A z = 0 Multiwavelength Galaxy Synthesis. I. A WISE and GALEX Atlas of Local Galaxies

Leroy, Adam K.; Sandström, Karin; Lang, Dustin; Lewis, Alexia R.; Salim, Samir; Behrens, Erica; Chastenet, Jérémy; Chiang, I-Da; Gallagher, Molly; Kessler, Sarah; Utomo, Dyas

doi:10.3847/1538-4365/ab3925

Cited by 252 publications

(494 citation statements)

References 95 publications

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“…(5-6) galaxy inclination and position angle (Lang et al 2020); (7-9) galaxy global stellar mass, SFR, and the effective (half-mass) radius estimated from the measured stellar scale length (Leroy et al 2019;A. K. Leroy et al 2020a, in preparation); (10-11) CO data rms noise and channel-to-channel correlation at 150 pc resolution;…”

Section: Galaxymentioning

confidence: 99%

Molecular Gas Properties on Cloud Scales across the Local Star-forming Galaxy Population

Sun

Leroy

Schinnerer

et al. 2020

ApJL

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Using the PHANGS-ALMA CO(2-1) survey, we characterize molecular gas properties on ∼100 pc scales across 102,778 independent sightlines in 70 nearby galaxies. This yields the best synthetic view of molecular gas properties on cloud scales across the local star-forming galaxy population obtained to date. Consistent with previous studies, we observe a wide range of molecular gas surface densities (3.4 dex), velocity dispersions (1.7 dex), and turbulent pressures (6.5 dex) across the galaxies in our sample. Under simplifying assumptions about subresolution gas structure, the inferred virial parameters suggest that the kinetic energy of the molecular gas typically exceeds its self-gravitational binding energy at ∼100 pc scales by a modest factor (1.3 on average). We find that the cloud-scale surface density, velocity dispersion, and turbulent pressure (1) increase toward the inner parts of galaxies, (2) are exceptionally high in the centers of barred galaxies (where the gas also appears less gravitationally bound), and (3) are moderately higher in spiral arms than in inter-arm regions. The galaxy-wide averages of these gas properties also correlate with the integrated stellar mass, star formation rate, and offset from the star-forming main sequence of the host galaxies. These correlations persist even when we exclude regions with extraordinary gas properties in galaxy centers, which contribute significantly to the inter-galaxy variations. Our results provide key empirical constraints on the physical link between molecular cloud populations and their galactic environment.

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Section: Galaxymentioning

confidence: 99%

Molecular Gas Properties on Cloud Scales across the Local Star-forming Galaxy Population

Sun

Leroy

Schinnerer

et al. 2020

ApJL

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“…For this purpose, we create a multiwavelength data set, which includes high-resolution PHANGS-ALMA CO (2−1) imaging data (A. K. Leroy et al 2020, in preparation) and GMC catalogs (A. Hughes et al 2020, in preparation;E.Rosolowsky et al 2020, in preparation), new and archival H I 21cm data (D. Utomo et al 2020, in preparation), processed Spitzer IRAC 3.6μm data (S G 4 ; Querejeta et al 2015), and combined GALEX near-UV and WISE mid-IR data (z0MGS; Leroy et al 2019). These data provide us with a comprehensive picture of the molecular gas distribution and kinematics on ∼60-120pc scales (i.e., cloud scales), as well as the distribution of gas mass, stellar mass, and SFR on ∼1kpc scales.…”

Section: Discussionmentioning

confidence: 99%

“…We combine GALEX near-UV (NUV) data and WISE mid-IR (MIR) data to derive kpc-scale SFR estimates. We use the postprocessed GALEX NUV images and WISE 12 μm images from the z=0 Multiwavelength Galaxy Synthesis (z0MGS; Leroy et al 2019). These images are corrected for background, aligned for astrometry, and masked to remove foreground stars.…”

Section: Galaxymentioning

confidence: 99%

Dynamical Equilibrium in the Molecular ISM in 28 Nearby Star-forming Galaxies

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Leroy

Ostriker

et al. 2020

ApJ

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We compare the observed turbulent pressure in molecular gas, P turb , to the required pressure for the interstellar gas to stay in equilibrium in the gravitational potential of a galaxy, P DE. To do this, we combine arcsecond resolution CO data from PHANGS-ALMA with multiwavelength data that trace the atomic gas, stellar structure, and star formation rate (SFR) for 28 nearby star-forming galaxies. We find that P turb correlates with-but almost always exceeds-the estimated P DE on kiloparsec scales. This indicates that the molecular gas is overpressurized relative to the large-scale environment. We show that this overpressurization can be explained by the clumpy nature of molecular gas; a revised estimate of P DE on cloud scales, which accounts for molecular gas self-gravity, external gravity, and ambient pressure, agrees well with the observed P turb in galaxy disks. We also find that molecular gas with cloud-scale »- P P k 10 K cm turb DE 5 B 3 in our sample is more likely to be self-gravitating, whereas gas at lower pressure it appears more influenced by ambient pressure and/or external gravity. Furthermore, we show that the ratio between P turb and the observed SFR surface density, S SFR , is compatible with stellar feedback-driven momentum injection in most cases, while a subset of the regions may show evidence of turbulence driven by additional sources. The correlation between S SFR and kpc-scale P DE in galaxy disks is consistent with the expectation from self-regulated star formation models. Finally, we confirm the empirical correlation between molecular-to-atomic gas ratio and kpc-scale P DE reported in previous works.

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“…In addition to these targets, we also include the galaxy NGC5194 for which archival observational data of Hα and CO(1-0) are also available at a similar spatial resolution (Pety et al 2013;Schinnerer et al 2013). The main characteristics Leroy et al (2019) and references therein, with typical uncertainties of 0.1 dex. b Mean molecular gas mass-weighted metallicity based on Pilyugin et al (2014), with typical uncertainties of 0.03 dex.…”

Section: Sample Selectionmentioning

confidence: 99%

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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A z = 0 Multiwavelength Galaxy Synthesis. I. A WISE and GALEX Atlas of Local Galaxies

Cited by 252 publications

References 95 publications

Molecular Gas Properties on Cloud Scales across the Local Star-forming Galaxy Population

Molecular Gas Properties on Cloud Scales across the Local Star-forming Galaxy Population

Dynamical Equilibrium in the Molecular ISM in 28 Nearby Star-forming Galaxies

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

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