PHANGS–JWST First Results: A Statistical View on Bubble Evolution in NGC 628

Watkins, Elizabeth J.; Barnes, Ashley; Henny, Kiana F.; Kim, Hwi; Kreckel, Kathryn; Meidt, Sharon E.; Klessen, Ralf S.; Glover, Simon C. O.; Williams, Thomas G.; Keller, Ben; Leroy, Adam K.; Rosolowsky, Erik; Boquien, M.; Anand, Gagandeep S.; Belfiore, Francesco; Bigiel, Frank; Blanc, Guillermo A.; Cao, Yixian; Chandar, Rupali; Chen, Ness Mayker; Chevance, Mélanie; Congiu, Enrico; Dale, Daniel A.; Deger, Sinan; Egorov, Oleg V.; Emsellem, Éric; Faesi, Christopher M.; Grasha, Kathryn; Groves, Brent; Hassani, Hamid; Henshaw, Jonathan D.; Herrera, Cinthya N.; Hughes, Annie; Jeffreson, Sarah; Jiménez-Donaire, María J.; Koch, Eric W.; Kruijssen, J. M. Diederik; Larson, Kirsten L.; Liu, Daizhong; Lopez, Laura A.; Pessa, Ismael; Pety, J.; Tosaki, Tomoka; Sandström, Karin; Scheuermann, Fabian; Schinnerer, E.; Sormani, Mattia C.; Stuber, Sophia K.; Thilker, David A.; Usero, A.; Whitmore, Bradley C.

doi:10.3847/2041-8213/aca6e4

Cited by 27 publications

(23 citation statements)

References 78 publications

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“…It is then interesting to consider if phantom voids are a common feature of other galaxies. Watkins et al (2023) estimates that there should be ∼1900 bubbles identifiable in the PHANGS-JWST observations per 1 M e yr −1 of star formation rate (Section 3.1). Hence, using their size distribution, we expect to find ∼1 with a radius ∼500 pc per 1 M e yr −1 of star formation rate.…”

Section: Are Phantom Voids Common In Galaxies?mentioning

confidence: 99%

“…In a companion Letter in this Issue, Watkins et al (2023) use a combination of JWST and Hubble Space Telescope (HST) observations to study the bubble population across the nearby (9.84 ± 0.63 Mpc; Anand et al 2021aAnand et al , 2021b, star-forming (1.8 ± 0.5 M e yr −1 ), face-on (i ∼9°; Lang et al 2020, and also see Blanc et al 2013), massive (M * = 10 10.3 M e , M H I = 10 9.7 M e , M H2 = 10 9.4 M e ; Walter et al 2008;Querejeta et al 2015;Leroy et al 2019Leroy et al , 2021a, spiral galaxy Messier 74 (also known as NGC 628 or the Phantom Galaxy). These authors manually identify bubbles using a combination of 7.7 μm JWST-MIRI observations (Lee et al 2023), B-band (438 nm) Physics at High Angular resolution in Nearby GalaxieS (PHANGS)-HST observations , and Very Large Telescope (VLT)-Multi Unit Spectroscopic Explorer (MUSE) Hα observations (Emsellem et al 2022).…”

Section: Introductionmentioning

confidence: 94%

“…These authors manually identify bubbles using a combination of 7.7 μm JWST-MIRI observations (Lee et al 2023), B-band (438 nm) Physics at High Angular resolution in Nearby GalaxieS (PHANGS)-HST observations , and Very Large Telescope (VLT)-Multi Unit Spectroscopic Explorer (MUSE) Hα observations (Emsellem et al 2022). For each bubble, Watkins et al (2023) fit circular or elliptical apertures to the bubble boundaries (i.e., the shells) seen within this multiwavelength data set, and in doing so identify ∼1700 bubbles with radii ranging between 6 and 500 pc (e.g., left panel of Figure 1). These structures are clearly pervasive across the galaxy, form a complex nested structure (where smaller bubbles are preferentially located at the edges of large bubbles), and are among the most striking features in the initial JWST images (see Watkins et al 2023 for an in-depth discussion of the nesting of these structures and their size distributions).…”

