PHANGS–JWST First Results: The Dust Filament Network of NGC 628 and Its Relation to Star Formation Activity

Thilker, David A.; Lee, Janice; Deger, Sinan; Barnes, Ashley; Bigiel, Frank; Boquien, M.; Cao, Yixian; Chevance, Mélanie; Dale, Daniel A.; Egorov, Oleg V.; Glover, Simon C. O.; Grasha, Kathryn; Henshaw, Jonathan D.; Klessen, Ralf S.; Koch, Eric W.; Kruijssen, J. M. Diederik; Leroy, Adam K.; Lessing, Ryan A.; Meidt, Sharon E.; Pinna, Francesca; Rosolowsky, Erik; Sandström, Karin; Schinnerer, E.; Smith, Rowan J.; Watkins, Elizabeth J.; Williams, Thomas G.; Anand, Gagandeep S.; Belfiore, Francesco; Blanc, Guillermo A.; Chandar, Rupali; Congiu, Enrico; Emsellem, Éric; Groves, Brent; Kreckel, Kathryn; Larson, Kirsten L.; Liu, Daizhong; Pessa, Ismael; Whitmore, Bradley C.

doi:10.3847/2041-8213/acaeac

Cited by 18 publications

(19 citation statements)

References 86 publications

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“…In the 21 μm map, this removes large-scale emission (constituting ∼50% of the total emission) originating from the interstellar radiation field, which is not related to recent massive star formation but has a nonnegligible contribution to the dust heating (Draine & Li 2007;Verley et al 2009). Thilker et al (2023) report a fraction of mid-infrared emission arising from filamentary structures (∼30%) that is qualitatively similar to the ∼50% obtained here. The fraction of large-scale emission removed is also broadly consistent with the contribution of the interstellar radiation field to Spitzer 24 μm wavelength measured in the Milky Way and in Local Group galaxies (20%-85%; Koepferl et al 2015;Viaene et al 2017;Williams et al 2019).…”

Section: Methodssupporting

confidence: 85%

“…This data was obtained from the Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute. 35 This mid-infrared wavelength has been widely used as a tracer of embedded star formation, because a substantial fraction of the emission, especially that with compact morphology, originates from dust excitation by radiation from surrounding massive stars and empirically exhibits a correlation with tracers of massive star formation (Kennicutt & Evans 2012;Galliano et al 2018;Hassani et al 2022;Leroy et al 2022;Thilker et al 2023). In particular, using four initial targets, Hassani et al (2022) have found that 90% of compact 21 μm sources are associated with H II regions detected in extinction corrected Hα maps from MUSE.…”

Section: Observationsmentioning

confidence: 99%

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PHANGS–JWST First Results: Duration of the Early Phase of Massive Star Formation in NGC 628

Kim¹,

Chevance

Kruijssen

et al. 2023

ApJL

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The earliest stages of star formation, when young stars are still deeply embedded in their natal clouds, represent a critical phase in the matter cycle between gas clouds and young stellar regions. Until now, the high-resolution infrared observations required for characterizing this heavily obscured phase (during which massive stars have formed, but optical emission is not detected) could only be obtained for a handful of the most nearby galaxies. One of the main hurdles has been the limited angular resolution of the Spitzer Space Telescope. With the revolutionary capabilities of the James Webb Space Telescope (JWST), it is now possible to investigate the matter cycle during the earliest phases of star formation as a function of the galactic environment. In this Letter, we demonstrate this by measuring the duration of the embedded phase of star formation and the implied time over which molecular clouds remain inert in the galaxy NGC 628 at a distance of 9.8 Mpc, demonstrating that the cosmic volume where this measurement can be made has increased by a factor of >100 compared to Spitzer. We show that young massive stars remain embedded for 5.1 − 1.4 + 2.7 Myr ( 2.3 − 1.4 + 2.7 Myr of which being heavily obscured), representing ∼20% of the total cloud lifetime. These values are in broad agreement with previous measurements in five nearby (D < 3.5 Mpc) galaxies and constitute a proof of concept for the systematic characterization of the early phase of star formation across the nearby galaxy population with the PHANGS–JWST survey.

