The MUSE Atlas of Discs (MAD): Ionized gas kinematic maps and an application to diffuse ionized gas

ABSTRACT We have obtained data for 41 star forming galaxies in the MUSE Atlas of Discs (MAD) survey with VLT/MUSE. These data allow us, at high resolution of a few 100 pc, to extract ionized gas kinematics (V, σ) of the centres of nearby star forming galaxies spanning 3 dex in stellar mass. This paper outlines the methodology for measuring the ionized gas kinematics, which we will use in subsequent papers of this survey. We also show how the maps can be used to study the kinematics of diffuse ionized gas for galaxies of various inclinations and masses. Using two different methods to identify the diffuse ionized gas, we measure rotation velocities of this gas for a subsample of six galaxies. We find that the diffuse ionized gas rotates on average slower than the star forming gas with lags of 0–10 km s−1 while also having higher velocity dispersion. The magnitude of these lags is on average 5 km s−1 lower than observed velocity lags between ionized and molecular gas. Using Jeans models to interpret the lags in rotation velocity and the increase in velocity dispersion we show that most of the diffuse ionized gas kinematics are consistent with its emission originating from a somewhat thicker layer than the star forming gas, with a scale height that is lower than that of the stellar disc.

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Towards sub-kpc scale kinematics of molecular and ionized gas of star-forming galaxies at z ∼ 1

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935896 ◽

2019 ◽

Vol 631 ◽

pp. A91 ◽

Cited By ~ 3

Author(s):

M. Girard ◽

M. Dessauges-Zavadsky ◽

F. Combes ◽

J. Chisholm ◽

V. Patrício ◽

...

Keyword(s):

Spatial Resolution ◽

Rotation Curve ◽

Velocity Dispersion ◽

Major Axis ◽

Stellar Disk ◽

Molecular Gas ◽

Ionized Gas ◽

Rotation Curves ◽

Star Forming ◽

Gas Kinematics

We compare the molecular and ionized gas kinematics of two strongly lensed galaxies at z ∼ 1 that lie on the main sequence at this redshift. The observations were made with ALMA and MUSE, respectively. We derive the CO and [O II] rotation curves and dispersion profiles of these two galaxies. We find a difference between the observed molecular and ionized gas rotation curves for one of the two galaxies, the Cosmic Snake, for which we obtain a spatial resolution of a few hundred parsec along the major axis. The rotation curve of the molecular gas is steeper than the rotation curve of the ionized gas. In the second galaxy, A521, the molecular and ionized gas rotation curves are consistent, but the spatial resolution is only a few kiloparsec on the major axis. Using simulations, we investigate the effect of the thickness of the gas disk and effective radius on the observed rotation curves and find that a more extended and thicker disk smoothens the curve. We also find that the presence of a strongly inclined (> 70°) thick disk (> 1 kpc) can smoothen the rotation curve because it degrades the spatial resolution along the line of sight. By building a model using a stellar disk and two gas disks, we reproduce the rotation curves of the Cosmic Snake with a molecular gas disk that is more massive and more radially and vertically concentrated than the ionized gas disk. Finally, we also obtain an intrinsic velocity dispersion in the Cosmic Snake of 18.5 ± 7 km s−1 and 19.5 ± 6 km s−1 for the molecular and ionized gas, respectively, which is consistent with a molecular disk with a smaller and thinner disk. For A521, the intrinsic velocity dispersion values are 11 ± 8 km s−1 and 54 ± 11 km s−1, with a higher value for the ionized gas. This could indicate that the ionized gas disk is thicker and more turbulent in this galaxy. These results highlight the diversity of the kinematics of galaxies at z ∼ 1 and the different spatial distribution of the molecular and ionized gas disks. It suggests the presence of thick ionized gas disks at this epoch and that the formation of the molecular gas is limited to the midplane and center of the galaxy in some objects.

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

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1272 ◽

2020 ◽

Vol 495 (2) ◽

pp. 2265-2284 ◽

Cited By ~ 2

Author(s):

Mathew R Varidel ◽

Scott M Croom ◽

Geraint F Lewis ◽

Deanne B Fisher ◽

Karl Glazebrook ◽

...