Section: Introductionmentioning

confidence: 99%

“…For each bubble, Watkins et al (2023) fit circular or elliptical apertures to the bubble boundaries (i.e., the shells) seen within this multiwavelength data set, and in doing so identify ∼1700 bubbles with radii ranging between 6 and 500 pc (e.g., left panel of Figure 1). These structures are clearly pervasive across the galaxy, form a complex nested structure (where smaller bubbles are preferentially located at the edges of large bubbles), and are among the most striking features in the initial JWST images (see Watkins et al 2023 for an in-depth discussion of the nesting of these structures and their size distributions).…”

Section: Introductionmentioning

confidence: 99%

“…In the Watkins et al (2023) catalog, one hole stands out due to its size (over ∼1 kpc in diameter), circular shape, and strong contrast with respect to its environment (e.g., right panel of Figure 1). We refer to this impressive feature as the Phantom Void, which is the focus of this Letter (Table 1 summarizes the main properties of the Phantom Void that have been determined within this work).…”

Section: Introductionmentioning

confidence: 99%

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PHANGS–JWST First Results: Multiwavelength View of Feedback-driven Bubbles (the Phantom Voids) across NGC 628

Barnes

Watkins

Meidt

et al. 2023

ApJL

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We present a high-resolution view of bubbles within the Phantom Galaxy (NGC 628), a nearby (∼10 Mpc), star-forming (∼2 M ⊙ yr−1), face-on (i ∼ 9°) grand-design spiral galaxy. With new data obtained as part of the Physics at High Angular resolution in Nearby GalaxieS (PHANGS)-JWST treasury program, we perform a detailed case study of two regions of interest, one of which contains the largest and most prominent bubble in the galaxy (the Phantom Void, over 1 kpc in diameter), and the other being a smaller region that may be the precursor to such a large bubble (the Precursor Phantom Void). When comparing to matched-resolution Hα observations from the Hubble Space Telescope, we see that the ionized gas is brightest in the shells of both bubbles, and is coincident with the youngest (∼1 Myr) and most massive (∼105 M ⊙) stellar associations. We also find an older generation (∼20 Myr) of stellar associations is present within the bubble of the Phantom Void. From our kinematic analysis of the H I, H2 (CO), and H ii gas across the Phantom Void, we infer a high expansion speed of around 15 to 50 km s−1. The large size and high expansion speed of the Phantom Void suggest that the driving mechanism is sustained stellar feedback due to multiple mechanisms, where early feedback first cleared a bubble (as we observe now in the Precursor Phantom Void), and since then supernovae have been exploding within the cavity and have accelerated the shell. Finally, comparison to simulations shows a striking resemblance to our JWST observations, and suggests that such large-scale, stellar-feedback-driven bubbles should be common within other galaxies.

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Section: Are Phantom Voids Common In Galaxies?mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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PHANGS–JWST First Results: Multiwavelength View of Feedback-driven Bubbles (the Phantom Voids) across NGC 628

Barnes

Watkins

Meidt

et al. 2023

ApJL

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Quantifying the energetics of molecular superbubbles in PHANGS galaxies

