The SAMI galaxy survey: gas velocity dispersions in low-z star-forming galaxies and the drivers of turbulence

Varidel, Mathew; Croom, S. M.; Lewis, Geraint F.; Fisher, David B.; Glazebrook, Karl; Catinella, Barbara; Cortese, Luca; Krumholz, Mark R.; Bland-Hawthorn, Joss; Bryant, Julia J.; Groves, Brent; Brough, Sarah; Federrath, Christoph; Lawrence, Jon; Lorente, Nuria P. F.; Owers, Matt S.; Richards, Samuel N.; López-Sánchez, Á. R.; Sweet, Sarah M.; Sande, Jesse van de; Vaughan, Sam P.

doi:10.1093/mnras/staa1272

Cited by 40 publications

(27 citation statements)

References 106 publications

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“…Following the generic predictions of star formation feedback models (e.g., Krumholz & Burkhart 2016;Hayward & Hopkins 2017;Hung et al 2019, and references therein) and results from a variety of observational studies (e.g., Green et al 2014;Varidel et al 2020), we expect that the MaNGA data should exhibit a positive correlation between the local gas-phase velocity dispersion in each spaxel (σ Hα ) and the corresponding local star formation rate surface density (Σ SFR ).…”

Section: The Local Relationmentioning

confidence: 82%

“…Numerous authors have similarly examined the relation between σ Hα and stellar mass in the past, with mixed results. Moiseev et al (2015) for instance concluded that the trend of σ Hα was stronger with Hα luminosity than with stellar mass for their sample of dwarf galaxies, as did Varidel et al (2020) for the SAMI galaxy sample. Unlike Varidel et al (2020) however, we do not see evidence of a residual correlation between σ Hα and M * after accounting for the SFR relation.…”

Section: Stellar Massmentioning

confidence: 93%

“…As indicated by Figure 4 (righthand panel), in the SFR range of overlap between the MaNGA and SAMI samples the MaNGA velocity dispersions are larger on average by about 0.4 km s −1 , consistent with the 0.7 km s −1 that we found in Law et al (2021a, see their Figure 21) for a sample of galaxies observed in common between the two surveys. We note, however, that Varidel et al (2020) made an inclinationdependent correction to their observations and thus estimate the vertical disk velocity dispersion σ z rather than the simple line-of-sight velocity dispersion. As discussed in §5, if we were to make such a correction our results would shift downward by ∼ 1.5 km s −1 , and nonetheless still be a reasonable match to within 1.1 km s −1 .…”

Section: Comparison To Recent Literaturementioning

confidence: 94%

“…Binning the results from their online supplemental data according to SFR (and applying a dust correction factor of 2.2 based on the average correction for the MaNGA star forming galaxy sample), we find a relation that matches the MaNGA data to within an average of 1.2 km s −1 . 2018), 59 dwarf galaxies from Moiseev et al (2015), 39 spiral galaxies from Andersen et al (2006), 153 galaxies from Epinat et al (2010), six starburst galaxies from Varidel et al (2016), 67 starburst galaxies from Green et al (2014), and 383 galaxies from the combined SAMI+DYNAMO sample (Varidel et al 2020). The histograms in the lower panels show the logarithmic number of spectra (left-hand panel) or galaxies (right-hand panel) contributing to each bin in SFR or Σ SFR for each of the different samples (assuming 100 spectra per galaxy for the Arribas et al (2014) More recently, observations from the SAMI IFU survey have also been used to assess the velocity dispersion of galactic disks.…”

Section: Comparison To Recent Literaturementioning

confidence: 99%

“…Zhou et al (2017) for instance analyzed SAMI velocity maps for 8 local star forming galaxies 17 and found σ Hα in the range 20-30 km s −1 for galaxies with Σ SFR ≈ 10 −2 M yr −1 kpc −2 , in excellent agreement with our results (Figure 4, left-hand panel). Likewise, Varidel et al (2020) analyzed a sample of 383 galaxies from the combined SAMI and DYNAMO samples and found a statistically significant correlation between SFR and σ Hα . As indicated by Figure 4 (righthand panel), in the SFR range of overlap between the MaNGA and SAMI samples the MaNGA velocity dispersions are larger on average by about 0.4 km s −1 , consistent with the 0.7 km s −1 that we found in Law et al (2021a, see their Figure 21) for a sample of galaxies observed in common between the two surveys.…”

Section: Comparison To Recent Literaturementioning

confidence: 99%

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SDSS-IV MaNGA: Understanding Ionized Gas Turbulence using Integral Field Spectroscopy of 4500 Star-Forming Disk Galaxies

Law,

Belfiore,

Bershady

et al. 2021

Preprint

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The Sloan Digital Sky Survey MaNGA program has now obtained integral field spectroscopy for over 10,000 galaxies in the nearby universe. We use the final MaNGA data release DR17 to study the correlation between ionized gas velocity dispersion and galactic star formation rate, finding a tight correlation in which σ Hα from galactic HII regions increases significantly from ∼ 18−30 km s −1 broadly in keeping with previous studies. In contrast, σ Hα from diffuse ionized gas (DIG) increases more rapidly from 20 − 60 km s −1 . Using the statistical power of MaNGA, we investigate these correlations in greater detail using multiple emission lines and determine that the observed correlation of σ Hα with local star formation rate surface density is driven entirely by the global relation of increasing velocity dispersion at higher total SFR, as are apparent correlations with stellar mass. Assuming HII region models consistent with our finding that σwe estimate the velocity dispersion of the molecular gas in which individual HII regions are embedded, finding values σ Mol = 5 − 30 km s −1 consistent with ALMA observations in a similar mass range. Finally, we use variations in the relation with inclination and disk azimuthal angle to constrain the velocity dispersion ellipsoid of the ionized gas σ z /σ r = 0.84 ± 0.03 and σ φ /σ r = 0.91 ± 0.03, similar to that of young stars in the Galactic disk. Our results are most consistent with theoretical models in which turbulence in modern galactic disks is driven primarily by star formation feedback.