Keyword(s):

Star Formation ◽

Velocity Dispersion ◽

Rotational Velocity ◽

Theoretical Models ◽

Total Sample ◽

Ionized Gas ◽

Star Forming ◽

Gas Kinematics ◽

Integral Field Spectrograph ◽

Integral Field

ABSTRACT We infer the intrinsic ionized gas kinematics for 383 star-forming galaxies across a range of integrated star formation rates (SFR ∈ [10−3, 102] M⊙ yr−1) at z ≲ 0.1 using a consistent 3D forward-modelling technique. The total sample is a combination of galaxies from the Sydney-AAO Multiobject Integral field Spectrograph (SAMI) Galaxy survey and DYnamics of Newly Assembled Massive Objects survey. For typical low-z galaxies taken from the SAMI Galaxy Survey, we find the vertical velocity dispersion (σv,z) to be positively correlated with measures of SFR, stellar mass, H i gas mass, and rotational velocity. The greatest correlation is with SFR surface density (ΣSFR). Using the total sample, we find σv,z increases slowly as a function of integrated SFR in the range SFR ∈ [10−3, 1] M⊙ yr−1 from 17 ± 3 to 24 ± 5 km s−1 followed by a steeper increase up to σv,z ∼80 km s−1 for SFR ≳ 1 M⊙ yr−1. This is consistent with recent theoretical models that suggest a σv,z floor driven by star formation feedback processes with an upturn in σv,z at higher SFR driven by gravitational transport of gas through the disc.

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Cold gas studies of a z = 2.5 protocluster

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320004226 ◽

2020 ◽

Vol 15 (S359) ◽

pp. 136-140

Author(s):

Minju M. Lee ◽

Ichi Tanaka ◽

Rohei Kawabe

Keyword(s):

Galaxy Evolution ◽

High Redshift ◽

Kinematic Model ◽

Molecular Gas ◽

General View ◽

Massive Galaxies ◽

Star Forming ◽

Gas Kinematics ◽

Narrow Band Filter ◽

Stellar Masses

AbstractWe present studies of a protocluster at z =2.5, an overdense region found close to a radio galaxy, 4C 23.56, using ALMA. We observed 1.1 mm continuum, two CO lines (CO (4–3) and CO (3–2)) and the lower atomic carbon line transition ([CI](3P1-3P0)) at a few kpc (0″.3-0″.9) resolution. The primary targets are 25 star-forming galaxies selected as Hα emitters (HAEs) that are identified with a narrow band filter. These are massive galaxies with stellar masses of > 1010Mʘ that are mostly on the galaxy main sequence at z =2.5. We measure the molecular gas mass from the independent gas tracers of 1.1 mm, CO (3–2) and [CI], and investigate the gas kinematics of galaxies from CO (4–3). Molecular gas masses from the different measurements are consistent with each other for detection, with a gas fraction (fgas = Mgas/(Mgas+ Mstar)) of ≃ 0.5 on average but with a caveat. On the other hand, the CO line widths of the protocluster galaxies are typically broader by ˜50% compared to field galaxies, which can be attributed to more frequent, unresolved gas-rich mergers and/or smaller sizes than field galaxies, supported by our high-resolution images and a kinematic model fit of one of the galaxies. We discuss the expected scenario of galaxy evolution in protoclusters at high redshift but future large surveys are needed to get a more general view.

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Survival of molecular gas in a stellar feedback-driven outflow witnessed with the MUSE TIMER project and ALMA

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1844 ◽

2019 ◽

Vol 488 (3) ◽

pp. 3904-3928 ◽

Cited By ~ 6

Author(s):

Ryan Leaman ◽

Francesca Fragkoudi ◽

Miguel Querejeta ◽

Gigi Y C Leung ◽

Dimitri A Gadotti ◽

...

Keyword(s):

