fesc(Lyα)): galaxies that show smaller ΔvLyα−[CII] have larger EW0(Lyα) and fesc(Lyα). Conclusions. We interpret these results in the framework of available models for the radiative transfer of Lyα photons. According to the models, the escape of Lyα photons would be favored in galaxies with high outflow velocities, producing large EW0(Lyα) and small ΔvLyα-[CII], in agreement with our observations. The uniform shell model would also predict that the Lyα escape in galaxies with slow outflows (0 < vout < 300 km s−1) is mainly determined by the neutral hydrogen column density (NHI) along the line of sight, while the alternative model by Steidel et al. (2010, ApJ, 717, 289) would more highly favor a combination of NHI at the systemic velocity and covering fraction as driver of the Lyα escape. We suggest that the increase in Lyα escape that is observed in the literature between z ∼ 2 and z ∼ 6 is not due to a higher incidence of fast outflows at high redshift, but rather to a decrease in average NHI along the line of sight, or alternatively, a decrease in HI covering fraction.

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“…Clumps have been detected in rest-frame UV imaging (e.g. Guo et al 2012Guo et al , 2015Guo et al , 2018Livermore et al 2012;Shibuya et al 2016;Soto et al 2017;Dessauges-Zavadsky & Adamo 2018;Messa et al 2019;Vanzella et al 2021) as well as in maps of Balmer (e.g. Hα, Hβ, see Livermore et al 2012;Mieda et al 2016;Fisher et al 2017;Zanella et al 2019;Whitmore et al 2020) and Paschen (e.g.…”

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confidence: 99%

Stellar feedback in a clumpy galaxy at z ∼ 3.4

Iani

Zanella

Vernet

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Giant star-forming regions (clumps) are widespread features of galaxies at z ≈ 1 − 4. Theory predicts that they can play a crucial role in galaxy evolution if they survive to stellar feedback for >50 Myr. Numerical simulations show that clumps’ survival depends on the stellar feedback recipes that are adopted. Up to date, observational constraints on both clumps’ outflows strength and gas removal timescale are still uncertain. In this context, we study a line-emitting galaxy at redshift z ≃ 3.4 lensed by the foreground galaxy cluster Abell 2895. Four compact clumps with sizes ≲ 280 pc and representative of the low-mass end of clumps’ mass distribution (stellar masses ≲ 2 × 108 M⊙) dominate the galaxy morphology. The clumps are likely forming stars in a starbursting mode and have a young stellar population (∼10 Myr). The properties of the Lyman-α (Lyα) emission and nebular far-ultraviolet absorption lines indicate the presence of ejected material with global outflowing velocities of ∼200–300 km s−1. Assuming that the detected outflows are the consequence of star formation feedback, we infer an average mass loading factor (η) for the clumps of ∼1.8 − 2.4 consistent with results obtained from hydro-dynamical simulations of clumpy galaxies that assume relatively strong stellar feedback. Assuming no gas inflows (semi-closed box model), the estimates of η suggest that the timescale over which the outflows expel the molecular gas reservoir (≃ 7 × 108 M⊙) of the four detected low-mass clumps is ≲ 50 Myr.

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Star-forming clumps in the Lyman Alpha Reference Sample of galaxies – I. Photometric analysis and clumpiness

Cited by 46 publications

References 97 publications

Star Clusters Near and Far

Star Clusters Near and Far

The ALPINE-ALMA [CII] survey

Stellar feedback in a clumpy galaxy at z ∼ 3.4

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