An uncertainty principle for star formation – II. A new method for characterizing the cloud-scale physics of star formation and feedback across cosmic history

Kruijssen, J. M. Diederik; Schruba, Andreas; Hygate, Alexander P. S.; Hu, Chia-Yu; Haydon, Daniel T.; Longmore, Steven N.

doi:10.1093/mnras/sty1128

Cited by 106 publications

(338 citation statements)

References 136 publications

(196 reference statements)

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“…We now briefly validate our measurements by verifying that all requirements listed in Kruijssen et al (2018) have been met. In addition, we carry out a comparison to other cloud lifetime measurements from the literature.…”

Section: Discussionmentioning

confidence: 80%

“…Our analysis method is formalised in the HEISENBERG code, which is presented and described in detail by Kruijssen et al (2018). Here we summarise the main steps of the method to measure the duration of the gas phase (t gas ), the duration of the feedback phase (t fb ), and the typical separation length between independent regions (λ).…”

Section: Application Of Analysis Methods To Our Galaxy Samplementioning

confidence: 99%

“…To measure the above time-scales for our nine target galaxies, we systematically fit the model from Kruijssen et al (2018) to the observed gas-to-SFR flux ratios measured as a function of the aperture size, when focusing apertures either on molecular gas emission peaks or on SFR emission peaks. The general steps of the procedure used for this analysis are described in Section 3.2 and are summarised as follows.…”

Section: General Conceptmentioning

confidence: 99%

“…Tables 2 and 3 present a selection of flags and input parameters used for our galaxy sample. The other flags and input parameters of the HEISENBERG code not listed here have been set to their default values as listed in tables 1 and 2 of Kruijssen et al (2018). We note that, while we have optimised the input parameters of the model (such as N ap and l ap,min ) and of the peak identification (∆ log 10 F and δ log 10 F ) to each of the galaxies in our sample, small variations of these numbers do not strongly affect the constrained quantities, as long as the physically relevant 10 Because the de-correlation between CO and Hα takes place below a size scale ∼ λ of typically a few hundreds of pc (see Section 4), our methodology is largely insensitive to galactic structure.…”

Section: Input Maps and Parameter Choicesmentioning

confidence: 99%

“…The characteristic scale at which the branches diverge from the galactic average is set by λ. The ratio t CO /t Hα governs the asymmetry between the branches, and the ratio t fb /τ, as well as the finite size of the CO and Hα peaks, regulate the flattening of the branches at small aperture sizes (see Kruijssen et al 2018 Table 4. Physical quantities describing the lifecycle of molecular cloud evolution, star formation, and feedback, obtained with the analysis described in Section 3.…”

Section: A Universal De-correlation Between Gas and Star Formation Onmentioning

confidence: 99%

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The lifecycle of molecular clouds in nearby star-forming disc galaxies

Chevance

Kruijssen

Hygate

et al. 2019

Monthly Notices of the Royal Astronomical Society

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It remains a major challenge to derive a theory of cloud-scale ( 100 pc) star formation and feedback, describing how galaxies convert gas into stars as a function of the galactic environment. Progress has been hampered by a lack of robust empirical constraints on the giant molecular cloud (GMC) lifecycle. We address this problem by systematically applying a new statistical method for measuring the evolutionary timeline of the GMC lifecycle, star formation, and feedback to a sample of nine nearby disc galaxies, observed as part of the PHANGS-ALMA survey. We measure the spatially-resolved (∼ 100 pc) CO-to-Hα flux ratio and find a universal de-correlation between molecular gas and young stars on GMC scales, allowing us to quantify the underlying evolutionary timeline. GMC lifetimes are short, typically 10−30 Myr, and exhibit environmental variation, between and within galaxies. At kpc-scale molecular gas surface densities Σ H 2 8 M pc −2 , the GMC lifetime correlates with time-scales for galactic dynamical processes, whereas at Σ H 2 8 M pc −2 GMCs decouple from galactic dynamics and live for an internal dynamical time-scale. After a long inert phase without massive star formation traced by Hα (75−90 per cent of the cloud lifetime), GMCs disperse within just 1−5 Myr once massive stars emerge. The dispersal is most likely due to early stellar feedback, causing GMCs to achieve integrated star formation efficiencies of 4−10 per cent. These results show that galactic star formation is governed by cloud-scale, environmentally-dependent, dynamical processes driving rapid evolutionary cycling. GMCs and HII regions are the fundamental units undergoing these lifecycles, with mean separations of 100−300 pc in star-forming discs. Future work should characterise the multi-scale physics and mass flows driving these lifecycles.

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Section: Discussionmentioning

confidence: 80%

Section: Application Of Analysis Methods To Our Galaxy Samplementioning

confidence: 99%

Section: General Conceptmentioning

confidence: 99%

Section: Input Maps and Parameter Choicesmentioning

confidence: 99%

Section: A Universal De-correlation Between Gas and Star Formation Onmentioning

confidence: 99%

See 3 more Smart Citations

The lifecycle of molecular clouds in nearby star-forming disc galaxies

Chevance

Kruijssen

Hygate

et al. 2019

Monthly Notices of the Royal Astronomical Society

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300

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The Molecular Cloud Lifecycle

et al. 2020

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Giant molecular clouds (GMCs) and their stellar offspring are the building blocks of galaxies. The physical characteristics of GMCs and their evolution are tightly connected to galaxy evolution. The macroscopic properties of the interstellar medium propagate into the properties of GMCs condensing out of it, with correlations between e.g. the galactic and GMC scale gas pressures, surface densities and volume densities. That way, the galactic environment sets the initial conditions for star formation within GMCs. After the onset of massive star formation, stellar feedback from e.g. photoionisation, stellar winds, and supernovae eventually contributes to dispersing the parent cloud, depositing energy, momentum and metals into the surrounding medium, thereby changing the properties of galaxies. This cycling of matter between gas and stars, governed by star formation and feedback, is therefore a major driver of galaxy evolution. Much of the recent debate has focused on the durations of the various evolutionary phases that constitute this cycle in galaxies, and what these can teach us about the physical mechanisms driving the cycle. We review results from observational, theoretical, and numerical work to build a dynamical picture of the evolutionary lifecycle of GMC evolution, star formation, and feedback in galaxies.

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Physical Processes in Star Formation

Girichidis¹,

Offner²,

Kritsuk³

et al. 2020

Space Sci Rev

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Star formation is a complex multi-scale phenomenon that is of significant importance for astrophysics in general. Stars and star formation are key pillars in observational astronomy from local star forming regions in the Milky Way up to high-redshift galaxies. From a theoretical perspective, star formation and feedback processes (radiation, winds, and supernovae) play a pivotal role in advancing our understanding of the physical processes at work, both individually and of their interactions. In this review we will give an

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An uncertainty principle for star formation – II. A new method for characterizing the cloud-scale physics of star formation and feedback across cosmic history

Abstract: The version presented here may differ from the published version or from the version of the record. Please see the repository URL above for details on accessing the published version and note that access may require a subscription.

Cited by 106 publications

References 136 publications

The lifecycle of molecular clouds in nearby star-forming disc galaxies

The lifecycle of molecular clouds in nearby star-forming disc galaxies

The Molecular Cloud Lifecycle

Physical Processes in Star Formation

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