Magnetic Field ◽

Star Formation ◽

Mechanical Energy ◽

Molecular Gas ◽

Ionized Gas ◽

Star Forming ◽

Stellar Feedback ◽

Dominant Component ◽

The Galaxy ◽

Field Lines

ABSTRACT Stellar feedback plays a significant role in modulating star formation, redistributing metals, and shaping the baryonic and dark structure of galaxies – however, the efficiency of its energy deposition to the interstellar medium is challenging to constrain observationally. Here we leverage HST and ALMA imaging of a molecular gas and dust shell ($M_{\mathrm{ H}_2} \sim 2\times 10^{5}\, {\rm M}_{\odot }$) in an outflow from the nuclear star-forming ring of the galaxy NGC 3351, to serve as a boundary condition for a dynamical and energetic analysis of the outflowing ionized gas seen in our MUSE TIMER survey. We use starburst99 models and prescriptions for feedback from simulations to demonstrate that the observed star formation energetics can reproduce the ionized and molecular gas dynamics – provided a dominant component of the momentum injection comes from direct photon pressure from young stars, on top of supernovae, photoionization heating, and stellar winds. The mechanical energy budget from these sources is comparable to low luminosity active galactic neuclei, suggesting that stellar feedback can be a relevant driver of bulk gas motions in galaxy centres – although here ≲10−3 of the ionized gas mass is escaping the galaxy. We test several scenarios for the survival/formation of the cold gas in the outflow, including in situ condensation and cooling. Interestingly, the geometry of the molecular gas shell, observed magnetic field strengths and emission line diagnostics are consistent with a scenario where magnetic field lines aided survival of the dusty ISM as it was initially launched (with mass-loading factor ≲1) from the ring by stellar feedback. This system’s unique feedback-driven morphology can hopefully serve as a useful litmus test for feedback prescriptions in magnetohydrodynamical galaxy simulations.

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Resolving the Disk-Halo Degeneracy using Planetary Nebulae

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317001144 ◽

2016 ◽

Vol 12 (S323) ◽

pp. 284-287

Author(s):

S. Aniyan ◽

K. C. Freeman ◽

M. Arnaboldi ◽

O. Gerhard ◽

L. Coccato ◽

...

Keyword(s):

Vertical Velocity ◽

Velocity Dispersion ◽

Mass Density ◽

Planetary Nebulae ◽

Disk Surface ◽

Scale Height ◽

Dark Halo ◽

Surface Mass ◽

Star Forming ◽

Light Spectra

AbstractThe decomposition of the 21 cm rotation curve of galaxies into contribution from the disk and dark halo depends on the adopted mass to light ratio (M/L) of the disk. Given the vertical velocity dispersion (σz) of stars in the disk and its scale height (hz), the disk surface density and hence the M/L can be estimated. Earlier works have used this technique to conclude that galaxy disks are submaximal. Here we address an important conceptual problem: star-forming spirals have an old (kinematically hot) disk population and a young cold disk population. Both of these populations contribute to the integrated light spectra from which σz is measured. The measured scale height hz is for the old disk population. In the Jeans equation, σz and hz must pertain to the same population. We have developed techniques to extract the velocity dispersion of the old disk from integrated light spectra and from samples of planetary nebulae. We present the analysis of the disk kinematics of the galaxy NGC 628 using IFU data in the inner regions and planetary nebulae as tracers in the outer regions of the disk. We demonstrate that using the scale height of the old thin disk with the vertical velocity dispersion of the same population, traced by PNe, results in a maximal disk for NGC 628. Our analysis concludes that previous studies underestimate the disk surface mass density by ~ 2, sufficient to make a maximal disk for NGC 628 appear like a submaximal disk.

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Jeans modelling of the Milky Way’s nuclear stellar disc

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2785 ◽

2020 ◽

Vol 499 (1) ◽

pp. 7-24

Author(s):

Mattia C Sormani ◽

John Magorrian ◽

Francisco Nogueras-Lara ◽

Nadine Neumayer ◽

Ralph Schönrich ◽

...

Keyword(s):

Velocity Dispersion ◽

Silicon Monoxide ◽

Theoretical Models ◽

Stellar Structure ◽

Kinematic Data ◽

Stellar Disc ◽

Star Forming ◽

Mass Distributions ◽

Evolution Experiment ◽

Or Modelling

ABSTRACT The nuclear stellar disc (NSD) is a flattened stellar structure that dominates the gravitational potential of the Milky Way at Galactocentric radii $30 \lesssim R \lesssim 300\, {\rm pc}$. In this paper, we construct axisymmetric Jeans dynamical models of the NSD based on previous photometric studies and we fit them to line-of-sight kinematic data of the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and silicon monoxide (SiO) maser stars. We find that (i) the NSD mass is lower but consistent with the mass independently determined from photometry by Launhardt et al. Our fiducial model has a mass contained within spherical radius $r=100\, {\rm pc}$ of $M(r\lt 100\, {\rm pc}) = 3.9 \pm 1 \times 10^8 \, \rm M_\odot$ and a total mass of $M_{\rm NSD} = 6.9 \pm 2 \times 10^8 \, \rm M_\odot$. (ii) The NSD might be the first example of a vertically biased disc, i.e. with ratio between the vertical and radial velocity dispersion σz/σR > 1. Observations and theoretical models of the star-forming molecular gas in the central molecular zone suggest that large vertical oscillations may be already imprinted at stellar birth. However, the finding σz/σR > 1 depends on a drop in the velocity dispersion in the innermost few tens of parsecs, on our assumption that the NSD is axisymmetric, and that the available (extinction corrected) stellar samples broadly trace the underlying light and mass distributions, all of which need to be established by future observations and/or modelling. (iii) We provide the most accurate rotation curve to date for the innermost $500\, {\rm pc}$ of our Galaxy.