Watkins¹,

Kreckel²,

Groves³

et al. 2023

A&A

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Context. Star formation and stellar feedback are interlinked processes that redistribute energy, turbulence, and material throughout galaxies. Because young and massive stars form in spatially clustered environments, they create pockets of expanding gas termed superbubbles, which retain information about the physical processes that drive them. As these processes play a critical role in shaping galaxy discs and regulating the baryon cycle, measuring the properties of superbubbles provides important input for galaxy evolution models. Aims. With the wide coverage and high angular resolution (∼50–150 pc) of the PHANGS–ALMA 12CO (J = 2−1) survey, we can now resolve, identify and characterise a statistically representative number of superbubbles using molecular gas in nearby galaxies. Methods. We identify superbubbles by requiring spatial correspondence between shells in CO with stellar populations identified in PHANGS–HST. Then, by combining the properties of the stellar populations with the CO, we quantify the energetics of the stars and constrain feedback models. We visually find 325 cavities across 18 PHANGS–ALMA galaxies, 88 of which have clear superbubble signatures (unbroken shells, central clusters, kinematic signatures of expansion). We measure their radii and expansion velocities using CO (2–1) to dynamically derive their ages and the mechanical power driving the bubbles, which we use to compute the expected properties of the parent stellar populations driving the bubbles. Results. We find consistency between the predicted and derived stellar ages and masses of the stellar populations if we use a supernova (SN) model that injects energy with a coupling efficiency of ∼10%. Not only does this confirm that molecular gas accurately traces superbubble properties, but it also provides key observational constraints for superbubble models. We also find evidence that the bubbles are sweeping up gas as they expand, and speculate that these sites have the potential to host new generations of stars. Conclusions. This work demonstrates that molecular superbubbles provide novel quantitative constraints on SNe feedback efficiencies and gas clearing times, and represent a promising environment to search for the propagation of star formation, all of which are needed to understand what sets the observed star formation rates in galaxies.

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Quantifying the energy balance between the turbulent ionised gas and young stars

Egorov,

Kreckel,

Glover

et al. 2023

A&A

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Context. Stellar feedback is a key contributor to the morphology and dynamics of the interstellar medium in star-forming galaxies. In particular, energy and momentum input from massive stars can drive the turbulent motions in the gas, but the dominance and efficiency of this process are unclear. The study of ionised superbubbles enables quantitative constraints to be placed on the energetics of stellar feedback. Aims. We directly compare the kinetic energy of expanding superbubbles and the turbulent motions in the interstellar medium with the mechanical energy deposited by massive stars in the form of winds and supernovae. With such a comparison, we aim to determine whether the stellar feedback is responsible for the observed turbulent motions and to quantify the fraction of mechanical energy retained in the superbubbles. Methods. We investigated the ionised gas morphology, excitation properties, and kinematics in 19 nearby star-forming galaxies from the PHANGS-MUSE survey. Based on the distribution of the flux and velocity dispersion in the Hα line, we selected 1484 regions of locally elevated velocity dispersion (σ(Hα) > 45 km s−1), including at least 171 expanding superbubbles. We analysed these regions and related their properties to those of the young stellar associations and star clusters identified in PHANGS-HST data. Results. We find a good correlation between the kinetic energy of the ionised gas and the total mechanical energy input from supernovae and stellar winds from the stellar associations. At the same time, the contribution of mechanical energy injected by the supernovae alone is not sufficient to explain the measured kinetic energy of the ionised gas, which implies that pre-supernova feedback in the form of radiation and thermal pressure as well as winds is necessary. We find that the gas kinetic energy decreases with metallicity for our sample covering Z = 0.5 − 1.0 Z⊙, reflecting the lower impact of stellar feedback. For the sample of well-resolved superbubbles, we find that about 40% of the young stellar associations are preferentially located in their rims. We also find a slightly higher (by ∼15%) fraction of the youngest (< 3 Myr) stellar associations in the rims of the superbubbles than in the centres and the opposite trend for older associations, which implies possible propagation or triggering of star formation. Conclusions. Stellar feedback is the dominant source for powering the ionised gas in regions of locally (on a 50–500 pc scale) elevated velocity dispersion, with a typical coupling efficiency of 10 − 20%. Accounting for pre-supernovae feedback is required to set up the energy balance between gas and stars.

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PHANGS–JWST First Results: A Statistical View on Bubble Evolution in NGC 628

Cited by 27 publications

References 78 publications

PHANGS–JWST First Results: Multiwavelength View of Feedback-driven Bubbles (the Phantom Voids) across NGC 628

PHANGS–JWST First Results: Multiwavelength View of Feedback-driven Bubbles (the Phantom Voids) across NGC 628

Quantifying the energetics of molecular superbubbles in PHANGS galaxies

Quantifying the energy balance between the turbulent ionised gas and young stars

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