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Section: Methodssupporting

confidence: 85%

Section: Observationsmentioning

confidence: 99%

PHANGS–JWST First Results: Duration of the Early Phase of Massive Star Formation in NGC 628

Kim¹,

Chevance

Kruijssen

et al. 2023

ApJL

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“…In addition, the 3.3 μm feature can be mapped with NIRCam at 2-3 times finer angular resolution than the 7.7 μm or 11.3 μm bands, yielding 5-10 pc resolution in our targets. This allows measurements of the sizes of H II regions and bubbles (see Barnes et al 2023;Watkins et al 2023), the identification of filamentary structure (Meidt et al 2023;Thilker et al 2023), the identification of embedded clusters (Rodriguez et al 2023), and potentially tracing the gas column at higher resolution than is routinely possible with any millimeter or radio facilities (Leroy et al 2023;Sandstrom et al 2023).…”

Section: Discussionmentioning

confidence: 99%

PHANGS–JWST First Results: Mapping the 3.3 μm Polycyclic Aromatic Hydrocarbon Vibrational Band in Nearby Galaxies with NIRCam Medium Bands

Sandström¹,

Chastenet

Sutter

et al. 2023

ApJL

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We present maps of the 3.3 μm polycyclic aromatic hydrocarbon (PAH) emission feature in NGC 628, NGC 1365, and NGC 7496 as observed with the Near-Infrared Camera imager on JWST from the PHANGS–JWST Cycle 1 Treasury project. We create maps that isolate the 3.3 μm PAH feature in the F335M filter (F335MPAH) using combinations of the F300M and F360M filters for removal of starlight continuum. This continuum removal is complicated by contamination of the F360M by PAH emission and variations in the stellar spectral energy distribution slopes between 3.0 and 3.6 μm. We modify the empirical prescription from Lai et al. to remove the starlight continuum in our highly resolved galaxies, which have a range of starlight- and PAH-dominated lines of sight. Analyzing radially binned profiles of the F335MPAH emission, we find that between 5% and 65% of the F335M intensity comes from the 3.3 μm feature within the inner 0.5 r 25 of our targets. This percentage systematically varies from galaxy to galaxy and shows radial trends within the galaxies related to each galaxy’s distribution of stellar mass, interstellar medium, and star formation. The 3.3 μm emission is well correlated with the 11.3 μm PAH feature traced with the MIRI F1130W filter, as is expected, since both features arise from C–H vibrational modes. The average F335MPAH/F1130W ratio agrees with the predictions of recent models by Draine et al. for PAHs with size and charge distributions shifted toward larger grains with normal or higher ionization.

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“…MIR bands, such as the Mid-Infrared Instrument's (MIRI) F770W, trace hot dust heated by young stars and polycyclic aromatic hydrocarbons (PAHs), where PAHs are vibrationally excited in the presence of starlight (Sandstrom et al 2023), especially when illuminated by UV photons. Therefore MIR observations allow us to identify new, young embedded clusters obscured at optical wavelengths (Rodriguez et al 2023), large-scale filamentary structures containing dense, cold gas expected to host future star formation (Thilker et al 2023), and hot dust emission shining in the presence of UV radiation emitted by OB stars (Leroy et al 2023). Piecing these results together provides the observations needed to trace recent star formation histories within these galaxies (Kim et al 2023).…”

Section: Introductionmentioning

confidence: 98%

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

Watkins¹,

Barnes

Henny

et al. 2023

ApJL

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The first JWST observations of nearby galaxies have unveiled a rich population of bubbles that trace the stellar-feedback mechanisms responsible for their creation. Studying these bubbles therefore allows us to chart the interaction between stellar feedback and the interstellar medium, and the larger galactic flows needed to regulate star formation processes globally. We present the first catalog of bubbles in NGC 628, visually identified using Mid-Infrared Instrument F770W Physics at High Angular resolution in Nearby GalaxieS (PHANGS)–JWST observations, and use them to statistically evaluate bubble characteristics. We classify 1694 structures as bubbles with radii between 6 and 552 pc. Of these, 31% contain at least one smaller bubble at their edge, indicating that previous generations of star formation have a local impact on where new stars form. On large scales, most bubbles lie near a spiral arm, and their radii increase downstream compared to upstream. Furthermore, bubbles are elongated in a similar direction to the spiral-arm ridgeline. These azimuthal trends demonstrate that star formation is intimately connected to the spiral-arm passage. Finally, the bubble size distribution follows a power law of index p = −2.2 ± 0.1, which is slightly shallower than the theoretical value by 1–3.5σ that did not include bubble mergers. The fraction of bubbles identified within the shells of larger bubbles suggests that bubble merging is a common process. Our analysis therefore allows us to quantify the number of star-forming regions that are influenced by an earlier generation, and the role feedback processes have in setting the global star formation rate. With the full PHANGS–JWST sample, we can do this for more galaxies.

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PHANGS–JWST First Results: The Dust Filament Network of NGC 628 and Its Relation to Star Formation Activity

Cited by 18 publications

References 86 publications

PHANGS–JWST First Results: Duration of the Early Phase of Massive Star Formation in NGC 628

PHANGS–JWST First Results: Duration of the Early Phase of Massive Star Formation in NGC 628

PHANGS–JWST First Results: Mapping the 3.3 μm Polycyclic Aromatic Hydrocarbon Vibrational Band in Nearby Galaxies with NIRCam Medium Bands

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

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