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Gas dynamics and star formation in “isolated” and interacting galaxies using FP observations

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319008238 ◽

2019 ◽

Vol 14 (S353) ◽

pp. 264-265

Author(s):

Isaura Fuentes-Carrera ◽

Nelli Cárdenas-Martínez ◽

Martín Nava-Callejas ◽

Margarita Rosado

Keyword(s):

Star Formation ◽

Gas Dynamics ◽

Equal Mass ◽

Interacting Galaxies ◽

Ionized Gas ◽

Star Forming ◽

Gas Kinematics ◽

Fabry Perot ◽

Different Types

AbstractWe present scanning Fabry-Perot observations of different types of star-forming galaxies from apparently isolated LIRGs to equal mass interacting galaxies. We analyze the ionized gas kinematics, its relation with the morphology of each system and the location of SF regions for different systems.

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Molecular and ionized gas kinematics in the GC Radio Arc

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316012242 ◽

2016 ◽

Vol 11 (S322) ◽

pp. 133-136

Author(s):

N. Butterfield ◽

C.C. Lang ◽

E. A. C. Mills ◽

D. Ludovici ◽

J. Ott ◽

...

Keyword(s):

Star Formation ◽

Molecular Cloud ◽

Molecular Clouds ◽

Radio Continuum ◽

Molecular Gas ◽

The South ◽

Ionized Gas ◽

Molecular Emission ◽

Gas Kinematics

AbstractWe present NH3 and H64α+H63α VLA observations of the Radio Arc region, including the M0.20 – 0.033 and G0.10 – 0.08 molecular clouds. These observations suggest the two velocity components of M0.20 – 0.033 are physically connected in the south. Additional ATCA observations suggest this connection is due to an expanding shell in the molecular gas, with the centroid located near the Quintuplet cluster. The G0.10 – 0.08 molecular cloud has little radio continuum, strong molecular emission, and abundant CH3OH masers, similar to a nearby molecular cloud with no star formation: M0.25+0.01. These features detected in G0.10 – 0.08 suggest dense molecular gas with no signs of current star formation.

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

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3525 ◽

2019 ◽

Vol 493 (2) ◽

pp. 2872-2909 ◽

Cited By ~ 44

Author(s):

Mélanie Chevance ◽

J M Diederik Kruijssen ◽

Alexander P S Hygate ◽

Andreas Schruba ◽

Steven N Longmore ◽

...

Keyword(s):

Star Formation ◽

Flux Ratio ◽

Molecular Gas ◽

H Ii Regions ◽

Dynamical Processes ◽

Nearby Star ◽

Star Forming ◽

Spatially Resolved ◽

Stellar Feedback ◽

Disc Galaxies

ABSTRACT It remains a major challenge to derive a theory of cloud-scale ($\lesssim100$ 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-H α 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 $10\!-\!30\,{\rm Myr}$, and exhibit environmental variation, between and within galaxies. At kpc-scale molecular gas surface densities $\Sigma _{\rm H_2}\ge 8\,\rm {M_\odot}\,{{\rm pc}}^{-2}$, the GMC lifetime correlates with time-scales for galactic dynamical processes, whereas at $\Sigma _{\rm H_2}\le 8\,\rm {M_\odot}\,{{\rm pc}}^{-2}$ GMCs decouple from galactic dynamics and live for an internal dynamical time-scale. After a long inert phase without massive star formation traced by H α (75–90 per cent of the cloud lifetime), GMCs disperse within just $1\!-\!5\,{\rm Myr}$ 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 H ii regions are the fundamental units undergoing these lifecycles, with mean separations of $100\!-\!300\,{{\rm pc}}$ in star-forming discs. Future work should characterize the multiscale physics and mass flows driving these lifecycles.

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