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Section: The Local Relationmentioning

confidence: 82%

Section: Stellar Massmentioning

confidence: 93%

Section: Comparison To Recent Literaturementioning

confidence: 94%

Section: Comparison To Recent Literaturementioning

confidence: 99%

Section: Comparison To Recent Literaturementioning

confidence: 99%

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SDSS-IV MaNGA: Understanding Ionized Gas Turbulence using Integral Field Spectroscopy of 4500 Star-Forming Disk Galaxies

Law,

Belfiore,

Bershady

et al. 2021

Preprint

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Evidence for supernova feedback sustaining gas turbulence in nearby star-forming galaxies

Fraternali

Iorio

Pezzulli

et al. 2020

A&A

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It is widely known that the gas in galaxy discs is highly turbulent, but there is much debate on which mechanism can energetically maintain this turbulence. Among the possible candidates, supernova (SN) explosions are likely the primary drivers but doubts remain on whether they can be sufficient in regions of moderate star formation activity, in particular in the outer parts of discs. Thus, a number of alternative mechanisms have been proposed. In this paper, we measure the SN efficiency η, namely the fraction of the total SN energy needed to sustain turbulence in galaxies, and verify that SNe can indeed be the sole driving mechanism. The key novelty of our approach is that we take into account the increased turbulence dissipation timescale associated with the flaring in outer regions of gaseous discs. We analyse the distribution and kinematics of HI and CO in ten nearby star-forming galaxies to obtain the radial profiles of the kinetic energy per unit area for both the atomic gas and the molecular gas. We use a theoretical model to reproduce the observed energy with the sum of turbulent energy from SNe, as inferred from the observed star formation rate (SFR) surface density, and the gas thermal energy. For the atomic gas, we explore two extreme cases in which the atomic gas is made either of cold neutral medium or warm neutral medium, and the more realistic scenario with a mixture of the two phases. We find that the observed kinetic energy is remarkably well reproduced by our model across the whole extent of the galactic discs, assuming η constant with the galactocentric radius. Taking into account the uncertainties on the SFR surface density and on the atomic gas phase, we obtain that the median SN efficiencies for our sample of galaxies are ⟨ηatom⟩ = 0.015−0.008+0.018 for the atomic gas and ⟨ηmol⟩ = 0.003−0.002+0.006 for the molecular gas. We conclude that SNe alone can sustain gas turbulence in nearby galaxies with only few percent of their energy and that there is essentially no need for any further source of energy.

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Vales

Molina

Ibar

Godoy

et al. 2020

A&A

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Context. Spatially resolved observations of the ionized and molecular gas are critical for understanding the physical processes that govern the interstellar medium (ISM) in galaxies. The observation of starburst systems is also important as they present extreme gas conditions that may help to test different ISM models. However, matched resolution imaging at ∼kpc scales for both ISM gas phases are usually scarce, and the ISM properties of starbursts still remain poorly understood. Aims. We aim to study the morpho-kinematic properties of the ionized and molecular gas in three dusty starburst galaxies at z = 0.12−0.17 to explore the relation between molecular ISM gas phase dynamics and the star-formation activity. Methods. We employ two-dimensional dynamical modelling to analyse Atacama Large Millimeter/submillimiter Array CO(1–0) and seeing-limited Spectrograph for INtegral Field Observations in the Near Infrared Paschen-α (Paα) observations, tracing the molecular and ionized gas morpho-kinematics at ∼kpc-scales. We use a dynamical mass model, which accounts for beam-smearing effects, to constrain the CO-to-H2 conversion factor and estimate the molecular gas mass content. Results. One starburst galaxy shows irregular morphology, which may indicate a major merger, while the other two systems show disc-like morpho-kinematics. The two disc-like starbursts show molecular gas velocity dispersion values comparable with those seen in local luminous and ultra luminous infrared galaxies but in an ISM with molecular gas fraction and surface density values in the range of the estimates reported for local star-forming galaxies. We find that these molecular gas velocity dispersion values can be explained by assuming vertical pressure equilibrium. We also find that the star-formation activity, traced by the Paα emission line, is well correlated with the molecular gas content, suggesting an enhanced star-formation efficiency and depletion times of the order of ∼0.1−1 Gyr. We find that the star-formation rate surface density (ΣSFR) correlates with the ISM pressure set by self-gravity (Pgrav) following a power law with an exponent close to 0.8. Conclusions. In dusty disc-like starburst galaxies, our data support the scenario in which the molecular gas velocity dispersion values are driven by the ISM pressure set by self-gravity and are responsible for maintaining the vertical pressure balance. The correlation between ΣSFR and Pgrav suggests that, in these dusty starbursts galaxies, the star-formation activity arises as a consequence of the ISM pressure balance.

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The SAMI galaxy survey: gas velocity dispersions in low-z star-forming galaxies and the drivers of turbulence

Cited by 40 publications

References 106 publications

SDSS-IV MaNGA: Understanding Ionized Gas Turbulence using Integral Field Spectroscopy of 4500 Star-Forming Disk Galaxies

SDSS-IV MaNGA: Understanding Ionized Gas Turbulence using Integral Field Spectroscopy of 4500 Star-Forming Disk Galaxies

Evidence for supernova feedback sustaining gas turbulence in nearby star-forming galaxies

Vales

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